I recently upgraded my hand-crank blower to a larger Buffalo forge one.  My old Champion has about 1-1/2" diameter output, compared to the buffalo which is closer to 3".  The little guy just takes a ton of cranking to get and keep a fire going.

The buffalo forge blower is putting out a lot more air which is nice because I can crank slower to keep things moving along.  I've noticed that there's a lot of resistance when I'm cranking compared to when the blower isn't connected to my tuyere.  "Firepig" has a 2-1/2" diameter inner pipe that tapers down to about 1-1/2" at the nozzle.  I tried to follow Mark Aspery's design on this.  He called for a restriction hole at the nozzle of roughly 3/4" irc.  The "snout" is a water jacketed tuyere that's plumbed to a remote bosh.  This photo shows it with the tub fairly empty, in use, I fill the tub with sand to insulate and to provide a ducks nest for the fire.

I'm wondering if I should open up the snout diameter a bit to ease the back pressure which should make it easier to turn the crank.  I haven't studied this stuff, so I don't really understand what the restriction is meant to achieve.  I don't know if opening the restriction some will adversely affect anything.  Thanks in advance.

opening the hole more will result in less pressure/force in the air coming out. i would think that would think that would end up with less air penetration into the fire ball and give you a fire with lopsided temperature. don't take my word for it. i'm no physicist, but it would make sense to me.

Tubalcain2, thanks for the reply.  I guess I could try opening it up to see if there's a problem.  If it is, I can always weld it back up.

I would try opening it up a little at a time until you find what works best.

Of course you don't find that till you have gone at least one step too far...

Why not replace the pig snout, water jacketed tuyere, with a piece of pipe sticking about the same length into the fire. Connect it directly to the blower with duct tape to keep it air tight. You can then easily replace the pipe with larger pipe of different inside diameters. When you get a pipe that is overly large for your purposes, you can switch back to check the results, and confirm the correct size. Problem solved with real time test results.

If the pig snout is attached as a part of the forge pan, then run the pipe into the pan at a angle with an elbow or bend so the final angle matches the same line of the opening of the pig snout. Read this as if the pig snout opening is at a x degree angle off horizontal, then match that angle. If the pig snout opening is horizontal than make the pipe horizontal. 

Use the new opening size for a while, to be sure it is what you want, before adjust the pig snout.

WL, Thomas,

I suspect that I could open the 3/4" hole to about 1-1/4" before I start to hit the ID of the nozzle.  If I was running an electric blower, it might be a bit more touch and go, but with the hand crank, I suspect I can accommodate small inefficiencies without it mattering too much.

Glenn,

That's a good idea that would probably dial me in fairly quickly.  I'll give it a try when I get a chance.