Question about a gas forge blower

Barry Clodfelter

Barry Clodfelter

Joined
May 29, 2007
Messages
572
I am looking for a good cheaper option for a forge blower. I found this one on fleabay and wondered if it would work? I know I'll have to fab something to make the square end fit into the round pipe but that's easily enough done.

Thought?
 
Two things; the max inlet temperature is 104 F and I've heard mentioned that squirrel cages on fleabay made poor blower motors for a forge.
 
I have a good sized squirrel cage of that style on my blown forge, which works well- but looking at prices on ebay just ticked me off. Things cost too much, period. This is the sort of item I'd look for second hand, in local stores or in your local craigslist. You should be able to find a good working one used for $20-30, or even free if you luck out.

Also, make sure you adapt the square output from the blower smoothly to the round input for your burner assembly. I recently rebuilt my burner, and took the time to fabricate a tapered cone adapter, 3.5" round for the 4" square flange on one end, tapering to 2" male pipe thread on the other end going into the 2" gate valve. Since rebuilding with this smoother transition, my burner definitely runs hotter and smoother. Previously it had just consisted of a square plate, with a circle burned in the middle and a 1.5" pipe nipple welded on for adaption.
 
Good options are going to a HVAC place and asking if they have a used burner blower for a NG burner from a heater/boiler. These are exactly what you want, and may be just junk to them. I had one felow point to the "bone yard" out back and say, "Help yourself".
Heck, you might be able to trade a knife for one.
 
Good point Stacy, I got an oilburner with a nice blower for free a couple years back, from a scrap iron pile for free. HVAC companies are often good to scrounge at, I'm running a grinder with a Baldor 3hp motor I got scrap at an HVAC place.
 
There are a couple HVAC places around here, think I'll check them out. Thanks Stacy.

Salem, I saw that big squirrel cage fan on the forge on your web site thats kinda where I got the idea to make one of those work. Kayne and sons want like $125 for a 60 CFM blower and go up from there. So I was hoping to make something work a little cheaper.

Can't remember where I saw it or who made it but the fellow made a blower with a squirrel fan, 5 gallon bucket and a 1/3 hp grinder motor buy attaching the bucket to the motor and the fan blade on the motor shaft, cut an outlet hole and epoxied a 2" pvc pipe to feed his forge. Looked a little goofy but he said it worked well.
 
Gonna give my 2c here. I've used multiple inexpensive blowers, I had a 75cfm surplus center blower on two different vertical forges, most recently. They were fine, but I'd run them pretty much full tilt, and was running around 4-6 psi pressure on the regulator. Didn't have a problem welding, but like the previous blowers I've used, I could tell they werent going to last, and I was using a lot of fuel. They burned out in about a year.


I finally broke down and bought one of the 112 CFM high pressure forge blowers from Kayne & Sons, they're spendy. My friend bought a bigger one for the Ribbon Burner forge he built also. The difference in pressure output of these things is *INSANE*. Now I'm running the damper completely closed (literally closed, not even cracked open), and 1-2 psi on my regulator (over 50' of line), and I'm having a hard time keeping the forge below welding heat. Probably going to have to add another air gate for further downward control.

Yes, they're spendy, but I know people that've been using their blowers for 10 years, leaving them on most of the time. My friend melted his thermocouples, and high temp cerachem (2800deg stuff) blanket with the bigger blower and a ribbon burner he built.



Just saying, these blowers are built for our actual needs. I've gone through enough cheap blowers (not to mention wasted fuel) to have easily justified the cost of one off the bat. So I'm just going to suggest that you may consider this a "get what you pay for" scenario, and think about the long term costs. Propane in NC is expensive compared to other states from my experience, so anything you can do to conserve fuel is a good investment.


CFM ratings aren't very the relevant stat for this application, because those ratings afaik are "full un-restricted output", i.e. blowing open, not into a pipe. We need high pressure output.
 
If you are running that blower into a completely closed damper, with 2 psi propane, and have trouble staying below welding heat, it would seem that your blower is overkill. I do like radial blowers better than squirrel cage, but- I got the squirrel cage for free and it's doing very well. When it quits, I have two others to take it's place. When keeping an eye out over time, surplus parts and components can really be "squirreled" away.

Also Javan, does your propane line terminate in a sized orifice at the burner, or just an open line end and maybe a needle valve? PSI is so relative to speak of when fuel jets and delivery methods vary so widely...
 
Javan I thought about that 112 one from Kayne as being a good fit but after hearing you say you run the damper closed do you think the 65 CFM one would be a better fit for your forge? I have an 8" square tube 18" long that I am going to wrap inswool and coat with satanite and ITC-100 to shape it more round inside with a fire brick on the bottom. So it is going to be a fairly small forge and mostly used for welding.
 
Bear in mind this forge is much smaller internal volume than your average vertical. I made it to just accommodate a 1.5x6x4-6" tall billet.

Your right Salem, the blower may be overkill, *but* I don't see how that's a negative since this forge is intended only for damascus, and it's increased the efficiency by a ton.


If you've never seen one of these blowers in action, you won't get what I'm saying here, but the high pressure, really changes the forge atmosphere for the better. That being said, in answer to Barry's question, for a forge my size, I could definitely get by with the 65 cfm version, which was not available when I bought my blower, and wasn't afaik available until just recently. If it's got the high pressure that the others do, then it'd be a great option.


FWIW, I've got my fuel line terminating into 2" black iron pipe a couple inches below the blower, from a 3/8" street-elbow, after a ball valve, which even at the above PSI I run only about 1/4 open.. If I crank the regulator psi down to about 1, I can open it up a bit and keep it within comfortable forging and HT range if I wanted. I have considered switching to a mig tip and a needle valve for more control, but I'm not looking for a "do everything forge", since vertical forges are crap for forging blades anyway, in my opinion.


Another advantage of these blowers is a plug already attached and an on/off switch, and the fact that they don't get hot from operation.


Anyway, take all that for what you will. Barry, I think you'll need to consider the internal volume of your forge more than anything before making a choice as to sizing a blower, but bear in mind, CFM may not be the appropriate variable to base that decision.


I am building a longer forge with a ribbon burner, so that I can get long billets heated up completely for drawing in the rolling mill to final thickness, but I've never met another vertical that heats an initial stack as fast and efficiently as mine. Most guys I know making damascus are using a forge much too big for their equipment, and the tiny stacks they work under the same, IMHO.
 
You really don't want or need a whole lot of air in a blown forge. Almost anything you buy is overkill. I have a nice kind of expensive fan, but even in my 21" by 10" forge, the air intake for the fan is shut down almost all the way almost all the time.
On my coal forge, I have a blower from a bathroom exhaust fan. it's almost twenty years old. Once I forgot where it was and found it again when I was using the grass trimmer- it had sat outside for over a year and had grass growing through it. It still works great. Do I have to say that it was free when I got it?
Been there done that.
Most people run way too much air in their forges and then wonder why they get so much scale and can't weld in there. I coach people a lot on that at blacksmithing events...
 
To prove I'm not just pontificating, here's a pic of my forge and the blower config:

IMG_2990%255B1%255D.JPG


Here's a shot showing my two hammer's (75lb Bull and a KA-75), and my rolling mill. Just re-arranged everything, which is why it doesn't quite look like a bomb went off:

IMG_2989%255B1%255D.JPG


And here's a pic of a knife I'm making from a new pattern I recently developed:

IMG_2977%255B1%255D.JPG



I'm not a very prolific knifemaker, but I make damascus almost every single day, FWIW.
 
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Very nice pattern, very unique...

For you blown guys, thoughts on ribbon vs pipe burner? I am building a larger forge than my current atmospheric and it will be blown. I have two 1" burners that were atmospheric using strainer y's so they are easy to turn into blown burners, but I have been wondering about the merits of a ribbon burner. Seems like a much more even and controllable burner source, no?
 
Javand, I'm curious- I have the exact same blower (with English brand marks) and a forge of similar size (though it's horizontal).
Question- I see the air gate on the intake is closed, and I operate mine with just a crack open.
Where do you set yours, generally?
Thanks,
Andy
 
Ribbon burners are sick. Quiet, efficient, and HOT. Even heat, too. The only thing about them is that the forge shell has to be built a little different to accommodate them. I've had one about half built for years, it'll be my next forge for sure. Well, after the sword length HT forge.

It is true that higher air pressure from the burner gives a more stable flame and better mix- as opposed to just higher volume, which can lead to scaling. The only drawback I can see about having too much burner for your welding forge is that I like to use the vertical for post-welding thermal cycles, since it's already warmed up. If I cut my burner off and leave the air on for a minute or two, then light it again, I can run a fuel rich atmosphere with a lower flame and normalize a few times. I even HT in it sometimes; the ability to dial in a good carburizing environment helps to heat for quenching without a lot of scale. Otherwise, I use satanite as anti-scale, which can be a pain to remove after HT. Or, a pipe muffle in my venturi forge, but that won't do chef blades over 2" wide very well.
 
Andy, I usually run mine just cracked also, atleast for the first 30 mins of operation or so. I search for that sound like an oxy cutting torch where it goes kind of quiet at the right ratio, then I'll let it get a little more reducing, for setting welds. If I'm just drawing a billet and not setting welds, I'll usually damper it back down to the position the damper is on now, to conserve fuel, while the iron is "out of the fire", since you can't really run two billets the size I like to work in rotation with this small forge.



On the note of Ribbon Burners, I'm planning to build one, and I gave my good friend the info on the Emmerling style burner for his production damascus forge (checkout http://www.zoecristknives.com/ for a shop tour of Crist Metal Works, and the ribbon burner forge he built). He's the one I said melted his thermocouples and the high temp ceramic fiber. These burners can be super efficient, and *super* high output, so all I'd say is, defer to building smaller, than bigger because even the smallest ribbon burner I've seen will probably have more output than you need.

Some of the commercial ribbon burners have super small jet holes, and require insanely high pressure blowers, so I'm not sure how economical or practical they are for our application, but building one yourself is mega easy. The only issue is, fine tuning puts you into a much less trodden area, so you'll mostly be on your own in that regard. If you're not already comfortable tuning your forge atmosphere, fuel and air ratios, etc, I'd recommend getting comfortable with a simple blown burner like the one I and many others are using, until you're more confident with it.



Another thing I wanted to mention in conjunction to Salem's info on using anti-scale compound is that borax works well too, a very light sprinkling of it on your blade or billet as you're bringing it up, while it's showing color but before it starts to scale will keep scale from forming, the same as it does inside a billet, anhydrous borax wont run off and do damage to your liner like the 20 mule team stuff will, and it only takes a tiny amount.
 
Thanks Javand!
I've only played with ribbon burners a couple times at conferences, but quite the Cadillac ride.
My only concern is, with a side blown burner you get fairly even heat due to the rolling flame.
Do you see any disadvantage to having the full power and authority of that ribbon burner shining straight down on your work?

Salem- Hooray for the H.I.N.! Have you been going to conferences? I always seem to be too busy scratching a living out of blacksmithing to go talk about it, I know, that's no excuse...
 
I've heard they distribute heat very evenly regardless, since the "burner" size is much larger in area with small jets distributed over it, unlike a venturi which is one large jet. Although some guys do mount them on a tangent, which I'm sure doesn't hurt.


That being said, I don't begin to pretend I'm an expert on ribbon or any other types of burners. I'm just sharing what info I know works for me in regards to a blown burner, and what little I've seen and heard about the ribbons.
 
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