Backlash Eliminators: What to expect?
Close
Login to Your Account
Page 1 of 2 12 LastLast
Results 1 to 20 of 21
  1. #1
    Join Date
    Mar 2012
    Location
    Boston, MA
    Posts
    118
    Post Thanks / Like
    Likes (Given)
    5
    Likes (Received)
    26

    Default Backlash Eliminators: What to expect?

    I have been playing with the backlash eliminator nuts on my 1950's era Cincinnati Toolmaster. I can dial it to about 0.003" of backlash and still get smooth turning action on the leadscrew, but if I try to snug it up more than that then the screw binds and does not want to turn. Is 0.003" considered to be about as good one can expect from these types of devices, or should I be able to bring that closer to 0 with the magic touch? Despite being 70 years old this is a low hours machine in great shape, so I don't think that wear on the screw is an issue in this case. It does not seem to matter where I am on the leadscrew when I adjust the backlash, same story all across the travel.
    Preempting the claims that I can do good work even with much more than 0.003" of backlash: Agreed. This is not about needing it to be better, but a general question on the function of the backlash eliminators.

    Thanks,
    Mike

  2. #2
    Join Date
    Jul 2007
    Country
    UNITED KINGDOM
    Posts
    5,265
    Post Thanks / Like
    Likes (Given)
    3178
    Likes (Received)
    2676

    Default

    With most feed screws and lead screws that's about as close as you can get. The thread form of the screw and the nut may not be perfeclty matched due to wear and the alignment of screw and nut may not be absolutely perfect, this leads to a very rapid increase in friction once you get binding on any part of the length of the nut and any part of the threadform.

    Most folk would be very happy with that amount of backlash on a new mill if it didn't have ball screws.
    Last edited by Mark Rand; 11-11-2020 at 04:22 PM.

  3. #3
    Join Date
    Jan 2007
    Location
    Norfolk, UK
    Posts
    20,901
    Post Thanks / Like
    Likes (Given)
    16341
    Likes (Received)
    16775

    Default

    Back in the day I only used a few mills with backlash eliminators and would rate 0.003'' as very good going.

    P.S. those mills had been ridden hard and not been given the best feed or stabling

  4. Likes Hardplates, gargamel, Ray Behner liked this post
  5. #4
    Join Date
    Mar 2012
    Location
    Boston, MA
    Posts
    118
    Post Thanks / Like
    Likes (Given)
    5
    Likes (Received)
    26

    Default

    Thanks Mark & Limi. You've confirmed my suspicions. Just figured I would ask as I have not tried adjusting one of these before.

  6. #5
    Join Date
    Jan 2007
    Location
    wales.uk
    Posts
    1,461
    Post Thanks / Like
    Likes (Given)
    262
    Likes (Received)
    306

    Default

    I thought the tool master was an opposing nut sprung cartridge affair, though the one I have hasn’t been tinkered with, however I have the square shaped one made in France.
    Mark

  7. #6
    Join Date
    Apr 2006
    Location
    Manchester, England
    Posts
    9,068
    Post Thanks / Like
    Likes (Given)
    1477
    Likes (Received)
    6017

    Default

    Quote Originally Posted by Limy Sami View Post
    Back in the day I only used a few mills with backlash eliminators and would rate 0.003'' as very good going.

    P.S. those mills had been ridden hard and not been given the best feed or stabling
    I always thought a better term would have been " backlash reducer " rather that " backlash eliminator ".

    Regards Tyrone.

  8. Likes Limy Sami liked this post
  9. #7
    Join Date
    Jan 2007
    Location
    wales.uk
    Posts
    1,461
    Post Thanks / Like
    Likes (Given)
    262
    Likes (Received)
    306

    Default

    Think it was sold as a climb milling thingy from memory, there’s definately somthing about climb cutting and the backlash exterminator, mind I can break cutters conventional milling, I’ve not pulled the table off mine, I should I suppose, add the leftover bits to the “ that will come in handy bin”, I like leftover parts, they’re so useful for fixing the thing you just fixed
    Mark

  10. Likes M.B. Naegle, memphisjed, Mark Rand liked this post
  11. #8
    Join Date
    Jul 2007
    Location
    Missoula Mt
    Posts
    1,031
    Post Thanks / Like
    Likes (Given)
    41
    Likes (Received)
    443

    Default

    After a few months of use, you will be able to set it tighter, maybe down to .0015 ...Phil

  12. #9
    Join Date
    Sep 2014
    Country
    UNITED STATES
    State/Province
    Georgia
    Posts
    450
    Post Thanks / Like
    Likes (Given)
    328
    Likes (Received)
    188

    Default

    Check the bearings that are controlling the thrust, too.

  13. Likes gargamel liked this post
  14. #10
    Join Date
    Mar 2012
    Location
    Boston, MA
    Posts
    118
    Post Thanks / Like
    Likes (Given)
    5
    Likes (Received)
    26

    Default

    Thanks all. For posterity, I'll see if I can dig up some pictures of the relevant mechanism from the Cincinnati docs. its a bit hard to photo no, but i might have one from when the table was off.

  15. #11
    Join Date
    Feb 2011
    Country
    UNITED STATES
    State/Province
    Texas
    Posts
    2,689
    Post Thanks / Like
    Likes (Given)
    2306
    Likes (Received)
    1213

    Default

    Quote Originally Posted by boslab View Post
    Think it was sold as a climb milling thingy from memory, there’s definately somthing about climb cutting and the backlash exterminator, mind I can break cutters conventional milling, I’ve not pulled the table off mine, I should I suppose, add the leftover bits to the “ that will come in handy bin”, I like leftover parts, they’re so useful for fixing the thing you just fixed
    Mark
    I know that Kearney & Trecker promoted their back-lash mechanism for that very purpose (climb milling).

  16. Likes boslab liked this post
  17. #12
    Join Date
    Mar 2012
    Location
    Boston, MA
    Posts
    118
    Post Thanks / Like
    Likes (Given)
    5
    Likes (Received)
    26

    Default

    Yes, it might tighten up a bit with more use. I am just finishing putting the machine back together after a teardown for moving into a restricted access (read basement) space. Im sure there were slight shifts and alignment changes for the components after cleaning out all of the old hardened oil and putting things back together.

    Quote Originally Posted by Phil in Montana View Post
    After a few months of use, you will be able to set it tighter, maybe down to .0015 ...Phil

  18. #13
    Join Date
    Mar 2012
    Location
    Boston, MA
    Posts
    118
    Post Thanks / Like
    Likes (Given)
    5
    Likes (Received)
    26

    Default

    Quote Originally Posted by David_M View Post
    Check the bearings that are controlling the thrust, too.
    No bearing on the right-hand side, only the left apron is currently installed. Seemed like it would be easier to get at the mechanism before putting the right side apron back on. Good point though, I'll poke it again after putting the RHS apron back on.

  19. #14
    Join Date
    Mar 2012
    Location
    Boston, MA
    Posts
    118
    Post Thanks / Like
    Likes (Given)
    5
    Likes (Received)
    26

    Default

    Attached should be a couple selections from the user manual for this machine relevant to the backlash mechanism. Looks like their official term is "anti-backlash", and my wording of "backlash eliminator" was maybe optimistic.

    Improved climb milling is also specifically called out as a benefit.

    toolmasterbacklash2.jpgtoolmasterbacklash1.jpg

  20. #15
    Join Date
    Nov 2019
    Country
    CANADA
    State/Province
    Ontario
    Posts
    362
    Post Thanks / Like
    Likes (Given)
    496
    Likes (Received)
    74

    Default

    better then some of my lathes, they have about 20 thou play in them.

  21. #16
    Join Date
    Jan 2007
    Location
    wales.uk
    Posts
    1,461
    Post Thanks / Like
    Likes (Given)
    262
    Likes (Received)
    306

    Default

    Quote Originally Posted by M.B. Naegle View Post
    I know that Kearney & Trecker promoted their back-lash mechanism for that very purpose (climb milling).
    It’s interesting, I have a tool master mill with the slotter on the back ( that’s been very very handy, no more fileing holes square, making dies, marvellous gadget, it’s not got the guts of the 36” shaper but I like it, I’d like a 36” too, but don’t think that’s on the cards)
    Anyway I had a K&T mill in my shop in work, and the tool master I now have, some spooky similarities, I was short a green and silver lever handle for the Cincinnati, it’s the same as the K&T, which I promptly removed and replaced with a black knob, it’s as if K&T and Cincinnati had some common ground?
    Mark

  22. #17
    Join Date
    Jun 2012
    Location
    Michigan
    Posts
    5,559
    Post Thanks / Like
    Likes (Given)
    5244
    Likes (Received)
    3541

    Default

    I would guess that's about as good as you're going to get with a lead screw and not a ball screw. I could be wrong though.

  23. #18
    Join Date
    Nov 2004
    Location
    Webster Groves, MO
    Posts
    7,862
    Post Thanks / Like
    Likes (Given)
    2038
    Likes (Received)
    3821

    Default

    A machine with that much use will usually have more wear in the mid part of the travel than at the ends. A typical place to start is set for .005" on an end, then check at various points along the travel. I have seen as much as .020" or more backlash difference between the end and middle. Remember that the difference is a loss in accuracy. If you measure travel over the range, you will find that the actual travel falls behind in the worn part and catches up at the other end.

    Bill

  24. #19
    Join Date
    Jan 2007
    Location
    Norfolk, UK
    Posts
    20,901
    Post Thanks / Like
    Likes (Given)
    16341
    Likes (Received)
    16775

    Default

    Quote Originally Posted by BT Fabrication View Post
    better then some of my lathes, they have about 20 thou play in them.
    Is that all? ...and I am NOT joking.

  25. #20
    Join Date
    Jul 2007
    Country
    UNITED KINGDOM
    Posts
    5,265
    Post Thanks / Like
    Likes (Given)
    3178
    Likes (Received)
    2676

    Default

    It depends quite a lot on the materials used in the screw and nuts. Bronze nuts as used on Bridgeports, have a tendancy to wear the screw severely. cast iron nuts as used on some other machines (like my Beaver) wear the nut in preference to the screw.


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
  •