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tomhumf

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About tomhumf

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    http://www.thelittlepotcompany.co.uk

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    Sheffield, UK

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  1. tomhumf

    Averting kiln disasters

    If you have a set of bowls the same size I wouldn't stack them as they are else they could crack. You can add sand between bowls, depending on their design, so the walls aren't touching and the weight is loaded onto the feet. This kind of dense stacking might prevent some of the inner bowls from reaching temp though depending on your firing cycle. I've suffered from some pinholing problems after doing this but not certain they were related.
  2. tomhumf

    Making ash

    I've collected some ash from the local wood fired pizza oven restaurant. Not used it yet, but its very handy to turn up with a tub and collect from their ash bin!
  3. tomhumf

    What's Your Work Music?

    I like BBC radio 6. It plays some really unusual stuff unlike any other radio station. But sometimes it gets too wierd even for me and I have to switch to radio 2 for a bit.
  4. Hmm, I was going to have metal angle iron on each edge of chimney. The just put wires around the kiln and chimney to pull them together, with this flue brick just butting up against a 6" x 3" chimney opening. But yes that brick is pretty fragile I guess, maybe I'll cut out some of chimney so it will slide over it like you suggested.
  5. I got my flue brick cut, which will feed into the stack. I decided to cut away the bottom of the brick so I wouldn't need to cut my kiln floor. So the brick goes in halfway and fits quite nice. I will mortar it in when the kiln is in position. The flue brick walls are only about ¾" thick but I'm thinking they should be ok for such a short distance? Otherwise I could mortar on another thin layer of brick.
  6. My bricks are 3" not 2.5". I could have the bottom shelf at 3", and set my output brick a bit lower, so everything is lined up. Will look into extension. Could you just use stainless steel tube used in extraction systems? Yes the cardboard shows where the wall brick/ hole will be.
  7. Thanks Mark. I was intending to leave the jacket on, just cutting a brick sized hole for flue. My drawing probably aren't clear. I picked up my bricks, mortar and propane today and have done some mocking up, bearing your comments in mind. For the chimney stack I think I'm going to go with a 6" x 3" internal size. This will mean I'll need to cut some bricks but I can't get a decent size without doing this. In the image of the chimney stack the kiln will be on a metal stand, and chimney will be on blocks. The chimney will be as high as kiln when finished. The closeup of brick is the one I'll put at base of kiln as the flue exit. It will be cut down to 7 inches long ( the same length as one of the 8 sides of kiln). After I put it in, I'll cut away the hashed section to give a 3" x 6" opening. In the image of the kiln floor, the bit of wood with arrows represents the burner port opening and direction. The peep hole plugs represent angle deflector bricks to push flames up. The brick with hashes would be cut in half - the hashed section removed. All the props represent the same brick size, there is a 6" opening where the ruler is. This is for flue entry. The bricks are 4.5" tall. The cardboard box shows the location where the exit in wall to chimney would be. The image of 1st shelf is a cardboard version of my shelf with 1/2" cut off end and 2" off each side. On top of this on bag when all side, there would be another row of 4.5" bricks, all across kiln. On the other side I could use props? And I suppose I would need a brick under the end of kiln shelf at the bottom of image, to restrict flue access to my intended opening on the left. Shelves for rest of kiln could have 2" cut off each side but sat more central in kiln?
  8. Ok, I take your point about the plates. Maybe I'll just have to wait until I build a bigger kiln for those. I've drawn what I understand you to mean, about the location of firebox and flue, is that correct?
  9. I did look at your thread, maybe my proposed flue size is too big, it would be around 6" x 6 " with my bricks. And your kiln looks to be a lot bigger. Didn't you say in your thread that you got 10^ down at some point though? Are you still using the kiln or moved onto something else? I have been trying to avoid cutting shelves as I though I would need to spend more money on a circular saw. I just tried cutting the edge with a hacksaw though and I reckon it wouldn't take too long with that. Do you think if I just took half an inch off the bottom couple of shelves that would be ok? It would leave around 4" gap on the other side. I really want to fire dinner plates on some shelves and they won't fit if I cut them all.
  10. Thanks Mark. I think my brick supplier does mortar too so I'll try get some off them. Thanks for your other suggestions. I've changed my mind a bit about the chimney, it seems I get a larger flue area by arranging the bricks interlocking, and it will make it fit into kiln better. Also, ignore what I said about the 2cm bridge thing. I could just put two bricks (cut down to 180mm long) into side of kiln, as in the high bridge pottery link I posted. Then cut the flue opening out of them. That would give a flat surface for the chimney to attach to. Would it be ok to have a bag wall that isn't the full height of flue opening? I'm thinking maybe a 114mm brick height bag wall running across kiln with a 45 degree deflector at the opposite wall to push the flame up to roof. The first shelf could sit on the bag wall, otherwise my first kiln shelf is going to be 1/3 way up kiln. Not sure if the flame might take a shortcut though? I've penciled the intended sections to cutout at the base of kiln in the image.
  11. I know this kind of thread has been done many times. I've read lots of them, watched lots of YouTube videos and clayart topics. From this I have learnt there are many problems with this kind of conversion. I have never fired with gas, but I love the look of reduction glazes and my old electric kiln was nearly dead anyway. Following a recent house move I faced the prospect of a costly electrician bill to install it in our outbuilding, and decided that converting it to gas would be comparable in cost. Initially I was going to do an updraft kiln. After reading many uneven firing woes I decided the cost and hassle of building a chimney would be worthwhile. I decided to spend a decent amount of money on a burner. I know one burner kilns aren't as good as 2 but I don't have money for another one. Mine will fire up to a 10 cubic ft kiln apparently. It has flame failure protection and a needle valve so it should be ok to fire my small kiln hopefully. My kiln is 17" width and 22" deep so around 3 cubic ft. So burner is overkill but perhaps I will build a bigger kiln from scratch in the future and I don't want to have to buy more burners. After ordering the burner I read this thread which is very close to what I intend to do. Joel originally had a very similar burner to mine, although his was 90 degree and mine is straight. I'm worried that this doesn't bode well for my success as he totally changed burner setup after failing to reach temp. I do think there might be something in the comments about his chimney size though... So I'm going to press on with a larger chimney. I'm hopefully goes to collect some 230x114x76mm insulation bricks next week. I have worked out on paper my chimney setup. Things I need to decide now: 1. Do I use 50/50 fireclay and grog mix with some sodium silicate or something else like expensive kiln mortar to stick bricks together. 2. Burner port placement. There isn't going to be much room at the base of kiln with that chimney opening. Can I have a burner port above the floor shelf? I guess pots directly in flame path would get too hot. 3. Connecting chimney to kiln opening. This needs to be insulated, so do I use like a 2cm thick strip of kiln brick as a kind of bridge all around the 4 planes of the connection. This would reduce the area of flue but would be worth it? Not sure if that will make sense to anyone? I could ramble all day about this, I will probably just keep posting my progress and hopefully someone may be able to help me out of the darkness and into the light! Edit: the 114 in image should read 76!
  12. I know this thread is like 3 years old. I just wondered how things ended up? Did you get it working, and did it fire really unevenly? I'm planning a similar thing but probably downdraft with external chimney, I only have one burner though.
  13. Well, I decided to get the cheap eBay one. Sputty, I did check bath potters but the cheapest option for my temp is a type R set which would be £210 Inc delivery. I'm watching one of the Fluke ones you suggested too Mark, will get one of those if it goes cheap, they look funky. Thanks
  14. I'm looking for a pyrometer for my adventures into gas firing. All the ones available from UK sellers are around £250 including tax and delivery. I've seen some cheapy ones on eBay - I guess I can't post a link but I'm sure you could find it. There are around $65 USD Inc delivery. They are k type, rated up to 1300 Celsius apparently. I just wondered if anyone has used ones like these? I would be using cones too, especially for final firing temp. Really I'm just looking for something to check if the kiln is climbing in temp. Thanks!
  15. Hi All, I have a old kiln sitter electric kiln. Having recently moved house I was going to get it hooked up in an outbuilding. The electrician quotes were very high and it's probably not got much life left in it anyway. I'm thinking of converting it to an updraft propane gas kiln as I want to try doing some reduction firing. I know downdraft are meant to be better in terms of temp distribution and efficiency but I don't want to spend a lot constructing a chimney right now. I'm mainly wanting a quick fix to get firing to ^8 asap as cheaply as possible. Once I have tested some glazes I may build a larger downdraft gas kiln from scratch. My current kiln internally is 22" deep and 17" diameter, which is around 2.9 cu ft I think. The bricks are in fairly good condition, apart from the base which is slightly cracked - I think this got worse during the move. It haven't been able to inspect the bottom to see if the crack goes all the way through yet. I've looked at a few pics of commercial kilns of a cylindrical design and done some sketches, I have a few questions, I've never used a gas kiln before… I've seen other conversions where the kiln elements have been removed, this is necessary I suppose? Would it been better to put another layer of soft rock on the base, maybe having the burner firing near the crack will open it up more? What would be best burner port and lid opening locations? My sketch is designed for flame to be directed around the curve of kiln, and chimney hole in middle of lid makes sense? Also, should the burner hole and chimney hole be around the same size? I have between 1.5 and 2 inch gap between wall and kiln shelves, is that ok for flame path? Would a simple hole in the lid create enough pull of air? I've seen some updraft designs with a large chimney stack. And would I be able to put kiln into reduction by just covering the lid hole with a spare fire brick? That's a lot of questions… Thanks
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