Re: [ATM] polish time for 13 inch

[Guy Brandenburg <gfbrandenburg@yahoo.com>]

Mel,

I was wondering about your opinion that neither cold- nor hot-pressing is necessary. I am wondering whether you think that this would work if somebody only does figuring sessions once a week? Or perhaps even less frequently? I would suspect that after a week or so, the lap has formed its own ideas of how it wants to be shaped, and has deviated markedly from whatever figure was pressed into it the last time it was used. In those cases, I would think that a gentle hot press would be required to bring the lap back into conformity. By hot press, I mean using a heat lamp to heat up the top part of the lap evenly on all parts so that a pencil point will go in with nearly no pressure, but it's not melting and flowing; then putting an appropriately-sized section of bag mesh from something used to hold onions or citrus fruit on the lap; then pressing the mirror firmly into the lap and mesh and then removing the mesh.

After that, I suspect that the mirror and lap will be in good contact with each other, since the mirror will soak up virtually all of the excess heat from the lap. Add some of your favorite polishing slurry (barnesite, cerium oxide, zirconium oxide, red rouge, black rouge) and away you go.

I think I like your suggestion of not cold pressing, however. It certainly means you can get a heck of a lot more done in one session, and you can try out lots of different things in a short period of time and find out what works.

Guy




Guy Brandenburg, Washington, DC
My home page on astronomy, mathematics, education:
http://home.earthlink.net/~gfbranden/GFB_Home_Page.html
or else 
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