draft inducer blower for a brake rotor forge?

[Randy Rue]

hi all

my propane tank / frosty tee forge is not very good for focused heat and not hot enough for welding so I'm gearing up to make a brake rotor forge. been reading about coal and just now about corn. in western WA state coal is not easy to get 

but first, the blower. I have a furnace draft inducer motor on hand, bigger than any hair dryer but not as overkill as a vacuum cleaner, leaf blower or bouncy house blower. seems like an obvious choice but I can't find anyone online talking about using them. am I missing something?

seems like I'll want some way to throttle it. a gate on the intake or output? a dump/spill gate? or a speed control on the motor?

let me know

randy in edmonds

[Glenn]

Build the forge with a 8 or 10 inch diameter chimney that is 3-4 feet taller than any surrounding obstructions that would affect the draft.  Just light a couple of sheets of newspaper in the chimney to get the draft going and no draft inducer needed. 

In western WA state you should be able to find firewood.  If not look for pallets.  Cut the wooden chunks about the size of a 2x4 and about 4 inches long.  You will have to make a deeper fire as you are burning the wood to make charcoal and the charcoal to make embers to forge with all at the same time.  

[Randy Rue]

sorry should have been clearer, I'm looking to use a draft inducer blower for the forge blower.

and having done some troubleshooting of my house gas furnace in the past, it occurs to me that blower is only meant to boost the flow of gasses in the chimney so regardless of it's physical size it might not be strong enough to feed the fire.

found the specs for the blower I have:

• Amps: 1.3
• HP: 1/25
• RPM: 3200

Specs don't include anything for CFM or static pressure but I did plug it in and it blows a nice breeze out of a 3.5" square flange. based on a highly scientific estimate of fast it makes me blink if I point it at my face compared to my wife's hair dryer, if I make a real reducer to 2" pipe and don't just weld a tube to a square plate, it would be comparable 

[Frosty]

If you plan on burning charcoal it needs very little blast so your blower should be enough for moderate sized projects, maybe more.

Frosty The Lucky.

[JHCC]

Short answer: yes, you can make it work.

Slightly longer answer: in order to make it work, you'll need to find some way to adjust the airflow. This can be done by (A) changing the speed of the motor, (B) changing how much air can get into the blower, or (C) changing how much air gets from the blower to the fire.

For (A), I don't know what kind of motor this has, but you might be able to use a variac (variable autotransformer) or a router speed control if it's powered by a universal motor.

For (B), check to see if it already has a pivoting plate that widens or narrows the air intake. If so, you're good. If not, be aware that some blowers (e.g., vacuum cleaner motors) rely on the air flow to keep cool, so limiting the air intake might cause the motor to overheat.

For (C), you have three options:

1. Create an adjustable gap between the blower and the tuyere, so that you can point the blower at or away from the tuyere depending on whether you need more or less air.
2. Connect the blower directly to the tuyere with a simple gate valve to limit the amount of air that can get through. This can increase the backpressure on the blower, though.
3. Use some kind of valve that dumps the excess air. People have used an electrical conduit body, like this:
   And I made a gate valve from scrap lumber that worked really well back when I was still burning solid fuel.

[Randy Rue]

I only just recently discovered this is a thing but I'm probably going to try using corn.

after looking at the two blower motors available from on line, the one I have on hand has more horsepower than their cheap one and a lot less than their expensive one. I think I'm just going to have to build this thing tape the motor on and give it a shot

 

[Frosty]

A yard/garage sale mattress inflater blower, under $20 at Wally World last time I looked are way more blower than even most coal forges need. They're available in both 12vDC and 120vac. I grab them at yard/garage sales if they're under a buck or two and they're often thrown into the deal free to entice me to buy something. I have a number but we have lots of new guys in the club that can use the help.

Corn has to be pyrolized to charcoal before it makes a good forge fire just like wood. It IS a good size and smells pretty good as it burns down.

Frosty The Lucky.

[PNW_Sparky]

Look up my post on the buffalo forge restoration. I used a furnace draft inducer blower with similar specs. It works great, except I have to keep the draft gate almost all the way closed or it will blow the coke out of the fire pot. I am going to wire in a speed controller for it soon.