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Casting Mirror Grinding Tools

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Posted by Ian McKernan on November 18, 2001 11:29:21 UTC

Hi! I'm new to this and am embarking on my first effort at mirror making. Am trying to make a tool cast to the right curvature to start with. I got the idea from a web page about using a previously used/made glass tool covered in the "dumps" from the centres of steel washers. Not having a 254mm / f6 tool i wondered about casting the basic shape? Anyone out there done this and got any comments? I went out and bought a sheet of hard polystyrene ("Polystyrene Gold"). I made a 2D template out of wood by tracing out the curve in my carport, and sanded a 254mm diam circle of this polystyrene out to a bowl with about 2.6mm saggita. Went round and round as i was sanding so i think its approx spherical. Wrapped it in tape and poured in some "Gyprock" brand cornice cement. I now have what looks to me like a plaster tool i can epoxy washer slugs onto after a few days drying. I think the curve will not be exact but will this matter? Will i be able to correct the curve as i grind? Anyhow, i'm doing this on the cheap, reading a lot on the net, knocking off other peoples ideas and modifying/adapting them. Any comments on whether or not people think i'm headed for a disaster would be appreciated. Frustration i know about !! The bl(*%y Leonids are on tonight and its cloudy and piddling down here!! Had a beautifull week, and even today it wasn't that cloudy. Now, solid overcast! Bugger!

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