Cutting circle from mullite kiln shelf

[Warren Weiss]

Hi,
I'm planning to cut a 12" circle from the center of an old 24" by 24" by 1.25" thick mullite kiln shelf. If anyone has experience doing this I would like to know. What cutting tools should be used? How to avoid splitting the shelf? I appreciate all input.
Thanks,

Warren

[jim burchett]

If you have the split blade for the Taurus that would probably work..otherwise its gonna be tricky

[Marty]

Drill a starter hole then use a drywall saw or a sabre saw. Keep it wet.

[rosanna gusler]

i would use a tile saw and cut a 12 or so sided shape. . r.nevermind. i was focusing on the donut , not the hole. that said, there is easier stuff to make a drop ring out of if that is what you are doing.

[charlie]

i would take a diamond blade in a 4" side angle grinder, and carefully lower the blade into the discarded piece near where the edges of the hole will be. make many cuts, and use the edge of it to round off and smooth (and probably bevel) the hole sides. make shallow cuts, deepening them with multiple passes.

this is essentially how they make on-site sink cutouts in granite countertops. if you have a water jet, or a diamond bit router, there's other ways to do this more easily.

i assume you're making a dropout shelf.

[Bert Weiss]

Waterjet will do it easily and perfectly.

[Warren Weiss]

Thanks to all for your replies. I think I will try a masonry drill bit for the starter hole and see if I can get a masonry blade for my sabre saw which I am will to sacrifice if necessary. I couldn't find a water jet shop in Richmond. The closest was in Norfolk or near DC. Yes, it is to be a large sturdy drop ring.

Warren

[Valerie Adams]

I'd ask Tim Yardic; perhaps he'll share how he did it.

http://www.warmglass.com/phpBB/viewtopi ... =3&t=41942

[Bert Weiss]

Thanks to all for your replies. I think I will try a masonry drill bit for the starter hole and see if I can get a masonry blade for my sabre saw which I am will to sacrifice if necessary. I couldn't find a water jet shop in Richmond. The closest was in Norfolk or near DC. Yes, it is to be a large sturdy drop ring.

Warren

Warren, I would start with a pivot hole in the center, and figure out some way to keep your blade stationary. The only way to get a clean circle is to spin the shelf around an axle.

[Warren Weiss]

Thanks all, it worked. Drilled pilot hole near edge of circle with masonry bit. At Bert's suggestion I placed the shelf on a lazy susan to feed shelf into sabre saw masonry (diamond) blade. Finished with file. Slow, but perfect.

Warren

[Peter Angel]

I've seen a shelf with a big hole cut out of it on a glass art supplies website.

However I don't recall the site. I will see if I can find the site.

Pete

[Peter Angel]

Found it!

http://shop.bullseyeglass.com/tools-sup ... 03-mm.html

[Bert Weiss]

Thanks all, it worked. Drilled pilot hole near edge of circle with masonry bit. At Bert's suggestion I placed the shelf on a lazy susan to feed shelf into sabre saw masonry (diamond) blade. Finished with file. Slow, but perfect.

Warren

Cool!