Lathe Chuck Design - Page 2
Close
Login to Your Account
Page 2 of 2 FirstFirst 12
Results 21 to 28 of 28
  1. #21
    Join Date
    Jun 2012
    Location
    Davis Junction, Illinois
    Posts
    156
    Post Thanks / Like
    Likes (Given)
    50
    Likes (Received)
    25

    Default

    Talyrond roundness checking machines had some kind of centering and tilt adjustment on the chuck. I haven't touched one in 20 years...

  2. #22
    Join Date
    Sep 2011
    Country
    UNITED STATES
    State/Province
    Virginia
    Posts
    27,596
    Post Thanks / Like
    Likes (Given)
    7561
    Likes (Received)
    8593

    Default

    Quote Originally Posted by Screwmachine View Post
    I think Hardinge guaranteed 40 millionths on their lathe spindles... You could just get a Moore Nanotech lathe, I'm sure they can advise on chuck options. At 10 millionths you better have surface finish to go along, the Moores can do it.
    Monarch 10EE's were 50 millionths standard, 35 millionths, extra fee. Hardinge would assuredly have seeen to that they competed. LeBlond & Timken did a JV in the mid/late 1960's that claimed tapered roller bearings @ 25 millionths. No idea how long they would HOLD that in-use.



    Time has passed. Lots of time.

    Nanotech, a Moore spin-out, is not the only present-day player.

    The OP may HAVE that need, as it seems "nano" -everything is a growing field.

  3. #23
    Join Date
    Jan 2005
    Location
    The Netherlands
    Posts
    5,816
    Post Thanks / Like
    Likes (Given)
    275
    Likes (Received)
    1489

    Default

    I have made some hydraulic expanding mandrels once
    Very easy
    Just a piece of scrap Turn a shoulder Make a long blind M6 threaded hole in the centre and make a connection from the end of the hole to just before the shoulder
    Weld on a bushing with a decent wallthickness on the piece of scrap Drill a vent hole in the weldment on the front
    Fill the threaded hole with grease with a long srew till it comes out of the vent hole Then block that hole with a set screw
    Then turn it to size
    You clamp the piece by turning the srew It will leak a bit at first but the long thread will seal the grease

    This contraption can clamp really hard So make sure you do not overdo it
    Its a bit like a inverted hydraulic collet chuck
    Make a couple and toss then once they get out of the chuck

    Peter from holland

  4. Likes Lumberjack liked this post
  5. #24
    Join Date
    Mar 2010
    Location
    pacific northwest
    Posts
    1,027
    Post Thanks / Like
    Likes (Given)
    6
    Likes (Received)
    204

    Default

    Quote Originally Posted by Peter from Holland View Post
    I have made some hydraulic expanding mandrels once
    Very easy
    Just a piece of scrap Turn a shoulder Make a long blind M6 threaded hole in the centre and make a connection from the end of the hole to just before the shoulder
    Weld on a bushing with a decent wallthickness on the piece of scrap Drill a vent hole in the weldment on the front
    Fill the threaded hole with grease with a long srew till it comes out of the vent hole Then block that hole with a set screw
    Then turn it to size
    You clamp the piece by turning the srew It will leak a bit at first but the long thread will seal the grease

    This contraption can clamp really hard So make sure you do not overdo it
    Its a bit like a inverted hydraulic collet chuck
    Make a couple and toss then once they get out of the chuck

    Peter from holland
    Peter, I am not sure I understand this. Is the grease expanding the mandrel, or the grease getting between the mandrel and part that clamps?

  6. #25
    Join Date
    Jun 2012
    Country
    UNITED STATES
    State/Province
    Michigan
    Posts
    10,178
    Post Thanks / Like
    Likes (Given)
    3454
    Likes (Received)
    3637

    Default

    How are they going to check it would be my first concern. It would seem a mandrel between centers would be a possible choice.

    Just holding some parts between centers often gets <.001

  7. #26
    Join Date
    Sep 2011
    Country
    UNITED STATES
    State/Province
    Virginia
    Posts
    27,596
    Post Thanks / Like
    Likes (Given)
    7561
    Likes (Received)
    8593

    Default

    Quote Originally Posted by stoneaxe View Post
    Peter, I am not sure I understand this. Is the grease expanding the mandrel, or the grease getting between the mandrel and part that clamps?
    Ermm.. if grease gets between the mandrel and the PART? The part has become a bearing.

    NOW we just call the mandrel an "axle".


  8. #27
    Join Date
    Jan 2005
    Location
    The Netherlands
    Posts
    5,816
    Post Thanks / Like
    Likes (Given)
    275
    Likes (Received)
    1489

    Default

    Quote Originally Posted by stoneaxe View Post
    Peter, I am not sure I understand this. Is the grease expanding the mandrel, or the grease getting between the mandrel and part that clamps?

    The part is clamped because the welded on bushing expands because by turning in the bolt the grease is pressurized and therefore the bushing expands
    wallthickness about 12% of OD is fine Even thicker is possible seeing how little is needed to clamp it

    Once after a production run I had to turn a pully with a keyway It was the correct size
    I put it on and started turning the screw
    Wel I kept turning almost with no resistance
    It turned out the welded on 5mm bushing was pushed in the 10 or 12mm keyway

    Thingking about it
    You could even give the inside of the welded on bushing a profile that compensates somewhat for the arc that you get when expanding
    More material in the middle


    Peter

  9. #28
    Join Date
    Oct 2014
    Country
    UNITED STATES
    State/Province
    Maine
    Posts
    873
    Post Thanks / Like
    Likes (Given)
    96
    Likes (Received)
    404

    Default

    Quote Originally Posted by Badbascom View Post
    Thanks everyone for some great ideas and discussion. The part I turn is an aluminum bushing for lack of a better term. The bushing comes with the ID already sized, my job is to turn the OD down to match a corresponding bore with the TIR of .001 between the ID and OD. This may sound easy however the ID is not perfectly round which I can see on the runout machine plus the ID has intricate fins.

    The first attempt was to use an expanding arbor however the alignment was the problem and the part failed. We finally turned down an aluminum arbor of sorts which the bushing holder pressed over and without disrupting the setup, we pushed the bushing over the holder and did the machining. The bushing marginally passed. If I were to remove and re-install this homemade arbor the alignment would be ruined.

    My thinking was that a good hydraulic expandable arbor with a X & Y tilt and center table would be the trick.
    It sounds like part of the problem is that, with the fins and out-of-roundness, it's very difficult to fix this with an ID arbor without turning a new one each time. If you could adjust the part in rather than trying to fixture it into place exactly correctly, your problem becomes easy.

    Thinking outside the lathe, what if you do this on a mill? Either use a tilting rotary table or put a rotary table on a sine plate. This gets you two axes of tilt on the mill's table, and you get X and Y with the mill's axes. You can sweep the part in with an indicator and get it dead on. Once it's locked in place, do the OD with a reversed boring bar.


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
  •