Burner Tangents...

Some small to mid size forges don't have a back port (opening/door). By having the burner at the back you get more even heating. On a front and back ported forge, it probably doesn't matter....unless you block the rear port for some reason.

BTW, just so people who plan on building a forge understand, you need a good size opening for the combustion gasses to escape or the forge will have back pressure...which you don't want. A close forge ( which I see people draw up regularly) wouldn't even work. Roughly, the ratio is the ports need to equal about 20 times the burner nozzle area. If the burner has 1sg.in. area, you need a port area of 20 sq.in. If you use 3X4" front and a 3X3" back port, that would just make it.
 
bladsmth said:
Some small to mid size forges don't have a back port (opening/door). By having the burner at the back you get more even heating. On a front and back ported forge, it probably doesn't matter....unless you block the rear port for some reason.

BTW, just so people who plan on building a forge understand, you need a good size opening for the combustion gasses to escape or the forge will have back pressure...which you don't want. A close forge ( which I see people draw up regularly) wouldn't even work. Roughly, the ratio is the ports need to equal about 20 times the burner nozzle area. If the burner has 1sg.in. area, you need a port area of 20 sq.in. If you use 3X4" front and a 3X3" back port, that would just make it.
Click to expand...

Great info, but just to clarify (I'm OCD), In my case I'll have burner tube made from 1" schedule 40 pipe which has a I.D. of 1.029 inches. If my math serves me right, this will give me a burner nozzle area of .83 inches and 20 times this area is 16.63 inches. Since my burner entry location is at 30/70 percent, how about I have a back port equaling 30 percent of the total needed area and a front port equaling 70% of this area, or would I be better off to just have a front port only that would be a little over 4x4"?

Thanks Stacy, this is a great site and I really appreciate the time you invest to help.
 
That would be fine...as long as the total exit area for the exhausted gasses is 20 times the entry area.

This is a minimum, and should be used as a guideline. If your forge is 18 times the burner area, or 25 times, you are fine. It is plny when you greatly exceede the guideline that the forge gets less efficient.
 
NC Biker said:
I'm a total newbie to knife making and have gotten to the point I want to heat treat some 1084. I've decided to build a propane forge for this purpose. I'm at the point in my build that I need to install the burner inlet nozzle and want to verify that I have it right. The info on these forums has been very helpful, but I've been a little confused as most of the forges I've seen have the nozzle going straight into the heat chamber and some even recommend installing the nozzle pointing towards the back of the chamber. So, before I strike an arc, I wanted to make sure I've got this right.

Does this look like I'm on the right track?

nozplace.png


Thanks for any feedback!!
Click to expand...

This is excellent. I have trouble interpreting text insturctions so this drawing makes it perfectly clear. I'm taking my forge to work tomorrow to cut the burner port off and move it to the back and fix the angle.
 
BladesByBaz said:
This is excellent. I have trouble interpreting text insturctions so this drawing makes it perfectly clear. I'm taking my forge to work tomorrow to cut the burner port off and move it to the back and fix the angle.
Click to expand...

Glad the drawing helped. Since posting the sketch, I built my forge as shown and it works great! Thanks again to Stacey for the info.
 
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