. .
Page 1 of 2 12 LastLast
  1. #1
    Hi,

    I'm making up a rotary indexer. In the headstock build i'm using a ER32 collet shaft extender. The shaft is 32mm OD and bearings 32mm ID but they are too tight a fit at the moment to slip on.

    The difference as measured by a collegue (shouted across the room) is 5000th of an inch, or 0.0127mm in my world.

    Will heating the bearings allow me to get these on or should I be looking at getting the shaft turned down, or another method?

    Thanks
    Last edited by marbles; 28-11-2018 at 12:05 PM.

  2. #2
    Clive S's Avatar
    Lives in Marple Stockport, United Kingdom. Last Activity: 13 Hours Ago Forum Superstar, has done so much to help others, they deserve a medal. Has been a member for 9-10 years. Has a total post count of 3,333. Received thanks 618 times, giving thanks to others 78 times. Made a monetary donation to the upkeep of the community. Is a beta tester for Machinists Network features.
    Quote Originally Posted by marbles View Post
    Hi,

    I'm making up a rotary indexer. In the headstock build i'm using a ER32 collet shaft extender. The shaft is 32mm OD and bearings 32mm ID but they are too tight a fit at the moment to slip on.

    The difference as measured by a collegue (shouted across the room) is 5000th of an inch, or 0.0127mm in my world.

    Will heating the bearings allow me to get these on or should I be looking at getting the shaft turned down, or another method?

    Thanks
    Try putting the shaft in the freezer overnight But have you got an extra zero in there
    ..Clive
    The more you know, The better you know, How little you know

  3. The Following User Says Thank You to Clive S For This Useful Post:


  4. #3
    Quote Originally Posted by Clive S View Post
    Try putting the shaft in the freezer overnight But have you got an extra zero in there
    Thanks, will do.
    Highly likely I have an extra zero 😀

  5. #4
    Just done some quick sums based on rough coefficient of expansion of steel. If your diameter difference is correct, then you will need a temperature difference of around 55C to get enough expansion/shrinkage. So, bearing in oven to, say, 100C, and shaft in freezer to give you around -15C. Difference should then mean that the bearing will drop on with a very small amount to spare, but will grab quickly as the temperatures equalise.

    Saying "5000th of an inch" is a bit difficult to interpret. I think you actually mean "half a thousandth of an inch" or "half a thou" or 0.0005", which is the imperial equivalent of 0,0127mm. Shows one advantage of the metric system!

    Good luck,

  6. The Following 2 Users Say Thank You to Neale For This Useful Post:


  7. #5
    I misread the original post and as Neal said expressing it as 5000 of an inch is misleading. That interference is fine if it's measured correctly. It needs to be pressed on squarely using tallow. Pressing things square here is the key. Put a shoulder on the end of the shaft if possible that is a slide fit on the bearing then press. This will keep the bearing square. Also use tallow if you have any.
    Last edited by spluppit; 28-11-2018 at 03:38 PM.

  8. The Following User Says Thank You to spluppit For This Useful Post:


  9. #6
    Quote Originally Posted by Neale View Post
    Just done some quick sums based on rough coefficient of expansion of steel. If your diameter difference is correct, then you will need a temperature difference of around 55C to get enough expansion/shrinkage. So, bearing in oven to, say, 100C, and shaft in freezer to give you around -15C. Difference should then mean that the bearing will drop on with a very small amount to spare, but will grab quickly as the temperatures equalise.

    Saying "5000th of an inch" is a bit difficult to interpret. I think you actually mean "half a thousandth of an inch" or "half a thou" or 0.0005", which is the imperial equivalent of 0,0127mm. Shows one advantage of the metric system!

    Good luck,
    Yeh I think your right about the "half a thousandth of an inch" or "half a thou" or 0.0005" :)

  10. #7
    Quote Originally Posted by spluppit View Post
    Put a shoulder on the end of the shaft if possible that is a slide fit on the bearing then press. This will keep the bearing square. Also use tallow if you have any.
    Thanks for the advice. I'm a tad light on tallow, never had a calling for it, must be something else I could try as a sub. I'll try the freeze and shrink thing first and see how that works.

  11. #8
    m_c's Avatar
    Lives in East Lothian, United Kingdom. Last Activity: 3 Days Ago Forum Superstar, has done so much to help others, they deserve a medal. Has been a member for 9-10 years. Has a total post count of 2,908. Received thanks 360 times, giving thanks to others 8 times.
    Quote Originally Posted by marbles View Post
    Hi,
    The difference as measured by a collegue (shouted across the room) is 5000th of an inch, or 0.0127mm in my world.
    Are you sure he didn't mean 5 thousands? Aka 0.127mm.
    In which case, it's going to be one very tight pressfit, which will most likely lock the bearing so it doesn't spin.
    Avoiding the rubbish customer service from AluminiumWarehouse since July '13.

  12. #9
    Quote Originally Posted by m_c View Post
    Are you sure he didn't mean 5 thousands? Aka 0.127mm.
    In which case, it's going to be one very tight pressfit, which will most likely lock the bearing so it doesn't spin.

    Thinking back I think he said "5 thou". Ok, if we assume its 5 thousands with bearing expansion and freezing the shaft will that not give the spacing to get them on?

  13. #10
    m_c's Avatar
    Lives in East Lothian, United Kingdom. Last Activity: 3 Days Ago Forum Superstar, has done so much to help others, they deserve a medal. Has been a member for 9-10 years. Has a total post count of 2,908. Received thanks 360 times, giving thanks to others 8 times.
    Quote Originally Posted by marbles View Post
    Thinking back I think he said "5 thou". Ok, if we assume its 5 thousands with bearing expansion and freezing the shaft will that not give the spacing to get them on?
    Not likely.
    Even if you did manage to get it on, it's highly likely the bearing will seize due to the pressure expanding the inner race. I don't even think an increased clearance bearing would even be able to handle that much expansion.
    Avoiding the rubbish customer service from AluminiumWarehouse since July '13.

  14. The Following User Says Thank You to m_c For This Useful Post:


Page 1 of 2 12 LastLast

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Fitting HD 16 instead of MGD 16
    By Noplace in forum General Discussion
    Replies: 5
    Last Post: 28-04-2015, 09:08 AM
  2. taper roller bearings vs deep groove ball bearings
    By dsc in forum Linear & Rotary Motion
    Replies: 8
    Last Post: 10-03-2014, 08:06 AM
  3. Simple Solution- Drive 1" Ball Screw Shaft with NEMA-23-Size Stepper Motor Shaft
    By LoveLearn in forum Gantry/Router Machines & Building
    Replies: 5
    Last Post: 08-02-2012, 01:52 AM
  4. Replies: 7
    Last Post: 28-09-2011, 12:04 AM
  5. Fitting new screws
    By Robin Hewitt in forum General Discussion
    Replies: 0
    Last Post: 15-02-2009, 09:34 PM

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
  •