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Adapting your lathe to use Vacuum chucks

Discussion in 'Tutorials and Tips' started by john lucas, Jan 11, 2021.

  1. john lucas

    john lucas AAW Forum Expert

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    I was answering a question in the forum about vacuum adaptors and thought that I should really put the answer here. If you want to try vacuum chucks there are some fantastic articles in American Woodturner about ten years ago or more. If you do a search of American Woodturner for vacuum chucks it brings up seven articles. The first few back in 2003 were extremely useful. I built my first one from an Automotive car compressor from plans in those articles. Since then found a used Ghast pump ( that I was able to size because of the directions in those articles). I have tried several ways to adapt the vacuum pumps to my lathes. So here are ways to do it.

    The first is a drawing of a wooden version of the commercial EZ vacuum adaptor. If you have any questions on how I built this just ask. This is the best way to go if your spindle has holes in it and won't conduct a vacuum. I know most lathes don't have that problem but a few do.

    ez-vacuum-chuck.jpg

    The second one shown with the Powermatic handwheel is an old vacuum adaptor sold by Nova to adapt a standard shop vac to the lathe. It had some holes in it to bleed air so it would not burn up your shop vac. When I started using vacuum pumps I plugged those holes. This adaptor is simply glued into a bearing. The Nova had the handwheel counterbored to fit the OD of the bearing. I took the handwheel of my Powermatic to a machinist and had it counterbored to match the bearing. I simply put a closed-cell foam gasket between the bearing and handwheel, turn on the pump and I'm ready to go. Sometimes I have to push on the bearing after I turn on the pump to get a really good seal but it works perfectly.

    powermatic vacuum adaptor.jpg

    I took this same idea and adapted it by using standard hose connectors. Threaded to 1/2" on one side and barbed on the other to fit in the hose. I simply insert these into a bearing with a 1/2" ID. You do have to turn the threads down a hair to get a snug fit but that's easily done on the wood lathe. epoxy this into the bearing and you're ready to go.

    vacuum chuck bearing inserts.jpg

    The last photo is how I set it up on my Delta midi lathe. Just turned a wooden insert to fit in the handwheel that accepts the bearing. Put the foam gasket in and I'm ready to go.

    Delta Midi vacuum adaptor.jpg

    I prefer the bearings to the EZ adaptor because if you need to use your knock-out bar you don't have to remove anything. It's also a lot faster than installing the EZ adaptor.
     
    Clifton C and Dennis Weiner like this.
  2. Bill Boehme

    Bill Boehme Administrator Staff Member

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    My only concern is the use of a single bearing. With that configuration, any side load created by the hose that goes to the vacuum pump will twist the inner race out of alignment with the outer race. When that happens, it will cause the rubber contact seal on each side of the bearing to slightly open up ... resulting in some vacuum loss which, depending on your pump and other factors, could be significant enough to be problematic. But, the worst thing is the loss of grease when that happens. The illustration below identifies the inner and outer races. The rubber seals aren't shown.

    ball bearing.jpg

    Better rotary couplers use two or more bearings to keep the inner and outer races properly aligned. The rotary couplers that were made by JT Turning Tools were among the best.
     
    Emiliano Achaval likes this.
  3. Emiliano Achaval

    Emiliano Achaval Administrator Staff Member

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    Also, my friend Bill Noble has some great articles about Vacuum chucks in general for woodturning. He also sells some really high-end pumps, used, refurbished, for great prices. https://www.wbnoble.com/index.html
     
  4. john lucas

    john lucas AAW Forum Expert

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    Bill I've been using that same bearing for well over 15 years now. I get between 23 and 24" everytime I use it if the wood doesn't leak.
     
  5. Bill Boehme

    Bill Boehme Administrator Staff Member

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    Your closed cell foam gasket probably effectively sealed the low pressure side of the bearing to prevent the grease from escaping. Some of my early attempts at using a single bearing didn't last very long.
     
  6. john lucas

    john lucas AAW Forum Expert

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    I thought I would follow up with a selection of chucks and how I make them. Just about anything works if you seal the wood properly to prevent the vacuum from leaking through. Over the years I have used plywood, mdf, solid wood and PVC. Plywood and MDF require a lot of work to seal properly. I usually just spread a layer of epoxy on. Same is true somewhat with solid wood. I don't use a solid blank because of wood movement but use glue ups of solid wood. I make my own faceplates for these out of the proper sized nuts and large washers that are welded on. I put a closed cell disc gasket inside to seal the vacuum. I put these on the lathe after mounting the faceplate and true everything up and then seal the wood.
    The best ones I have are made from PVC pipe and plastic decking material. Decking usually has texture that needs to be cut away to make the blank. After I get it trued up I drill and tap a hole for my spindle. Beale sells an inexpensive tap. I cut a groove to fit the PVC pipe and epoxy the pipe into the groove. You can get PVC in step adaptor sizes such as 4" to 8". These work really well for the larger chucks. Once I have it glued into the Decking I mount it on the lathe and true everything up. Then I use either vacuum gasket material or closed cell foam to glue to the top for the seal.
     

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