Re: ATM (More!) tile tool questions

[Mike Coslo <mjc5@psu.edu>]

Brian Yankee wrote:

> First, has anyone used glazed tiles, but glued them onto the tool
> upside
> down so that the unglazed side is up? Is there any point to doing
> this?

        For myself, I'd probably go with porcelain tiles, unglazed, especially
in consideration that you are going to go with one tool through your
whole process, which I also kinda like.

> Second, what is the ideal (or minimum/maximum) spacing between tiles
> for grinding 6" and and 8" mirrors?

If you get the 3/4 inch porcelian tiles, you'll end up with a nice
spacing across the tool. Probably the most important thing is to not
have the tiles butt up against each other.Use a glass cutter to cut any
tiles that stick out.

> Third, I plan on using the tile tool right from the start (hogging out
> phase).  I realize that I may have to replace worn down tiles. My
> question is, why doesn't this cause all sorts of uneven wear on the > mirror?  It seems 
>to me that putting a brand new, unshaped, full >thickness tile on a tool that has been 
>shaped by the grinding process >would be potentially disastrous.

        You are correct in that you can get some weird stuff happening when
using a "soft" tile tool. It seems to me that if you have to make more
than one tool, you are wasting time. Even if you make your tool after
hogging out, you still have to seat it in. My tool was very nicely
seated after hogging.

        Bear in mind that many fine mirrors have been made in the other
fashion, but I really like the method of making one tool with porcelain
tiles to take me the whole way through the process. It hogged very fast,
and I suspect I can make plenty more mirrors with it if I like.

        - Mike -