Burner Tangents...

69_knives

69_knives

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Nov 20, 2008
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I'm building a new pipe forge and was wondering about burner angle. I know to offset from centre but I also read about putting it at a tangent to get a swirl going to heat the area more efficiently. Is this recommended or just point it straight in?
 
The burner tubes (the burners should have a tube that they slide into) should enter the forge at the tangent of the chamber.
Draw a circle the size of the chamber, which is roughly 2.5" less than the pipe size when using 1" wool (shell inner diameter, minus twice the wool thickness, minus 1/2" for the satanite and ITC-100). Make a tangent line. Add a second line below the tangent the distance of the burner tube. Now, draw a second circle the size of the pipe. This diagram will be how the burner tubes should be installed. The burner tube should be placed about 30% from the back of the forge, and angling forward at about 20-30 degrees. So ,for a 12-14" forge the burner is about 4" from the back.

With the burner installed at the tangent,and angled forward a bit, the flames swirl around the forge walls, creating a tunnel of flame, not a single hot spot on the far wall. The blade will not get over heated in one spot as easily this way. The other thing is that the flame is heating the walls, which need to come up to the desired temperature of the forge evenly if you are going to do HT in it.

A thermocouple can be mounted in a ceramic or stainless tube that runs down the top of the forge and is placed about an inch away from the walls. A bare thermocouple will work, but will not last as long or read as accurately.

Stacy
 
bladsmth said:
A thermocouple can be mounted in a ceramic or stainless tube that runs down the top of the forge and is placed about an inch away from the walls. A bare thermocouple will work, but will not last as long or read as accurately.

Stacy
Click to expand...

I'm going to guess that this is something I should build into the forms before I pack the cement, assuming that drilling the cement after it sets wouldn't be a good idea.?
 
Thanks Stacy for the details. I have been planning a forge for sometime but the detail of angleing the burner toward the front or back has eluded me in every tutorial I've found. Granted I ain''t read them all (just too many).
I would like to ask for some clarification here. Does this apply to horiz. and vert. forges?
 
Stacy,

Thanks for the info on this type forge, that sounds like an efficient design. I'm going to have to build one similar to that real soon.

Do you think a 10o forward angle is sufficient on the burner tube?

Thanks
 
If you are building a two burner forge , 10-15 degres are sufficient. On a one burner forge it would be hot in the back and cool in the front.
Stacy
 
bladsmth said:
If you are building a two burner forge , 10-15 degres are sufficient. On a one burner forge it would be hot in the back and cool in the front.
Stacy
Click to expand...

Stacy,

Do you have experience with verticle forges and burner aiming... both one and multiple burner verticles? Is an up angle necessary/desireable?

Mike
 
You build a vertical ( yes, I have built them) pretty much the same as a horizontal.You could probably get away with a slightly lesser angle , but some up angle on the tube will still be needed.

FWIW, there are two types of vertical forges. An upright forge, which is nothing but a horizontal forge on end (with the bottom end closed) ,which is top loading, and often used for long blades to do the HT; and a vertical forge used for welding and forging through side ports. I think there is a good argument for the second type (vertical forging forges), as you tend to work only the hot area of the blade. For sword work, they are far better than a horizontal in preventing heating of any area other than the current forging spot. ( Note to newbies - you don't want to heat the whole blade at one time while forging a long blade).
They are as easy to build , and take a little less space up. Another plus is also in the fact that you have to tend the steel more, and it gets a more even heating ,since it isn't laying on the forge floor.

Someone on this forum used to make a vertical forge with poured refractory, and use a small beach ball as the form to create the chamber, IIRC.
Stacy
 
I know that Del has reccomended to me on occaision that he's used a soccer ball for the form for his forge body. Might that be what you're thinking about?
 
Yes, I believe it was a soccer ball. Delbert sounds right ,too.
The ball was used to make a spherical chamber for a vertical forge. The flame had the sphere to swirl around in more evenly ( less turbulence), and the heated walls radiated equally toward the center ( equidistant).
Stacy
 
Yes, guys that would be me.
I use an 8" diameter soccer ball as the inside part of the form using a castable refractory. So far it is the most efficient of the forges I have used for welding. My typical billets for this forge are 2x3x6". I have had great sucess with this type of forge, although I'm not using one at the moment because for my current project, I have to forge 2x4x6" billets.
Del
 
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!!
 
delbert ealy said:
Yes, guys that would be me.
I use an 8" diameter soccer ball as the inside part of the form using a castable refractory. So far it is the most efficient of the forges I have used for welding. My typical billets for this forge are 2x3x6". I have had great sucess with this type of forge, although I'm not using one at the moment because for my current project, I have to forge 2x4x6" billets.
Del
Click to expand...
not to hijack too much, but this sounds awesome. Any pics?

for the OP, that picture looks exactly like what Stacy was recommending.
 
This is an old thread, but a weekly topic, so it is still good info. Your drawing is correct.
 
This is a good topic and I probably would have never thought of the spherical forge without seeing this thread. I'll have to store that for a later project.

I've noticed that many of the DIY mini forges and even the Atlas mini forge have burners at the front of the forge. It kinda makes sense to me since most of the blade mass will be toward the opening when the blade is inserted tip first. Having the heat source there should help bring the blade to temp more evenly and prevent overheating the thinner tip of a tapered blade.
What is the advantage of placing the burner at the back of the forge?
 
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