Stacy E. Apelt - Bladesmith
ilmarinen - MODERATOR
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Knifemaker / Craftsman / Service Provider
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- Aug 20, 2004
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I have been helping a member with his forge build. I thought I would post some of the info on building the burner.
He had asked about my reference to a "chamber" in the burner.
It is a good idea to have a "bulge" in the burner as a mixing chamber. This is where the gas and air mix to more fully burn in the chamber. It adds a lot to the forge efficiency. You just use a larger piece of pipe and two "bell reducer" adapters. If the burner is 1" pipe, then a 3" piece of 3" pipe is the mixing chamber. Thus, you use two 1" to 3" bell reducer adapters to make the burner go from 1" to 3" to 1" again, and then out into the forge chamber. The bell reducers are standard fittings at plumping supply and hardware stores. Here is a link to what I am talking about. Use the sizes available in your area. The chamber can be any size at least twice the burner pipe size. 2.5 or 3" works great.
http://catalog.industrialpipega.com/viewitems/black-malleable-sch-40-80-fittings/bell-reducers-2
The burner pipe size for a medium size forge could be 1" or 1.25". That mostly depends on what use it will see. If doing regular forging and HT, 1" is plenty. If welding damascus, 1.25 would be great (but the 1" will still do fine). 1" is what I would suggest, unless you plan on making a larger forge in the future, or doing lots of welding. ( The whole burner can be moved from forge to forge for many years of use.) The length of the pipe pieces used to make the burner isn't terribly important as long as it has about an 8" long pipe as the burner tube going to the forge.
If I was to make up a shopping list for building a top notch 1" burner for a 5-6" chamber by 14-16" long forge it would be (starting from the blower):
Blower - 100-150CFM range, preferably variable speed. A fan/light controller will often work as a speed control. DC blowers are super if you find one.
2" floor flange. You need some sort of flange or other fitting so the blower can connect to the burner piping.**
2" closed nipple to connect flange to next item.
2" gate valve. A gate valve is placed here to adjust the blast from the blower. If using a speed control, the valve may not be needed, but a ball valve is still a good idea.****
4" piece 2" pipe.
2" by 1" bell reducer
1" closed nipple.
1" street elbow ( ell) ****
1" tee with a 1"X1/4" reducer bushing in the side port. This is where the gas valve is placed. A 1/4" needle valve is used to control the gas flow. The gas line connects here. Using "quick connect" gas fittings on the gas hose is a really good idea. HTT&R has them, as well as most everything else needed to make a great burner.
3" piece of 1" pipe
1" by 3" bell reducer
3" piece of 3" pipe
1" by 3" bell reducer
8" piece of 1" stainless steel pipe. This is the burner tube to enter the forge. Stainless pipe is recommended here, everything else can be black iron. Buy a spare of this pipe, as it will need replacing eventually.
** A plain piping floor flange is a good looking and easy way to mount the blower to the burner piping. Just make some sort of "O" ring or rubber gasket and bolt them together. There are many other ways to do it, too. Use whatever seems simplest for you. Try and match the pipe size coming from the blower with the blower outlet size to some degree. All that matters is that the pipe out of the blower should be larger than the burner pipe by at least twice the size. 2", 2.5", or 3" pipe usually works right, depending on the blower used. Maintain that diameter until the elbow.
Here is what a floor flange looks like:
http://shopping.search.yahoo.com/se...8x?p=pipe+floor+flange&trbkt=VIP226&fr=mcafee
****If everything was kept linear, the whole burner would be a good 36" long. That will work fine, but takes up a lot of room and is a balance issue. Placing an "ell" in the setup right before the "tee" not only shortens the length of the assembly, but places the blower in a hanging down position below the forge which keeps hot gases from flowing up into the blower when the forge is shut off. A good practice is to always shut off the gate/ball valve when shutting down the forge.
Make a bracket or brace of some sort to support the burner arm and blower, as just hanging it from the forge is pretty unstable. If building the forge on a rolling cart, weld this brace to the cart.
In many setups, the floor flange, gate valve, and first length of pipe before the tee are PVC pipe fittings. Since this part of the burner should always be cool, that works fine. However, iron piping will never crack or break on you." Penny wise, pound foolish" applies here.
Also, it might seem easier to just use the tee to do the job the street ell is doing, but a street ell fitted on the end of the tee makes a much smoother path for the air stream. The gas entering the air stream from the side of the tee also increases mixing. Again, the couple extra dollars spent here is well invested if you want the max from your burner.
A burner certainly can be built cheaper and simpler, but the burner is like the engine on a car. Why build a classy hot rod and then put a Yugo engine in it. Money spent on a good burner will be money well spent. A properly built burner can last a lifetime. You might change the blower, and certainly will change the burner tube at the forge end, but everything between them can last forever....so build it like a tank.
http://hightemptools.com/supplies-mainpage.html
He had asked about my reference to a "chamber" in the burner.
It is a good idea to have a "bulge" in the burner as a mixing chamber. This is where the gas and air mix to more fully burn in the chamber. It adds a lot to the forge efficiency. You just use a larger piece of pipe and two "bell reducer" adapters. If the burner is 1" pipe, then a 3" piece of 3" pipe is the mixing chamber. Thus, you use two 1" to 3" bell reducer adapters to make the burner go from 1" to 3" to 1" again, and then out into the forge chamber. The bell reducers are standard fittings at plumping supply and hardware stores. Here is a link to what I am talking about. Use the sizes available in your area. The chamber can be any size at least twice the burner pipe size. 2.5 or 3" works great.
http://catalog.industrialpipega.com/viewitems/black-malleable-sch-40-80-fittings/bell-reducers-2
The burner pipe size for a medium size forge could be 1" or 1.25". That mostly depends on what use it will see. If doing regular forging and HT, 1" is plenty. If welding damascus, 1.25 would be great (but the 1" will still do fine). 1" is what I would suggest, unless you plan on making a larger forge in the future, or doing lots of welding. ( The whole burner can be moved from forge to forge for many years of use.) The length of the pipe pieces used to make the burner isn't terribly important as long as it has about an 8" long pipe as the burner tube going to the forge.
If I was to make up a shopping list for building a top notch 1" burner for a 5-6" chamber by 14-16" long forge it would be (starting from the blower):
Blower - 100-150CFM range, preferably variable speed. A fan/light controller will often work as a speed control. DC blowers are super if you find one.
2" floor flange. You need some sort of flange or other fitting so the blower can connect to the burner piping.**
2" closed nipple to connect flange to next item.
2" gate valve. A gate valve is placed here to adjust the blast from the blower. If using a speed control, the valve may not be needed, but a ball valve is still a good idea.****
4" piece 2" pipe.
2" by 1" bell reducer
1" closed nipple.
1" street elbow ( ell) ****
1" tee with a 1"X1/4" reducer bushing in the side port. This is where the gas valve is placed. A 1/4" needle valve is used to control the gas flow. The gas line connects here. Using "quick connect" gas fittings on the gas hose is a really good idea. HTT&R has them, as well as most everything else needed to make a great burner.
3" piece of 1" pipe
1" by 3" bell reducer
3" piece of 3" pipe
1" by 3" bell reducer
8" piece of 1" stainless steel pipe. This is the burner tube to enter the forge. Stainless pipe is recommended here, everything else can be black iron. Buy a spare of this pipe, as it will need replacing eventually.
** A plain piping floor flange is a good looking and easy way to mount the blower to the burner piping. Just make some sort of "O" ring or rubber gasket and bolt them together. There are many other ways to do it, too. Use whatever seems simplest for you. Try and match the pipe size coming from the blower with the blower outlet size to some degree. All that matters is that the pipe out of the blower should be larger than the burner pipe by at least twice the size. 2", 2.5", or 3" pipe usually works right, depending on the blower used. Maintain that diameter until the elbow.
Here is what a floor flange looks like:
http://shopping.search.yahoo.com/se...8x?p=pipe+floor+flange&trbkt=VIP226&fr=mcafee
****If everything was kept linear, the whole burner would be a good 36" long. That will work fine, but takes up a lot of room and is a balance issue. Placing an "ell" in the setup right before the "tee" not only shortens the length of the assembly, but places the blower in a hanging down position below the forge which keeps hot gases from flowing up into the blower when the forge is shut off. A good practice is to always shut off the gate/ball valve when shutting down the forge.
Make a bracket or brace of some sort to support the burner arm and blower, as just hanging it from the forge is pretty unstable. If building the forge on a rolling cart, weld this brace to the cart.
In many setups, the floor flange, gate valve, and first length of pipe before the tee are PVC pipe fittings. Since this part of the burner should always be cool, that works fine. However, iron piping will never crack or break on you." Penny wise, pound foolish" applies here.
Also, it might seem easier to just use the tee to do the job the street ell is doing, but a street ell fitted on the end of the tee makes a much smoother path for the air stream. The gas entering the air stream from the side of the tee also increases mixing. Again, the couple extra dollars spent here is well invested if you want the max from your burner.
A burner certainly can be built cheaper and simpler, but the burner is like the engine on a car. Why build a classy hot rod and then put a Yugo engine in it. Money spent on a good burner will be money well spent. A properly built burner can last a lifetime. You might change the blower, and certainly will change the burner tube at the forge end, but everything between them can last forever....so build it like a tank.
http://hightemptools.com/supplies-mainpage.html
