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NEW Leadscrew for Atlas/Craftsman 6" lathe from Clausing

Discussion in 'ATLAS, CRAFTSMAN & AA' started by SG51Buss, Feb 13, 2015.

  1. SG51Buss

    SG51Buss United States Active User Active Member

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    I've been meaning to replace the 65 year old leadscrew on my Atlas/Craftsman 6x18 101.07301 6" lathe for over 25 years.
    The Acme threads look like V-threads in the middle of the screw.
    I had investigated 3 options:

    1- Cut/machine/join a piece of precision Acme threaded rod to the original.
    -- Couldn't find precision 1/2" - 16 TPI Acme rod, without expensive special order.

    2- Acquire an eBay item.
    -- After looking at various eBay $25-$100 offerings, I just knew there would be wear and other secret problems.

    3- Buy a new one from Clausing or Sears.
    -- Sears wanted $180, Clausing $148

    The new LeadScrew from Clausing arrived in 3 days in a stout cardboard tube.
    It had been pickled and wrapped very thoroughly.:ups:

    LeadScrew-3950-16.jpg

    The original part number, L9-35, has been superceded by part number 3950-16, which includes the fitted thrust collar.
    The parts support representative at Clausing said they had been out-of-stock, and have replenished the supply from a new run in September 2014.

    Clausing Service Center
    2019 North Pitcher St.
    Kalamazoo, Michigan 49007-1822
    (800) 323-0972

    LeadScrew-3950-16.jpg
     
    Charles Spencer likes this.
  2. SG51Buss

    SG51Buss United States Active User Active Member

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    Be advised that this new leadscrew is not a drop-in replacement.
    Need to do some meticulous work. :fingerwag:

    Cleaned off the new leadscrew and checked for straightness.
    Found a very slight bend, only about 0.005" runout. Got it to less than 0.002".

    Leadscrew-AxTrue.jpg

    Leadscrew-AxTrue.jpg
     
  3. SG51Buss

    SG51Buss United States Active User Active Member

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    The thrust collar, as fitted, is about 0.285" thick.
    The stud spacers that fit between changegears and the banjo are 1/4" thick.
    To provide proper gear alignment, and clearance to any large gears that may run behind a spaced-out leadscrew gear, the thrust collar needs to be faced down to 0.247".

    The threaded/keyed end of the leadscrew holds the leadscrew gear and its spacer.
    Since the gears and spacers are 3/8" wide, their total width is 3/4".
    To ensure that the leadscrew's gear clamping screw presses against the gear/spacer, and not prematurely bottom on the leadscrew shaft, the protruding end of the leadscrew needs to be a little shorter.
    In this case, 0.735" will work.

    Here are the dimensions of the original ~1950 leadscrew end.

    LeadScrew-Dims.jpg

    LeadScrew-Dims.jpg
     
  4. SG51Buss

    SG51Buss United States Active User Active Member

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    Measure the new leadscrew's thrust collar and protrusion.
    With the above dimensions in mind, perform the appropriate facing cuts.

    LeadScrew-Facing.jpg

    LeadScrew-Facing.jpg
     
  5. SG51Buss

    SG51Buss United States Active User Active Member

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    The tops of the threads of the new leadscrew were slightly distorted from thread forming.
    Instead of squared/flat tops, they had a slight "U" shape.
    This made the leadscrew's outside diameter about 0.503"-0.504", too big to fit through the original support bearing.
    The leadscrew had to be turned and carefully fine-filed and stoned to a diameter of about 0.4995"-0.5000".

    This pic shows a close-up of the reworked new leadscrew, the thread tops resurfaced and flat.
    The original 65 year old leadscrew shows V-shape thinning of its threads.

    LeadScrew-Thread.jpg


    Want minimal wear on bearings and half-nuts.
    So, finely sanded any rough spots and burrs, then polished the threads and shaft bearing surfaces.
    Thoroughly clean, wipe everything down with a "red shop rag".
    If any red fibers can be found on a surface, it needs to be polished some more.

    This new leadscrew works great...:morningcoffee:

    LeadScrew-Thread.jpg
     
  6. Crafted

    Crafted United States Youtube's Crafted channel Registered Member

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    My QC42 is worn sharper than that. Great post. Learned something. I'll be replacing mine as part of my refurb. I remember 18 years ago when I obtained it. I bought some parts that were missing, replaced a broken handle, purchased the milling attachment. However, I remember choking at the screw price. Wish I had gotten it then.
     
    Round in circles likes this.
  7. great white

    great white Active User Active Member

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    Great post. Subscribed for future ref!

    :thumbzup:
     
  8. SG51Buss

    SG51Buss United States Active User Active Member

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    Thanx, guys. Just another "measure twice, cut once" type of thread.

    It would be great if someone could comment/confirm that thrust collar dimension.
    The 0.285" thickness may actually be correct for a different 6" lathe, I just don't know...
     
  9. T Bredehoft

    T Bredehoft Active User H-M Supporter-Premium

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    My pre-1963 (no Zip Code) Atlas Clausing 6" x 18" very nearly unused lathe had a .237-8 spacer.

    As to mis-alignment of the lead screw, I disassembled the compound and lead screw to clean dried grease from them, upon re-assembly I first put in the lead screw and secured it, the slid the compound onto the ways.I had to lift the end of the lead screw about quarter inch. This put a bind on the screw where it went through the frame. I removed the compound and put the support for the right end of the lead screw on the screw. I had to raise it about 1/4 in to get the screws in.

    Tom
     
  10. wa5cab

    wa5cab Downloads Moderator Staff Member H-M Supporter-Premium

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    Steve,

    The part number 3950-16 indicates that it was made for the 6" MK2. I wasn't aware that there was any difference but that's handy to know. Unfortunately, we don't have the drawing of the original part.
     
  11. Tailormade

    Tailormade United States Iron Registered Member

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    I know this is an old post, so appologies if that is frowned on around here, but since no one else commented on it, I was wondering if you had any further info on this interesting straightening jig/setup on what appears to be your wood lathe.
     

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