Results 1 to 15 of 15

Thread: Brass bearings.

  1. #1
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,443

    Thumbs up Brass bearings.

    Hi Guys,

    I need some advice !

    13-09-2019006.JPG 13-09-2019005.JPG 13-09-2019004.JPG
    I've been trying to make some bearings. The pictures show what I've been making !
    My issue is whilst holding these in a square ER32 collet block, they are moving and causing the faces to be machined at an angle. I thought that the collet was not tight enough and have tried with a 12" inch wrench to tighten them further, but they still slip round. This is my third lot and is probably the best of the bunch.

    The threaded bit is 8 mm in diameter and 10 mm long, the head is 10 mm thick and 18 mm diameter before putting the flats on.

    Help !!!
    Best Regards:
    Baron J.

  2. #2
    Join Date
    Apr 2012
    Location
    Healesville
    Posts
    2,129

    Default

    Hi John, maybe fill the hole, you could try tightening a cap screw in them and they might hold tighter with less distortion/flex/crush in the collet.

    cheers, shed

  3. #3
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,443

    Default

    Hi John,

    Thanks for your reply. OK I'll try that ! It hadn't occurred to me that the collet might be crushing the brass.
    I will report back.
    Best Regards:
    Baron J.

  4. #4
    Join Date
    Sep 2009
    Location
    Newcastle
    Posts
    341

    Default

    Lighter cuts when machining to reduce the force?

  5. #5
    Join Date
    Jun 2007
    Location
    sydney ( st marys )
    Age
    64
    Posts
    4,887

    Default

    10 mm is not very much to hold going into a 30mm long collet, they may just be too short for the collet to grip correctly.

  6. #6
    Join Date
    Oct 2011
    Location
    Norwood-ish, Adelaide
    Age
    59
    Posts
    6,542

    Default

    I agree with Peter - the spigot you are holding is not long enough. Screw a piece in to the spigot to extend it or add a loose piece so that the collet has equal diameters along it's length (or at least at both ends) and you will be able to hold it much more firmly.

    Michael

  7. #7
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,443

    Default

    Hi Guys,

    Thank you very much for your replies and very useful suggestions ! Now that you have pointed things out it now makes a lot of sense to me.

    I propose to use a long cap screw and put an 8 mm extension piece screwed on behind the bearing bush. I'll do this today, I can turn down one of the scrap pieces to make one 20 mm long. I did look inside the collet and there is a 30 mm long section without any breaks, so nothing at the back end.

    I will report back, thanks.
    Best Regards:
    Baron J.

  8. #8
    Join Date
    Apr 2009
    Location
    Ballina N.S.W.
    Posts
    644

    Default

    Baron J
    Extending the grip length will help with the holding. I have found by wrapping the diameter with a piece of 600 wed & dry paper with the grit side bearing on the shaft can increase your hold. Are you milling the flats working parallel to the longitudinal axis and taking light cuts?
    Bob

  9. #9
    Join Date
    Feb 2009
    Location
    jilliby nsw
    Age
    71
    Posts
    111

    Default

    Hi, I would place a couple of machinist jacks under the first milled flat to support the work and stop it rotating. Agree with the others that their is insufficient material in the collett to grip the work tight enough. The othewr option is machine the first flat then place the work in a small vice and in some parallels , then machine the second flat. Hope this helps

  10. #10
    Join Date
    Aug 2008
    Location
    Melbourne
    Age
    34
    Posts
    1,075

    Default

    Quote Originally Posted by pipeclay View Post
    10 mm is not very much to hold going into a 30mm long collet, they may just be too short for the collet to grip correctly.
    This.

    With so much of the collet clamping air, when you tighten it you are going to crush the back of the collet and flare the front so you only really have a ring of single point contact on the end of the part (you also risk permanently deforming the collet). The minimum recommended clamping length is 2/3 the collet length, so an extension or filler should sort it out.

  11. #11
    Join Date
    Feb 2009
    Location
    jilliby nsw
    Age
    71
    Posts
    111

    Default

    Yes I agrees with what you say elanjacobs re collett grip length. If I were to make these I would turn the blanks in the lathe and then mill the flats using a fly cutter or similar whilst holding the work piece in a machine vice.

  12. #12
    Join Date
    Aug 2007
    Location
    Saskatoon, Saskatchewan, Canada
    Posts
    292

    Default

    I would consider cutting the flats on a long bar and hold it in the lathe with the 4 jaw. Do all the turning and threading and then part to length. Advance the bar and repeat.

    Pete

  13. #13
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,443

    Default

    Quote Originally Posted by krisfarm View Post
    Baron J
    Extending the grip length will help with the holding. I have found by wrapping the diameter with a piece of 600 wed & dry paper with the grit side bearing on the shaft can increase your hold. Are you milling the flats working parallel to the longitudinal axis and taking light cuts?
    Bob
    Hi Bob, Yes exactly that.

    Thanks, but to do that I would have to go up in size to a 9 - 8 collet.
    Best Regards:
    Baron J.

  14. #14
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,443

    Default

    Quote Originally Posted by hpa1 View Post
    Yes I agrees with what you say elanjacobs re collett grip length. If I were to make these I would turn the blanks in the lathe and then mill the flats using a fly cutter or similar whilst holding the work piece in a machine vice.
    Hi Hpa1,

    Yes I turned the blanks in the lathe, but I was limited by the length of the piece of brass bar that I had, so worked from both ends.

    Using a square collet block and an 8 mm collet is the obvious way.
    Best Regards:
    Baron J.

  15. #15
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,443

    Default

    Hi Guys,

    Many thanks to all for the helpful and useful suggestions. I'm still learning

    The job is now done. I hadn't understood just how much brass can move under pressure, particularly when clamping what was effectively a thin wall tube.

    14-09-2019=006.JPG 14-09-2019=005.JPG
    This how I got the problem sorted. I turned one of the bad bushes so that it was an 8 mm diameter M6 threaded tube. I put a bolt through and screwed the tube onto the bolt so that it provided more material for the collet to grip.

    14-09-2019=001.JPG 14-09-2019=002.JPG 14-09-2019=003.jpg
    This is how I set up the collet and collet block. Put the whole lot in the mill vise and carefully machined the flat on both sides. I also machined a small flat on one end to make it easier drill a 1/4" hole through it.

    So success ! I can now carry on with my Brooks TCG.

    Thanks again guys.
    Attached Images Attached Images
    Best Regards:
    Baron J.

Similar Threads

  1. what rods for thin brass to brass ??
    By Mathuranatha in forum WELDING
    Replies: 7
    Last Post: 23rd Nov 2020, 08:17 PM
  2. Bearings
    By neddyo in forum THE HERCUS AREA
    Replies: 5
    Last Post: 19th Feb 2014, 10:02 PM
  3. VICTORIA Brass Flat Bar Assorted Sizes & 1/4" SWB Threaded Rod & 260 Carbide Brass Sheet
    By thumbsucker in forum METALWORK - Machinery, Equipment, MARKET
    Replies: 7
    Last Post: 18th Mar 2013, 03:36 PM
  4. Bearings
    By Anorak Bob in forum METALWORK GENERAL
    Replies: 10
    Last Post: 16th Feb 2011, 08:05 AM
  5. What Bearings?
    By zuffen in forum TRAILERS & OTHER FABRICATED STUFF
    Replies: 8
    Last Post: 11th Apr 2010, 09:22 AM

Posting Permissions

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