You don't need a vacuum pump......

Once you go Vac you won't turn back

john lucas

I built one using a car compressor as described in American Woodturner many years ago. It worked fantastic. then I found a compressor at the flea mkt and stepped up to the real thing. When I was looking to set up a system I tried the Venturi style units but they were incredibly noisy and needed a compressor much larger than I had.

With the advent of the newer style Venturi units all those problems are gone. The Holdfast system will run off one of those pancake compressors. Impressive. The new Powermatic 2442 has one built into it.

The only problem with them is the strength of the holding power is directly related to the square inches of surface area. So if you are something 3 1/2" in diameter like my pocket mirrors you barely have enough strength hold them. The length of the turning can also cause problems because of the leverage of taking cuts out on the end. For turning platters with a 6" vacuum chuck you have lots of holding power. It's about the best thing there is for reverse turning bowls.

Re: Once you go Vac you won't turn back

Gbalock

Vaccum is great, but don't forget the extra security of using duct tape and keeping the tail stock up until the very end. Having the Vaccum give out at an I opportune time can be way too exciting.

They're also good for holding odd shapes

David Walser

A few years ago, the American Woodturner published a series of articles showing how to make a vacuum chuck that conformed to odd shapes, such as natural edged bowls. The chuck has a thick layer of rice (or similar medium) inside a plastic bag/donut. The turning is sandwiched in the chuck between the the rice and a compression ring. The edges of the plastic bag are extended outside of the compression ring, sealing on the inside of the ring against the turning. When the vacuum is turned on, it draws out the air from around the rice and sucks the compressing ring down onto the turning, holding it tightly in the chuck.

The combination of the having the rice conform to the shape of the turning and the normal holding power of a vacuum chuck, allows odd shapes to be held very securely. It's an interesting and flexible concept. The first article can be found in the June 2012 issue.

Video showing method to hold odd shapes *LINK*

Dave Paine

In addition to the AAW article, this video shows using what the demonstrator calls a "compliant" vacuum chuck to hold odd shapes.

A long video. The complaint chuck part starts at 1 hr 32 mins to the end.

Essentially using a large bag of rice or sand in a large diameter vacuum chuck to support irregular shapes. I can see this being useful. Also shows what he calls a "force ring" to mount the irregular piece for finishing the centre.


https://www.youtube.com/watch?v=PEN5GkoeIbY

Re: You don't need a vacuum pump......

Peter Hyde

Correct! Although I use one occasionally it still has it's negative aspects, like loss of vacuum at a critical moment. As for holding irregular shapes it can be done with additional padding like bags of sand as already mentioned.

So the thing I use most is the good old simple donut chuck. I use my jumbo jaws just opened enough to allow the through bolts of the chuck to slide. Put a suitable sized disk of plywood on the jaws as a stiffener then cut a ring with a hole from another disk and drill the 4 holes in line with the slots. Use thumb (wing) nuts on the headstock side and use threaded rods available from any hardware store as your bolts.

Simple, quick, cheap, and silent and it will hold a cube positioned on a point. That's not easy with a vacuum chuck