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Re: [atlas_craftsman] ER40 Collete Chuck

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  • Robert Silas
    Scott, You can center a round piece in a 3 jaw chuck too. I use different plates thickness, copper plates and bend it around one of the jaw, or around 2 jaws,
    Message 1 of 9 , Mar 31, 2009
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      Scott,
      You can center a round piece in a 3 jaw chuck too. I use different plates
      thickness, copper plates and bend it around one of the jaw, or around 2
      jaws, it's a bit of a pain but with some luck it could work, as it did in
      the past.

      Talking about the nut again, if you have some welding equipment you can cut
      an internal thread in a tube section, then weld a pre-turned end onto it,
      screw it on the spindle, finish outside of the nut, surface and end, center
      it in a chuck and with a hole-tool finish the inside of the welded
      end-plate. I've done this before, though not for your purpose.

      Cutting metric thread on the 10" Atlas is not a problem, the table inside
      the cover gives the change gear arrangement. The only thing is that once you
      locked the half-nuts you cannot open it till the job is finished. Tell you
      the truth, it happened that I had to open it, or opened it accidentally. In
      that case first I locked the half nut, then moved the carriage to the right
      against the screw to take up the slop, then went into the thread with the
      tool using the cross-slide and the compound and taking small cuts I finished
      the job. When I did this I had no reversing switch on the motor and for each
      cut I backed the carriage back by turning the countershaft by hand while
      keeping the half nut locked.
      Robert

      ----- Original Message -----
      From: Scott Henion
      To: atlas_craftsman@yahoogroups.com
      Sent: Wednesday, April 01, 2009 12:54 AM
      Subject: Re: [atlas_craftsman] ER40 Collete Chuck


      Robert Silas wrote:
      > Scott,
      > Nice pictures and write up.
      > Could you have used the outside nut came with the set??
      >

      Yes, but I am on a budget. I hope the sell the MT3-->ER40 adapter. It is
      not worth much without the nut.

      I just found one on ebay for $10+shipping. Guess I will learn how to cut
      metric threads ;)

      > BTW, to polish aluminum on the lathe try final sanding with an 800 paper
      > and
      > oil, motor oil is ok. I even used 1000 and 2000 papers. My sons own a bar
      > and I made 7 beer-tap handles which was finished as above. Mirror finish,
      > no
      > scratch marks.
      > Robert
      >

      I used a buffing wheel on a drill with a mild compound. Run lathe and
      use wheel at a alternating 45 degree angles. Works well. If there is any
      grooving, I'll use some 1000 grit sandpaper first.

      I tested it with some 3/4" 12L14 steel (not precision ground.) I could
      vary the center by adjusting the 3 screws. Turns out my angle on the
      8-degree taper was off a bit. I had used a collet and did the taper
      until it fit with no rocking front or back (and spun it to see if it was
      rubbing more front or back.) Guess the real test is with something _in_
      the collet. Then had a slightly different angle. Touched up the taper
      and now it works perfectly. You can tighten only one screw and the work
      hardly moves.

      Now measuring again with the 12L14 bar, I get less than 0.001" wobble in
      a test gauge. Turns out it wobbles 2 times per revolution so i guess the
      bar is not perfectly round. Extended about 3" out and slowly advanced
      the cutter near the end with the lathe running at about 20 rpm. As soon
      as the cutter touched, it did a 360 degree groove. ;)

      It is not perfect, but much better than my 3-jaw and faster to set up
      than the 4-jaw. This turned out cheaper than getting a better 3-jaw
      chuck. The scroll on mine is worn and does not center consistently.

      As most of what I do is 1 inch or less, this works perfectly. Well not
      for my hex stock though ;)

      <Scott>

      --

      ------------------------------------------
      | Scott G. Henion| shenion@... |
      | http://shdesigns.org/Craftsman-12x36/ |
      ------------------------------------------






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    • Scott Henion
      I mentioned the thread table in my Atlas manual was wrong. It cut a 1.5 threads per mm instead of 1.5mm per thread. I found a later table and it was completely
      Message 2 of 9 , Apr 12, 2009
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        I mentioned the thread table in my Atlas manual was wrong. It cut a 1.5
        threads per mm instead of 1.5mm per thread.

        I found a later table and it was completely different. Tried out this at
        1.5mm and it cut 1 thread = 3mm. It was odd the table used the 32-tooth
        idler gear while the other table used the 16. By switching to the
        16-tooth( flip over all gear stacks), I had a good 1.5mm thread.

        Of course, I ruined the ER40 collet chuck adapter I was making by
        cutting the wrong thread. Tried to TIG up the trheads, but this 6063
        takes a lot of heat, could not fill it with my 4043 wire, it just melted
        before I got to the weld pool. So, grabbed the MIG, some 5356 wire and
        used the lathe as a work positioner and welded up the adapter. I did
        make a brass plug that fit the back end of the spindle that had a
        sliding contact for the work lead from the welder (kinda like a sleeve
        bearing but no oil.)

        After welding, turned it again down to 50mm. The cut some decent 1.5mm
        threads. The adapter finally came out well. Will be nice for smaller
        stuff. Often times I need to reverse the work to make adapters between
        two shafts. With a standard chuck, I usually had some wobble. This
        should be more accurate and repeatable.

        The whole steps in making the chuck and the welding is described on my
        pages here:

        http://shdesigns.org/Craftsman-12x36/er40.shtml

        BTW, the MT3 to ER40 adapter shown at the top of the above page is no
        longer needed. It is listed for about $35 on ebay with shipping. If
        anyone wants one, I'll sell it for $25 including shipping to anyone who
        wants it. You would just need to buy some collets. Contact me off list
        if interested.

        --
        ------------------------------------------
        | Scott G. Henion| shenion@... |
        | Consultant | Stone Mountain, GA |
        | SHDesigns http://www.shdesigns.org |
        ------------------------------------------

        today's fortune
        The autodecrement is not magical.
        -- Larry Wall in the perl man page
      • anthrhodes@aol.com
        Scott, Would you post to the group or send to me privately the three gear trains for 1.5 mm pitch which produced the different pitches (0.667, 3.0, and 1.5 mm
        Message 3 of 9 , Apr 12, 2009
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          Scott,

          Would you post to the group or send to me privately the three gear trains
          for 1.5 mm pitch which produced the different pitches (0.667, 3.0, and 1.5
          mm respectively)? I'm interested in gear trains for screw cutting and would
          like to see the variants.

          Thanks.
          Anthony
          Berkeley, Calif.
          ***************************************************

          In a message dated Sun Apr 12, 2009 7:38 pm (PDT), Scott Henion writes:

          I mentioned the thread table in my Atlas manual was wrong. It cut a 1.5
          threads per mm instead of 1.5mm per thread.

          I found a later table and it was completely different. Tried out this at
          1.5mm and it cut 1 thread = 3mm. It was odd the table used the 32-tooth
          idler gear while the other table used the 16. By switching to the
          16-tooth( flip over all gear stacks), I had a good 1.5mm thread.


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          [Non-text portions of this message have been removed]
        • Scott Henion
          ... In the files area of the group, there is a folder called Thread Gear Programs Download the generalthread.zip. Enter in the gears including the double
          Message 4 of 9 , Apr 13, 2009
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            anthrhodes@... wrote:
            > Scott,
            >
            > Would you post to the group or send to me privately the three gear trains
            > for 1.5 mm pitch which produced the different pitches (0.667, 3.0, and 1.5
            > mm respectively)? I'm interested in gear trains for screw cutting and would
            > like to see the variants.
            >
            >

            In the files area of the group, there is a folder called "Thread Gear
            Programs" Download the generalthread.zip.

            Enter in the gears including the double tumbler gear. I put in 0.07%
            maximum error and it found the same set of gears that worked:

            1.5mm thread on 12x36
            _position_ - Back/Front
            Lead screw - 44/S
            Pos C - 52I/40S
            Pos A - 20S/46I
            Tumbler - 16

            For 3mm, swap inner/outer gears/spacers to use the 32-tooth tumbler.

            0.667 (1.5mm pitch in the manual that is wrong)

            Lead screw: 44
            Pos C - 52/40
            Pos A - 20S/64I
            Tumbler - 16

            These all give 0.060% error using the 52/44 gear ratio instead of a 127
            tooth gear.

            The program works, takes a bit of thinking how to set up the gears.
            --

            ------------------------------------------
            | Scott G. Henion| shenion@... |
            | http://shdesigns.org/Craftsman-12x36/ |
            ------------------------------------------
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