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MMD > Archives > October 1996 > 1996.10.14 > 03Prev  Next

Simplex Pneumatics
By Craig Brougher

Brett Mohr asked about removing pneumatic cloth from Simplex pneumatics: Getting off the hide glue isn't actually necessary, Brett. New hide glue will go right over the old stuff just fine, and you will find should make an ever better bond because it was top quality stuff and has penetrated the wood, sizing it well. Leave it on. That's not to say, "leave on some of the old cloth along with it." You will have a hard time getting the halves apart then.

I will say however that you picked a real "doozy" for your first player job. Talk about "where angels fear to tread," you're driving a sports car. There are a number of details about doing a Simplex valve pneumatic that may not be immediately obvious to you. I strongly suggest building a test stand to check each one, having a matching gasket and vac supply set to a low pressure, like 5- 6" of H2O. Do one completely, first. Get it operating at a very low intensity. It should work real snappy, although weak at 5". You'll provide a bleed in your tester for each pneumatic. Just copy the stack board and fix it to clamp vertically to your bench.

Getting the halves apart is not very simple, in most cases. But if you have a really great freezer, one that gets down to sub-zero temperatures, or can get some dry ice in a large cooler, try this: After you have popped out the valve poppets and taken off the outside valve seats, put them three at a time into a microwave and get them really hot, so that the old glue will totally dry to powder. Then put them in a freezer for several days. When you take them out, get a very large screwdriver that just fits the supply hole. Insert and give it a twist while they are still very very cold (use gloves). It should break open.

By the way, you can also try the microwave trick, and then break them open while still hot. They will sometimes work that way fairly well. Expect some splitting. I wouldn't try soaking them. There are two wooden dowels that would expand and bust the back end of the top half. When that happens, you can't screw them down any longer. You could predrill each dowel with a small 1/16" bit, but there are 176 of them, making for a very unrewarding afternoon. As far as warpage is concerned, the only maple I've found that doesn't warp when it gets wet is quartersawn. So to the degree that the grain isn't parallel to the part is the degree that it will warp a little. You can do without that problem.


(Message sent Mon 14 Oct 1996, 13:06:01 GMT, from time zone GMT.)

Key Words in Subject:  Pneumatics, Simplex

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