drop ring – size of hole and size of glass

[davidgustafson]

I took a drop bowl course several years ago but my notes are silent on how big I can make a hole in the concretized ceiling tile I bought.

More specifically, I have a 3/8 piece of glass about 11 inches square. I have a 12 inch square of the tile.

If I’m dropping the bowl 4 inches what is the limit to the size of the hole I can cut in the tile?

 

I fear that if I go near 9 inches the glass may pull away from the top of the tile and flop down the hole in the center of the tile onto the kiln shelf

I realize that a very cautious “lower slower” schedule will have to be used.

 

I’d appreciate any wisdom that might be lurking

Dave Gustafson