More Dangerous Chuck mounting

Read the recent posts about above subject. I have a 13" older LeBlonde with threaded chucks. My maximum RPM is 500 and I would like to increase it.
Already have the VFD but not set up.
What are my safety options? Never reverse. Never quick-stop. etc.
Is there a clever way of securing the chucks (3 jaw and 4 jaw) to the lather? Can I pass something through the spindle and bolt to the left side of the headstock? Any other tricks?
BTW, I ask this because years ago I did try to run the lathe backwards while grinding with a Dremel setup. Chuck started to demount immediately. I reversed quickly and never repeated the operation again.
Thanks,
Ivan Vegvary
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Ivan, depending on the VFD, you can set parameters such as starting time, stopping time, reversing time etc, to make sure that you are not accelerating (or decelerating) too hard.
The unfortunate part is that your VFD does not know in which gear is your lathe. In low gear, obviously, faster ramp-up and ramp-down times are appropriate.
i
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wrote:

Thanks Iggy!! BTW it is YOUR VFD that I will be using.
Ivan Vegvary
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I would, then, look at page 41 of the manual, Acceleration/Deceleration time. Also check pages 64, 65 for braking information.
i
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Green Loctite?
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I have a 13 inch logan/powermatic with a threaded spingle (2 1/4 X8) - I've never had any hint of unthreading in reverse -- the lathe is driven by a VFD, and I don't use reverse for any serious cutting - I'm sure a sudden reversal could unwind the chuck, but with the VFD there is a deceleration profile that would prvent this

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My 7" Emco lathe has a screw on chuck that does not use a locking ring. I once tried running it at maximum speed and when I pushed the stop button, the chuck started to unscrew. I found that if the screw threads are really clean and have no oil/grease, then the chuck will stay mounted. Even running in reverse, it will not unscrew.
When I need to remove the chuck, I put the lathe in lowest gear and open the chuck jaws so an old axe handle will fit across the jaws and give a yank and it lostens the chuck. So, try cleaning the threads with paint thinner,etc. and see if that helps.
Paul
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If the chuck has been screwed on properly it won't unscrew. Lock the mandrel. screw The chuck on all but the last quarter turn. do the last quarter turn fairly hard.
Mark Rand (Myford ML7 lathes for the last 42 years, no unscrewed chucks) RTFM
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Unless it interferes with your work you may be able to pass a long bolt thru a suitable washer, thru the spindle and another washer and tighten with a nut. If you need to extend the bolt use a piece of all-thread and a coupling nut.
A refinement might be a flanged tube to retain use of the hollow spindle but it would need to be strong enough to stand the force.
Don Young
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    First off -- it is a "lathe", not a "lather". The work which it performs is called "turning", not "lathing".

    That could work -- as long as it contacts the body of the chuck between the jaws. Or perhaps (if there is a step between the chuck bore and the threaded backplate, you could make a thick disc to fit there, and run a threaded rod into a tapped hole in the center. I would strongly advise that the threaded rod and such be left hand threaded.

    Were you ever able to get that chuck off afterwards? You could have screwed it back on hard enough so you would have it stuck in place by doing that.
    As for other tricks -- if there is a smooth cylindrical section of the spindle still visible between the chuck and the headstock, you could bore a piece of steel so it just barely slips onto that part of the spindle, then slot it from one side, and drill and tap so a Allen head cap screw can draw the slot closed. Then mount it on the back of the chuck's backplate with one or two screws about opposite the slot.
    Screw this onto the spindle most of the way but not firmly, then try tightening the capscrew and see whether you can rotate the chuck relative to the spindle. If not. loosen the bolt, screw the chuck the rest of the way on, and re-tighten the bolt. I've seen photos of chucks so fitted for Myford lathes.
    Good Luck,         DoN.
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The slit allows the neck to be compressed & grip. The 2-piece collet provides the gripping force.
These two will keep the chuck in place, IMHO.
--
John English


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