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Hey folks,

I am running into a bit of a problem specifying the correct elastic material for an air cannon. I have worked on several of these and we always used black neoprene rubber sheet. We used material already laying about the shop so I had to guess at the proper durometer. We used material 1/16" thk but it would tear fairly easily.  For the one I did recently I specified an elastic natural Gum rubber with a durometer of about 40A. It proved way too stiff.  The folks at McMaster-Carr have suggested an Ultra-elastic Natural Latex rubber with a durometer of 35A.

The cannon is smaller than most at 8" diameter versus the usual 12-18" diameter ones most of us have built. But it is shooting a shorter distance and the mock up worked well with a plastic bag as diaphragm.

Can anyone offer a specification for a good elastic diaphragm? 

--
Erich Rose
Exhibit, Environmental and Industrial Design
807 The Living End
Austin, TX 78746
512-626-9930; [log in to unmask]

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