Overflow casting

[Peter Angel]

Hello all.

I miscalculated the amount of glass to use (even though I was using the Archimedes bath tub method).

Anyway, now I have some overflowing glass.

The overflow is about 3 - 5 mm thick.

How do I trim the excess glass away?

Pete

[Morganica]

I'm really good at calculating the amount of glass to use in a mold. I'm really bad at believing my calculations, so I typically stick another billet or so in the mold at the last minute.

When that happens I make some judicious incisions around the neck of the excess with a diamond cut-off wheel on my Foredom, and crack it through with a small hammer, then pull it away. Then once it's out of the mold, I can use the cut-off wheel (if it won't fit under the saw) to take it back to a couple of millimeters from where it should be. Then I can coldwork the rest.

Looks like the cracks have already started. (Is that R&R910?) If the neck of the overflow is very thick it can take awhile, but a cut-off wheel in stages usually works.

[Peter Angel]

Thanks Cynthia.

I'm going to buy a glass cutting saw. Useful tool.

Its plaster + course silica + ceramic fibre + a big scoop of R&R910.

[Morganica]

Yeah, the green kinda gives it away.

I have a hankering for this compound miter-chop-wet-diamond-saw I once spied in a big glassblowing shop. Really beautiful, could slice through 8 inches of glass at all kinds of angles with almost no throat or table depth problems. They were using it to cut big, thick cylinders into rings. Probably costs more than a new car. Sigh.

[bhawbaker]

If you were really careful you could do this.

https://www.youtube.com/watch?v=Khyi0Ff ... e=youtu.be

This is a tile cutting saw from Harbor Freight with a glass blade.