Securing a threaded on chuck for reverse rotation
Close
Login to Your Account
Results 1 to 14 of 14
  1. #1
    Join Date
    Nov 2016
    Country
    UNITED STATES
    State/Province
    California
    Posts
    12
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    5

    Default Securing a threaded on chuck for reverse rotation

    Good evening,

    I do little gun smithing but I note this forum is more accommodating of Asian machine discussions than the general forum so I thought I would ask the following:

    I have a Grizzly 12X37 lathe (along with an SB Model A and Wells Index 747 mill, and access to a Lodge and Shipley 18X54.) Do the latter get me a pass, Don?

    I prefer to thread from the head stock out so I want to secure the chuck for reverse operations.

    There is room to drill and tap the back plate on the three and four jaw chucks I have to 3/8"-16.

    So my thought is a dog point or cup point set screw securing the chuck. (not on the spindle threads, obviously).

    I thought about using a brass or lead plug under the screws but abandoned that as there is only .500" depth to work with.

    Three at 120 degrees should to the job?

    I know the spindle is hardened. I know how to not over tighten a chuck on the spindle

    Typically I don't take heavy cuts when threading and grooving.

    So wattaya think?

    Tony

  2. #2
    Join Date
    Feb 2001
    Country
    UNITED STATES
    State/Province
    Arizona
    Posts
    2,041
    Post Thanks / Like
    Likes (Given)
    4
    Likes (Received)
    249

    Default

    Both of my lathes have threaded spindles (although the back plate seems to be frozen to the spindle on the older machine) and I have not had any problems with the spindle unscrewing while running in reverse. But neither machine has any way of braking the spindle so hard that the chuck will unscrew. Also, the old machine won't go very fast so the chuck does not acquire a great deal of angular momentum. If threading is your only need for reverse, I doubt you will be running so fast as to unscrew on starting, either.

  3. #3
    Join Date
    Nov 2016
    Country
    UNITED STATES
    State/Province
    California
    Posts
    12
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    5

    Default

    Good morning,

    Good points. I had thought of that particularly starting. The green machine has an eight inch four jaw that is pretty heavy. (for the size of the machine.) The machine is capable of thirteen hundred rpm but I seldom go beyond nine hundred. I swap chucks fairly often and don't secure them gorilla tight. It's making a 1"-2" long deep cut in the middle of a shaft that I'm thinking about. If the tool jams.......Obviously a follow rest or steady rest helps. There are times when I could get away without the extra work setting up the rest to eliminate noise and chatter. And.... Threading in reverse gives the option of increasing the speed without the fear of crashing to get a better finish and not having to cut a relief at the end of the thread.

    I think I'll drill and tap for a couple of set screws over brass slugs (that I'll have hunt down in the chip pan and on the floor every time I switch chucks) in the back plate. Peace of mind, I guess.

    A little off topic:

    In the 70s a machinist who had spent thirty plus years at CAT showed me how to thread from the head stock out. Same for running in reverse cutting wide deep grooves in nasty or hard materials. In addition, replacing a live center with a dead center when all else fails to control noise and chatter. I was in his shop on a day when he did it. Later, beer in hand, I remarked that I couldn't feel much if any play in the live center. His only comment was, "It doesn't take much". ENd of discussion.

    Thanks for responding.

    Tony

  4. #4
    Join Date
    Jun 2012
    Country
    UNITED STATES
    State/Province
    Michigan
    Posts
    8,288
    Post Thanks / Like
    Likes (Given)
    2465
    Likes (Received)
    2757

    Default

    I don't thread out from the chuck.. but if I did I would keep RPM low...
    I have used a lot of threaded spindles and have not lost a chuck.

  5. #5
    Join Date
    Sep 2009
    Location
    Phoenix,AZ
    Posts
    1,366
    Post Thanks / Like
    Likes (Given)
    2183
    Likes (Received)
    303

    Default

    You CAN get set screws with a inserted soft tip !

  6. #6
    Join Date
    Oct 2005
    Location
    Pittsburgh, PA
    Posts
    1,581
    Post Thanks / Like
    Likes (Given)
    4
    Likes (Received)
    101

    Default

    The better back plate /chuck designs usually used split collars to prevent unscrewing.
    Attached Thumbnails Attached Thumbnails emco-face-plate-1.jpg   emco-face-plate.jpg  

  7. #7
    Join Date
    Sep 2011
    Country
    UNITED STATES
    Posts
    17,010
    Post Thanks / Like
    Likes (Given)
    7162
    Likes (Received)
    5317

    Default

    Quote Originally Posted by Andy St View Post
    The better back plate /chuck designs usually used split collars to prevent unscrewing.
    Some among us settled for a strategically placed slice of copper or aluminium foil, "company lathe" and no messing about with set screws allowed.

    Don't leave it in there after the job is done, though. Bubba is only criticized when his jackleg tricks to JFDI and git 'er DONE are caught-out a year later when the chuck ain't COMING off when one wants it to.

  8. #8
    Join Date
    Jan 2014
    Location
    South Jordan, Utah, USA
    Posts
    352
    Post Thanks / Like
    Likes (Given)
    802
    Likes (Received)
    124

    Default

    Quote Originally Posted by thermite View Post
    Some among us settled for a strategically placed slice of copper or aluminium foil, "company lathe" and no messing about with set screws allowed.

    Don't leave it in there after the job is done, though. Bubba is only criticized when his jackleg tricks to JFDI and git 'er DONE are caught-out a year later when the chuck ain't COMING off when one wants it to.
    Please elaborate. I'm interested.

  9. #9
    Join Date
    Sep 2011
    Country
    UNITED STATES
    Posts
    17,010
    Post Thanks / Like
    Likes (Given)
    7162
    Likes (Received)
    5317

    Default

    Quote Originally Posted by Yan Wo View Post
    Please elaborate. I'm interested.
    Lessee... late 1950's. SB 10" & Logan. 2 and something 8 per if old memory serves.

    Copper foil was thin strip, VERY! Not wide atall, no ROOM for it otherwise, and it is wedged, chuck not actually allowed to go 100% onto the register shape at the rear.

    OTOH, it dasn't offer to come off easily, either.

    Downside was it took expertise to PLACE it just-so. Upside is it was easily portable, later, to Day Job where the machines were not mine.

    The "School solution" we worked out later was better - took no skill. We cut a narrow, large-bore "washer', of 26 ga. soft aluminium and put it on first, chuck second. Didn't even affect TIR all that much, and it was a school, so TIR didn't matter as much has "concept". And safety of school-age kids. Started 'em younger back when their Dad's were working for mills and such. Or RAN them. A classmate's Dad was CFO, Mesta Machine. His Uncle Louie was CEO. Rank and file or ULM, all still recognized metal working as a valuable skill, whether one worked at it or hired those who hired those who hired it done.

    That "washer" TOTALLY stopped the chronic pranksters that would push the "REV" button of a 3-Phase 3/4 HP instant-reversing motor at full-gallop to roll a chuck at the feet of their classmates.

    And the SB even more than the Logan would DO that, and with great reliability before we added the washer.

    Most ere sayin' it ain't a problem are not bored school kids trying to MAKE it happen, is all.

    Meanwhile - glad to have seen the back of threaded noses altogether, but that was as much luck as planning.

  10. #10
    Join Date
    May 2017
    Country
    FINLAND
    Posts
    952
    Post Thanks / Like
    Likes (Given)
    230
    Likes (Received)
    453

    Default

    Quote Originally Posted by GGaskill View Post
    Both of my lathes have threaded spindles (although the back plate seems to be frozen to the spindle on the older machine) and I have not had any problems with the spindle unscrewing while running in reverse. But neither machine has any way of braking the spindle so hard that the chuck will unscrew. Also, the old machine won't go very fast so the chuck does not acquire a great deal of angular momentum. If threading is your only need for reverse, I doubt you will be running so fast as to unscrew on starting, either.
    My 11x24 Kerry has also threaded chuck. I thought that its not a problem until it once got loose on threading operation... NOT fun when 160mm chuck is spinning on lathe ways and jumps towards your toes!
    Thanks to fast reflexes my toes are still intact but the ways took couple of extra dents.

    I added split ring to clamp on the collar. Kind of hard to believe at first but I didn't need to split the collar, it's very close fitting so just tightening the ring around the chuck collar locks it in place.

  11. Likes thermite liked this post
  12. #11
    Join Date
    Oct 2005
    Location
    Pittsburgh, PA
    Posts
    1,581
    Post Thanks / Like
    Likes (Given)
    4
    Likes (Received)
    101

    Default

    Quote Originally Posted by MattiJ View Post
    My 11x24 Kerry has also threaded chuck. I thought that its not a problem until it once got loose on threading operation... NOT fun when 160mm chuck is spinning on lathe ways and jumps towards your toes!
    Thanks to fast reflexes my toes are still intact but the ways took couple of extra dents.

    I added split ring to clamp on the collar. Kind of hard to believe at first but I didn't need to split the collar, it's very close fitting so just tightening the ring around the chuck collar locks it in place.
    I agree with MattiJ on this. If the back plate is a good fit to the register just a split collar will do, no need to split the back plate / mount. One problem is that not all lathes with lets say 1 1/2" 8tpi have exactly the same size register. So a third party chuck might fit a South bend correctly but not a Rockwell.

  13. #12
    Join Date
    Nov 2016
    Country
    UNITED STATES
    State/Province
    California
    Posts
    12
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    5

    Default

    Quote Originally Posted by JohnEvans View Post
    You CAN get set screws with a inserted soft tip !

    Arrrgggg! Forgot about them. Thanks for the reminder.

    Tony

  14. #13
    Join Date
    Feb 2017
    Country
    UNITED STATES
    State/Province
    Ohio
    Posts
    67
    Post Thanks / Like
    Likes (Given)
    3
    Likes (Received)
    5

    Default

    Quote Originally Posted by tcom View Post
    Arrrgggg! Forgot about them. Thanks for the reminder.

    Tony
    Or you can make them

  15. #14
    Join Date
    Sep 2011
    Country
    UNITED STATES
    Posts
    17,010
    Post Thanks / Like
    Likes (Given)
    7162
    Likes (Received)
    5317

    Default

    Quote Originally Posted by Brodytonelotti View Post
    Or you can make them
    ... or thumbtacks.. or Bostich staples...or 4-penny box nails .. but WHY?


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
  •