Tip for New Vacuum Chuck Users

Updated: Mar 4

Here is an Oak bowl being finished on the inside.

In the photo you can see that this is a large, deep, heavy bowl with a concave bottom on a 6” vacuum chuck. Six-inch is not the ideal chuck size to use but the larger size vacuum chuck would not work here because the bowl is out of round.

The photo clearly shows a vacuum of 17.5 inHg. The big question: is this safe to wood turn at 17.5 inHg, using a small vac chuck, standard speed of the lathe, with a large heavy out of round bowl?

NO! Not unless you use a live center and in this case we cannot.

Obviously, the problem is that the woodturner cannot draw a good vacuum because the open grain is allowing air to pass through the wood.

The fix is to add something to the end grain to stop the air leaks, in this case tape. In this picture one piece of tape has been added and some of the air leaks have been stopped. The vacuum is now up to 22.5 inHg.

In this picture two pieces of tape are on the end grain and the vacuum is now 27 inHg.

However, the interior work to be done is sanding only. Is it OK to sand with a 17.5 inHg, small vac chuck, a large piece, and SLOW speed?

Yes, it is safe, for the woodturner.

However, maybe not for the bowl because there is a high risk of the bowl coming off the chuck and falling on the floor.

Is it better to be using 27 inHg? YES, for both the woodturner and the bowl.


As a reminder when sanding with a vacuum chuck that is leaking vacuum through the wood grain, the woodturner must be aware that the sanding abrasives will be trapped by the vacuum and could contaminate the finer grit sanding media. Take extra time and care in the removal of dust and abrasives.

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