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cutting kiln shelves

Posted: Fri Aug 17, 2012 8:16 am
by theanimallover
I'm thinking of making my kiln work for me better by buying a new kiln shelf. I have a hotstart pro which has 7 sides, but a round kiln shelf. I get a bit frustrated as space is wasted. I'm thinking of getting a shelf and cutting it down to size - seven sided with some finger space to lift in and out. Does anyone have tips on cutting? Is it likely to crumble or crack? My boyfriend should be able to do it as he spends his days cutting up paving slabs!

Also, has anyone tried vermacite board as a kiln shelf, this looks like another option.

Thanks,
Karen

Re: cutting kiln shelves

Posted: Fri Aug 17, 2012 9:43 am
by Brad Walker
Kiln shelves cut with a tile saw. Not difficult, just go slow. It's rough on the blade; I usually cut kiln shelves to sharpen my blade.

Vermiculite board can work as a kiln shelf, but use shelf paper or fiber paper (not kiln wash) and support well to prevent warping. 2" thick board is best for a shelf, but 1" is ok for small kilns.

Re: cutting kiln shelves

Posted: Fri Aug 17, 2012 11:00 am
by Bert Weiss
Be aware that close to kiln walls, especially brick walls, the temperature changes considerably. During the heatup, it is cooler, during the cool down it is hotter. Annealing can only take place when the entire piece of glass is within 5ÂșC. Placing glass too close to the kiln walls can make it impossible to anneal.

I can't exactly say how close is too close, but it is something to consider when problem solving. I'll guess that a finger's width is too close.

The tests I use to determine internal stresses are usually drilling, sawing, or glass cutter cutting. If you can drill a hole through the glass without breaking it, you are probably in the clear. I am assuming that a polarizer look will not show stress because of the absence of a clear base.

Re: cutting kiln shelves

Posted: Fri Aug 17, 2012 11:12 am
by theanimallover
Thanks Brad.
Thanks Bert, bearing that in mind I'll do the template at least 1cm away from the kiln wall and see if it actually gives me much more space inside.

K

Re: cutting kiln shelves

Posted: Fri Aug 17, 2012 5:03 pm
by DonMcClennen
1" not 1cm. away from wall is what has been suggested many times in the past..

Re: cutting kiln shelves

Posted: Sat Aug 18, 2012 6:28 am
by seachange
Hi,

adding to Brad's post about cutting the kiln shelves (mullite) with a tile saw, have just recently done this for the very first time with the blade that came with the machine, it worked nicely. This was a trial run for the tile saw and for me, so was rather pleased.

This blade has no diamonds, it has a slightly wavy edge all around. Thought it was worthwhile trying it and reserve my nice, and expensivish, diamond saw for glass.

Tried it also on a porcelain tile (the only one I had at home), but it chipped the porcelain a bit.

Good luck with your project, seachange

Re: cutting kiln shelves

Posted: Sat Aug 18, 2012 8:35 pm
by theanimallover
Thanks - I'll cut about an inch away from edge.
We have an angle grinder, is this too heavy handed?
Tile saws are mentioned, would a (cheap) hand held one work? I don't want to pay out for any machinery.

Thanks,
K

Re: cutting kiln shelves

Posted: Sat Aug 18, 2012 10:57 pm
by seachange
theanimallover wrote:Thanks - I'll cut about an inch away from edge.
We have an angle grinder, is this too heavy handed?
Tile saws are mentioned, would a (cheap) hand held one work? I don't want to pay out for any machinery.

Thanks,
K
Angle grinder works also, my husband used it to cut my shelves before we had the tile saw. Ours is a 2300W unit. It should be possible with less powerful grinders as well, probably would need to go slow not to get stuck.

You need a stone cutting wheel, and a steady hand. He cut the shelves outside, makes a mountain of dust.

Best wishes, seachange

Re: cutting kiln shelves

Posted: Sun Aug 19, 2012 12:58 am
by Bert Weiss
theanimallover wrote:Thanks - I'll cut about an inch away from edge.
We have an angle grinder, is this too heavy handed?
Tile saws are mentioned, would a (cheap) hand held one work? I don't want to pay out for any machinery.

Thanks,
K
You can probably get away with a diamond blade on a skilsaw, with a helper squirting water from a spray bottle.

Re: cutting kiln shelves

Posted: Sun Aug 19, 2012 8:39 am
by rosanna gusler
any dry cutting can damage the bearings of the saw/grinder with masonry dust. rosanna

Re: cutting kiln shelves

Posted: Sun Aug 19, 2012 12:17 pm
by theanimallover
Thanks everyone. I'll tell you how I get along soon!
K