Horror Stories About The Chuck Coming Off While Running Backwards

I never even thought about a chuck unscrewing until I saw this. My baby armature lathe is the only lathe I've operated that had a screw on chuck and it doesn't have reverse. I have a 14 X 48 Clausing (L-OO spindle) and would like to get another lathe, a little smaller for small work. It'll probably be one with a threaded spindle and I'll remember this.

Rodney
 
My Atlas/Craftsman 6" and my Grizzly G0602 both have screw-on chucks. The G0602 has two retainers which prevent the chuck from unscrewing.

I had used the Atlas in reverse on occasion in the past . It allowed me to use the same cutting tool for both internal and external work when I had a production setup running. However, the parts were Delrin and less than a 1/2" in diameter so torque from the cutting tool was negligible. I don't recall ever having the chuck unscrew unintentionally.

When I got my G0602, it was still sitting on the base of the packing crate awaiting its new bench. Like a kid on Christmas morning, I couldn't resist playing with it. I had pulled the pre-mounted three jaw chuck off and cleaned all the gunk off and screwed it back on but didn't reinstall the two retainers. I powered up the lathe and flipped it into reverse and the chuck promptly spun off. That is when I found that the hardened ways weren't really all that hard. A couple of dings in the ways are there to remind me to always install the chuck retainers before powering up. Fortunately, the dings are in a location not normally traveled by the carriage or tailstock so the only damage was to my pride.:headache:

Bob
 
Note that my post said "I know how to get away with it". That was not meant to imply that you should play in traffic,drive fast and take chances!
 
A right hand threaded chuck unscrewing when operating in reverse is such a natural happening that it is not an accident when it happens. You can almost count on it to happen. The laws of physics dictate it and that's why they always put a left hand thread on the right hand pedal of a bicycle or it will come off 'accidentally'.
I have seen a few screws for holding drill chucks on that were left hand threads, why go to the bother of left hand threads ?
 
Tozguy said:
A right hand threaded chuck unscrewing when operating in reverse is such a natural happening that it is not an accident when it happens. You can almost count on it to happen. The laws of physics dictate it and that's why they always put a left hand thread on the right hand pedal of a bicycle or it will come off 'accidentally'.
I have seen a few screws for holding drill chucks on that were left hand threads, why go to the bother of left hand threads ?
Click to expand...

The right-hand thread on the actual arbor will tend to tightened when the drill is turning in the normal forward direction.

The internal l-ft-hand screw, on the other hand, will tend to tighten when the drill is run in the reverse direction(like when using it to remove screws, etc)
 
With all due respect Andy, this thread is about a lathe chuck loosening, not a drill chuck. For a drill your answer is spot on.

"Billy G"
 
Bill Gruby said:
With all due respect Andy, this thread is about a lathe chuck loosening, not a drill chuck. For a drill your answer is spot on.

"Billy G"
Click to expand...
Hi Bill:

With all due respect as well, did you see the last sentence of the post I was responding to?
 
Yup, just went over it again. My bad.

"Billy G"
 
Ok, lets accept that some of us have seen it happen and have concerns about it happening and want to take safeguards.

Are there any simple locking mechanisms people have added to the lathe that make it impossible for the chuck to accidentally unscrew on an old threaded chuck/spindle ?
 
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