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Propane Forge Burner Designs
The Modified Side Arm Burner & New Mini-Side Arm Burner

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Modified Side Arm Burner

The Modified Side Arm Burner was built and designed by Larry Zoeller, this design was inspired by the work of Jerry Frost and others.   I know that there are a lot of burner designs out there that work just as well, but I feel the ease with which you can build the modified sidearm design makes it worth using.

Update 06/21/08:  The Side-Arm Burner BTU output chart above was complied from testing done at the University of Kentucky, Center for Applied Energy Research.   The BTU output chart above is not theoretical numbers but are the actual measured BTU output of the Side Arm Burner.

Update 07/21/06: The rule of thumb for side arm burners to forge volume is: (1) 3/4" side arm burner for every 350 cu/in of interior forge space.  These figures are for a forge that has been properly insulated, for example: two layers of 1"Durablanket with 8 lb. density 1260°C (2300°F) temperature grade rating for the forge lining and forge lining coated with Plistix 900 F.  I have also posted a link on my FAQs page to an online calculator to figure the area of a cylinder.

Update 04/21/06:  If you are going to use a manufactured pipe nipple or a pipe nipple that was cut with a roll style pipe cutter for your burner tube there are several things that you will need to do to it to get the best performance out of it.  The first thing that you need to do is if you are going to buy a threaded nipple is buy a 3/4" x 9" nipple and cut 1" off one end.   The flares are designed to fit on the outside of 3/4" pipe and if you use a 3/4" x 8" nipple your burner flare will be a very poor fit because of the threads on the end that the flare goes on.  The other things that you will need to do is file the rolled end off  threaded end of the pipe and file or sand the seam inside the pipe smooth.  I cut all of the pipe that I use for burner tubes on a bandsaw, so you will not have the rolled edge on the end of the threads.  It also seems to me that the better quality brands of pipe will have very little if any seam on the inside.

I have had a lot of people ask me if they can use a shorter burner tube than 8" long stated in the plans.  So I took some time out in the shop playing with different length burner tubes, sure I could get them to run on 6", 7", and 7 1/2"  burner tubes but they were very erratic and it also caused the burner flares to get red hot.  I would guess that the flame was actually burning up inside of the burner flare instead of the end of it.  So I would say that 8" is definitely the shortest that you will want to try and run with the 3/4" side arm burner.

I posted the update on 05/20/04 about an alternative method of holding the 1/8" pipe in place.  I still prefer to use the 1 1/4" pipe plugs and drilling the hole for the 1/8" pipe using a lathe. This method ensures that your pipe nipple will be centered correctly.  Using the pipe bushing in the alternative method you are depending on the threads on the bushings to be threaded on center, I have found that this is not always true, so this could cause your burner to run erratic.

I am now using the 14T-35 contact tip made by Tweco, this is the longer contact tip with the taper on it.  I feel that it improves the performance over the standard 14-35 tips.  The following link is to a pdf file of the Tweco contact tips chart it also shows the actual inside i.d. of all of the tips.  Tweco contact tip chart

I have also created a frequently asked question page that covers tuning the side arm burners and other commonly asked questions concerning atmospheric gas burners and forge building.

Update 05/20/04: I received a e-mail from Mike Murphy of Tallahassee, Florida.  He has an alternative method of holding the 1/8" pipe nipple in place. Michael writes,  "I swiped an idea from Mike Porter’s book and added it to your sidearm burner design.  Instead of using a bored-out stopper (pipe plug) with a setscrew to mount the accelerator, I put in a 1 1/4 to 3/8 bushing.  Then I took a 3/8 to 1/8 bushing, drilled it out to 27/64, and slit the ends of the threads like on Page 57 of Mike’s book.  (He says to use a 1/4 to 1/8 bushing bored to 13/32, but that hole is too small to fit the pipe nipples I have.)  Anyway, it works pretty well.  I do not see a large increase in efficiency (if any), but its a lot easier and more accurate than drilling out the stopper and drilling and tapping the setscrew hole.  At least for me it is; I don't have access to a machine shop, so I'm doing a lot of this stuff with a regular drill press, hand taps and dies, homemade jigs, etc.  I'm assuming, of course, that the bushings and pipe couplers are accurately cast and tapped."
Note: I tried this method and it works well, the only thing that I did differently was use a 13/32" drill bit instead of a 27/64" like Mike used. The outside diameter of pipe nipples will vary, so I would recommend measuring the outside diameter of the nipples that you are using before drilling the bushing out.
alternative method

Update 04/10/04: Single Style Choke Plate.  File or sand the branch opening of the reducing tee to provide a smooth mating surface for the choke plate.  Using a #36 drill bit drill a hole in the branch opening of the tee and tap it for a 6-32 NC screw.  Note: a compression spring under the cap screw will help hold the choke plate in a set position.
Choke Plate

UPDATE 10/09/03:  An alternative to the using of the 1/8" schedule 80 pipe nipple is to use a 1/8" x 3 1/2" std. black pipe nipple with a 1/8" std. black coupling and 1/8"pipe plug installed on one end.  The 1/8" pipe plug needs to be drilled and tapped to 1/4"-28 NF to accept the contact tip.

Drawing of the alternative method

UPDATE 1/2/04: Make sure that you use the Ward brand reducing tees to make the Side Arm Burners.  The other brands such as Grinnell and Anvil do not have the nice taper that the Ward have and do not burn as well.  If you also try to go with larger openings such as a 1 1/2" x 3/4" x 1 1/2"with the Ward brand it will not have the taper either, it will look like the Anvil brand reducing tee shown on the right.
Wrong Tee

Side Arm Burner Assembly

This is a picture the burner using a 1 1/4" x 3/4" x 1 1/4"(Ward) reducing tee.   The reducing tee
acts like the bell reducer used on the Reil simple burner.

View of the contact tip

Here you can see the pipe plug drilled out for the 1/8" schedule 80 pipe nipple and the contact tip.   You can use either a .035 or .045 contact tip ( note: the contact tips are used in the MIG gun on MIG welders they are available at your local welding supply shop).   There are several brands of contact tips that will work, just make sure that they have 1/4"-28 NF threads.

Click on the following link to view a pdf file of the Modified Side Arm Burner
PDF File: Side Arm Burner Drawing

 To access these files, you must download the most current Adobe Acrobat PDF Reader by clicking on the icon above. This is a free download.


Parts List for the Modified Side Arm Burner
(1) 3/4" standard pipe 8 to 9 inches long with threads on one end.
(1) Ward 1 1/4" x 3/4" x 1 1/4" std. black reducing tee,
(1) 1/8" x 3 1/2" schedule 80 pipe nipple
(1) 1 1/4" std. black pipe plug
(1) .035 or .045  contact tip
(1) Stainless steel burner flare

Note: You need to tap one end of the 1/8" pipe with a 1/4"-28 N.F. tap for the contact tip.  There is no need to drill it before tapping the threads.

Mini-Side Arm Burner

The Mini-Side Arm Burner is a scaled down version of the Modified Side Arm Burner.   This is another simple to build burner that performs well.  I have had a lot of people tell me that the modified side arm burner works great but they do not need a burner that big, they just want to work in a smaller forge.   I have heard this a lot, especially from the Bladesmiths that forge and heat treat small knives.  This mini burner would be great for a mini forge with the inside volume of about 60 cu/in .

Mini-Side Arm Burner

Click on the following link to view a pdf file of the Mini-Side Arm Burner

PDF File: Mini-Side Arm Burner Drawing


Parts List for the Mini-Side Arm Burner
(1) 1/2" x 6" std. black pipe nipple
(1) Ward 1" x  1/2" x  1" std. black reducing tee.
(1) 1/8" x 3 1/2" schedule 80 pipe nipple
(1) 1" std. black pipe plug
(1) .023 contact tip
(1) Stainless steel burner flare

If you are looking for parts to build a gas forge, please check my gas forge supply page.  I am now selling burner flares, propane regulators, LP hoses, gauges, valves, tank fittings and Durablanket.
Zoeller Forge Gas Forge Parts

Disclaimer Notice:
Zoeller Forge specifically disclaim any responsibility or liability for damages or injuries as a result of any construction, design, use or application of information contained on this web site.

Please send your comments or suggestions to : zman59@earthlink.net

Copyright ©2000-2015 Larry Zoeller (Zoeller Forge)

Last Revision 12/06/15

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