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Hope y’all don’t mind a crossover from the sawdust sniffers… Making a really cool hands-on science/engineering exhibit for a prototype education center here in Cincinnati. I want to make a piston pump using clear 2″ PVC to return water for a water ram. My plumbing friend said I needed to shape leather into a cup washer for the plastic piston I will be turning on a lathe, but he has never done so. Can anyone offer any suggestions regarding what to look for in leather, how to stretch/shape it, how far it should extend back along the piston, how much clearance between the piston and PVC wall, … Thanks.
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Don , Go to an agriculure tractor dealer and get a neopreme cup washer for a hydrolic cylinder. The ag dealer will or should be a lot cheaper than an industial dealer. Don
*interestingly, i just watched a t.v. program (Junkyard Wars on TLC wednesday nights) where they used wet leather as a sort of piston ring to pump air into a dive suit. Due to circumstances, i wasn't able to catch the end of the program to see if it worked but i thought it might make for some good brain candy.g
*If I understand your question correctly, it would be simple to make the leather cup. But the leather would not extend along the piston. Properly it extends in front of the piston face. The piston would act as backing for the leather cup that extends forward. On the forward end the leather cup would have a fender washer slightly smaller that the cup. The plastic piston you are making should not bea tight seal on the cylinder wall, that is the job of the leather. The pressure of what you are pumping pushes the leather to the cylinder wall for the seal.Take apart an old tire pump and see the construction.gws
*the old hand bilge pumps were a good example of leathers for gaskets..the circular leather was any stiff leather.. the stiffer (thicker) the better.. if you can't get stiff, then the washer has to be bigger...usually the leather is the same diameter as teh inside diameter of the tube.. when it gets wet , it swells to form the seal... you can slightly oversize it.. but at each cycle it will reverse the cup.... push-flex- cup... pull-flex-cup...used to watch the bosun at the sailboat shack cut them from leather scraps...b but hey, whadda i no
*For 2" pipe, you can probably find a cheap plain leather belt to cut the washer from (would be stiff and thick). Cut it just to the inside diameter of the pipe, even if it leaks a little, it will still work. Good luck. Hope this helps. Rich.
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Hope y'all don't mind a crossover from the sawdust sniffers... Making a really cool hands-on science/engineering exhibit for a prototype education center here in Cincinnati. I want to make a piston pump using clear 2" PVC to return water for a water ram. My plumbing friend said I needed to shape leather into a cup washer for the plastic piston I will be turning on a lathe, but he has never done so. Can anyone offer any suggestions regarding what to look for in leather, how to stretch/shape it, how far it should extend back along the piston, how much clearance between the piston and PVC wall, ... Thanks.