Collet chuck body material
Close
Login to Your Account
Results 1 to 5 of 5
  1. #1
    Join Date
    Feb 2002
    Location
    Peralta, NM USA
    Posts
    5,643
    Post Thanks / Like
    Likes (Given)
    48
    Likes (Received)
    462

    Default Collet chuck body material

    I'm making a new body for an existing collet chuck, a Pratt Burnerd LC-15. I never was able to find a chuck with a D1-3 back and finally found a really good deal on one with a different back. So I'm making a D1-3 back. Yeah, I don't really *have* to have it but it's shiny and all that...

    The original is pretty hard, I'd guess about 50-55RC (I didn't break out the hardness checker, a file skates nicely). The fit between parts is very close (almost interference) and the original is ground. I believe I can toolpost grind the 2 inside diameters that need to be close.

    I need to decide on the material to be used. It's a pretty hefty chunk for me - 5"x5" for a finished 4.5"x5" with a 2.2" hole through. I'm thinking of maybe using 4140PH, I know it won't be as hard but I'm not going to use the chuck in any industrial capacity in my home shop. I might rough turn, harden (I have some HT facilities available) and finish grind.

    Thoughts?

  2. #2
    Join Date
    Apr 2010
    Country
    UNITED STATES
    State/Province
    Wisconsin
    Posts
    6,038
    Post Thanks / Like
    Likes (Given)
    4168
    Likes (Received)
    3689

    Default

    Pre Hard is rarely actually more than 25/26 C scale. Throw the lump in, harden and temper it to 43/45, and then machine it. It will machine nicely, leave a great finish, and perform very well for longevity.

  3. Likes Ray Behner liked this post
  4. #3
    Join Date
    Sep 2011
    Country
    UNITED STATES
    State/Province
    Virginia
    Posts
    26,722
    Post Thanks / Like
    Likes (Given)
    7561
    Likes (Received)
    8362

    Default

    Quote Originally Posted by rke[pler View Post
    I'm making a new body for an existing collet chuck, a Pratt Burnerd LC-15. I never was able to find a chuck with a D1-3 back and finally found a really good deal on one with a different back. So I'm making a D1-3 back. Yeah, I don't really *have* to have it but it's shiny and all that...

    The original is pretty hard, I'd guess about 50-55RC (I didn't break out the hardness checker, a file skates nicely). The fit between parts is very close (almost interference) and the original is ground. I believe I can toolpost grind the 2 inside diameters that need to be close.

    I need to decide on the material to be used. It's a pretty hefty chunk for me - 5"x5" for a finished 4.5"x5" with a 2.2" hole through. I'm thinking of maybe using 4140PH, I know it won't be as hard but I'm not going to use the chuck in any industrial capacity in my home shop. I might rough turn, harden (I have some HT facilities available) and finish grind.

    Thoughts?
    I have a coupla slugs of 8620 5 1/4" OD or better by about the same long - IIRC, from a cancelled project as might could do.

    Good-old "ordnance steel" is legendary for being amenable to either/both of through-hardening OR case-hardening at anywhere from mere surface skin to way, way deeply, depending on the need.

    I have a need to do a D1-3 ELSE a Cazaneuve adapter mount in place of a D1-4 Burnerd Multi on their lever-closer meself. Also declining energy levels and free time to ever DO it, what with several OTHER collet systems already here and mounted. Both 10EE and HBX 360 BC I have Jacobs Rubberflex for, which is "similar" if not as good as P-B.

    If of no other aid, I shall be very pleased to at least follow your project!

  5. #4
    Join Date
    Feb 2002
    Location
    Peralta, NM USA
    Posts
    5,643
    Post Thanks / Like
    Likes (Given)
    48
    Likes (Received)
    462

    Default

    lc15_chuck_start.jpgI went with 4140 since I kind of know it. Since I don't know the material state I'm thinking my process will be to rough machine it leaving most everything .010 over, send it out for vacuum heat treat (maybe a couple of anneal cycles first?) then a finish machining. I have the D1-3 end machined now and am about to start the roughing. Looking at the collet chuck the inner sleeve seems to be lapped into the chuck body, the dimensions are odd that way (and the fit is below tenths), so I'm considering grinding close then lapping for the final fit - or sending it out for honing.

    So - thoughts on heat treat? Should I send it out before roughing? I could take it close and get a better through hardness on the thin body sections, I'm thinking that's the best way to go. But I do have some concerns on warping and decarb.

  6. #5
    Join Date
    Sep 2011
    Country
    UNITED STATES
    State/Province
    Virginia
    Posts
    26,722
    Post Thanks / Like
    Likes (Given)
    7561
    Likes (Received)
    8362

    Default

    Quote Originally Posted by rke[pler View Post
    lc15_chuck_start.jpgI went with 4140 since I kind of know it. Since I don't know the material state I'm thinking my process will be to rough machine it leaving most everything .010 over, send it out for vacuum heat treat (maybe a couple of anneal cycles first?) then a finish machining. I have the D1-3 end machined now and am about to start the roughing. Looking at the collet chuck the inner sleeve seems to be lapped into the chuck body, the dimensions are odd that way (and the fit is below tenths), so I'm considering grinding close then lapping for the final fit - or sending it out for honing.

    So - thoughts on heat treat? Should I send it out before roughing? I could take it close and get a better through hardness on the thin body sections, I'm thinking that's the best way to go. But I do have some concerns on warping and decarb.
    How much USE are you likely to put onto it, and how critical the level of perfection, anyway, time it has left to serve yah, and all the other options you are already tooled-up with?

    Seriously. Nothing lasts forever. Spring collets will lobe hard Chrome or a Carbide liner, given time and cycles and used-up collets enough. But that's balls to the walls 3-shift CNC, it ain't "we".

    I'd be tempted to leave it as-had, run a touch-up grind in situ ever' year or so IF/AS/WHEN it actually makes a damn.

    Will it? Even once?

    Disclosure: HAVE the grinders, but all the used closers I have work OK if I but see the collets "clock" into the lobes. The new ones (5C) were under $300, each. ER even less.

    Not intending to invest any real time into any of 'em, life as short as it is has been getting.


Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •