Vacuum Chuck - Canadian Woodworking Magazine

vacuumchuck_lead

Vacuum Chuck



Vacuum chucking is used to hold a workpiece on a lathe, so that it can be turned or sanded. Vacuum chucking is particularly suitable for finishing off natural edge bowls and salad bowls.

The system that I show here can use a vacuum cleaner, a Shop Vac, or a vacuum pump. I use an Electrolux vacuum when I need it to be very quiet, but I use a vacuum pump when I need good holding power.

My set-up is built to fit my 160-260 General lathe, but it would work on most lathes. The system consists of a round wood fixture (the housing), which fits over the handwheel, a support arm on the outboard end, and a PVC vacuum chuck with a leather sealing ring.

Start by turning a housing that will friction fit over your handwheel, (see accompanying sketch). I used a piece of 2"x6" birch to fashion mine. After you have turned the housing, cut a chuck mount on the inside and bore a hole for the vacuum nozzle to run in. This hole must be accurately bored for the hole to run true when installed over your handwheel. My vacuum required a 1.260" hole.

The holding fixture consists of two pieces; a 2.75" square birch block, and a support arm made from 1"x4" birch. Install a 'T' nut in the center of the birch block to hold the nozzle support arm. Install the block on the outboard end of the lathe. Be sure to position the hole in the support arm to align with the hole in the handwheel fixture.

The support arm should be about 15" long for a 12" lathe and 18" long on the 20" lathe. If you position everything correctly the support arm holds the vacuum nozzle centrally in the handwheel hole, and the clearance between the hole and the nozzle provides cooling air for the motor. This method seems crude, but it does work. A household vacuum will pull up to 3" of vacuum. A Shop Vac will pull up to 5", but are quite noisy.

To make the vacuum chuck you will need a 4" black PVC coupling, a dedicated 3" faceplate, some wood for the mounting block, and leather for the sealing ring. Fasten a piece of 2" hardwood (that you have bandsawn round) to the faceplate, and turn it to about 5 1/2" in diameter. Turn a stub tenon 1/2" long over which you install the PVC coupling and epoxy it on. Go for a tight fit. When dry, install it on the lathe, true up the face and glue on the leather seal with contact cement. Finally, drill a 1/2" hole in the block to pass the vacuum hose through. Now you are ready to try it out.
 

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RON CLEMMONS
RonClemmons

Prince George, BC
Tel: 250.563.1860