Forge blower.

J

jackrabbitslim

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Jan 28, 2008
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I'm in the preliminary stages of planning a gas forge and I'm wondering, how big a blower do I really need? I've been using a shop-vac with a router speed controller with my charcoal forge but I'd rather have a dedicated blower for the gas one (space considerations, mostly). How many CFM should I look for? The part number IG's forge plans recommend is no longer available at Surplus Center. There's a pretty broad range available. I don't know where to start.
Thanks guys,
Gavin
 
My recommendation is to get a blower that is designed for a forge. Something like....
http://www.blacksmithsdepot.com/Tem...=/Resources/Products/Forges_and_Parts/blowers

The problem with "squirrel cage" blowers is that they are not designed to work under back pressure, and the more back pressure that exists in the application, the less air they put out. This causes them to overheat and burn out prematurely. They will work, but be prepared to replace them often if you forge a lot. I used them for several years, but went through 8-10 of them in that time. I switched to the 164 cfm model in the above link about 6 years ago, and haven't have a moment's problem from it. I hooked it up through a ceiling fan speed control (using a light rheostat on this type of blower will burn it up) and have the full range of speed available. Most of the time it runs at about 1/2 speed, pushing 6psi of propane into my welding forge. Although it's an import, its worked very well, and lasted, for me.
 
I am using an old pump from a whirlpool tub and I control the cfm with a valve on the 1 1/" line to my 2" burner pipe .Seems to work well for me ,I get to forging temp. at about 3 p.s.i.
 
I've been using Dayton (and similar) 'squirrel cage' blowers (similar to the kind Ed has mentioned--maybe not quite as nice) for forge and salt pots. About 120CFM is fine, IMO.

This one's been in service on this forge for about 12 years.

I think it's important not to run a fan that is pushing too much air. I have a friend running a leaf blower as his blower. It's shuttered, but that doesn't seem to matter. He needs to run the gas way up to get decent combustion, but it's way too violent and he has trouble with delicate pattern welding. He burns/melts the outer layers before the inner part of the billet is even close to temp.
Good luck!
 

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Solid. Thanks guys. That really helps with the blower question. I'm currently in the middle of a related dilemma. I'm trying to decide whether to do a forced-air burner based on IG's plans or to spring for a T-Rex. Not having to depend on electricity and a reduced noise signature are distinct advantages to the T-Rex but high initial cost and (potentially) reduced fuel-air flexibility are points against. Any input from the peanut gallery? :D
 
I don't have experience with the T-Rex, but I'd recommend the blower for a stationary forge.
They work well, offer great flexibility and are cheap.
 
jackrabbitslim said:
Solid. Thanks guys. That really helps with the blower question. I'm currently in the middle of a related dilemma. I'm trying to decide whether to do a forced-air burner based on IG's plans or to spring for a T-Rex. Not having to depend on electricity and a reduced noise signature are distinct advantages to the T-Rex but high initial cost and (potentially) reduced fuel-air flexibility are points against. Any input from the peanut gallery? :D
Click to expand...

Just FWIW, my forced air burner (from Darren Ellis, slightly modified) is MUCH less noisy than any venturi setup I've yet come across....

-d
 
JCaswell said:
I think it's important not to run a fan that is pushing too much air. I have a friend running a leaf blower as his blower. It's shuttered, but that doesn't seem to matter. He needs to run the gas way up to get decent combustion, but it's way too violent and he has trouble with delicate pattern welding. He burns/melts the outer layers before the inner part of the billet is even close to temp.
Good luck!
Click to expand...
If it is pushing to much air, why doesn't he put a gate valve between it and the forge?????
 
OK this maybe a stupid question, but where can a person see these IG designed plans for a blower propane forge?
 
Anyone ever consider using a bathroom exhaust fan for a blower? I won't say who has been using one for several years but there's a fable in these parts about a bald headed, gray bearded oldman thats got one set up and it purrs just like a kitten.
 
What ever works Right! 2" pipe with 2" gate valve then 2" pvc

03-05-08_1607.jpg
 
Rusty McDonald,

Is that a vertical forge or a crucible furnace?

Pretty soon I'm going to start working on the patterns I need to cast my own blower :D
 
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