On 11 February 2011 13:06, Philip Pemberton wrote: > (EE because "making stuff" is part of engineering :P ) > > This has been annoying me since about 8PM. > > I'm building a case for the night-vision tube using a couple of lengths > of PVC pipe. One 90mm dia. length holds the tube proper, and a 50mm-dia. > length serves as a spacer to keep the focal-plane distance (distance > from the lens to the input coupler) correct. There's a 90mm pipe cap on > either end -- one to hold the eyepiece, the other to hold the lens mount > and spacer. > > What I need to do is knock a ~45mm hole in the front of one of the pipe > caps. > > Problem 1: these are EXTREMELY thick pipe caps. The plastic walls are > about 15mm thick! > > Problem 2: I don't have a hole-saw suitable for PVC (actually, I don't > have a hole-saw at all: the one in the toolbox has a broken setscrew so > the drill bit won't pass any motion onto the saw-blade). > > I've tried using the hot-knife bit on an Antex GasCat, which sort-of > worked... apart from the fact that it filled my kitchen with acrid smoke > and I had to give up part-way through. Turning the heat down only served > to completely stop the PVC from melting. Lovely. > > The Dremel won't work either -- the router bit gets clogged with bits of > PVC very, VERY quickly and just plain stops cutting. I suspect my PCB > router bit isn't geared up for uPVC, or the Dremel is moving too fast > and melting the plastic (not surprising). > > Short of "buy a new holesaw" (apparently *not* stocked by the local > B&Q), does anyone have any ideas how I might be able to cut these holes? > How about chain-drilling the hole, then finishing off with a sharp knife? Matt --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .