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Lathemaster 8x14 shutting itself of under load

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  • ironring1
    Hey, all. I was trying to part off a small piece today, and my lathe kept turning itself of when I started to cut with the parting tool. I looked at the
    Message 1 of 25 , May 28, 2006
      Hey, all. I was trying to part off a small piece today, and my lathe kept turning itself of
      when I started to cut with the parting tool. I looked at the wiring, and the chuck shield switch
      and the gear-cover switch seem to be fine. Is there some way that the motor can shut itself
      off? My lathe's motor has 4 leads (plus ground): white, blue, red and black. I had been
      working for about half an hour, so the motor was quite warm.

      I should point out that there was some chatter with the cutter (more of a high pitched
      vibration), but I can't run the machine any slower than 125rpm. The piece that I was parting
      has an OD of 4cm (1.57"), making the cutting speed 26cm/s or 0.86ft/s.

      -Chris
    • James Early
      Some motors have thermal overload switches in them but the usually require manual resetting. JWE Long Beach, CA ... From: ironring1 To:
      Message 2 of 25 , May 29, 2006
        Some motors have thermal overload switches in them but the usually require
        manual resetting.
        JWE
        Long Beach, CA

        ----- Original Message -----
        From: ironring1 <parker@...>
        To: <mlathemods@yahoogroups.com>
        Sent: Sunday, May 28, 2006 11:55 PM
        Subject: [mlathemods] Lathemaster 8x14 shutting itself of under load


        Hey, all. I was trying to part off a small piece today, and my lathe
        kept turning itself of
        when I started to cut with the parting tool. I looked at the wiring, and
        the chuck shield switch
        and the gear-cover switch seem to be fine. Is there some way that the motor
        can shut itself
        off? My lathe's motor has 4 leads (plus ground): white, blue, red and
        black. I had been
        working for about half an hour, so the motor was quite warm.

        I should point out that there was some chatter with the cutter (more of
        a high pitched
        vibration), but I can't run the machine any slower than 125rpm. The piece
        that I was parting
        has an OD of 4cm (1.57"), making the cutting speed 26cm/s or 0.86ft/s.

        -Chris
      • Richard Kleinhenz
        Did it work once you let everything cool off? I don t think the motor has a thermal overload. I just took mine off yesterday my wiring is the same colors as
        Message 3 of 25 , May 29, 2006
          Did it work once you let everything cool off? I don't think the motor has a thermal overload. I just took mine off yesterday my wiring is the same colors as yours.

          I think maybe you are drawing too much current and the push-button switch trips. I *THINK* it has a circuitbreaker in it. I started out by using the F/R switch to turn the lathe on while the ON button stayed locked on. Very frequently the motor start-up torque would trip the switch. When I switched to leaving the F/R switch set and using the buttons to start the lathe, it never tripped again.

          So I would suspect that for some reason you are pulling too much current, or maybe that switch is faulty.

          On 5/29/2006 at 6:55 AM ironring1 wrote:

          >Hey, all. I was trying to part off a small piece today, and my lathe
          >kept turning itself of
          >when I started to cut with the parting tool. I looked at the wiring, and
          >the chuck shield switch
          >and the gear-cover switch seem to be fine. Is there some way that the
          >motor can shut itself
          >off? My lathe's motor has 4 leads (plus ground): white, blue, red and
          >black. I had been
          >working for about half an hour, so the motor was quite warm.
          >
          > I should point out that there was some chatter with the cutter (more
          >of a high pitched
          >vibration), but I can't run the machine any slower than 125rpm. The piece
          >that I was parting
          >has an OD of 4cm (1.57"), making the cutting speed 26cm/s or 0.86ft/s.

          --
          Regards,
          Rich
          ================================
          Richard Kleinhenz
          http://beautifulhandmadepens.com
          http://www.woodpens.com/rkleinhenz.htm
          ================================
        • Chris Parker
          There seems to be some connection between the motor and the circuit breaker trip mechanism. Try this out on your lathe: Power it on, and lightly depress the
          Message 4 of 25 , May 29, 2006
            There seems to be some connection between the motor and the circuit
            breaker trip mechanism. Try this out on your lathe: Power it on,
            and lightly depress the stop button (just enough to take up slack).
            Just as the slack is gone and you start to actually close the switch,
            there is a vibration under the switch as though the circuit breaker
            mechanism is being pulsed regularly (it's hard to describe, but if
            you try it, you'll know what I mean)...

            Of course, this would be a lot easier if I knew what the four leads
            on the motor do (can find my power systems textbook, grrr). Does
            anybody know the purpose for each of the motor's four leads? I know
            that three of them are associated with running the motor (since it is
            reversible), but what about the fourth?

            -Chris

            On 29-May-06, at 7:16 AM, Richard Kleinhenz wrote:

            > Did it work once you let everything cool off? I don't think the
            > motor has a thermal overload. I just took mine off yesterday my
            > wiring is the same colors as yours.
            >
            > I think maybe you are drawing too much current and the push-button
            > switch trips. I *THINK* it has a circuitbreaker in it. I started
            > out by using the F/R switch to turn the lathe on while the ON
            > button stayed locked on. Very frequently the motor start-up torque
            > would trip the switch. When I switched to leaving the F/R switch
            > set and using the buttons to start the lathe, it never tripped again.
            >
            > So I would suspect that for some reason you are pulling too much
            > current, or maybe that switch is faulty.
            >
            > On 5/29/2006 at 6:55 AM ironring1 wrote:
            >
            > >Hey, all. I was trying to part off a small piece today, and my lathe
            > >kept turning itself of
            > >when I started to cut with the parting tool. I looked at the
            > wiring, and
            > >the chuck shield switch
            > >and the gear-cover switch seem to be fine. Is there some way that
            > the
            > >motor can shut itself
            > >off? My lathe's motor has 4 leads (plus ground): white, blue, red
            > and
            > >black. I had been
            > >working for about half an hour, so the motor was quite warm.
            > >
            > > I should point out that there was some chatter with the
            > cutter (more
            > >of a high pitched
            > >vibration), but I can't run the machine any slower than 125rpm.
            > The piece
            > >that I was parting
            > >has an OD of 4cm (1.57"), making the cutting speed 26cm/s or
            > 0.86ft/s.
            >
            > --
            > Regards,
            > Rich
            > ================================
            > Richard Kleinhenz
            > http://beautifulhandmadepens.com
            > http://www.woodpens.com/rkleinhenz.htm
            > ================================
            >
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            [Non-text portions of this message have been removed]
          • Mike Jones
            One answer to that is you re using a very slow seed for reasonably thick stock if it s steel. The slow speed causes high amp draw and the motor heats up. If
            Message 5 of 25 , May 29, 2006
              One answer to that is you're using a very slow seed
              for reasonably thick stock if it's steel. The slow
              speed causes high amp draw and the motor heats up. If
              the motor is termal protected, it will kick off or
              kill power till the motor cools down to a point it
              kicks in again.
              Mike

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            • Richard Kleinhenz
              Really? This is not variable speed. This is a 500W motor that always spins at 1700 RPM. When you slow the motor down with a high load or stall or near-stall
              Message 6 of 25 , May 29, 2006
                Really? This is not variable speed. This is a 500W motor that always spins at 1700 RPM. When you slow the motor down with a high load or stall or near-stall - I understand that it'll draw more.

                On 5/29/2006 at 5:26 PM Mike Jones wrote:

                >One answer to that is you're using a very slow seed
                >for reasonably thick stock if it's steel. The slow
                >speed causes high amp draw and the motor heats up. If
                >the motor is termal protected, it will kick off or
                >kill power till the motor cools down to a point it
                >kicks in again.

                --
                Regards,
                Rich
                ================================
                Richard Kleinhenz
                http://beautifulhandmadepens.com
                http://www.woodpens.com/rkleinhenz.htm
                ================================
              • Chris Parker
                But the motor always runs at the same speed. The speeds are controlled by belts and pulleys in between the spindle and the motor shaft. This reduces the
                Message 7 of 25 , May 29, 2006
                  But the motor always runs at the same speed. The speeds are
                  controlled by belts and pulleys in between the spindle and the motor
                  shaft. This reduces the torque on the motor.

                  Right now, I am doing up a proper wiring diagram of the controller
                  (since the one in the manual is completely useless). I'll share what
                  I learn later tonight.


                  On 29-May-06, at 6:26 PM, Mike Jones wrote:

                  > One answer to that is you're using a very slow seed
                  > for reasonably thick stock if it's steel. The slow
                  > speed causes high amp draw and the motor heats up. If
                  > the motor is termal protected, it will kick off or
                  > kill power till the motor cools down to a point it
                  > kicks in again.
                  > Mike
                  >
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                • Chris Parker
                  Okay. Here is what I have for wiring. The motor has four wires: Blue, Black, White and Red. Black and Red are the plain winding, White and Blue are the
                  Message 8 of 25 , May 29, 2006
                    Okay. Here is what I have for wiring. The motor has four wires:
                    Blue, Black, White and Red.
                    Black and Red are the plain winding, White and Blue are the winding
                    with the series capacitor. The direction switch has three settings:
                    "left," "0" and "right."

                    In the left position, Black and Blue are connected to Live, Red and
                    White are connected to Neutral. In the right position, Black and Red
                    reverse (to give the 180 phase shift to reverse the motor). The
                    power switch is held in the "on" position by a solonoid that is
                    connected to neutral (I assume that it is connected to live in the
                    switch body) through two safety switches when the switch is closed.
                    One of these switches is on the transmission housing door and the
                    other is on the chuck guard. THERE IS NO CONNECTION BETWEEN THE
                    MOTOR AND THE SOLONOID.

                    This last point leads me to two possible conclusions.
                    1) one of the two safety switches is faulty
                    2) I am overloading the motor which is browning out the power to the
                    solonoid.

                    I haven't retried the parting off since I started this little
                    investigation, but I will report back when I do. The first thing
                    that I will test if the problem persists is the safety switches,
                    which easily can be checked by shorting their contacts (only during
                    the test!). I'll let you guys know how I fair.

                    -Chris
                    On 29-May-06, at 8:19 PM, Chris Parker wrote:

                    > But the motor always runs at the same speed. The speeds are
                    > controlled by belts and pulleys in between the spindle and the motor
                    > shaft. This reduces the torque on the motor.
                    >
                    > Right now, I am doing up a proper wiring diagram of the controller
                    > (since the one in the manual is completely useless). I'll share what
                    > I learn later tonight.
                    >
                    >
                    > On 29-May-06, at 6:26 PM, Mike Jones wrote:
                    >
                    >> One answer to that is you're using a very slow seed
                    >> for reasonably thick stock if it's steel. The slow
                    >> speed causes high amp draw and the motor heats up. If
                    >> the motor is termal protected, it will kick off or
                    >> kill power till the motor cools down to a point it
                    >> kicks in again.
                    >> Mike
                    >>
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                  • Steve Tompson
                    Chris Parker wrote ..... Black and Red are the plain winding, White and Blue are the winding with the series capacitor..... ==================================
                    Message 9 of 25 , May 30, 2006
                      Chris Parker wrote ..... Black and Red are the plain winding, White and Blue
                      are the winding
                      with the series capacitor.....
                      ==================================

                      You are describing a single phase induction motor.

                      They are easier to understand if you look at the working of a 3-phase motor.
                      In this the 3 coils produce magnetic fields that rise and fall in sequence,
                      thus the field appears to 'rotate'. The armature is usually a casting and
                      is in fact a number of 'coils' with only one winding. The field coils
                      induce a current into the armature which itself creates a magnetic field in
                      sympathy with the rotating field. Thus the armature tries to rotate with
                      the field rotation but doesn't quite catch-up. This is called the 'slip
                      speed' and is usually quoted as 2900ish rpm for a 3000rpm field (50 Hz in
                      UK/Europe). For the US at 60 Hz this would be a 3600rpm field and an
                      appropriate slip for actual speed. If the number of field coils is doubled
                      then we get a 1475ish rpm (1500) motor, 3 sets of coils 900ish (1000), etc.

                      Now to look at a single phase motor. There is no rotating field so the
                      armature will just 'hum'. To get it started a second, smaller, starter coil
                      is arranged at right-angles to the main field coil. In series with this is
                      a capacitor that electrically changes the phase of the AC current (the peak
                      through this winding thus occurs earlier than the peak in the main). What
                      we now have is a crude 2-phase motor with the similar rotating field and
                      slip characteristics as the 3-phase. Once up to speed the starting winding
                      is usually cut out by a centrifugal switch.

                      The problem, however, is that a single-phase motor does not have the
                      slip-range of the 3-phase and if overloaded the armature will 'lose' its
                      relationship with the rotating field (which isn't actually rotating but
                      keeps popping-up when the armature goes past). The net result is that the
                      motor stops !!!!

                      Another easily identified fault with single phase motors is when they just
                      hum at start-up but will run if the shaft is rotated by hand (I have to do
                      this on my polisher/wire brush/belt sander). First blow an air-line at the
                      internal centrifugal switch which may be clogged with dust (common). Then
                      check that the starting winding is not short or open circuit (rare). Then
                      change the capacitor (also common) and it will probably be OK (99% of the
                      time).

                      I did come across a 2-speed 3-phase planer that got extremely hot on slow
                      speed. Instead of bringing in the extra set of field coils in sympathy with
                      the fast winding to 'slow down' the rotating field, it was wired so that
                      they were in opposition to the fast. It sort of worked but severely
                      overheated. When corrected, the slow was slower than before and could run
                      all day without getting more than tepid !!!

                      Steve Tompson
                    • Chris Parker
                      The problem wasn t that I didn t know what motor I had (I have a degree in electrical engineering with a specialization in power machinery), it was that there
                      Message 10 of 25 , May 30, 2006
                        The problem wasn't that I didn't know what motor I had (I have a
                        degree in electrical engineering with a specialization in power
                        machinery), it was that there was no wiring diagram accompanying the
                        lathe. Ok, there was one, but it is completely useless. As we have
                        been stating in other posts, the motor always runs at full speed.
                        Speed control of the spindle is carried out via belt and pulley
                        reduction.

                        I was posting my identification of the leads so that everybody else
                        on this list with the 8x14 could make the notes in their manuals if
                        they wanted.

                        Incidentally, the rotary switch (the one with positions labeled "R,"
                        "O" and "L") is a type ZH-A from Kedu, in China (no big surprise).
                        However, the diagram on the switch doesn't tell you the different
                        ways that the contacts sit in the various positions. You can get the
                        diagram for it from their website (google Kedu switches, go to
                        products and search for switch type "ZH-A"), which was really helpful.

                        BTW, after reading Mike's post again (about going too slow), I opened
                        copy of "Machine Shop Practice" to check on cutting-off speeds. I
                        had been told by many people in the hobby to go slow and steady with
                        the parting tool (Hence the 125 RPM). Even though the motor was
                        turning at full speed, I might have been digging in or something (who
                        knows). According to MSP:

                        "The cutting speed used to cut off stock can usually be as fast as
                        recommended for turning. Occasionally, a very deep cut must be taken
                        to cut off a part, in which case the cutting speed should be
                        reduced. This is done more in the nature of a safety measure than to
                        decrease the cutting load on the tool. The cutting load, or cutting
                        force, on the tool will not be reduced by decreasing the cutting
                        speed, but by reducing the feed."

                        I am turning 6061 aluminum about 1.5" in diameter. the recommended
                        500-600 fpm speed amounts to about 1200rpm! since I can choose 1000
                        or 2000, I have set the machine to 1000. The problem hasn't come
                        back, and perhaps I never will find the true culprit!


                        -Chris

                        On 30-May-06, at 3:33 AM, Steve Tompson wrote:

                        > Chris Parker wrote ..... Black and Red are the plain winding, White
                        > and Blue
                        > are the winding
                        > with the series capacitor.....
                        > ==================================
                        >
                        > You are describing a single phase induction motor.
                        >
                        > They are easier to understand if you look at the working of a 3-
                        > phase motor.
                        > In this the 3 coils produce magnetic fields that rise and fall in
                        > sequence,
                        > thus the field appears to 'rotate'. The armature is usually a
                        > casting and
                        > is in fact a number of 'coils' with only one winding. The field coils
                        > induce a current into the armature which itself creates a magnetic
                        > field in
                        > sympathy with the rotating field. Thus the armature tries to
                        > rotate with
                        > the field rotation but doesn't quite catch-up. This is called the
                        > 'slip
                        > speed' and is usually quoted as 2900ish rpm for a 3000rpm field (50
                        > Hz in
                        > UK/Europe). For the US at 60 Hz this would be a 3600rpm field and an
                        > appropriate slip for actual speed. If the number of field coils is
                        > doubled
                        > then we get a 1475ish rpm (1500) motor, 3 sets of coils 900ish
                        > (1000), etc.
                        >
                        > Now to look at a single phase motor. There is no rotating field so
                        > the
                        > armature will just 'hum'. To get it started a second, smaller,
                        > starter coil
                        > is arranged at right-angles to the main field coil. In series with
                        > this is
                        > a capacitor that electrically changes the phase of the AC current
                        > (the peak
                        > through this winding thus occurs earlier than the peak in the
                        > main). What
                        > we now have is a crude 2-phase motor with the similar rotating
                        > field and
                        > slip characteristics as the 3-phase. Once up to speed the starting
                        > winding
                        > is usually cut out by a centrifugal switch.
                        >
                        > The problem, however, is that a single-phase motor does not have the
                        > slip-range of the 3-phase and if overloaded the armature will
                        > 'lose' its
                        > relationship with the rotating field (which isn't actually rotating
                        > but
                        > keeps popping-up when the armature goes past). The net result is
                        > that the
                        > motor stops !!!!
                        >
                        > Another easily identified fault with single phase motors is when
                        > they just
                        > hum at start-up but will run if the shaft is rotated by hand (I
                        > have to do
                        > this on my polisher/wire brush/belt sander). First blow an air-
                        > line at the
                        > internal centrifugal switch which may be clogged with dust
                        > (common). Then
                        > check that the starting winding is not short or open circuit
                        > (rare). Then
                        > change the capacitor (also common) and it will probably be OK (99%
                        > of the
                        > time).
                        >
                        > I did come across a 2-speed 3-phase planer that got extremely hot
                        > on slow
                        > speed. Instead of bringing in the extra set of field coils in
                        > sympathy with
                        > the fast winding to 'slow down' the rotating field, it was wired so
                        > that
                        > they were in opposition to the fast. It sort of worked but severely
                        > overheated. When corrected, the slow was slower than before and
                        > could run
                        > all day without getting more than tepid !!!
                        >
                        > Steve Tompson
                        >
                        >
                        >
                        >
                        >
                        >
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                      • Gene Horr
                        ... parting tool (Hence the 125 RPM). As you found out those many people are wrong. This is one of the most common myths told to newcomers and the result is
                        Message 11 of 25 , May 30, 2006
                          > I had been told by many people in the hobby to go slow and steady with the
                          parting tool (Hence the 125 RPM).

                          As you found out those "many people" are wrong. This is one of the most
                          common myths told to newcomers and the result is poor equipment performance
                          and higher tool wear. Like many tech/engineering related myths it spouts
                          from a truth that is misapplied.

                          If you look at the tables in the Machinery's Handbook there are two speeds
                          given. One is for most efficient production (the most work in the least
                          time) and the other is for maximum tool life. The maximum tool life speed
                          is slower than the maximum production speed. People have taken this fact
                          then extrapolated that the slower the spindle speed the better. This is not
                          the case. Going slower than maximum tool life speed does not increase tool
                          life any more, produces more strain on the system, and can actually decrease
                          tool life.

                          While I'm on the soapbox the other myth is that carbide tooling is better
                          than HSS. The problem is that carbide is better only if you can take deep
                          cuts. The small hobby lathes generally cannot do this. So for small
                          equipment use HSS is usually the better choice. Using carbide can often at
                          least lead to chatter if not stopping the spindle.

                          Gene Horr
                        • Ellis Cory
                          Gene wrote.....If you look at the tables in the Machinery s Handbook there are two speeds given. One is for most efficient production (the most work in the
                          Message 12 of 25 , May 30, 2006
                            Gene wrote.....If you look at the tables in the Machinery's Handbook there are two speeds given. One is for most efficient production (the most work in the least time) and the other is for maximum tool life. The maximum tool life speed........

                            I am not sure what version of Machinery's you have, but mine states on the opening page of Speeds & Feeds -
                            ' The cutting speed is governed principally, by the hardness of the metal to be turned; the kind of steel of which the turning tool is made; the shape of the tool and it's heat-treatmant; the feed and depth of cut; the cooling medium used, if any; the power of the machine and it's design and condition'. It then goes on to give a table for various metals in hard, medium and soft state. Dragging my mind back to my years in college when I studied metallurgy and machine design, I seem to remember that it was always a compromise and we added one more factor 'the bravery of the operator !'. All these factors give rise to the suggestion that parting off should be at a slower speed, usually because of the tool shape. Cutting speeds used in industry are also a compromise, it is no use increasing speed and output if you also increase down time because tools need more sharpening. At hoem, we can have the luxury of slower speeds and gain in tool life, because usually we are not dependant on output rate.
                            HTH
                            Ellis

                            [Non-text portions of this message have been removed]
                          • troy burns
                            Cutting speed with a cutoff tool in a lathe, cannot be properly measured in RPM, except at one depth of cut. Feet per minute would be a better speed
                            Message 13 of 25 , May 30, 2006
                              Cutting speed with a cutoff tool in a lathe, cannot be properly
                              measured in RPM, except at one depth of cut. Feet per minute would
                              be a better speed indicator, and to keep that measurement constant,
                              the rpm must be INCREASED as the cut gets deeper. This is easily
                              done with the 7" Chinese lathes; not so easily done with a constant
                              speed motor.

                              That is just opposite from what MSP recommends, but is in line with
                              common sense, in my opinion and in my experience.

                              Also, any deep cut should be started off wider than the cutoff tool
                              and kept wider until the cut is almost completed, so there is not
                              much friction built up on the SIDES of the tool.

                              tb

                              At 12:07 PM 5/30/2006, you wrote:
                              >The problem wasn't that I didn't know what motor I had (I have a
                              >degree in electrical engineering with a specialization in power
                              >machinery), it was that there was no wiring diagram accompanying the
                              >lathe. Ok, there was one, but it is completely useless. As we have
                              >been stating in other posts, the motor always runs at full speed.
                              >Speed control of the spindle is carried out via belt and pulley
                              >reduction.
                              >
                              >I was posting my identification of the leads so that everybody else
                              >on this list with the 8x14 could make the notes in their manuals if
                              >they wanted.
                              >
                              >Incidentally, the rotary switch (the one with positions labeled "R,"
                              >"O" and "L") is a type ZH-A from Kedu, in China (no big surprise).
                              >However, the diagram on the switch doesn't tell you the different
                              >ways that the contacts sit in the various positions. You can get the
                              >diagram for it from their website (google Kedu switches, go to
                              >products and search for switch type "ZH-A"), which was really helpful.
                              >
                              >BTW, after reading Mike's post again (about going too slow), I opened
                              >copy of "Machine Shop Practice" to check on cutting-off speeds. I
                              >had been told by many people in the hobby to go slow and steady with
                              >the parting tool (Hence the 125 RPM). Even though the motor was
                              >turning at full speed, I might have been digging in or something (who
                              >knows). According to MSP:
                              >
                              >"The cutting speed used to cut off stock can usually be as fast as
                              >recommended for turning. Occasionally, a very deep cut must be taken
                              >to cut off a part, in which case the cutting speed should be
                              >reduced. This is done more in the nature of a safety measure than to
                              >decrease the cutting load on the tool. The cutting load, or cutting
                              >force, on the tool will not be reduced by decreasing the cutting
                              >speed, but by reducing the feed."
                              >
                              >I am turning 6061 aluminum about 1.5" in diameter. the recommended
                              >500-600 fpm speed amounts to about 1200rpm! since I can choose 1000
                              >or 2000, I have set the machine to 1000. The problem hasn't come
                              >back, and perhaps I never will find the true culprit!
                              >
                              >
                              >-Chris
                              >
                              >On 30-May-06, at 3:33 AM, Steve Tompson wrote:
                              >
                              > > Chris Parker wrote ..... Black and Red are the plain winding, White
                              > > and Blue
                              > > are the winding
                              > > with the series capacitor.....
                              > > ==================================
                              > >
                              > > You are describing a single phase induction motor.
                              > >
                              > > They are easier to understand if you look at the working of a 3-
                              > > phase motor.
                              > > In this the 3 coils produce magnetic fields that rise and fall in
                              > > sequence,
                              > > thus the field appears to 'rotate'. The armature is usually a
                              > > casting and
                              > > is in fact a number of 'coils' with only one winding. The field coils
                              > > induce a current into the armature which itself creates a magnetic
                              > > field in
                              > > sympathy with the rotating field. Thus the armature tries to
                              > > rotate with
                              > > the field rotation but doesn't quite catch-up. This is called the
                              > > 'slip
                              > > speed' and is usually quoted as 2900ish rpm for a 3000rpm field (50
                              > > Hz in
                              > > UK/Europe). For the US at 60 Hz this would be a 3600rpm field and an
                              > > appropriate slip for actual speed. If the number of field coils is
                              > > doubled
                              > > then we get a 1475ish rpm (1500) motor, 3 sets of coils 900ish
                              > > (1000), etc.
                              > >
                              > > Now to look at a single phase motor. There is no rotating field so
                              > > the
                              > > armature will just 'hum'. To get it started a second, smaller,
                              > > starter coil
                              > > is arranged at right-angles to the main field coil. In series with
                              > > this is
                              > > a capacitor that electrically changes the phase of the AC current
                              > > (the peak
                              > > through this winding thus occurs earlier than the peak in the
                              > > main). What
                              > > we now have is a crude 2-phase motor with the similar rotating
                              > > field and
                              > > slip characteristics as the 3-phase. Once up to speed the starting
                              > > winding
                              > > is usually cut out by a centrifugal switch.
                              > >
                              > > The problem, however, is that a single-phase motor does not have the
                              > > slip-range of the 3-phase and if overloaded the armature will
                              > > 'lose' its
                              > > relationship with the rotating field (which isn't actually rotating
                              > > but
                              > > keeps popping-up when the armature goes past). The net result is
                              > > that the
                              > > motor stops !!!!
                              > >
                              > > Another easily identified fault with single phase motors is when
                              > > they just
                              > > hum at start-up but will run if the shaft is rotated by hand (I
                              > > have to do
                              > > this on my polisher/wire brush/belt sander). First blow an air-
                              > > line at the
                              > > internal centrifugal switch which may be clogged with dust
                              > > (common). Then
                              > > check that the starting winding is not short or open circuit
                              > > (rare). Then
                              > > change the capacitor (also common) and it will probably be OK (99%
                              > > of the
                              > > time).
                              > >
                              > > I did come across a 2-speed 3-phase planer that got extremely hot
                              > > on slow
                              > > speed. Instead of bringing in the extra set of field coils in
                              > > sympathy with
                              > > the fast winding to 'slow down' the rotating field, it was wired so
                              > > that
                              > > they were in opposition to the fast. It sort of worked but severely
                              > > overheated. When corrected, the slow was slower than before and
                              > > could run
                              > > all day without getting more than tepid !!!
                              > >
                              > > Steve Tompson
                              > >
                              > >
                              > >
                              > >
                              > >
                              > >
                              > > ------------------------ Yahoo! Groups Sponsor --------------------
                              > > ~-->
                              > > Get to your groups with one click. Know instantly when new email
                              > > arrives
                              > > http://us.click.yahoo.com/.7bhrC/MGxNAA/yQLSAA/RUTolB/TM
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                              > >
                              > > Yahoo! Groups Links
                              > >
                              > >
                              > >
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                              > >
                              >
                              >
                              >
                              >
                              >
                              >Yahoo! Groups Links
                              >
                              >
                              >
                              >
                              >
                              >
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                            • Chris Parker
                              Right, which is why I did the conversion from fpm to rpm. I realize that the cutting speed will decrease as I get deeper into the stock. One of these days, I
                              Message 14 of 25 , May 30, 2006
                                Right, which is why I did the conversion from fpm to rpm. I realize
                                that the cutting speed will decrease as I get deeper into the stock.
                                One of these days, I will get around to building a variable speed
                                controller for my lathe, but there is no rush right now.

                                Of course, increasing the speed with cut depth is a dangerous
                                proposition if you take it too far; If we don't place any limits on
                                what we are doing, you would have to spin the chuck infinitely fast
                                at the end of your cut (which would make whatever you are parting off
                                a spinning terror!). Even if we continue this down to the last 1/2"
                                of stock (diameter), I would have had to have the chuck going at
                                4500rpm to get a cutting speed of 600fpm. No thank-you, even if my
                                lathe COULD do that!

                                As for the problems that I was having with the machine, I can say
                                with almost certainty that I have found the problem. One of the two
                                safety micro-switches is causing the problem. It seems as though the
                                spring holding the contacts shut is not enough with some of the
                                vibration that I was getting (spindle speed and feed-rate related).
                                I put a jumper across the pair and the problem went away (they are
                                normally open and in series, so shorting across them removes them
                                from the circuit). The lathe stopped shutting itself down! Now I
                                just have to figure out which one (I suspect the one on the chuck
                                guard...) and replace it.

                                -Chris

                                PS: On the topic of operator bravery, the tool chatter that was
                                causing the vibration (I am using a 5/8" cut-off tool and holder from
                                Busy Bee) went away when I sucked up my courage and INCREASED the
                                feed-rate. This is consistent with MSP, which states that a low feed-
                                rate would be 0.0005"/revolution of the stock. At 1000rpm, that
                                means that a SLOW feedrate would have been a half inch per minute, or
                                8.3 thousandths/second! I was feeding WAY below the slowest
                                recommended rate.

                                On 30-May-06, at 2:00 PM, troy burns wrote:

                                > Cutting speed with a cutoff tool in a lathe, cannot be properly
                                > measured in RPM, except at one depth of cut. Feet per minute would
                                > be a better speed indicator, and to keep that measurement constant,
                                > the rpm must be INCREASED as the cut gets deeper. This is easily
                                > done with the 7" Chinese lathes; not so easily done with a constant
                                > speed motor.
                                >
                                > That is just opposite from what MSP recommends, but is in line with
                                > common sense, in my opinion and in my experience.
                                >
                                > Also, any deep cut should be started off wider than the cutoff tool
                                > and kept wider until the cut is almost completed, so there is not
                                > much friction built up on the SIDES of the tool.
                                >
                                > tb
                                >
                                > At 12:07 PM 5/30/2006, you wrote:
                                >> The problem wasn't that I didn't know what motor I had (I have a
                                >> degree in electrical engineering with a specialization in power
                                >> machinery), it was that there was no wiring diagram accompanying the
                                >> lathe. Ok, there was one, but it is completely useless. As we have
                                >> been stating in other posts, the motor always runs at full speed.
                                >> Speed control of the spindle is carried out via belt and pulley
                                >> reduction.
                                >>
                                >> I was posting my identification of the leads so that everybody else
                                >> on this list with the 8x14 could make the notes in their manuals if
                                >> they wanted.
                                >>
                                >> Incidentally, the rotary switch (the one with positions labeled "R,"
                                >> "O" and "L") is a type ZH-A from Kedu, in China (no big surprise).
                                >> However, the diagram on the switch doesn't tell you the different
                                >> ways that the contacts sit in the various positions. You can get the
                                >> diagram for it from their website (google Kedu switches, go to
                                >> products and search for switch type "ZH-A"), which was really
                                >> helpful.
                                >>
                                >> BTW, after reading Mike's post again (about going too slow), I opened
                                >> copy of "Machine Shop Practice" to check on cutting-off speeds. I
                                >> had been told by many people in the hobby to go slow and steady with
                                >> the parting tool (Hence the 125 RPM). Even though the motor was
                                >> turning at full speed, I might have been digging in or something (who
                                >> knows). According to MSP:
                                >>
                                >> "The cutting speed used to cut off stock can usually be as fast as
                                >> recommended for turning. Occasionally, a very deep cut must be taken
                                >> to cut off a part, in which case the cutting speed should be
                                >> reduced. This is done more in the nature of a safety measure than to
                                >> decrease the cutting load on the tool. The cutting load, or cutting
                                >> force, on the tool will not be reduced by decreasing the cutting
                                >> speed, but by reducing the feed."
                                >>
                                >> I am turning 6061 aluminum about 1.5" in diameter. the recommended
                                >> 500-600 fpm speed amounts to about 1200rpm! since I can choose 1000
                                >> or 2000, I have set the machine to 1000. The problem hasn't come
                                >> back, and perhaps I never will find the true culprit!
                                >>
                                >>
                                >> -Chris
                                >>
                                >> On 30-May-06, at 3:33 AM, Steve Tompson wrote:
                                >>
                                >>> Chris Parker wrote ..... Black and Red are the plain winding, White
                                >>> and Blue
                                >>> are the winding
                                >>> with the series capacitor.....
                                >>> ==================================
                                >>>
                                >>> You are describing a single phase induction motor.
                                >>>
                                >>> They are easier to understand if you look at the working of a 3-
                                >>> phase motor.
                                >>> In this the 3 coils produce magnetic fields that rise and fall in
                                >>> sequence,
                                >>> thus the field appears to 'rotate'. The armature is usually a
                                >>> casting and
                                >>> is in fact a number of 'coils' with only one winding. The field
                                >>> coils
                                >>> induce a current into the armature which itself creates a magnetic
                                >>> field in
                                >>> sympathy with the rotating field. Thus the armature tries to
                                >>> rotate with
                                >>> the field rotation but doesn't quite catch-up. This is called the
                                >>> 'slip
                                >>> speed' and is usually quoted as 2900ish rpm for a 3000rpm field (50
                                >>> Hz in
                                >>> UK/Europe). For the US at 60 Hz this would be a 3600rpm field
                                >>> and an
                                >>> appropriate slip for actual speed. If the number of field coils is
                                >>> doubled
                                >>> then we get a 1475ish rpm (1500) motor, 3 sets of coils 900ish
                                >>> (1000), etc.
                                >>>
                                >>> Now to look at a single phase motor. There is no rotating field so
                                >>> the
                                >>> armature will just 'hum'. To get it started a second, smaller,
                                >>> starter coil
                                >>> is arranged at right-angles to the main field coil. In series with
                                >>> this is
                                >>> a capacitor that electrically changes the phase of the AC current
                                >>> (the peak
                                >>> through this winding thus occurs earlier than the peak in the
                                >>> main). What
                                >>> we now have is a crude 2-phase motor with the similar rotating
                                >>> field and
                                >>> slip characteristics as the 3-phase. Once up to speed the starting
                                >>> winding
                                >>> is usually cut out by a centrifugal switch.
                                >>>
                                >>> The problem, however, is that a single-phase motor does not have the
                                >>> slip-range of the 3-phase and if overloaded the armature will
                                >>> 'lose' its
                                >>> relationship with the rotating field (which isn't actually rotating
                                >>> but
                                >>> keeps popping-up when the armature goes past). The net result is
                                >>> that the
                                >>> motor stops !!!!
                                >>>
                                >>> Another easily identified fault with single phase motors is when
                                >>> they just
                                >>> hum at start-up but will run if the shaft is rotated by hand (I
                                >>> have to do
                                >>> this on my polisher/wire brush/belt sander). First blow an air-
                                >>> line at the
                                >>> internal centrifugal switch which may be clogged with dust
                                >>> (common). Then
                                >>> check that the starting winding is not short or open circuit
                                >>> (rare). Then
                                >>> change the capacitor (also common) and it will probably be OK (99%
                                >>> of the
                                >>> time).
                                >>>
                                >>> I did come across a 2-speed 3-phase planer that got extremely hot
                                >>> on slow
                                >>> speed. Instead of bringing in the extra set of field coils in
                                >>> sympathy with
                                >>> the fast winding to 'slow down' the rotating field, it was wired so
                                >>> that
                                >>> they were in opposition to the fast. It sort of worked but severely
                                >>> overheated. When corrected, the slow was slower than before and
                                >>> could run
                                >>> all day without getting more than tepid !!!
                                >>>
                                >>> Steve Tompson
                                >>>
                                >>>
                                >>>
                                >>>
                                >>>
                                >>>
                                >>> ------------------------ Yahoo! Groups Sponsor --------------------
                                >>> ~-->
                                >>> Get to your groups with one click. Know instantly when new email
                                >>> arrives
                                >>> http://us.click.yahoo.com/.7bhrC/MGxNAA/yQLSAA/RUTolB/TM
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                                >>>
                                >>> Yahoo! Groups Links
                                >>>
                                >>>
                                >>>
                                >>>
                                >>>
                                >>>
                                >>
                                >>
                                >>
                                >>
                                >>
                                >> Yahoo! Groups Links
                                >>
                                >>
                                >>
                                >>
                                >>
                                >>
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                              • Chris Parker
                                Thanks, Gene. I may know electronics/robotics, but I do need a bit of help in the machining department! I was doing just fine this morning after the
                                Message 15 of 25 , May 30, 2006
                                  Thanks, Gene. I may know electronics/robotics, but I do need a bit
                                  of help in the machining department! I was doing just fine this
                                  morning after the reassembly, and then I started having the same
                                  problem: the lathe shuts itself off when I am parting off. I was
                                  fine for the first while, though.
                                  On 30-May-06, at 11:32 AM, Gene Horr wrote:

                                  >> I had been told by many people in the hobby to go slow and steady
                                  >> with the
                                  > parting tool (Hence the 125 RPM).
                                  >
                                  > As you found out those "many people" are wrong. This is one of the
                                  > most
                                  > common myths told to newcomers and the result is poor equipment
                                  > performance
                                  > and higher tool wear. Like many tech/engineering related myths it
                                  > spouts
                                  > from a truth that is misapplied.
                                  >
                                  > If you look at the tables in the Machinery's Handbook there are two
                                  > speeds
                                  > given. One is for most efficient production (the most work in the
                                  > least
                                  > time) and the other is for maximum tool life. The maximum tool
                                  > life speed
                                  > is slower than the maximum production speed. People have taken
                                  > this fact
                                  > then extrapolated that the slower the spindle speed the better.
                                  > This is not
                                  > the case. Going slower than maximum tool life speed does not
                                  > increase tool
                                  > life any more, produces more strain on the system, and can actually
                                  > decrease
                                  > tool life.
                                  >
                                  > While I'm on the soapbox the other myth is that carbide tooling is
                                  > better
                                  > than HSS. The problem is that carbide is better only if you can
                                  > take deep
                                  > cuts. The small hobby lathes generally cannot do this. So for small
                                  > equipment use HSS is usually the better choice. Using carbide can
                                  > often at
                                  > least lead to chatter if not stopping the spindle.
                                  >
                                  > Gene Horr
                                  >
                                  >
                                  >
                                  >
                                  >
                                  >
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                                • Michael Shelley
                                  Chris, I don t know the hardware involved, but if the microswitch is bouncing it would seem logical to introduce a springy connection between the switch
                                  Message 16 of 25 , May 30, 2006
                                    Chris,

                                    I don't know the hardware involved, but if the microswitch is
                                    "bouncing" it would seem logical to introduce a springy connection
                                    between the switch actuator and whatever it presses against. This
                                    would ensure continued pressure on the switch even when vibrating.
                                    Microswitches with a spring arm are ideal for this.

                                    Mike

                                    >
                                    >
                                    >As for the problems that I was having with the machine, I can say
                                    >with almost certainty that I have found the problem. One of the two
                                    >safety micro-switches is causing the problem. It seems as though the
                                    >spring holding the contacts shut is not enough with some of the
                                    >vibration that I was getting (spindle speed and feed-rate related).
                                    >I put a jumper across the pair and the problem went away (they are
                                    >normally open and in series, so shorting across them removes them
                                    >from the circuit). The lathe stopped shutting itself down! Now I
                                    >just have to figure out which one (I suspect the one on the chuck
                                    >guard...) and replace it.
                                    >
                                    >-Chris
                                    >
                                    >PS: On the topic of operator bravery, the tool chatter that was
                                    >causing the vibration (I am using a 5/8" cut-off tool and holder from
                                    >Busy Bee) went away when I sucked up my courage and INCREASED the
                                    >feed-rate. This is consistent with MSP, which states that a low feed-
                                    >rate would be 0.0005"/revolution of the stock. At 1000rpm, that
                                    >means that a SLOW feedrate would have been a half inch per minute, or
                                    >8.3 thousandths/second! I was feeding WAY below the slowest
                                    >recommended rate.
                                  • David Lee
                                    I am turning 6061 aluminum about 1.5 in diameter. the recommended 500-600 fpm speed amounts to about 1200rpm! since I can choose 1000 or 2000, I have set
                                    Message 17 of 25 , May 31, 2006
                                      "I am turning 6061 aluminum about 1.5" in diameter. the recommended
                                      500-600 fpm speed amounts to about 1200rpm! since I can choose 1000
                                      or 2000, I have set the machine to 1000. The problem hasn't come back, and
                                      perhaps I never will find the true culprit!"

                                      Please excuse me if I'm stating the obvious. I may be wrong but the
                                      recommended 500 - 600 feet per minute is surface feet per minute. With at
                                      1.5" diameter rod, the circumference is 4.712" or 0.393 ft. To turn it at
                                      500 surface feet per minute, that would be 1272 RPM. At 600 sfm, that would
                                      be 1527 RPM. Maybe you are going too slow. As the cut necks down the work,
                                      the sfm gets slower at a constant RPM.

                                      David Lee

                                      ----------------------------------------------------------------------------
                                      ----


                                      -----Original Message-----
                                      From: mlathemods@yahoogroups.com [mailto:mlathemods@yahoogroups.com]On
                                      Behalf Of Chris Parker
                                      Sent: Tuesday, May 30, 2006 1:08 PM
                                      To: mlathemods@yahoogroups.com
                                      Subject: Re: [mlathemods] Lathemaster 8x14 shutting itself of under load


                                      The problem wasn't that I didn't know what motor I had (I have a
                                      degree in electrical engineering with a specialization in power
                                      machinery), it was that there was no wiring diagram accompanying the
                                      lathe. Ok, there was one, but it is completely useless. As we have
                                      been stating in other posts, the motor always runs at full speed.
                                      Speed control of the spindle is carried out via belt and pulley
                                      reduction.

                                      I was posting my identification of the leads so that everybody else
                                      on this list with the 8x14 could make the notes in their manuals if
                                      they wanted.

                                      Incidentally, the rotary switch (the one with positions labeled "R,"
                                      "O" and "L") is a type ZH-A from Kedu, in China (no big surprise).
                                      However, the diagram on the switch doesn't tell you the different
                                      ways that the contacts sit in the various positions. You can get the
                                      diagram for it from their website (google Kedu switches, go to
                                      products and search for switch type "ZH-A"), which was really helpful.

                                      BTW, after reading Mike's post again (about going too slow), I opened
                                      copy of "Machine Shop Practice" to check on cutting-off speeds. I
                                      had been told by many people in the hobby to go slow and steady with
                                      the parting tool (Hence the 125 RPM). Even though the motor was
                                      turning at full speed, I might have been digging in or something (who
                                      knows). According to MSP:

                                      "The cutting speed used to cut off stock can usually be as fast as
                                      recommended for turning. Occasionally, a very deep cut must be taken
                                      to cut off a part, in which case the cutting speed should be
                                      reduced. This is done more in the nature of a safety measure than to
                                      decrease the cutting load on the tool. The cutting load, or cutting
                                      force, on the tool will not be reduced by decreasing the cutting
                                      speed, but by reducing the feed."

                                      I am turning 6061 aluminum about 1.5" in diameter. the recommended
                                      500-600 fpm speed amounts to about 1200rpm! since I can choose 1000
                                      or 2000, I have set the machine to 1000. The problem hasn't come
                                      back, and perhaps I never will find the true culprit!


                                      -Chris

                                      On 30-May-06, at 3:33 AM, Steve Tompson wrote:

                                      > Chris Parker wrote ..... Black and Red are the plain winding, White
                                      > and Blue
                                      > are the winding
                                      > with the series capacitor.....
                                      > ==================================
                                      >
                                      > You are describing a single phase induction motor.
                                      >
                                      > They are easier to understand if you look at the working of a 3-
                                      > phase motor.
                                      > In this the 3 coils produce magnetic fields that rise and fall in
                                      > sequence,
                                      > thus the field appears to 'rotate'. The armature is usually a
                                      > casting and
                                      > is in fact a number of 'coils' with only one winding. The field coils
                                      > induce a current into the armature which itself creates a magnetic
                                      > field in
                                      > sympathy with the rotating field. Thus the armature tries to
                                      > rotate with
                                      > the field rotation but doesn't quite catch-up. This is called the
                                      > 'slip
                                      > speed' and is usually quoted as 2900ish rpm for a 3000rpm field (50
                                      > Hz in
                                      > UK/Europe). For the US at 60 Hz this would be a 3600rpm field and an
                                      > appropriate slip for actual speed. If the number of field coils is
                                      > doubled
                                      > then we get a 1475ish rpm (1500) motor, 3 sets of coils 900ish
                                      > (1000), etc.
                                      >
                                      > Now to look at a single phase motor. There is no rotating field so
                                      > the
                                      > armature will just 'hum'. To get it started a second, smaller,
                                      > starter coil
                                      > is arranged at right-angles to the main field coil. In series with
                                      > this is
                                      > a capacitor that electrically changes the phase of the AC current
                                      > (the peak
                                      > through this winding thus occurs earlier than the peak in the
                                      > main). What
                                      > we now have is a crude 2-phase motor with the similar rotating
                                      > field and
                                      > slip characteristics as the 3-phase. Once up to speed the starting
                                      > winding
                                      > is usually cut out by a centrifugal switch.
                                      >
                                      > The problem, however, is that a single-phase motor does not have the
                                      > slip-range of the 3-phase and if overloaded the armature will
                                      > 'lose' its
                                      > relationship with the rotating field (which isn't actually rotating
                                      > but
                                      > keeps popping-up when the armature goes past). The net result is
                                      > that the
                                      > motor stops !!!!
                                      >
                                      > Another easily identified fault with single phase motors is when
                                      > they just
                                      > hum at start-up but will run if the shaft is rotated by hand (I
                                      > have to do
                                      > this on my polisher/wire brush/belt sander). First blow an air-
                                      > line at the
                                      > internal centrifugal switch which may be clogged with dust
                                      > (common). Then
                                      > check that the starting winding is not short or open circuit
                                      > (rare). Then
                                      > change the capacitor (also common) and it will probably be OK (99%
                                      > of the
                                      > time).
                                      >
                                      > I did come across a 2-speed 3-phase planer that got extremely hot
                                      > on slow
                                      > speed. Instead of bringing in the extra set of field coils in
                                      > sympathy with
                                      > the fast winding to 'slow down' the rotating field, it was wired so
                                      > that
                                      > they were in opposition to the fast. It sort of worked but severely
                                      > overheated. When corrected, the slow was slower than before and
                                      > could run
                                      > all day without getting more than tepid !!!
                                      >
                                      > Steve Tompson


                                      [Non-text portions of this message have been removed]
                                    • Chris Parker
                                      Yes, but when your lathe has speeds: 125, 210, 420, 625, 1000 and 2000 rpm, you choose the closest setting without getting too carried away. Thus 1000rpm, not
                                      Message 18 of 25 , May 31, 2006
                                        Yes, but when your lathe has speeds: 125, 210, 420, 625, 1000 and
                                        2000 rpm, you choose the closest setting without getting too carried
                                        away. Thus 1000rpm, not 2000rpm. See my other post about why I
                                        don't increase speed as I increase depth here.

                                        On 31-May-06, at 5:05 AM, David Lee wrote:

                                        > "I am turning 6061 aluminum about 1.5" in diameter. the recommended
                                        > 500-600 fpm speed amounts to about 1200rpm! since I can choose 1000
                                        > or 2000, I have set the machine to 1000. The problem hasn't come
                                        > back, and
                                        > perhaps I never will find the true culprit!"
                                        >
                                        > Please excuse me if I'm stating the obvious. I may be wrong but the
                                        > recommended 500 - 600 feet per minute is surface feet per minute.
                                        > With at
                                        > 1.5" diameter rod, the circumference is 4.712" or 0.393 ft. To
                                        > turn it at
                                        > 500 surface feet per minute, that would be 1272 RPM. At 600 sfm,
                                        > that would
                                        > be 1527 RPM. Maybe you are going too slow. As the cut necks down
                                        > the work,
                                        > the sfm gets slower at a constant RPM.
                                        >
                                        > David Lee
                                        >
                                        > ----------------------------------------------------------------------
                                        > ------
                                        > ----
                                        >
                                        >
                                        > -----Original Message-----
                                        > From: mlathemods@yahoogroups.com
                                        > [mailto:mlathemods@yahoogroups.com]On
                                        > Behalf Of Chris Parker
                                        > Sent: Tuesday, May 30, 2006 1:08 PM
                                        > To: mlathemods@yahoogroups.com
                                        > Subject: Re: [mlathemods] Lathemaster 8x14 shutting itself of
                                        > under load
                                        >
                                        >
                                        > The problem wasn't that I didn't know what motor I had (I have a
                                        > degree in electrical engineering with a specialization in power
                                        > machinery), it was that there was no wiring diagram accompanying the
                                        > lathe. Ok, there was one, but it is completely useless. As we have
                                        > been stating in other posts, the motor always runs at full speed.
                                        > Speed control of the spindle is carried out via belt and pulley
                                        > reduction.
                                        >
                                        > I was posting my identification of the leads so that everybody else
                                        > on this list with the 8x14 could make the notes in their manuals if
                                        > they wanted.
                                        >
                                        > Incidentally, the rotary switch (the one with positions labeled "R,"
                                        > "O" and "L") is a type ZH-A from Kedu, in China (no big surprise).
                                        > However, the diagram on the switch doesn't tell you the different
                                        > ways that the contacts sit in the various positions. You can get
                                        > the
                                        > diagram for it from their website (google Kedu switches, go to
                                        > products and search for switch type "ZH-A"), which was really
                                        > helpful.
                                        >
                                        > BTW, after reading Mike's post again (about going too slow), I
                                        > opened
                                        > copy of "Machine Shop Practice" to check on cutting-off speeds. I
                                        > had been told by many people in the hobby to go slow and steady with
                                        > the parting tool (Hence the 125 RPM). Even though the motor was
                                        > turning at full speed, I might have been digging in or something
                                        > (who
                                        > knows). According to MSP:
                                        >
                                        > "The cutting speed used to cut off stock can usually be as fast as
                                        > recommended for turning. Occasionally, a very deep cut must be
                                        > taken
                                        > to cut off a part, in which case the cutting speed should be
                                        > reduced. This is done more in the nature of a safety measure
                                        > than to
                                        > decrease the cutting load on the tool. The cutting load, or cutting
                                        > force, on the tool will not be reduced by decreasing the cutting
                                        > speed, but by reducing the feed."
                                        >
                                        > I am turning 6061 aluminum about 1.5" in diameter. the recommended
                                        > 500-600 fpm speed amounts to about 1200rpm! since I can choose 1000
                                        > or 2000, I have set the machine to 1000. The problem hasn't come
                                        > back, and perhaps I never will find the true culprit!
                                        >
                                        >
                                        > -Chris
                                        >
                                        > On 30-May-06, at 3:33 AM, Steve Tompson wrote:
                                        >
                                        >> Chris Parker wrote ..... Black and Red are the plain winding, White
                                        >> and Blue
                                        >> are the winding
                                        >> with the series capacitor.....
                                        >> ==================================
                                        >>
                                        >> You are describing a single phase induction motor.
                                        >>
                                        >> They are easier to understand if you look at the working of a 3-
                                        >> phase motor.
                                        >> In this the 3 coils produce magnetic fields that rise and fall in
                                        >> sequence,
                                        >> thus the field appears to 'rotate'. The armature is usually a
                                        >> casting and
                                        >> is in fact a number of 'coils' with only one winding. The field
                                        >> coils
                                        >> induce a current into the armature which itself creates a magnetic
                                        >> field in
                                        >> sympathy with the rotating field. Thus the armature tries to
                                        >> rotate with
                                        >> the field rotation but doesn't quite catch-up. This is called the
                                        >> 'slip
                                        >> speed' and is usually quoted as 2900ish rpm for a 3000rpm field (50
                                        >> Hz in
                                        >> UK/Europe). For the US at 60 Hz this would be a 3600rpm field and an
                                        >> appropriate slip for actual speed. If the number of field coils is
                                        >> doubled
                                        >> then we get a 1475ish rpm (1500) motor, 3 sets of coils 900ish
                                        >> (1000), etc.
                                        >>
                                        >> Now to look at a single phase motor. There is no rotating field so
                                        >> the
                                        >> armature will just 'hum'. To get it started a second, smaller,
                                        >> starter coil
                                        >> is arranged at right-angles to the main field coil. In series with
                                        >> this is
                                        >> a capacitor that electrically changes the phase of the AC current
                                        >> (the peak
                                        >> through this winding thus occurs earlier than the peak in the
                                        >> main). What
                                        >> we now have is a crude 2-phase motor with the similar rotating
                                        >> field and
                                        >> slip characteristics as the 3-phase. Once up to speed the starting
                                        >> winding
                                        >> is usually cut out by a centrifugal switch.
                                        >>
                                        >> The problem, however, is that a single-phase motor does not have the
                                        >> slip-range of the 3-phase and if overloaded the armature will
                                        >> 'lose' its
                                        >> relationship with the rotating field (which isn't actually rotating
                                        >> but
                                        >> keeps popping-up when the armature goes past). The net result is
                                        >> that the
                                        >> motor stops !!!!
                                        >>
                                        >> Another easily identified fault with single phase motors is when
                                        >> they just
                                        >> hum at start-up but will run if the shaft is rotated by hand (I
                                        >> have to do
                                        >> this on my polisher/wire brush/belt sander). First blow an air-
                                        >> line at the
                                        >> internal centrifugal switch which may be clogged with dust
                                        >> (common). Then
                                        >> check that the starting winding is not short or open circuit
                                        >> (rare). Then
                                        >> change the capacitor (also common) and it will probably be OK (99%
                                        >> of the
                                        >> time).
                                        >>
                                        >> I did come across a 2-speed 3-phase planer that got extremely hot
                                        >> on slow
                                        >> speed. Instead of bringing in the extra set of field coils in
                                        >> sympathy with
                                        >> the fast winding to 'slow down' the rotating field, it was wired so
                                        >> that
                                        >> they were in opposition to the fast. It sort of worked but severely
                                        >> overheated. When corrected, the slow was slower than before and
                                        >> could run
                                        >> all day without getting more than tepid !!!
                                        >>
                                        >> Steve Tompson
                                        >
                                        >
                                        > [Non-text portions of this message have been removed]
                                        >
                                        >
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                                      • Richard Kleinhenz
                                        Of course there is also this common-sense thing of looking at the chips coming off, listening to the chatter etc. It s easy to know when it s right - not
                                        Message 19 of 25 , May 31, 2006
                                          Of course there is also this common-sense thing of looking at the chips coming off, listening to the chatter etc. It's easy to know when it's right - not quite so easy when it's wrong, and how to correct :-)

                                          I'm in the process of converting to 3-phase. So my switches will go by the wayside. I will wire control signals back to the VFD. Probably an EMO to shut the VFD down,, a REV/OFF/FWD rotary switch, and a potentiometer. Sounds like the on/off switch can't be used as EMO because the solenoid needs 110V. Maybe I'll add an RPM readout also, because I will try to preserve the existing gearing to always be able to get into a good torque range.

                                          --
                                          Regards,
                                          Rich
                                          ================================
                                          Richard Kleinhenz
                                          http://beautifulhandmadepens.com
                                          http://www.woodpens.com/rkleinhenz.htm
                                          ================================
                                        • Tim Gunn
                                          What is an EMO? I can manage the other TLAs (three-letter acronyms), but this has me stumped. I am guessing at some form of self-holding relay with No-Volt
                                          Message 20 of 25 , Jun 2, 2006
                                            What is an EMO? I can manage the other TLAs (three-letter acronyms), but
                                            this has me stumped. I am guessing at some form of self-holding relay with
                                            No-Volt Release to ensure it does not restart itself after a power loss.

                                            Going 3-phase with a Variable Frequency Drive needn't necessarily mean
                                            getting rid of the existing switches. If you are used to them, you can
                                            probably wire the contacts back to the VFD control terminals so that the
                                            start, stop and reverse functions are where you expect them to be; this may
                                            be a significant safety consideration for some people.

                                            Most VFDs seem to be pretty freely configurable on the digital inputs. so
                                            you should have no trouble making it work as if it had an NVR. I would fit
                                            some means of disconnection on the (single phase?) supply side of the VFD to
                                            allow isolation when changing belts, etc. I use an RCBO; combined earth
                                            leakage circuit breaker and thermal/magnetic overcurrent breaker. I have no
                                            idea what it would be called west of the pond.

                                            Which VFD are you using? I used a Siemens G110 and am not overly impressed
                                            with it. I much prefer the Telemechanique Altivar 11 and really love the
                                            AutomationDirect GS2, both of which I have used at work.

                                            Regards

                                            Tim Gunn

                                            >Of course there is also this common-sense thing of looking at the chips
                                            >coming off, listening to the chatter etc. It's easy to know when it's
                                            >right - not quite so easy when it's wrong, and how to correct :-)
                                            >
                                            >I'm in the process of converting to 3-phase. So my switches will go by the
                                            >wayside. I will wire control signals back to the VFD. Probably an EMO to
                                            >shut the VFD down,, a REV/OFF/FWD rotary >switch, and a potentiometer.
                                            >Sounds like the on/off switch can't be used as EMO because the solenoid
                                            >needs 110V. Maybe I'll add an RPM readout also, because I will try to
                                            >preserve the existing >gearing to always be able to get into a good torque
                                            >range.
                                          • Gary Harper
                                            Emergency Off From: mlathemods@yahoogroups.com [mailto:mlathemods@yahoogroups.com] On Behalf Of Tim Gunn Sent: Friday, June 02, 2006 12:56 PM To:
                                            Message 21 of 25 , Jun 2, 2006
                                              Emergency Off





                                              From: mlathemods@yahoogroups.com [mailto:mlathemods@yahoogroups.com] On
                                              Behalf Of Tim Gunn
                                              Sent: Friday, June 02, 2006 12:56 PM
                                              To: mlathemods@yahoogroups.com
                                              Subject: [mlathemods] Re: Lathemaster 8x14 shutting itself of under load



                                              What is an EMO? I can manage the other TLAs (three-letter acronyms), but
                                              this has me stumped. I am guessing at some form of self-holding relay with
                                              No-Volt Release to ensure it does not restart itself after a power loss.

                                              Going 3-phase with a Variable Frequency Drive needn't necessarily mean
                                              getting rid of the existing switches. If you are used to them, you can
                                              probably wire the contacts back to the VFD control terminals so that the
                                              start, stop and reverse functions are where you expect them to be; this may
                                              be a significant safety consideration for some people.

                                              Most VFDs seem to be pretty freely configurable on the digital inputs. so
                                              you should have no trouble making it work as if it had an NVR. I would fit
                                              some means of disconnection on the (single phase?) supply side of the VFD to

                                              allow isolation when changing belts, etc. I use an RCBO; combined earth
                                              leakage circuit breaker and thermal/magnetic overcurrent breaker. I have no
                                              idea what it would be called west of the pond.

                                              Which VFD are you using? I used a Siemens G110 and am not overly impressed
                                              with it. I much prefer the Telemechanique Altivar 11 and really love the
                                              AutomationDirect GS2, both of which I have used at work.

                                              Regards

                                              Tim Gunn

                                              >Of course there is also this common-sense thing of looking at the chips
                                              >coming off, listening to the chatter etc. It's easy to know when it's
                                              >right - not quite so easy when it's wrong, and how to correct :-)
                                              >
                                              >I'm in the process of converting to 3-phase. So my switches will go by the

                                              >wayside. I will wire control signals back to the VFD. Probably an EMO to
                                              >shut the VFD down,, a REV/OFF/FWD rotary >switch, and a potentiometer.
                                              >Sounds like the on/off switch can't be used as EMO because the solenoid
                                              >needs 110V. Maybe I'll add an RPM readout also, because I will try to
                                              >preserve the existing >gearing to always be able to get into a good torque
                                              >range.









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                                              [Non-text portions of this message have been removed]
                                            • Richard Kleinhenz
                                              EMO = Emergency Machine Off or Emergency Off Well, I don t like the on/off switch arrangement on the 8x14. The covered button to turn power on is a royal
                                              Message 22 of 25 , Jun 2, 2006
                                                EMO = Emergency Machine Off or Emergency Off

                                                Well, I don't like the on/off switch arrangement on the 8x14. The covered button to turn power on is a royal pain, IMO. I prefer using the rotary switch next to it - but it trips my machine all the time. So I will wire a rotary switch to the VFD and have it my way :-)

                                                My VFD is a Reliance Electric, bought used. Made by Rockwell Automation. It's nothing to write home about, but it works. And yes, I put a wall switch right next to the VFD. This VFD has a constant fan running - hardly consumes any power I'm sure, but it's a low-level hum that's just not necessary.

                                                The only other VFD I know is the Teco Westinghouse FM100 which is a more modern unit and a bit nicer.

                                                --
                                                Regards,
                                                Rich
                                                ================================
                                                Richard Kleinhenz
                                                http://beautifulhandmadepens.com
                                                http://www.woodpens.com/rkleinhenz.htm
                                                ================================
                                              • Roy E. Burrage
                                                You might check the rating on your motor, Rich. Not all motors are rated for variable frequency drive and you might destroy it along with the drive. Unless
                                                Message 23 of 25 , Jun 2, 2006
                                                  You might check the rating on your motor, Rich. Not all motors are
                                                  rated for variable frequency drive and you might destroy it along with
                                                  the drive. Unless specified for VFD, a motor must run at or near its
                                                  rated speed in order to provide adequate cooling...even under light load
                                                  conditions.


                                                  REB


                                                  Richard Kleinhenz wrote:

                                                  >EMO = Emergency Machine Off or Emergency Off
                                                  >
                                                  >Well, I don't like the on/off switch arrangement on the 8x14. The covered button to turn power on is a royal pain, IMO. I prefer using the rotary switch next to it - but it trips my machine all the time. So I will wire a rotary switch to the VFD and have it my way :-)
                                                  >
                                                  >My VFD is a Reliance Electric, bought used. Made by Rockwell Automation. It's nothing to write home about, but it works. And yes, I put a wall switch right next to the VFD. This VFD has a constant fan running - hardly consumes any power I'm sure, but it's a low-level hum that's just not necessary.
                                                  >
                                                  >The only other VFD I know is the Teco Westinghouse FM100 which is a more modern unit and a bit nicer.
                                                  >
                                                  >--
                                                  >Regards,
                                                  >Rich
                                                  >================================
                                                  >Richard Kleinhenz
                                                  >http://beautifulhandmadepens.com
                                                  >http://www.woodpens.com/rkleinhenz.htm
                                                  >================================
                                                  >
                                                  >
                                                  >


                                                  [Non-text portions of this message have been removed]
                                                • Mike Jones
                                                  David, Yes, there is an answer. The lathe is running dead slow, amp draw is high at that speed and the motor is not running fast enough to keep itself cool, so
                                                  Message 24 of 25 , Jun 3, 2006
                                                    David,

                                                    Yes, there is an answer. The lathe is running dead
                                                    slow, amp draw is high at that speed and the motor is
                                                    not running fast enough to keep itself cool, so the
                                                    termal discontact kicked out and stopped the motor
                                                    till it cooled down sufficiently to run safely again.
                                                    Electric motors must run fast enough to keep
                                                    themselves cool.

                                                    Mike Jones

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                                                  • Richard Kleinhenz
                                                    That s a good point, Roy, but I will chance it, since I have the motor, and the price was right. How would I know of such a rating? I am waiting for a buddy
                                                    Message 25 of 25 , Jun 3, 2006
                                                      That's a good point, Roy, but I will chance it, since I have the motor, and the price was right. How would I know of such a rating?

                                                      I am waiting for a buddy of mine to build me an angle mounting plate right now, don't know when I get to try it. A TEFC motor will draw little air at low speed. What sort of enclosure or rating would I look for, if this thing does not survive? I only ran it without load to test, so of course with a load there will be more heat generated - will have to see

                                                      On 6/2/2006 at 6:55 PM Roy E. Burrage wrote:

                                                      >You might check the rating on your motor, Rich. Not all motors are
                                                      >rated for variable frequency drive and you might destroy it along with
                                                      >the drive. Unless specified for VFD, a motor must run at or near its
                                                      >rated speed in order to provide adequate cooling...even under light load
                                                      >conditions.

                                                      --
                                                      Regards,
                                                      Rich
                                                      ================================
                                                      Richard Kleinhenz
                                                      http://beautifulhandmadepens.com
                                                      http://www.woodpens.com/rkleinhenz.htm
                                                      ================================
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