Need Ideas for non concentric turning
Largest Manufacturing Technology
Community On The Web
Close
Login to Your Account

Page 1 of 2 12 LastLast
Results 1 to 20 of 26
  1. #1
    Join Date
    Mar 2004
    Location
    Waukesha, WI
    Posts
    7,315
    Post Thanks / Like
    Likes (Given)
    668
    Likes (Received)
    1751

    Post

    I have a part to make where the O.D. runs out from the I.D. by .056. In other words, the I.d. will be machined first, and then I need to fixture it so the I.D. is running out by .056, and then I can turn the O.d. Part is going to have a .500 - .503 I.D., and will be 1.9 inches in length. Really not a hard part at all, just need some good ideas.

  2. #2
    Join Date
    Apr 2003
    Location
    Portland, ME, USA
    Posts
    2,086
    Post Thanks / Like
    Likes (Given)
    3
    Likes (Received)
    3

    Post

    Mount in 4-jaw, machine the ID.
    Get some dial indicators and move the part .056" off center in the chuck, then turn OD.

    Or drill the hole, then mount it on an expanding collet in the mill and mill circles around the outside.

  3. #3
    Join Date
    Mar 2004
    Location
    Waukesha, WI
    Posts
    7,315
    Post Thanks / Like
    Likes (Given)
    668
    Likes (Received)
    1751

    Post

    Ok, dopey me left out an important piece of information. This part I have to make will be a 500 piece order. Sorry. Needs to be fast loading and unloading.

    I'll take my dope slap to go please.

  4. #4
    Join Date
    Aug 2003
    Location
    PA
    Posts
    1,402
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    4

    Post

    Mount expanding collet in collet block, and mill the offset on the collet, or, put in 4-jaw, and turn the offset.

    RAS

  5. #5
    Join Date
    Jun 2002
    Location
    U.S.A.
    Posts
    123
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    0

    Post

    I do some larger parts by turning an ATS expanding mandrel off-center, but due to your small id size and long length this might not work, is there any way you can turn the od first then holding off-center in the collet/pads?

  6. #6
    Join Date
    Mar 2004
    Location
    Waukesha, WI
    Posts
    7,315
    Post Thanks / Like
    Likes (Given)
    668
    Likes (Received)
    1751

    Post

    Ras,

    I don't have a 4 jaw for my cnc lathe, and it would be expensive to buy one for this job, as I'm not sure this job will repeat. It could be one time only.

    dcrace,
    I guess I should describe a little more of the part. There is an O.d. and an I.D that run true to each other, and then there will be 2 flanges on the ends that need to run out from the rest of the part. So, there really is nothing left to chuck on with the O.D.
    I already thought of using an expanding collet from Mitee-bite. I will machine it down for the .5015 grip, and then mount it off center by .056, and then I can turn the O.D.

    I'm still open to other ideas though, just in case there's something I haven't thought of yet.

    Appreciate the help so far.

  7. #7
    Join Date
    Feb 2005
    Location
    Ann Arbor, Michigan USA
    Posts
    1,336
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    3

    Post

    Dave:

    Is the runout the radial offset or is it TIR? Needs to be defined. What accuracies are required.

    Turn the concentric stuff, then circular mill the offset items.

    Run on a lathe that can do eccentric turning.

    If the part is steel use a cam grinder to create the eccentric elements.

    .

  8. #8
    Join Date
    Jun 2001
    Location
    downhill from Twain\'s study outside Elmira, NY
    Posts
    10,559
    Post Thanks / Like
    Likes (Given)
    3726
    Likes (Received)
    3498

    Post

    I've posted these parts a few times. Everthing here is offset including the axis of the ball on the threaded stud.

    Does not have to cost much. Bore a 5c extended reach collet, and make inserts to fit the bore. (the collet bore is on center, the inserts are bored in a mill to whatever offset is needed).

    I usually bore the inserts by mounting the collet set up in a hardinge dividing head, because everthing fits just like on the lathe. Close the collet, bore the insert, then remove it and saw the compression slots on a band saw.

    But any method that keeps the bore axial (parallel to the long axis) will work. This one is 1-3/4" bore due to the fact that I had a bar of that size aluminum to chop off whenever a new insert is needed. If you are going to run 500 parts, it would be worth starting with steel. Aluminum does wear and ther edges round a bit over time.



    smt

    smt

  9. #9
    Join Date
    Mar 2004
    Location
    Waukesha, WI
    Posts
    7,315
    Post Thanks / Like
    Likes (Given)
    668
    Likes (Received)
    1751

    Post

    The runout is radial offset. Accuracies are only plus or minus .005.

    If I run the eccentric on a mill, I will need to do both sides individually since they are on opposite ends of the part. That would mean two times of chucking. On a lathe, I can chuck only one time and turn both ends. I don't have a lathe that does eccentric turning. Needs to be fast. There are 500 pcs to do.

  10. #10
    Join Date
    Mar 2004
    Location
    Waukesha, WI
    Posts
    7,315
    Post Thanks / Like
    Likes (Given)
    668
    Likes (Received)
    1751

    Post

    Stephen,

    Sounds interesting, but I can't see the pics. Is it just me or did something go wrong?


    EDIT: Nevermind, it just opened up.

  11. #11
    Join Date
    Mar 2005
    Location
    Kansas
    Posts
    6,244
    Post Thanks / Like
    Likes (Given)
    304
    Likes (Received)
    2414

    Post

    I'm still a little vague on this part. Are you going to finish the id complete, then do the od to the offset finished id?

    You can mount them on a mandrel with offset centers. Put a dog on the mandrel and run them between centers. For faster cycle times, make two mandrels.

  12. #12
    Join Date
    Mar 2004
    Location
    Waukesha, WI
    Posts
    7,315
    Post Thanks / Like
    Likes (Given)
    668
    Likes (Received)
    1751

    Post


  13. #13
    Join Date
    Mar 2004
    Location
    Waukesha, WI
    Posts
    7,315
    Post Thanks / Like
    Likes (Given)
    668
    Likes (Received)
    1751

    Post

    I will do the O.D. and I.D. together. Then I want to I.D. chuck offcenter, and turn the two ends.

  14. #14
    Join Date
    Mar 2004
    Location
    Waukesha, WI
    Posts
    7,315
    Post Thanks / Like
    Likes (Given)
    668
    Likes (Received)
    1751

    Post

    You can mount them on a mandrel with offset centers. Put a dog on the mandrel and run them between centers.
    What would drive the part? If the dog drives the mandrel, what's stopping the part from spinning on the mandrel?

  15. #15
    Join Date
    Feb 2007
    Location
    Coquitlam, BC, Canada
    Posts
    373
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    0

    Post

    Heres a shaft i turned



    bolted the 4 jaw to the mill...dialed it in and zeroed the axises over center..cranked X over 1.500 (1 thou tol on offset and runout), tossed the 3 jaw on and kept adjusting the 4 jaw till the 3jaw was zeroed....clamped, bolted, bolted on counter weight...mounted on lathe, dialed rough part in (machined it in 3 peices, then pressed the shafts into the plate and welded)

    part came out perfect (3 0.0005 dia on one side and a 0.001 tol dia on the other)

  16. #16
    Join Date
    Mar 2007
    Location
    East Anglia - England
    Posts
    45
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    0

    Post

    Dave - due to the qty i would either make an offset mandrel with a drill tapped end and use a bolt to nip the part in place or

    make an offset split bush to locate on the centre dia. - hold this in bored jaws on cnc turn end 1 turn comp. around turn end 2

    Smudge

  17. #17
    Join Date
    Mar 2002
    Location
    Scotland
    Posts
    4,240
    Post Thanks / Like
    Likes (Given)
    1019
    Likes (Received)
    468

    Post

    This part can be made on a cnc lathe with driven tooling in one hit.Probably make more profit and certainly less hassle subbing it out.Even easier on a swiss if you can find someone who can be bothered setting up for 500 pieces.

  18. #18
    Join Date
    Mar 2004
    Location
    Waukesha, WI
    Posts
    7,315
    Post Thanks / Like
    Likes (Given)
    668
    Likes (Received)
    1751

    Post

    Smudger,

    Yeah, that's kinda the ideas I had in mind, but I posted this in hopes that someone would have some magical idea for it.

    Mark,

    I don't have a lathe with driven tooling. Subbing it out would defeat the purpose of taking the job in the first place.

  19. #19
    Join Date
    Aug 2005
    Location
    Bremerton, Wa
    Posts
    2,589
    Post Thanks / Like
    Likes (Given)
    62
    Likes (Received)
    60

    Post

    If you are holding on the OD, use an Emergency 5C collet and machine the bore .056 off center.
    If you are holding on the ID, do the same thing with an expanding mandrel
    I do this all the time. Then I can run them in my turning center just like any other part.

  20. #20
    Join Date
    Mar 2004
    Location
    Waukesha, WI
    Posts
    7,315
    Post Thanks / Like
    Likes (Given)
    668
    Likes (Received)
    1751

    Post

    I'm going to use the expanding mandrel offcenter. That way the only thing I need to cut while off center, is the 2 ends. I think it's the best I'm going to get.

    Thanks to everyone for the ideas. Still open for that magic wand type idea.


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
  •