Finally got the fittings I needed, so was able to plumb the gas forge up. Now that I’ve finished it, here’s the article.
The body of the forge is an old hot water service donated by a good mate of mine. I cut the ends off with an angle grinder and welded on some lugs to bolt through (some old front control arm washers I had lying around). I lined the forge with ceramic insulation from refractory ceramics in Mulgrave http://www.refractoryandceramic.com.au/. The staff there were very helpful.
I put a layer of fibre board on the bottom of the hot water service and put fire bricks on top of that. Then I lined the walls with high temperature blanket (1400 degrees celcius, should be just enough to forge weld steel). Now, a few quick notes here- I used fire brick so that the floor was a relatively hard surface so it doesn’t wear too fast, but the fire bricks aren’t great insulators, which is why I put the boards underneath. The wool is about as good as it gets, but is flimsy. The thermal conductivity of all the materials are on refractory ceramics’ webpage, so you can do your calcs at home to check, which I did but when I went to buy the gear, the staff made some changes to save me money and verified it with their own software, so it was probably a waste of time.
The board is best cut with a hacksaw. The blanket cuts easily with a thin, non-serrated knife. Wear a face mask, this stuff can’t be healthy to breathe. I also bought an adhesive to help hold it all together. It’s kind of like grout.
It was a real bastard to get the sheets of wool cut to length and stuck together. The best way I found was to cut it oversize and then bend it into a kind of an “M” shape. I’d put the M in place in the centre with the two outer “legs” of the M on each side of the fire brick. Then I’d push the middle upwards to the roof of the forge. Because it’s oversize, the compression will tend to hold the roof in place and stop if from falling down while the adhesive dries.
Then I bolted the front back on and cut a little door into it.
I made a second mini-forge out of some offcuts and an extra large fish food tin. (my parents own an aquarium).
The burner from the forge is a T-Rex burner from http://www.hybridburners.com/. It runs on LPG and puts out a massive amount of heat. Here’s a photo with the burner fully choked.
Here’s the burner not-quite-so choked:
Now, a problem with building this stuff in Australia is that nobody will sell gas fittings unless you are class B certified, qualified, bona fide, classified gassitrician with government approval, a union, council approval and are constructing a heritage listed forge of important historical significance. So just tell them it’s for compressed air. You’ll only be running 50psi max anyway. Another thing is that the T-Rex burner has an NPT fitting (American) whereas everything you buy here will be BSP (British). So you’ll need an adaptor.
Anyway, look up what fittings you need on the Legris website and then buy them from Pneutech (http://www.pneutech.com.au/). My setup is below. It’s all 3/8″BSP. There’s a branch that runs through a needle valve that you can bypass with a ball valve. This way, there’s an “idle” setting and a “full” setting.
A final note: Don’t use the normal white teflon tape. That’s for water. For gas, there’s yellow stuff. There’s also thread sealants you can use.
Sure looks hot in there. I need to buy a thermocouple to find out how hot.
The finished setup.