A woodturner friend demonstrated a simple vacuum chuck system a few years ago at a workshop. From this demonstration my mind raced to copy the system then simplify it for my own use.
Once a bowl turner has used a vacuum chuck it soon becomes a most important accessory for the lathe. There are several ways to reverse mount a bowl to finish turn it's foot. The vacuum chuck has to be the easiest to use when the critical sealed bearing is permanently mounted on the lathe as will be described below.
 The system I have on my lathe consists of a 1.5 CFM vacuum pump, an air filter, vacuum gauge, ball valve, vinyl plastic tubing, tubing to bearing plastic connector loaded with 5, o- rings, sealed bearing mounted on the lathe hand wheel and various size vacuum chucks.
The vacuum pump that I use is a Robinaire 1.5 CFM model. Several of my turner friends use the 2.5 CFM vacuum pump from Harbor Freight and these “do it yourself” systems can be put together for less than $200. I have mounted an on/off switch for the pump at the lathe. I feel having this on/off switch close to the work area is not only for convenience but helps in adjusting bowl positions as needed. The switch gets power from a wall outlet.
The plastic vinyl tubing used in the system is available at most hardware stores. Either ¼" or 3/8" tubing to fit the connectors is adequate.
I use a disposable paint sprayer air filter in the supply line to the vacuum pump. This filter is required to prevent sawdust from being sucked into the pump. I change the filter once a year as routine maintenance.
The Powermatic lathe and some other lathes are supplied with a "cage". I can see no use for the cage so I cut the cage off the mounting rod and by reversing the directions of the rod, toward the left of the headstock, the rod then serves as a perfect place for mounting the filter, vacuum gauge, ball valve for venting the system and vacuum pump power switch.
 Connecting the vacuum pump to the lathe is critical to the purpose of the system. The parts I use are available from bearing suppliers and hardware stores. The bearing I use is Model Number 1621 DC from General Bearing Corporation, made in China. I have tried other bearings of this same size but none had seals that work as well.
The bearing needs to be permanently mounted to the hand wheel. The ½" hole in the bearing allows use of a knock out bar for removing a spur drive when spindle turning. The bearing is shown mounted in 1 ¼" plastic water pipe which is glued in a "rabbit" joint in ½" X 3" diameter Plexiglas that is screwed to the hand wheel with ¼"-20 threads per inch flat head machine screws. A gasket between the Plexiglas and the headstock arbor shaft is necessary as the shaft has a key way that will leak if a gasket is not used.
I removed the hand wheel from the lathe for bearing holder installation. Make a guide to align the bearing with the hand wheel. This guide can be a turned dowel sized to fit the hand wheel and on its other end sized to fit the inside of the bearing. With the guide in place for alignment, mark the machine screw mounting holes. Drill and tap the holes in the hand wheel. Replace the hand wheel on the lathe shaft so that the lathe shaft protrudes slightly beyond the hand wheel. This is necessary so the gasket will block the shaft key way as the bearing holder and gasket are mounted with the screws to the hand wheel.
The connector to the bearing from the vacuum pump is a bit hard to find. What I use is available in my area and works so well that I have not looked for an alternative. I put 5 o-rings on the connector for a great seal. I routinely get at least 25" of hg during vacuum chuck use.
Caution: Be sure to only put the connector into the bearing when using the vacuum chuck. The reason for this is that with the connector in the bearing the "life" of the bearing seals will be shortened. I use my vacuum chuck system several times a month and have had the same bearing in use for 2 or 3 years, so with care the seals will last a long time.
The last part of the system is the vacuum chuck itself. I mount the chuck using a dedicated faceplate screwed to ½" Plexiglas disk of a desired diameter. The chuck body can be made from thick walled sewer pipe or plastic sewer pipe couplings which come in different sizes. The coupling is glued in a turned "rabbit joint" cut into the Plexiglas, this centers the chuck body. A ¼" hole in the center of the Plexiglas is all that is needed. I glue dense ½" thick foam from common floor mats to make the seal collar where the bowl will be attached for turning. Thinner foam will work but with some bowls that do not have uniformly flat inside bottoms, the thick foam allows for uneven surface attachment.
 Check for system leaks. If you do not get 20" of Hg vacuum pressure with a bowl on the chuck, there is a problem. Start at the bearing connector, where you should get near 25" of Hg. Then check the right side of the headstock arbor shaft, with your hand plugging the shaft hole, you again should see near 25" of Hg. If you don't you have a leak in the bearing or its attachment to the hand wheel. I test the bearing holder before installing it on the hand wheel. If it checks out OK then mount it. Make sure the gasket seals the keyway. Another place for a leak is the threads of the faceplate. I cut a gasket to fit inside the faceplate to stop leaks at the threads.
My last recommendation is to use a small gouge and make careful cuts when using the vacuum chuck system for finishing the foot of a bowl or for other turnings. A "catch" can ruin your whole day.
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