[TBm]

Hi, all ==

My first post here. I'm an aspiring sculptor drawn to ceramic/clay because of its versatility.

I would like to know if there are accepted (and safe) methods for drilling into stoneware that is already high fired (cone 10). I'd also like to know if there is a method for grinding straight, flat edges into fully fired stoneware objects.

I have wood working experience, where drill press and table saw solve these problems easily. But clay shrinkage and the potential for airborne silica make ceramic solutions more challenging.

EXAMPLE illustrating what I want to do:
Imagine a picture frame made of fired stoneware, into which I will set a mirror from behind. a) I want to create an accurate rabbet, a ledge or channel cut into the back side of the frame to accommodate a precut mirrored glass (I imagine a grinding operation would form the rabbet). I also want to drill accurately-sized holes into the back of the frame for inserting hanging apparatus.

I realize I could cut the mirrored glass after firing the clay, so the glass would accommodate the post-shrinkage size of the frame opening. But I have other projects in mind that will need to be resized accurately, and with particularly straight edges. I also envision the need for holes of accurate diameter, which to my mind, involves drilling after final firing.

Any advice is much appreciated,
Tom

[jennifire]

Hi Tom,
In my experience grinding high-fired clay is pretty futile, requiring diamond/carbide drill bits, and pretty inacurrate, and,yes a health hazard. Any holes for hanging can easily be made when leather hard. Have you done shrinkageg tests on your clay body? This could help you to determine the size of your rabbet, and you could make it with some leeway and then fill it in with some sort of caulking...
Good Luck,
J

TBm, on 07 April 2010 - 01:39 AM, said:

Hi, all ==

My first post here. I'm an aspiring sculptor drawn to ceramic/clay because of its versatility.

I would like to know if there are accepted (and safe) methods for drilling into stoneware that is already high fired (cone 10). I'd also like to know if there is a method for grinding straight, flat edges into fully fired stoneware objects.

I have wood working experience, where drill press and table saw solve these problems easily. But clay shrinkage and the potential for airborne silica make ceramic solutions more challenging.

EXAMPLE illustrating what I want to do:
Imagine a picture frame made of fired stoneware, into which I will set a mirror from behind. a) I want to create an accurate rabbet, a ledge or channel cut into the back side of the frame to accommodate a precut mirrored glass (I imagine a grinding operation would form the rabbet). I also want to drill accurately-sized holes into the back of the frame for inserting hanging apparatus.

I realize I could cut the mirrored glass after firing the clay, so the glass would accommodate the post-shrinkage size of the frame opening. But I have other projects in mind that will need to be resized accurately, and with particularly straight edges. I also envision the need for holes of accurate diameter, which to my mind, involves drilling after final firing.

Any advice is much appreciated,
Tom

[TBm]

jennifire, on 07 April 2010 - 09:36 AM, said:

In my experience grinding high-fired clay is pretty futile, requiring diamond/carbide drill bits, and pretty inacurrate, and,yes a health hazard.

Jennifire ==
Thanks for the reply. I hear you regarding level of difficulty and health concerns.

I don't have a clay body yet. I'm seeking a stoneware for sculpture/handbuilding that comes as close to white as possible (no porcelain, though).
If anybody has a suggestion, please let fly.

I intend to interconnect ceramic elements with elements made from other materials, so the ability to create an accurate hole in terms of diameter and placement will be a big help to me.

Other suggestions?
After years of wood working (and some metal machining) I'm not afraid to $PEND at bit on tooling that will do the job (in fact, I'm kinda numb...)

[Mudlark]

Clean accurate holes can be cut using silicon carbide grit. I use number 80 which I originaly bought to make volcanic glazes. For the "drill" you need a length of brass or copper rod of the desired diameter. A drill press is needed as a hand held tool is not steady enough. Firmly mount the work on the drill press. The back of the work behind the drill contact point needs to be well supported ( I use a block of wood ) as the drilling pressure cause a break through as the hole gets deeper which results in a rough edge to the back of the hole. Make a small clay dam around the area to be drilled and add a couple of teaspoons full of water, to this add a 1/4 of a teaspoon full of grit. With the drill set at it's lowest speed GENTLY apply enough pressure to start the cutting action, you can tell when this happens as it causes a crunching sound. When the sound ceases slightly withdraw the drill which allows more grit and fresh water to fall into the hole, continue in this manner until the hole is drilled. Provided the water level is maintained there is no dust from this method as the water contains it.

[TBm]

Mudlark, on 07 April 2010 - 11:35 AM, said:

Clean accurate holes can be cut using silicon carbide grit. I use number 80. For the "drill" you need a length of brass or copper rod of the desired diameter. A drill press is needed. The back of the work behind the drill contact point needs to be well supported. Make a small clay dam around the area to be drilled and add a couple of teaspoons full of water, to this add a 1/4 of a teaspoon full of grit. With the drill set at it's lowest speed GENTLY apply enough pressure to start the cutting action. When the sound ceases slightly withdraw the drill which allows more grit and fresh water to fall into the hole. Provided the water level is maintained there is no dust from this method as the water contains it.

EXCELLENT! I could not ask for a more complete process outline, and the airborn health issues being contained by the wet cutting is a tremendous benefit.

Now that I understand that silicon carbide grit #80 will work, I'll set about looking for ready-made drills or other tooling. If I don't find any, your method should work just fine.

Thanks very much, Mudlark.

[Cindy in SD]

I'd suggest, Mudlark, that you look into lapidary supplies and books. What you want to do is more on that line than pottery. I don't know a lot about stone carving--have done a little bit with my grandfather, who was a rockhound--but there's a lot of info out there, and those tools are the ones you'll be needing for what you want to do.

Best wishes, Cindy

[AmeriSwede]

.... and if buying more expensive equipment doesn't scare you off.... you could purchase a drill press plumbed with water, that uses hollow diamond core drills.
These machines are typically made for the glass industry but can be utilized in ceramics as well. I've used up to 5" (wide) diamond holes saws that could eat through 6" solid borosilicate glass in short order... and glass, I believe is more temperamental to thermal shock than stoneware. The recirculating water keeps all dust problems at bay just as the copper tubes and the 'grinding' grit.

Along the same line, but a great deal cheaper is the 'Water Swivel Adapters' that you could probably fit to a standard drill press, you would need to build a pan unit to collect the water to be recirculated or discharged. These also fit the diamond core drill bits.

[Mudlark]

Cindy in SD, on 09 April 2010 - 04:17 AM, said:

I'd suggest, Mudlark, that you look into lapidary supplies and books. What you want to do is more on that line than pottery. I don't know a lot about stone carving--have done a little bit with my grandfather, who was a rockhound--but there's a lot of info out there, and those tools are the ones you'll be needing for what you want to do.

Best wishes, Cindy

Thanks Cindy,
I only need to drill the odd hole now and then which does not justify the cost of buying specialist tools and equipment. The procedure I outlined came from a Lapidary book that I came across when browsing in a second hand bookshop. I made a mental note of it and tried it out when I got home. It was one of those moments when you are exposed to an idea that causes you to say"Why did'nt I think about that"

Thanks for your interest
Mudlark

[TBm]

Cindy in SD and AmeriSwede ==

Thanks very much for these insights. With such a well-rounded base of knowledge, I'm sure I'll find an inexpensive way (yeah, jerry-rigged) to accomplish the hole drilling - and maybe grinding of an occassional smooth, straight edge. Focusing on Lapidary tooling/methods is a great suggestion.

BTW - I've been slow to respond to contributors to this thread. That's because I'm not seeing any email notification when new posts are entered (as is available in other online forums). Is there a way to turn that function ON here? If so, I haven't found it yet...

Tom

[JBaymore]

TBM,

As a woodfirer since 1969, I often have to clean up pieces that have wadding stuck on, large thick runs of glass on the bottoms, and other such issues. I utilize a diamond blade in an angle grinder for much of the work. (The blades are well under $50 US.) It goes thru high fired stoneware clay like a hot knife thru butter. A diamond blade in a brick saw will cut thru high duty SK32 hardbrick quickly too.....I do it all the time when building kilns for clients. So there is no reason you can not cut fired clay if you need to. You'll just need the right tools.

Fired clay dust is bad news to breathe. Water cool the blades AND also use P100 / HEPA respirator filters..... and local pickup ventilation if appropriate.

best,

..................john

[TBm]

JBaymore, on 10 April 2010 - 05:09 PM, said:

I often have to clean up pieces that have large thick runs of glass on the bottoms, and other such issues. I utilize a diamond blade in an angle grinder (well under $50 US.) It goes thru high fired stoneware clay like a hot knife thru butter. A diamond blade in a brick saw will cut thru high duty SK32 hardbrick quickly too.....I do it all the time when building kilns for clients. You'll just need the right tools.

Fired clay dust is bad news to breathe. Water cool the blades AND also use P100 / HEPA respirator filters..... and local pickup ventilation if appropriate.

Many thanks, John. As your comments indicate, its not really so complex after all. I've used similar tools/techniques in building things of a utilitarian nature for years, but I suppose the prospect of "creating Art" causes me to overthink/worry more than necessary. Thanks for the grounding. Tom

[ron]

TBm, on 12 April 2010 - 09:12 AM, said:

JBaymore, on 10 April 2010 - 05:09 PM, said:

I often have to clean up pieces that have large thick runs of glass on the bottoms, and other such issues. I utilize a diamond blade in an angle grinder (well under $50 US.) It goes thru high fired stoneware clay like a hot knife thru butter. A diamond blade in a brick saw will cut thru high duty SK32 hardbrick quickly too.....I do it all the time when building kilns for clients. You'll just need the right tools.

Fired clay dust is bad news to breathe. Water cool the blades AND also use P100 / HEPA respirator filters..... and local pickup ventilation if appropriate.

Many thanks, John. As your comments indicate, its not really so complex after all. I've used similar tools/techniques in building things of a utilitarian nature for years, but I suppose the prospect of "creating Art" causes me to overthink/worry more than necessary. Thanks for the grounding. Tom

[ron]

Please share side grinder disc you use,brand,where to get it etc. I need to clean some shelves.

[JBaymore]

ron, on 12 April 2010 - 01:32 PM, said:

Please share side grinder disc you use,brand,where to get it etc. I need to clean some shelves.

I've used numerous brands over the years. They have all worked fine. Any Home Depot, Lowes, Harbour Freight (online), and so on should have them. Just get the correct arbour size for your grinder and correct outer diameter for the housing.

Be CAREFUL on kiln shelves! Any high alumina or corderite or mullite type shelves will also disappear very fast under that blade. REALLY fast. Regular silicon carbide also gets cut into. I'm even very careful on my Advancers . And I only use that grinder on shelves for something like a big drip......not for "general cleanup".

Remember that one of the worst dusts for you to breathe is FIRED kiln wash. The lack of fused silica in the firing of the wash causes the existing crystalline silica to convert to a more dangerous respirable form. I'd strongly suggest for generalized cleaning.... have them professionally sandblasted to take the whole white layer off down to the shelf itself. It won't cost you that much, the job will be just about perfect, and you have transfered the risk of the dust issue to a place that has the hoods to reallyu deal with that stuff. Your shelves will look just about like new.

Just do your own grinding for the "major disasters". And use locals pickup vent and appropriate respirator (mentioned above).

best,

..................john