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Re: [multimachine] Midgeport mill assumptions+math

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  • keith gutshall
    Hello Lance I can not find Pat s photo, On a vertical mill the knee lifts every thing.  It is mounted to the column .    An acme thread 1.x5 is only 23%
    Message 1 of 17 , Sep 2, 2010
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      Hello Lance
      I can not find Pat's photo, On a vertical mill the knee lifts every thing.
       It is mounted to the column .
       
       An acme thread 1.x5 is only 23% efficent. Roton Products Inc.
       
       Keith

      Deep Run Portage
      Back Shop
      " The Lizard Works"

      --- On Thu, 9/2/10, Lance <gbof@...> wrote:

      From: Lance <gbof@...>
      Subject: Re: [multimachine] Midgeport mill assumptions+math
      To: multimachine@yahoogroups.com
      Date: Thursday, September 2, 2010, 3:44 PM

       
      Pat,

      I did some prelim assumptive figger'n and this is what I came up with.
      NB:  all math done in SI units and converted back to Imperial


      Load 1000 lbs (knee)  No work piece mass included
      screw  1.5" x 5 tpi
      wheel 14.4 " diameter

      mill is horizontal, zero degrees incline, therefore no part of the knee's
      mass has to be lifted.

      Force needed is inertial+frictional+acceleration
      Assume loads is carried by rolling steel wheels on top of steel plate
      so COF = 0.002. 
      If sliding steel on lubed steel, COF goes up to 0.16 a whopping 80 times more.

      Result:
      An operator force of 2.2 lbs on the wheel will generate
      a knee movement of 0.25" in 1.8 seconds.

      I would CERTAINLY hope some one else does the math to
      check my work.

      If you incline the knee/table, you have to lift some of the knee's mass
      so the effort goes up.
      So, what's the benefit of the tilted knee vs flat?

      lance
      ++++
      On Sep 2, 2010, at 2:36 PM, Pat wrote:

      In the "1 Concrete Mill" photo folder I put a concept drawing of a new type of concrete milling machine. The "knee" could weigh at least a thousand pounds (like real mills). The angle of the incline, the lead screw thread and the handwheel size will have to be figured out by someone smarter than me.


    • Lance
      Hi keith, pat s sketch had the knee lying on a bed at 45 degree back tilt. I figured it lying flat, more like a vise on the bed base. Roton = Great site. So
      Message 2 of 17 , Sep 2, 2010
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        Hi keith,

        pat's sketch had the knee lying on a bed at 45 degree
        back tilt.

        I figured it lying flat, more like a vise on the bed base.

        Roton = Great site.

        So let's use 1.0 x 5 tpi w/ bronze nut 31% at 5000 lbs op rating.

        2.2/31%=7 lbs operator input force.

        What IS an acceptable input force?
        I figured 5 lbs max effort?

        We can make the wheel larger or maybe change the diam of the
        rolling wheel/axle combo.

        lance
        ++++
        On Sep 2, 2010, at 6:07 PM, keith gutshall wrote:

        Hello Lance
        I can not find Pat's photo, On a vertical mill the knee lifts every thing.
         It is mounted to the column .
         
         An acme thread 1.x5 is only 23% efficent. Roton Products Inc.

      • keith gutshall
        Hello Lance  I figured it takes 0.7071lbs of force to lift one pound of weight up a 45* angle  That is no counting friction.    But with the table set at
        Message 3 of 17 , Sep 2, 2010
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          Hello Lance
           I figured it takes 0.7071lbs of force to lift one pound of weight up a 45* angle
           That is no counting friction.
           
           But with the table set at the same angle things are going to slide off it with
           the same force.
           
           Keith

          Deep Run Portage
          Back Shop
          " The Lizard Works"

          --- On Thu, 9/2/10, Lance <gbof@...> wrote:

          From: Lance <gbof@...>
          Subject: Re: [multimachine] Midgeport mill assumptions+math
          To: multimachine@yahoogroups.com
          Date: Thursday, September 2, 2010, 5:33 PM

           
          Hi keith,

          pat's sketch had the knee lying on a bed at 45 degree
          back tilt.

          I figured it lying flat, more like a vise on the bed base.

          Roton = Great site.

          So let's use 1.0 x 5 tpi w/ bronze nut 31% at 5000 lbs op rating.

          2.2/31%=7 lbs operator input force.

          What IS an acceptable input force?
          I figured 5 lbs max effort?

          We can make the wheel larger or maybe change the diam of the
          rolling wheel/axle combo.

          lance
          ++++
          On Sep 2, 2010, at 6:07 PM, keith gutshall wrote:

          Hello Lance
          I can not find Pat's photo, On a vertical mill the knee lifts every thing.
           It is mounted to the column .
           
           An acme thread 1.x5 is only 23% efficent. Roton Products Inc.


        • Lance
          True. The knee weighs 1000# so to move just it would take 707 #. I can t exert that much force, can you? lance ++++
          Message 4 of 17 , Sep 2, 2010
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            True.
            The knee weighs 1000#

            so to move just it would take 707 #.
            I can't exert that much force, can you?

            lance
            ++++
            On Sep 2, 2010, at 7:01 PM, keith gutshall wrote:

            Hello Lance
             I figured it takes 0.7071lbs of force to lift one pound of weight up a 45* angle
             That is no counting friction.
             
             But with the table set at the same angle things are going to slide off it with
             the same force.

          • keith gutshall
            Hello Lance I think it has to do with leverage.The threads on the leadscrew plus a lever arm  a (handle) of the correct lenght would move it fine.   With the
            Message 5 of 17 , Sep 2, 2010
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              Hello Lance
              I think it has to do with leverage.The threads on the leadscrew plus a lever arm
               a (handle) of the correct lenght would move it fine.
               
              With the knee at 45* puts 1000 lbs  of weight on the ways.
               
              Keith

              Deep Run Portage
              Back Shop
              " The Lizard Works"

              --- On Thu, 9/2/10, Lance <gbof@...> wrote:

              From: Lance <gbof@...>
              Subject: Re: [multimachine] Midgeport mill assumptions+math
              To: multimachine@yahoogroups.com
              Date: Thursday, September 2, 2010, 7:21 PM

               
              True.
              The knee weighs 1000#

              so to move just it would take 707 #.
              I can't exert that much force, can you?

              lance
              ++++
              On Sep 2, 2010, at 7:01 PM, keith gutshall wrote:

              Hello Lance
               I figured it takes 0.7071lbs of force to lift one pound of weight up a 45* angle
               That is no counting friction.
               
               But with the table set at the same angle things are going to slide off it with
               the same force.


            • Lance
              Hi Keith, I may not be explaining my idea correctly. If the knee moves vertically, the screw must provide 100% (1000# + work.) = mass + stiction+
              Message 6 of 17 , Sep 2, 2010
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                Hi Keith,

                I  may not be explaining my idea correctly.

                If the knee moves vertically, the screw must provide 100%  (1000# + work.) = mass
                + stiction+ acceleration.

                If the knee moves horizontally, the screw must provide
                for rolling friction and a small acceleration of the mass.
                The full weight of the mass is borne by the ways (bed).

                If the knee is inclined at 45 deg, then the screw must provide
                71% of the mass + rolling friction + acceleration.

                The lowest load on the screw is in the horizontal position
                of the "knee"  ie: a horizontal mill.

                If there is an advantage to the tilted bed, what is it?

                lance
                ++++

                On Sep 2, 2010, at 9:41 PM, keith gutshall wrote:

                Hello Lance
                I think it has to do with leverage.The threads on the leadscrew plus a lever arm
                 a (handle) of the correct lenght would move it fine.
                 
                With the knee at 45* puts 1000 lbs  of weight on the ways.

              • keith gutshall
                Hello Lance  Pat is thinking about a Bridgeport type machine with the knee that moves. He is tilting it over to 45* ,trying to  make the load easier to move.
                Message 7 of 17 , Sep 2, 2010
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                  Hello Lance
                   Pat is thinking about a Bridgeport type machine with the knee that moves.
                  He is tilting it over to 45* ,trying to  make the load easier to move.
                  With the high weight 1000lbs no matter which way it moves it the same weght.
                   
                   After a machine gets to a certian size it is easier just to move the carriage and table
                   the spindle and motor might have a set of ways  to move on.
                  The motor and spindle is easier to move then a large knee.
                   
                  From my view of a tilted bed,There is no advantage to it .It looks dangerous to me,
                  at that angle all the parts will slide off on you foot.
                  I ran a machine a long time ago, and handled large heavy parts.If the bed had of been tilted
                   at 45* it would have been impossable to set up the parts.
                   
                  Keith

                  Deep Run Portage
                  Back Shop
                  " The Lizard Works"

                  --- On Thu, 9/2/10, Lance <gbof@...> wrote:

                  From: Lance <gbof@...>
                  Subject: Re: [multimachine] Midgeport mill assumptions+math
                  To: multimachine@yahoogroups.com
                  Date: Thursday, September 2, 2010, 9:24 PM

                   
                  Hi Keith,

                  I  may not be explaining my idea correctly.

                  If the knee moves vertically, the screw must provide 100%  (1000# + work.) = mass
                  + stiction+ acceleration.

                  If the knee moves horizontally, the screw must provide
                  for rolling friction and a small acceleration of the mass.
                  The full weight of the mass is borne by the ways (bed).

                  If the knee is inclined at 45 deg, then the screw must provide
                  71% of the mass + rolling friction + acceleration.

                  The lowest load on the screw is in the horizontal position
                  of the "knee"  ie: a horizontal mill.

                  If there is an advantage to the tilted bed, what is it?

                  lance
                  ++++

                  On Sep 2, 2010, at 9:41 PM, keith gutshall wrote:

                  Hello Lance
                  I think it has to do with leverage.The threads on the leadscrew plus a lever arm
                   a (handle) of the correct lenght would move it fine.
                   
                  With the knee at 45* puts 1000 lbs  of weight on the ways.


                • Bruce Bellows
                  The only advantage that I see in a set of inclined bed ways would be the positional accuracy of the bed due to it s always resting firmly on the ways because
                  Message 8 of 17 , Sep 2, 2010
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                    The only advantage that I see in a set of inclined bed ways would be the
                    positional accuracy of the bed due to it's always resting firmly on the
                    ways because of it's mass. But that same accuracy can be built into any
                    bed no matter what direction to traveled in.

                    Bruce

                    Lance wrote:
                    >
                    > Hi Keith,
                    >
                    >
                    > I may not be explaining my idea correctly.
                    >
                    > If the knee moves vertically, the screw must provide 100% (1000# +
                    > work.) = mass
                    > + stiction+ acceleration.
                    >
                    > If the knee moves horizontally, the screw must provide
                    > for rolling friction and a small acceleration of the mass.
                    > The full weight of the mass is borne by the ways (bed).
                    >
                    > If the knee is inclined at 45 deg, then the screw must provide
                    > 71% of the mass + rolling friction + acceleration.
                    >
                    > The lowest load on the screw is in the horizontal position
                    > of the "knee" ie: a horizontal mill.
                    >
                    > If there is an advantage to the tilted bed, what is it?
                    >
                    > lance
                    > ++++
                    >
                    > On Sep 2, 2010, at 9:41 PM, keith gutshall wrote:
                    >
                    >> Hello Lance
                    >> I think it has to do with leverage.The threads on the leadscrew plus
                    >> a lever arm
                    >> a (handle) of the correct lenght would move it fine.
                    >> With the knee at 45* puts 1000 lbs of weight on the ways.
                    >>
                    >
                    >
                  • keith gutshall
                    HI Bruce You are correct about a mass staying on the ways. But is mass and brute force the answer? The smaller machines seem to do fine without a lot of mass.
                    Message 9 of 17 , Sep 3, 2010
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                      HI Bruce
                      You are correct about a mass staying on the ways.
                      But is mass and brute force the answer?
                      The smaller machines seem to do fine without a lot of mass.
                      Is mass the answer to the problem,or is it something we have
                      overlooked in our designs?

                      Keith
                      Deep Run Portage
                      Back Shop
                      " The Lizard Works"


                      --- On Thu, 9/2/10, Bruce Bellows <bbellows@...> wrote:

                      > From: Bruce Bellows <bbellows@...>
                      > Subject: Re: [multimachine] Midgeport mill assumptions+math
                      > To: multimachine@yahoogroups.com
                      > Date: Thursday, September 2, 2010, 11:35 PM
                      > The only advantage that I see in a
                      > set of inclined bed ways would be the
                      > positional accuracy of the bed due to it's always resting
                      > firmly on the
                      > ways because of it's mass. But that same accuracy can be
                      > built into any
                      > bed no matter what direction to traveled in.
                      >
                      > Bruce
                      >
                      > Lance wrote:
                      > >
                      > > Hi Keith,
                      > >
                      > >
                      > > I may not be explaining my idea correctly.
                      > >
                      > > If the knee moves vertically, the screw must provide
                      > 100% (1000# +
                      > > work.) = mass
                      > > + stiction+ acceleration.
                      > >
                      > > If the knee moves horizontally, the screw must
                      > provide
                      > > for rolling friction and a small acceleration of the
                      > mass.
                      > > The full weight of the mass is borne by the ways
                      > (bed).
                      > >
                      > > If the knee is inclined at 45 deg, then the screw must
                      > provide
                      > > 71% of the mass + rolling friction + acceleration.
                      > >
                      > > The lowest load on the screw is in the horizontal
                      > position
                      > > of the "knee" ie: a horizontal mill.
                      > >
                      > > If there is an advantage to the tilted bed, what is
                      > it?
                      > >
                      > > lance
                      > > ++++
                      > >
                      > > On Sep 2, 2010, at 9:41 PM, keith gutshall wrote:
                      > >
                      > >> Hello Lance
                      > >> I think it has to do with leverage.The threads on
                      > the leadscrew plus
                      > >> a lever arm
                      > >> a (handle) of the correct lenght would move it
                      > fine.
                      > >> With the knee at 45* puts 1000 lbs of weight on
                      > the ways.
                      > >>
                      > >
                      > >
                      >
                      >
                      > ------------------------------------
                      >
                      > Yahoo! Groups Links
                      >
                      >
                      >     multimachine-fullfeatured@yahoogroups.com
                      >
                      >
                      >
                    • wildstrumph
                      ... I believe it s a design issue. If you examine the old How to Build document from several years ago, you will see that Pat raised the knee with a scissor
                      Message 10 of 17 , Sep 3, 2010
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                        --- In multimachine@yahoogroups.com, keith gutshall <drpshops@...> wrote:
                        >
                        > HI Bruce
                        > You are correct about a mass staying on the ways.
                        > But is mass and brute force the answer?
                        > The smaller machines seem to do fine without a lot of mass.
                        > Is mass the answer to the problem,or is it something we have
                        > overlooked in our designs?

                        I believe it's a design issue. If you examine the old "How to Build" document from several years ago, you will see that Pat raised the knee with a scissor jack, which he placed next to the column. This provides support for the knee close to the column only, allowing the weight of the knee to pull it away from the slides. This caused the slides to jam and prevented the knee from sliding freely despite the nicely gibbed slide assembly.

                        Tipping the machine back 45* could solve the problem (at the expense of introducing others), but so should moving the jack out from the column. I think the ideal place for it is probably below the center of mass for the knee/table/cross-slide. The old knee mills I've seen place the screw near the middle of the knee.


                        --
                        brian
                      • David G. LeVine
                        ... Give me a long enough lever, a fulcrum, and a place to stand and I can...
                        Message 11 of 17 , Sep 3, 2010
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                          On 09/02/2010 08:21 PM, Lance wrote:
                          True.
                          The knee weighs 1000#

                          so to move just it would take 707 #.
                          I can't exert that much force, can you?

                          lance
                          ++++

                          Give me a long enough lever, a fulcrum, and a place to stand and I can...
                        • David G. LeVine
                          ... WARNING: SILLINESS ALERT! Well, you won t have to curse when the cutter grabs something on the knee and flings it across the room into a window, it will
                          Message 12 of 17 , Sep 3, 2010
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                            On 09/02/2010 10:24 PM, Lance wrote:
                            <SNIP>If there is an advantage to the tilted bed, what is it?

                            lance
                            ++++
                            WARNING:  SILLINESS ALERT!

                            Well, you won't have to curse when the cutter grabs something on the knee and flings it across the room into a window, it will have fallen off already!
                          • Lance
                            Group, My camera and I took a walk thru our local concrete yard looking for lathe parts. Found bed, carriage, head and tail stock parts. Concrete can be
                            Message 13 of 17 , Sep 4, 2010
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                              Group,

                              My camera and I took a walk thru our local
                              concrete yard looking for lathe parts.

                              Found bed, carriage, head and tail stock parts.
                              Concrete can be polished smooth to make a
                              sliding surface.

                              Take a look here:


                              http://yhoo.it/d8ohKw
                            • Shannon DeWolfe
                              Lance, I think you would spend more time and effort adding hardware to those pre-cast pieces than you would building forms and pouring with reinforcement,
                              Message 14 of 17 , Sep 4, 2010
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                                Lance,

                                I think you would spend more time and effort adding hardware to those
                                pre-cast pieces than you would building forms and pouring with
                                reinforcement, prestressed rods, threaded inserts, cast in place bars, etc.

                                Regards,

                                Mr. Shannon DeWolfe
                                --I've taken to using Mr. because my name misleads folks on the WWW. I am a 54 year old fat man.


                                On 9/4/2010 7:05 PM, Lance wrote:
                                > Group,
                                >
                                > My camera and I took a walk thru our local
                                > concrete yard looking for lathe parts.
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