Thread: Near Miss? Screwed Chuck.

Hi,


After re-arranging my shed again I decided I wanted to try out the new layout by making something quick and easy.

I've always wanted to make a machinist jack so I gave that ago.

I used some MS of unknown quality (possibly 1020). The finish was unusually bad (even for my lathe). I remember looking at it and thinking, "must be the bearings finally going or the motor" and just continuing on. Then I noticed the whole job and chuck wobble a bit. So I stopped the cut and lathe.

The screw on chuck had unscrewed itself and was coming off! In the 6 years I've had the lathe that's never happened before. A bit of an eye opener. I guess I might not of tightened it enough when I put it on last.

Ben.

That's a lovely screw jack, Ben.

Q: Why would your lathe chuck unscrew? Just using it would tend to tighten, surely?
I've learnt not to screw my chuck too tight, just take up the play is enough, no problems with that.
I used to spin it on hard, but got tired of the wrestling match that often followed to remove the thing.

Jordan

I'm also intrigued. Like Jordan, I just screw my chuck on by hand until it's resting against the shoulder on the spindle nose. Even then it still requires a strap wrench to remove it. Do you have a VFD with braking?

I'm at a loss as to why the screw chuck came loose. I think (and I maybe wrong) I didn't tighten it enough the last time I put the 3 jaw back on. I have been swapping the chucks out lately. As I said, it's never happened before. No VFD or brake either. Didn't use reverse either.

I have now been checking the chuck before use.

Hi Guys,

In the very early days, when I first got the Myford, I was warned not to screw the chuck on more than hand tight ! Certainly it will tighten in use, particularly if its doing an interrupted cut. Whilst the Myford has a spindle lock, I just put it into back gear and by using the chuck key, a quick tug and it will unscrew.

If you have been swapping chucks, it is essential that the threads on the mandrel and in the chuck are scrupulously clean and well oiled before mating. I know a guy that broke the teeth off his back gear by using a long piece of 3/4" X 1" steel bar between the chuck jaws.