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An interest of mine which I am trying to turn into a hobby is building miniature steam engines out of brass. So far, I'm a good way away from a working engine, but I decided to post a quick mini-Instructable about a tool that I built to make my life easier. It seems a bit obvious to me, but it is useful, so here it is.
Specifically, I needed a high heat work surface to protect the shiny new Formica that I recently added to my workbench from the heat of the mini-torch that I use when soldering brass. I will probably also end up using it as a general-purpose work surface for electronics soldering and rework, although as these applications are much less demanding, I have been using the steel base plate from my Desk Squid until now.
Specifically, I needed a high heat work surface to protect the shiny new Formica that I recently added to my workbench from the heat of the mini-torch that I use when soldering brass. I will probably also end up using it as a general-purpose work surface for electronics soldering and rework, although as these applications are much less demanding, I have been using the steel base plate from my Desk Squid until now.
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Signing UpStep 1Building the surface.
I started by buying a 12"x12" white ceramic tile from Home Depot for about $1. Being made of kiln-fired ceramic, this tile should be a perfect refractory material. Still, there were a few things that concerned me:
1) Ceramic tile is very hard and has a rough bottom. This isn't good for my bench.
2) Ceramic tile is brittle. Under spot heating, it may even crack.
3) Many ceramics are actually rather good heat conductors. While I have not done a thermal gradient analysis on this tile, if it turns out to conduct heat, then this would reduce the problem of #2, while allowing the bottom of the tile to reach a temperature that may be uncomfortable for my bench.
The answer to all these problems, as I see it, is cork. Cork is an extremely effective thermal insulator, and it does not melt. To destroy cork requires igniting and burning it off, which is a slow process. It is also soft, and won't scratch my bench. If the tile should crack, the cork will give my desk protection long enough for me to remove the heat source.
I bought a couple $1 cork boards from the Dollar Store. They came with some plush heads stuck to them with hot glue, which I removed with my hot air rework station, set to about 250°C and maximum air flow. Cork is difficult to cut with an Exacto knife, so I used the rotary cutter from my sewing room to cut it down to shape. You may be able to find cork in appropriate sizes already cut; a few days after I built this, I saw some 12"x12" cork squares for a couple dollars at Walmart.
I glued the cork to the back of the tile with rubber cement, and put 100lbs of stuff on top of it overnight to let it set. It seems to have held well enough, but I suspect that it may fail under thermal stress, as rubber cement is not known for its temperature stability. Both materials are very porous, so they take adhesives quite well, but the back of the tile is uneven, so it requires a space-filling adhesive. If I had to do it again, I would use a two-part epoxy. Epoxy generally survives high temperatures well, and it bonds strong.
1) Ceramic tile is very hard and has a rough bottom. This isn't good for my bench.
2) Ceramic tile is brittle. Under spot heating, it may even crack.
3) Many ceramics are actually rather good heat conductors. While I have not done a thermal gradient analysis on this tile, if it turns out to conduct heat, then this would reduce the problem of #2, while allowing the bottom of the tile to reach a temperature that may be uncomfortable for my bench.
The answer to all these problems, as I see it, is cork. Cork is an extremely effective thermal insulator, and it does not melt. To destroy cork requires igniting and burning it off, which is a slow process. It is also soft, and won't scratch my bench. If the tile should crack, the cork will give my desk protection long enough for me to remove the heat source.
I bought a couple $1 cork boards from the Dollar Store. They came with some plush heads stuck to them with hot glue, which I removed with my hot air rework station, set to about 250°C and maximum air flow. Cork is difficult to cut with an Exacto knife, so I used the rotary cutter from my sewing room to cut it down to shape. You may be able to find cork in appropriate sizes already cut; a few days after I built this, I saw some 12"x12" cork squares for a couple dollars at Walmart.
I glued the cork to the back of the tile with rubber cement, and put 100lbs of stuff on top of it overnight to let it set. It seems to have held well enough, but I suspect that it may fail under thermal stress, as rubber cement is not known for its temperature stability. Both materials are very porous, so they take adhesives quite well, but the back of the tile is uneven, so it requires a space-filling adhesive. If I had to do it again, I would use a two-part epoxy. Epoxy generally survives high temperatures well, and it bonds strong.
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May 7, 2009. 10:31 AMBeschaulicheit
says:
This seems like a very good idea. I do some glass sculpture work and have always had trouble with finding work surfaces I can have confidence in for much less than a lot more than I'd rather pay.
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3
May 7, 2009. 4:46 PMCaladanJen (author)
says:
Glass requires much higher temperatures than soldering. If you make one of these for glass sculpture, let me know how it works for you.
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1
Mar 18, 2009. 7:59 PMcokebottle tuque
says:
How bout adding a metal plate in the middle it should help spread the heat thus reducing the chance of cracking.
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3
Mar 18, 2009. 8:41 PMCaladanJen (author)
says:
That would probably defeat the purpose. Spreading the heat would make it harder to solder metal objects on it. Plus, the metal plate would be likely to bond to the solder. Besides, the chance of the tile cracking is pretty remote. The temperature coefficient of expansion for porcelain (which is a similar if not identical ceramic) is about a quarter of what it is for glass, and half of that of borosilicate glass, which is known for its exceptional thermal survival. And even if it does crack, so long as the cork pad protects my desk, I can just build another one for $3.
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1
Mar 18, 2009. 9:20 PMcokebottle tuque
says:
In between the cork and the tile, not as the work surface.
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3
Mar 18, 2009. 10:16 PMCaladanJen (author)
says:
Oh I see what you mean. I'm not sure that would work either. The tile is thick enough that a substantial thermal gradient would develop across the thickness alone, reducing the effectiveness of the metal. Besides that, the bottom surface of the tile is covered in protrusions that would prevent contact between the tile and the metal. Still, an interesting idea, thanks :)
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