Horror Stories About The Chuck Coming Off While Running Backwards

[kvt]

RJ have seen that a couple of times on small lathes like my sherline, only a 3.5 inch chuck, but gripping heavy object, shut down the motor slows/stops quickly, and the thing unscrews and goes for a bouncing ride. Jump out of the way and hope it all survives. Did the same with a Asian 10X24, At least it was not spinning that fast. But a lot bigger chuck and had a 7x5 piece of steel chuck up in it, lathe stopped and the chuck did not. Again step out of the way and hope all turns out ok Thus next lathe will have a different type of setup.

 

[RJSakowski]

RJ have seen that a couple of times on small lathes like my sherline, only a 3.5 inch chuck, but gripping heavy object, shut down the motor slows/stops quickly, and the thing unscrews and goes for a bouncing ride. Jump out of the way and hope it all survives. Did the same with a Asian 10X24, At least it was not spinning that fast. But a lot bigger chuck and had a 7x5 piece of steel chuck up in it, lathe stopped and the chuck did not. Again step out of the way and hope all turns out ok Thus next lathe will have a different type of setup.

I am surprised that I have never had an incident with my Craftsman 6 x 18. I have run a 4"3 jaw chuck on it for most of its life and had run it in reverse numerous times without problems. It may be due to my tightening the H out of it. It usually takes a rap with a mallet to break it free.

 

[ch2co]

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[hman]

Years ago, when I worked at HP in Corvallis, I recall a visit to our in-house machine shop. A bunch of the guys were gathered around one of the lathes. Don't know what kind of lathe it was, but it had a threaded spindle. Apparently the machinist had turned it on in reverse, seen the chuck start to unwind, and quickly switched to forward. The weight/momentum of the (8"?) chuck made it slam forcefully onto the register, jamming it into place. The machinists there were trying everything they could think of to free it. I heard later that they were working on it for a couple of days. Finally, they devised a way to get a parting tool into position behind the chuck and cut a groove into the backplate about 1/16" from the end. Had to replace the back plate, obviously, but luckily no other damage to the lathe or chuck. Don't recall hearing anything about the machinist getting into any further trouble.

 

[Silverbullet]

I think it still comes down to the operator. If your going to run in reverse to do any cutting , the chuck should be tightened and checked . And if your threading you should be watching it automatically seems to me they can be stopped slowly even with brakes . If that chuck unscrews while threading , the cuts to heavy or your cutting to a blind stop and hit . All part of being safe , I've seen things fly out or off machines many times but the most unsafe is a drill press with un skilled labor using them. No machinist would not hold his material in a vise or clamp right.... If I had a left hand threading job to be safe I'd have the tailstock with a center up close or in the end. It would stop the total coming off problem.

 

[Wreck™Wreck]

Spun a 24" threaded chuck off once backing out a large tap, it was inelegant but not catastrophic, run away is my advice.

Also this is the year 2017, do not use threaded spindles if at all possible.

As mentioned above it can be very difficult getting them off as well.

 

[Eaglewood]

I have a Maximat Standard with a 1 1/8-12 spindle nose. The spindle has a 1.25 dia with a 45 degree grove. The backing plate has a 6mm screw appropriately positioned to lock the Chuck against the spindle flange. Works fine when you remember to tighten it

 

[GK1918]

Silver Bullit has the correct answer. Get in the habit of using the tail stock then the chuck has no place to go ......

 

[mcostello]

Fil was a kid and came across a fence in the woods going to a new fishing hole. Grabbed onto the wire and could not let go. It was hooked up to 110 volt. Not all electric fences use chargers. Some one had to find a big branch and pound Him off the wire.

 

[kwoodhands]

I have had a chuck start to come off when i turned on the lathe. This was on a Taig and I had just put the chuck on. I do not put them on very tight because they tend to get tighter and are sometimes hard to get off. don

Cut a piece of shirt type cardboard and install between the spindle and backing plate. You can tighten the chuck but still be able to remove it without a 4'-0" spanner wrench. After a while the cardboard compresses. When the chuck is harder to remove again ,replace the cardboard with a new piece. I made about 10 at a time with two holesaws. First was the smaller holesaw for the spindle . The larger one just for outside diameter. I placed the cardboard between two scraps of plywood, screwed them together and bored the holes. I call them gaskets from the dry cleaners.
mike