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Collets

Discussion in 'SOUTH BEND LATHE WORKS' started by ebolton, Mar 18, 2017.

  1. ebolton

    ebolton United States Iron Registered Member

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    I could use a primer on collets. I inherited my 1966 9A lathe, and it came with the handwheel draw tube, 3 identical collet closers, and 14 collets from 1/16 to 7/16 including a 1/4" square collet. Some of the collets appear to be original South Bend parts, and are marked with the number 3 along with the size. Some are just marked 3 along with the size, and I guess they are 3rd party. Some aren't marked at all, and appear to be custom diameters for some job the original user must have needed.

    I just turned a knob for my motorcycle using one of the collets, and it worked out well.

    I was wondering what I should look for if I wanted to expand the collection. Will any Morse Taper 3 collet work?

    I am new to this equipment so please go easy on me-

    -Ed
     
  2. john.oliver35

    john.oliver35 United States H-M Supporter - Premium Content H-M Supporter-Premium

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    Because you say draw 'tube' I presume the tube is hollow and not a solid drawbar? If used with a hollow tube closer, then these likely not MT3 collects but 3C collets. My understanding is that these were standard on the South Bend 9 lathes.
     
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  3. ebolton

    ebolton United States Iron Registered Member

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    It is hollow. Most of the collets are engraved "South Bend", the size, and "3". No other identification.
     
  4. Dave Paine

    Dave Paine United States Active Member Active Member

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  5. ebolton

    ebolton United States Iron Registered Member

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    Perfect! This is the kind of info I am looking for.

    -Ed
     
  6. woodtickgreg

    woodtickgreg United States Active User H-M Supporter-Premium

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    My little Burke no. 4 vertical attachment takes 3c collets as well.
     
  7. ewkearns

    ewkearns United States Active Member Active Member

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    The South Bend #3 collet was the same as a 3C collet....
     
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  8. ebolton

    ebolton United States Iron Registered Member

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    OK, so I can look at 3c collets.

    Question, how far off the nominal size can 3c collets hold? I notice the free dimension for the SB 3 collets that I have measures +.010 over the nominal dimension. The part I just turned in the 1/4" collet measured .240 diameter, which is -.010 of course. Held fine through most of the process, but chattered like crazy when I tried to part it off. I cut it with a hacksaw then faced it instead.

    Any and all information is appreciated.

    -Ed
     
  9. Dave Paine

    Dave Paine United States Active Member Active Member

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    I do not know the grip range for 3C, but 10 thou feels like it should grip.

    Chattering when parting may not be due to the collet. So many variables can impact parting. Tool, relief angle, spindle speed, feed rate, type of metal, width of parting tool. I have often experienced chattering. More experienced forum members may have advise. I would look at some YouTube videos. Toms Techniques, Joe Pieczynski are two example channels.
     
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  10. Bob Korves

    Bob Korves H-M Supporter - Premium Content H-M Supporter-Premium

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    Try not to go more than .005" off the nominal size to get a good hold. The closer to nominal, the better the hold.
     
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  11. woochucker

    woochucker United States Active Member Active Member

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    As John said you have a 3c collet, I have a 194?? 9a, it's a 3C.
     
  12. woochucker

    woochucker United States Active Member Active Member

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    Well it might have been the collet, you may only have had a bite on it and the very end, rather than along the area that is made to hold parts.. not sure how much. So yes, it could have chattered from that.
    It also could have chattered from too much stick out on the parting tool, from loose gib screws, from not being perpendicular, to being too low with the tool. You want to be dead center when parting. You can put a scale in between the parting tip and the piece and if it is straight up and down you are probably dead center, too high and it leans back, too low and it leans toward you.
    if you part to high it will stop cutting, too low and first chatter, then it can actually lift the part and crash.
     
  13. ebolton

    ebolton United States Iron Registered Member

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    I had issues with parting at first, but it hasn't been an issue for me lately, till I tried this part in the collet. I know of the alignment/adjustment requirements, minimal tool stickout, copious oil, etc. I also know the work has to be maximally supported, and that's where I think the problem was this time. It was chattering badly and cutting only minimally, so I stopped before anything broke and grabbed the hacksaw. Turning and facing went fine.

    I like the collets for being able to take the part out and returning it without runout, and for not marring the part. Beats soft jaws on a chuck by a mile and a half.

    -Ed
     

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