One of the challenges of turning wood bowls is finishing off the side and bottom of the bowl's foot. To meet this challenge, some rather time-consuming and (alternatively) expensive solutions have developed.
One is to carefully part the bowl from the lathe and finish the bottom by hand. This works fine, but can be time consuming, especially if you are producing a large number of pieces. Another approach is to turn the bowl around and use a jam chuck or scroll chuck to hold the bowl from the inside while you finish off the bottom. But a shop-made jam chuck can take a while to set up; it has to fit in the bowls opening correctly, and it's usually only good for the one project. A scroll chuck is a lot faster and more versatile but can cost as much or more than your lathe.
Just about the slickest method is to use a vacuum chuck. It's a simple idea; you use the vacuum pressure supplied by a pump the stick the workpiece to the lathe. But there again, vacuum chuck systems that use mechanical vacuum pumps are spendy. The HoldFast Vacuum Chuck System gets around this by using much less expensive vacuum generating system: a venturi vacuum generator the operates on the flow af air produced by a standard shop-sized air compressor. The HoldFast system generates a surprising 19+ inches of vacuum using a modestly-sized air compressor capable of generating 2.5 cfm at 65 psi, comes with a chuck adapter kit that makes set-up easy, and is guaranteed to hold your work securely in place while you put the finishing touches on you bowl turning projects.