Before I try to re-invent the wheel . .

[Peter Blair]

Before I try to re-invent the wheel so to speak I thought I's ask the experts here on the Creek.
I have a Oneway 3" vacuum chuck but of late I have been in need of something a little smaller to hold the pieces I am presently making
My 'plan' is to use a piece of 2" plastic pipe and turn some sort of adaptor to fit into the 3" oneway then glue a piece of plastic pipe to the adaptor, and wrap with soft rubber.
Has anyone already done something like this make a chuck bigger or smaller. I don't think I need to make totally new chuck. Or do I?

[Steve Mawson]

Not too familiar with the Oneway, however that is how I change sizes on the JT vacuum and it works quite well.

[Peter Blair]

Hey Steve. Thanks for the note. What I can't seem to get my thick skull around is if I leave the piece on a chuck and then thread it on the tail stock to re-chuck it does it matter if the adaptor is exactly centred on the vacuum chuck or will it run pretty true either way? I am concerned that whatever I make may not seat exactly in the center of the Oneway chuck.

[Peter Fabricius]

Hi Peter,
If you go to the WWF Site and look in the Buy and Sell section you will find an item on Vacuum Chuck Seals at the bottom of page one.
You can make these Vacuum Chucks in any size you want and they work great. Set the PVC pipe in a hardwood block that has been threaded for your lathe spindle with the Beall Tap.
Peter F.

[Jeffrey J Smith]

Peter: I've made several chucks using small faceplates and attaching a base made from everything from MDF and plywood to solid hardwood. Most have a recess turned to seat a pvc sewer adapter, some are just laminated and turned to shape. As long as you seal the wood (I've used marine epoxy because it was handy, or shellac because I was in a hurry) and chase down any leaks, it all seems to work.

I'd think that the only potential problem with your plan is that the more connections you need to seal, the more places for potential leaks.

Like Steve, I've been using the JT Turning Tools vacuum hub. It's beautifully machined from aluminum with a o-ring sealed recess that fits standard 2" pvc adapters. You can change them out at will. There's six set screws around the perimeter to secure the adapter in the groove, but I've been lazy and left them loose with no problems. YMMV. I've got 2", 3", 4" and 6" adapters that I've located for it. Just true up the end with a scraper at very low speed, index it to the hub and they stay true even when changing out sizes. A little closed cell foam and you're good to go.

As far as centering, maybe I'm just not adept enough, but I find that even using a chuck reversing adapter in the tail stock, the bowl still doesn't center precisely. I just went through this with a 16" bowl this afternoon. I just get it close with the tailstock, then I use my tool rest for final adjustments. Just bring the toolrest under the foot of the piece, turn by hand to locate the highest spot, turn off the vacuum holding the piece in place and bump it with the palm of your hand. Usually a couple of gentle bumps gets it pretty well centered. If there's a center nub left on the bottom, I've found it just as easy to use this to get the piece rough centered. Just bring up the live center, adjust the nub until it meets the centerpoint then adjust as mentioned.

[Peter Blair]

Thanks!

I'm still somewhat on the fence about which way to go.

I don't really want to spend more money on another hub but on the other hand don't want to waste time and build something that doesn't work.

Peter if I go with your suggestion do I need a gasket to seal the block to the headstock and do I need to do anything to seal the threads after I tap them?

[Peter Fabricius]

Hi Peter B.You do not need anything to seal the chuck onto the spindle. I do apply oil / wax mixture or Tung Oil to the chuck base.For the seals on the PVC, sure I could say you need my seals, but you can use craft foam as well.Good luck with your challenges.Peter F.