Woodworker's Journal 2010-34-2, страница 23

Vacuum chucks make sanding a sphere a much easier operation. Because they are spheres, they are virtually self-centering.

removing the air inside the bowl or vessel. Then the air pressure outside pushes the turned object onto the cylinder. Since air pressure varies in different parts of I he world and with different weather conditions, the amount of pressure you'll need will vary. In general, manufacturers call for about 20 to 25 PS1 on the gauge, but you'll most likely discover that the amount you need will vary within a greater range than that.

Having something flv off the lathe from a vacuum chuck is, for the most part, not particularly dangerous to the operator, but it certainly could cause the object to be damaged. A more worrisome problem would be a vessel imploding from loo much air pressure. If that happens, the bowl could disintegrate with pieces flying everywhere. As with all woodturning operations, wear a faceshicld!

Larger objects attached with a vacuum chuck are actually more safely held than small objects. This is somewhat counterintuitive, but it has to

do with the amount of vacuum pressure required to hold small objects: the smaller the object, the more pressure it takes to hold the piece in place. If an object is small and thin, that's a potential recipe for a cracked vessel or parts flying

Once the bowl is properly centered onto the vacuum chuck, the next step is to engage the vacuum pump and then release the original chuck — the bowl is now ready to have its base completed.

If you are going to make your ow^rn vacuum system, be aware that you could end up with something that doesn't work and in the end costs more than a commercial system. Do your research first on vacuum systems and the requirements for holding objects onto a

lathe. With that said, however, I realize that many readers enjoy making and tinkering with new devices. If that's the case, enjoy!

Betty Scarpino's only vacuum is the one she does not use regularly to clean her house. All visitors must call way

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