Hey everyone! It's finally nice out and I spent a few days out in the shed getting things squared away, failing at making paper micarta, and finally some grinding! I bought a bunch of steel, and I'm just waiting on my Kydex foam order. Here's my first question; What kind of thermocouple could I buy for it, just to get myself a little bit better off an accuracy in my heat. I know it won't be perfectly accurate, but it will give me something. My second question; I've seen a few different designs for the 2 brick forge. Round chamber, 90° square chamber, 45° square chamber. Which is the most efficient? Does it make a difference?
Hi Kevin, A round chamber will aid in evening the heat out. If you point your torch tip port in on an angle and up or down on an angle you can get the flame to swirl around inside the chamber. Most 2-brick forges I have seen are literally a half round long-wise scoop in each brick. Then the bricks are mated to make the chamber into a cylindrical shape. Make the chamber only as larger as you think you're going to need it. If you are making knives, scoops can be about 1-1/2" which will leave you with a 3" diameter chamber. Larger diameter chamber means more surface area loading and more cool air getting in. You can also block off the backside with another brick to reduce heat loss. For gas forges, most guys use a pyrometer, which has the thermocouple probe with it. The most common probes are "type-K." Ideally get a meter that can read up to 1200°C or more and comes with some protection for the thermocouple. A ceramic tube or what-have-you. The probes tend to oxidize and disintegrate over time with the heat we're talking about. Some digital multi-meters have a jack for a type-K thermocouple. I can't vouch for the quality or accuracy, but this is an example of a low cost pyrometer. Dan
Dan's right. I mostly see type k thermocouples used; they're rated to 2300 F but will start oxidizing below that. I had to look up 2-brick forge. I don't think you'll be getting too hot in that. I would recommend that you don't think about the shape of the cavity too much. Just use that smallest cavity that will suit your needs and don't point the burner directly at you work pieces. If you don't like how it works in the end, you can easily change it. Try not to get caught up in the minutiae, you'll learn everything you need to know by doing what you want to do. Magnus
What brand of burner are you using? I'm thinking about doing a 2BF to see if forging blades is a something I really want to do, without investing too much money up front (buying the more expensive stuff can always come later). Plus, if I decide I don't want to pursue this as a hobby, I'd have an extra 20lb propane tank for the bbq rather than a bunch of empty non-refilable canisters.
I'm using a 30k BTU burner from Atlas Knife and Tool out of the US. I'm using one of these. http://www.atlasknife.com/product/atlas-30k-burner/ I'm thinking of upgrading to the bigger 100k burner. The small one works well for heat treating knives nice and quickly but I would love to be able to do a little bit more with it.
