Vacuum chuck for lathe?

[David Sochar]

I am considering building a vacuum chuck for a lathe.

I need to turn 1-3/4” th x 12” stool seats. They are to be held on the top finish side while I work what will be the underside of the seat, out to and including the edge or rim. The top is to have no holes, etc.

Contact area will be about 9” circular.

Does anyone have a source for parts to fit an older Powermatic lathe?

1-1/4” threaded spindle (reverse threads) with some sort of rotary affair, and connectors to vacuum hose/air compressor.

Dave Sochar
”Small Shop Production of Custom Wood Doors”

[Edward Weber]

Are you looking for something like this?
https://woodturnerswonders.com/produ...gn=sag_organic

[Richard Coers]

Holdfast used to make an adapter that didn't thread onto anything. It was called the Universal headstock Vacuum Adapter. Basically a piece of lamp rod that sealed on the front side with a flange and gasket and a bearing adapter on the rear. I can't find anyplace that has them in stock. Some folks just use a quick disconnect on the back side and let that be the rotating connector. The o-ring in the disconnect won't last forever, but it does work.
Screenshot 2023-12-14 at 11.52.43 AM.pngScreenshot 2023-12-14 at 12.02.34 PM.jpg

[Gary Pennington]

Check with Bob at https://www.frugalvacuumchuck.com/home.html His approach is inexpensive, functional and very flexible. You can get the pieces from him to "roll your own" to suit your application.

Gary

[Thomas Wilson80]

Check with Bob at https://www.frugalvacuumchuck.com/home.html His approach is inexpensive, functional and very flexible. You can get the pieces from him to "roll your own" to suit your application.

Gary

+1 for frugal vacuum chucks. I just got a complete setup (because I’m not great at DIY) and Bob is great to work with. I keep asking myself why didn’t I do this sooner.
Tom

[Robert Hayward]

+2 for Frugal. Excellent budget minded vacuum setups.

[David Sochar]

That is a big help. Going thru the lathe head was where I got lost.

I used to see plywood part holding jigs that had a seal that fit into a 1/4” x 1/4” groove, making a circle around the center evacuation point. Things held so well no other clamp was needed. Used for sanding and machining mostly. This was before CNC and it’s holding challenges.

So….a ball valve on the vacuum hose left of the head, spinning capable hose and bearing thru the head, 3/4” plywood plate about 10” diameter with a plow near the rim, on the face, to receive the seal. To hold a 2” x 12” piece of Hard Maple.

[Bill Howatt]

You didn't mention 2 things, an easy readable gauge and a filter. Having a gauge on the pump is nice but having one where you can easily see with a quick glance it is much better. In your current project of thick hard maple that is likely in good condition it isn't quite as necessary but if you are turning bowl bottoms that may have invisible cracks, punky areas or is type of wood that is porous it is good to monitor the vacuum as you cut away material.
If you have porous wood or a small opening appears as you work it will suck dust into the pump without a filter.
If you are going to use the chuck for various turnings, having a small bleed valve can be handy. A thin platter can be broken if it has a large area under a high vacuum. You can often see the thin platter flex as you increase and decrease the vacuum with bleed valve.
Remember the force on the piece is highly dependent on the area under vacuum which is why vacuum chucking is often poor to useless for small items even if the vacuum is the maximum attainable.