Photos My new forge from Atlas Forge!

[N.W. Gean]

http://www.atlasknife.com/product/hellfire-forge-cast-prototype/

It's a prototype hellfire with blown burners and a cast body (Plicast LWI 24, according to the site).

Despite the fact that it has 2 burners, I'm hoping that I can hit HT temps because it's forced air.

https://imgur.com/a/7EaO3lM

I have a couple questions about this forge though.

1. According to the FAQ, "Your burner is too far into the chamber. The tip should not be visible in the chamber". Where should the burner be in relation to the chamber? I saw another thread from awhile back that said 1/4" behind the wall, but that was for the mini forge with a venturi burner. Does the same apply for forced air?

2. What is the best way to light it for the 1st time? I found this guide but I'm still a little confused. http://www.rayrogers.com/forge_lighting.htm There's the valve on the propane tank and the red valve on the hose to adjust pressure if I understand correctly. So the propane tank itself should be full blast while the red dial is open just enough, correct?

Thanks to Charles at Atlas forge, and to Stacy for those threads about forced air burners. This forge is really well made and I think it's going to be very versatile as my skills grow.

Edit: I also see from the pictures at Atlas forge that the blower should be more to the side. That's a quick fix. I had just put it together right quick to see it.

 

[HSC ///]

looks nice, thinking about one myself...
Stacy E. Apelt - Bladesmith what's the advantage of a blown setup like this vs venturi on this type of forge?

Harbeer

 

[Stacy E. Apelt - Bladesmith]

Blown is more efficient and runs at lower pressure.
You can balance the flame and chamber atmosphere easily with a blown burner.
Blown can deliver a larger BTU output.
Blown can run at lower flame than a venturi when doing HT.

 

[Ken H>]

I wrote this up yesterday but didn't post hoping somebody (Stacy?, Charles?) would answer your questions. Since it seems nobody had addressed your questions I'll take an attempt here. First to make a couple of comments on the forge, next on lighting forge.

Nice looking forge.

Depending on size of hole in insulation for burner, assuming the hole in insulation is sized to be a good fit for burner tube, the burner tip should be about flush with the insulation, 1/8" or so inside insulation might be ok, but not way up inside, nor should the burner tip be sticking outside the insulation. That would burn pipe off pretty quickly.

Ray Rogers gives good advice on lighting a blown forge, and note you do need an OFF-ON valve located at the burner tube. Since that looks like uses a full size pipe opening for gas injection a needle valve would be VERY nice to have next to the burner tube for adjusting the flame. Is the blower adjustable speed? OR have a choke to restrict airflow? Without some type of airflow adjustment I'm not sure how well you'll be able to run at HT'ing temps. I'll leave comments to that for other folks to make, and especially Charles if he gets a chance to comment. He's the "real" expert on that forge.

Since you don't have an ON-OFF valve at burner tube nor pressure gauge, I think the following should be safe if handled carefully and outside, but protected from wind: Do you have a handheld propane torch? Those are by far the best thing around for lighting a forge. With that forge the way it's setup (really need a 0-15 pisg pressure gauge) it looks like to light would be ( 1) confirm tank valve CLOSED and have regulator turned down to zero flow (2) IMPORTANT to start blower before gas flow, (sure would be nice to restrict air flow), (3) light propane torch, (4) hold propane torch in forge body opening, turn tank valve OPEN, then slowly open regulator to allow propane to flow which will light off.

 

[Ken H>]

In an effort to learn a bit here I'm going to ask a couple of question because I don't understand the reasoning.

Blown is more efficient and runs at lower pressure.

I have read time and again how a blown burner is more efficient and will provide more heat than a venturi burner with the same amount of propane gas. I don't understand that since a gallon of propane only has around 90,000 BTUs. Provided the venturi burner is tuned for max efficiency air/gas mixture, how do you get more BTUs with a blown burner? Is it because the blown burner is more often more correctly tuned than is the venturi burner? i.e. in theory they would be the same, but in actual practice the blown burner is usually more correctly tuned?

Blown can deliver a larger BTU output

That is a fact because you can "stuff" more air to make use of more propane, just like a blower on a drag car.

Blown can run at lower flame than a venturi when doing HT

Absolutely correct, a blown burner can be adjusted over a much larger range than a venturi. While you can adjust the air flow on a venturi slightly with a choke plate, it's still not anywhere near the range of a blown burner air adjustment. I LOVE MY BLOWN FORGE!!! Thank you Stacy

 

[N.W. Gean]

Thanks, Ken. The blower is variable speed. The regulator is 0-20 PSI if I'm not mistaken.

 

[Ken H>]

The regulator is 0-20 PSI if I'm not mistaken.

OK, the regulator is 0-20psi, you still have no idea what pressure you're working at. I suggested a 0-15psi gauge because it's doubtful you'll ever go over 15 psi, and the 0-15 range gives better resolution than a 0-30psi gauge. I've got both and tend to like the 0-15 range better.

 

[N.W. Gean]

Fair enough. All I've had to work with before now is my little 2 brick and torch forge. I suppose a pressure gauge should be next on the list.

 

[Fallbrook Forge]

So I was asking about forges recently, would this be a better option than the Graham Forge?

it sounds like this is easier to get to HT temps.

thanks

 

[Stacy E. Apelt - Bladesmith]

Ken,
In theory, a pound of propane is a pound of propane … but empirically, it is in how that gets used.

The only way to turn up a venturi is to raise the pressure. The high speed jet pulls in the air by the venturi principle. There are a lot of variables in how well that draw works. Also, because the orifice is a fixed size, most venturi burners have a pretty short range between not enough fluid speed to create a draw and too much speed to burn properly. Most venturi burners are somewhat inefficiently due to too much gas being injected.
A blown burner only needs the amount of gas (at low pressure) raised and lowered and the air raised and lowered to adjust from a bare minimum flame to a screaming jet exhaust. The only limit is the size of the burner tube. Balancing this flame for complete burning of all the gas is very easy. You can chance the forge chamber from reducing to neutral to oxidizing in seconds. For running at a set temperature, blown is the only good option.