Threaded holes in Jaws

Re: Threaded holes in Jaws

Robert Cox

>684 RPM? Seems like that is really really low

But I don't have a chuck yet or much experience.

Re: Threaded holes in Jaws

Barry Irby

>I have to admit I was surprised to see 684 RPM. I use two chucks and commonly turn fastert han that with the regular jaws. I have the lighter duty Nova chuck that uses the tommy bars to adjust it. Did not like it much. Got a new Super Nova with my new lathe and I like it. I put the cole jaws on the old chuck and leave them on there. The light duty chuck works fine for that. The cole jaws say right on them not to exceed 600 rpm, and I don't, but I understand that with those big jaws it might be dangerous to run too fast.

My son, who is not a wood worker, saw the electronic speed adjustment on my lathe and turned it all the way up to 3500 rpm and turned the lathe on with the cole jaws on the chuck on the lathe. I was stunned and shouted at him. He turned it off with no ill effects, but it was frightening. Probably a good reason to put the chuck away and not leave it on the lathe.

The answer.

steve antonucci in NW NJ

>I am willing to bet I know exactly why 684 rpm.

It's the speed on the third step of the pulley on a Nova lathe. The next step is 1080 IIRC.

That being said, I finished a plate with a set of Oneway Cole Jaws on my SuperNova chuck at about 1400 rpm this afternoon on my Nova 3000. The Oneways jaws advise no more than 1000 rpm. At that speed, the Cole jaws act like a fan and blow sawdust all ofver the place. Lucky for me I only had the lathe running for a minute.

Steve

Re: Threaded holes in Jaws

Peter Teubel

>I believe the speed limitation is two-fold. One, product liability. Nuf said there...

Two, the cole jaws (or mega jaws in Oneway slang) do not hold pieces as securely as regular jaws. I mean, the contact points are flexible rubber bumpers. They flex and the forces on them from your work turning at high speed will cause them to deflect. All at once, you'll have a frisbee...

Re: Threaded holes in Jaws

GeeSeaWhy

>The manual for the accessory jaws has a table listing the max. recommended speeds for all the Supernova jaws. The only jaws they list a max. speed > 684rpm for are the 25mm, pin and 50mm jaws. Even the Powergrip should not be used above 684rpm!

Another theory: they expect you to use the most appropriate jaws for the size of the blank. The 100mm jaws are recommended for bowls up to 14" dia., which you really shouldn't be turning at over 650rpm anyway. If your bowl is only 8" you can go faster but why would you use the 100mm jaws when the 50mm would work fine?

I've never used the bolt holes on the 100mm jaws but the idea is you attach pieces of wood (or maybe plastic) to the jaws then turn a custom jawset into the wood. Then you can hold your workpiece in the custom jaws without damaging it. If you need to hold a bowl by its already finished foot, perhaps. Or possibly as a slightly adjustable jam chuck - now there's an idea I could use. Thanks!

Graeme

Re: Threaded holes in Jaws

Barry Irby

>Thanks for the responses, I understand about the 684 rpm now. I have a Nova 3000, but it is the DVR version, so I don't have those steps. It does start at 600 rpm if you turn it off and back on. Handy for setting the speed for the cole jaws.

I think the light is going on about the threaded holes. Its a little dim at this point, but I think I get it. If I were turning something repitious, I could make a set of custom jaws. Or as you said a ajustable jamb chuck. Hmmm? What are the possibilities? Thanks again.

Barry Irby