Vacuum chucking-on a Conover

[Jeff Willard]

Just wondering, does anybody know if it is viable-or even possible?

[Steve Schlumpf]

Jeff - I am not familiar with your lathe but would think that as long as it has a hollow spindle - you should be able to figure a way to do vacuum chucking.

[Jeff Willard]

Here are the issues with this machine:

1) Cross holes in spindle. Am I mistaken in thinking that these could be safely plugged?

2) Outboard end of spindle has no nose, instead it has an internal (female) thread to accept the handwheel, and it's a thread type that I don't recognize. I've seen the Holdfast vacuum adapter available from Packard and CS, and think that something along these lines would work, but...

3) The spindle on a Conover is reamed for a #3 MT, and all of the vacuum adapters state that they are for a #2 taper.

Any ideas?

[Steve Schlumpf]

Do you have a manual for your lathe that would identify the threads on the outboard side of the spindle? Only ask because you can make adapters (or have one made) and I would think that you should be able to plug the holes in the spindle.

I got my adapter from Tom Steyer and he has a number of adapters - even a complete vacuum system that he offers. Check him out and see what he can do for you. Great guy to do business with and he is very knowledgeable on vacuum systems!

http://www.jtturningtools.com/

[Lance kanaby]

There use to be a vacuum adapter that threaded onto the spindle, but I can't find it listed any place. Contact Bill Grumbine as he use to sell them as he used them on his Poolewood lathes.

[Jeff Nicol]

Jeff, The threads should be reverse threads so that whatever is threaded in will not unthread itself. To overcome the threads and the MT#3 you would need to get an adapter that runs a hollow tube completly through the headstock and spindle. What are the threads on the spindle? This will determine how to make your adapters to work. First make the vacuum chuck to fit the threads on the spindle and the tube through the spindle to either be tightened into each vacuum chuck (If you use the hollow all thread for lamps this is easy to do) or the rod will be made with a wood or plastic MT#3 that the tube is threaded into and the outer adapter with the bearing in it tightens against the spindle to seal the spindle. If you have some more questions send me a PM and I can help you out with some of it. Or draw some pictures on it. I believe it can be found on the web somewhere. There are 2 different adapters that can be made to work in the Packard Tools catalog, a One Way and a Hold fast one. Check them out and see if the length will work.

Hope I did not confuse you more,

Jeff

[Jeff Willard]

Do you have a manual for your lathe that would identify the threads on the outboard side of the spindle?


Can't track the manual down at the moment, but don't recall a thread ID for the handwheel hub. IIRC, at one point they sold the hub seperately but ended that practice, citing liability issues.

Jeff, the spindle nose is threaded 1 1/2-8. The through hole in the handwheel hub is 25/32". The hub thread measures 7/8" OD, and 11/16" at the root. I've attached a couple of snaps so that you can see exactly what I am dealing with.

[Jeff Willard]

And here's one of the whole mess.

[Ryan Baker]

You can handle the cross-drilled holes issue by inserting a tube through the hollow spindle. If you can find some good photos of the Hold Fast adapter, it uses that design. Lots of people have built their own using threaded lamp rod or something similar. Mike Mahoney demos his setup like this on one of his DVDs. Seal the tube at the chuck end against the end of the spindle. On the outboard end, you attach a sealed bearing in a turned housing (or something along those lines) ... whatever works for your lathe.

If all that fails, you can always use a vacuum adapter like Bill Grumbine sells, which has the rotating adapter assembly mounted on the spindle outside the headstock (designed for solid spindles), but it is expensive. You should have little trouble cobbling together a system that works on your spindle for very little money.