Hiyah Guys! Thanks for the reply's. I looked up the page on Steve Lee's website again , and had another read. Apparently he and some mates have succesfully ground down through the grits with a dump covered tool, and he has a photo of a 200mm f4.5 tool he used, where there are quite large areas of no contact, (much larger than i have so far, i used smaller diameter dumps).
Ive tried emailing him direct, but the address wouldn't connect.
Anyhow, with a bit of luck i'll get the hole hogged out at our groups next meeting, and i'll see how spherical it turns out. Question though? At the moment im doing centre over centre, MOT, to hack out the glass asap. Would offsetting the mirror (using a more chordal stroke) be more likely to give me a better spherical shape at this stage??
Hopefully i'll know if this is going to work in the next couple of weeks. If not then i'll cast a tile tool off the rough blank as has been suggested, true that up with 80 grit and keep on going.
Seeyahs!

• Cast tool - bobmay - April 1, 2002 - 19:37 UTC