jimmy shoes
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hi,
im gonna be building a very basic forge soon, and i wonder what will give a better heat, hot or cold air
heres a simple design of my forge.
advice is welcomed
Cold air, you theoritically get a more dense charge of air, will it make a diference? who knows.
hair dryer? is that beefy enough? my neighbour uses a vaccuum cleaner to feed her forge with good results.
Chunko'.
i thought i'd just put BBG coal in it.
well i saw a video on youtube of a guy making a knife out of an old file, so seems that i got a few old files i thought i'd give it a shot. plus if i get any future projects where i need alot of heat i can use the forge.
Air volume is more important than temperature, plenty of industrial size forges run on cold air, just with MUCH more airflow than a hairdryer. Also you'll pay for the power to heat the air (most of the hairdryer's power consumption) which is a waste of money.
You need a throttle on the air supply too, for regulating flow and to shut it down when you are working on the metal in between heats. Just put a sliding 'gate' in the pipe, with a handle so you can slide it across. You'll burn through a LOT of fuel otherwise - when my forge is on full pelt you can literally see the coke being used up - almost like pouring liquid into the middle of the fire.
I controlled a forge this way once and the hoover motor burned out because it was running at too high RPM due to underload.
Better to control the hoover discharge air flow with a valve on a Y branch of the pipe so you can vent the excess air rather than restrict it.
A horizontal pipe into the forge about 3 inches up from the bottom is better than one coming from below, about a 1" pipe is fine with just the open end, no grating. The proper blow pipe (called a tue iron) would be like a double pipe and the outer would be water cooled like the water jacket on an engine, the main reason for water cooling was to stop the pipe melting with the heat in the fire.
Good luck with it...