# Question on Threaded Spindle Chuck



## John TV (Jul 2, 2017)

Very new to this hobby but learning, and I keep seeing videos on different ways to thread.  Some techniques use reversing the lathe to feed away from the chuck so you don't have to worry about stopping the thread exactly at the right time. Those showing the technique also warn against using a spin on chuck for this technique since the chuck can easily spin off.  My old MW Logan has a threaded spindle and it does have a reversing switch for the motor. 

Question, is there a way to "lock" on a threaded chuck or reduce the likelihood of it spinning off?   If there is an old discussion on this, I apologize for not finding it.  Thanks for your thoughts.

John in Minnesota


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## JR49 (Jul 2, 2017)

John TV said:


> Question, is there a way to "lock" on a threaded chuck or reduce the likelihood of it spinning off?



John,  I also have a threaded spindle, and have been hesitant to do any machining on the spindle, as this pic shows.  I can't find the thread that explains it, but if you go to post #9984 under the thread "PODT, project of the day what did you do in the shop today"  you will see a pic of one solution.  Will be watching this thread, and hope to hear  other options.  Good luck,  JR49

EDIT;  that thread is 333 pages long!  its on the last page


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## wa5cab (Jul 2, 2017)

John,

First choice would be to use a collet if (a) the part isn't too large for the collets that fit your machine, and (b) the collet chuck isn't a screw-on.  Lacking that, in the special case of wanting to run the parting off tool inverted, several makers offered longer cross slides that had a rear tool post for mounting the inverted blade.  The one that Atlas offered was considered a turret lathe accessory.

Finally, a few chuck makers have over the years offered a chuck with a built-in lock.  I'm not sure how the Grizzly one works but the one that I have has an extension on the rear of the chuck that when you tighten some pinch bolts, clamps around the spindle flange just behind the register.  I don't recall the maker but they were in West Germany.


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## Silverbullet (Jul 2, 2017)

My lathe has screw on chucks 2 1/4"-8 , Logan . I've used it alot over the last forty years , I've never had one spin free even in reverse. If your lathe has a brake to stop the chuck it would be more likely to happen. But normal operations will not make a chuck come free. When you mount the chuck clean both spindle and Ck threads use your hands to feel any chips or burrs . Clean them if any , mount the chuck tightly not just screw till it stops put a wrench on a jaw and snug it good and tight. So much it takes a couple raps with a hammer to get it off.


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## Tozguy (Jul 2, 2017)

Here is one:
http://www.hobby-machinist.com/thre...ackwards-threading-with-screw-on-chuck.55564/

I remember seeing some pics of chuck locks somewhere here too.


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## eeler1 (Jul 7, 2017)

wa5cab said:


> John,
> 
> First choice would be to use a collet if (a) the part isn't too large for the collets that fit your machine, and (b) the collet chuck isn't a screw-on.



yes, just use a collet if you are going to thread this way.  otherwise, practice up with the chuck and get good at it with the normal travel.  the chuck doesn't have to come off to ruin your work, just has to shift slightly, get loose a little bit.  upside down and backwards is a ruined workpiece waiting to happen, or possibly worse.

or, go ahead and try it, learn by personal experience.


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## T Bredehoft (Jul 7, 2017)

Quick and dirty. Remove the chuck, drill and tap a quarter inch hole to end up in the threads. drop a brass plug in and run a set screw down on it once the chuck has been tightened on the spindle.


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