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I've been following the "portable side blast forge" thread with growing interest as it looks like a good way to go. However there are some aspects that are a bit foggy for me, for example, the bosh volume. Mark Aspery has a design for a tuyere and bosh Building the Side Blast Forge That design calls for a tank that's going to hold 16 gallons or so, and the instructions specify that it keeps the water from boiling off. I found this company that makes tuyere's and boshes, however the dimensions listed would put the bosh capacity at around 9 gallons. I'd be using a 2-1/2" diameter champion hand crank blower for air supply and I'm burning coke as my fuel. I found a video here that shows a tuyere design at 15:22 which is designed to be connected via hoses to a remote bosh tank. I thought I'd mimic it with 6" round schedule 40 tapering to 3-1/2" per Mark Aspery's design with a 2-1/2" air pipe tapering to 1-1/2" inside. I sounds like I should have a 1" diameter hole in the nozzle plate, but I'd appreciate any guidance from folks who know about these things. I called around for sheet metal pricing and found that I could buy a metal wash tub or trash can for less than half the cost for enough 1/8" thick sheet metal to fabricate a 9 gallon bosh. The tubs and cans are lighter gauge, but they wouldn't be as close to the fire, and they comes pre-galvanized. As I understand it, the tuyere has to be close to the bottom of the bosh level for the heat to pump the water. A 16 gallon tub would have about 133+ lbs of water in it, which isn't too bad, but a smaller container would be easier to accommodate in a mobile setup. Plus that's less water that I have to fill or drain every time I want to move the forge. We have horrible mosquito borne illnesses out here in Colorado so I wouldn't want to leave stagnant water for them to breed in. I'd like this to work properly, preferably without scalding hot water right next to where I'd be standing. Most of the built-in boshes I'm seeing are behind the breastplate of the forge. That seems like it would give the smith some protection between them and the bosh, but I don't know what a "normal" bosh temperature would be relative to it's volume. I'd appreciate some help in determining how much bosh volume I'd need to make this work safely. Thanks in advance