Building a gas forge burner

Everything Mac

Bushcrafter (boy, I've got a lot to say!)
Nov 30, 2009
3,106
78
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Scotland
So I've had to build myself a new gas burner and thought I'd take this opportunity to share the process.

I use a gas injector by the company Burlen. They make carburettors and bunsen burners and all sorts of clever stuff. The Amal branded gas injectors are THE best in the business. Not only offering one handed control of the gas/ air mix but you can also adjust the size of the injector tip itself giving further control over your flame and thus forge environment.

Almost all of the parts are pictured here:


In no particular order - glycerin filled pressure gauge, needle valve, gas rated shut off valve, various brass adapters, a quick connect adapter, propane gas hose, Amal gas injector, 8" of mild steel tube, stainless steel flare.

Not pictured is a 0-4bar propane regulator fitted to the propane tank.


Up close you can see the amal injector is a quality bit of kit. Many smiths make their own DIY forge burners and many are ok but they are essentially cobbled together from bits not intended for the task. - They may do the job but will never be as good as one of these.

This particular one is a 3/4" injector, they range from 1/2" up to 2". For general forge use the 3/4" or 1" is more than enough.

So after a bit of screwing together after applying PTFE tape we get this:


I test all joints for leaks with a spray bottle full of soapy water. This is very important! You really don't want any leaks.

I use a quick connect fitting on my gas hose as I like to be able to completely disconnect the forge for ease of storage.

Right then, lets light it up.



The air inlet full closed above, so lets crank it up.


This is at 10 psi:



This is at 30 psi:



It really is an absolute beast. The needle valve allows very fine adjustments to be made which makes monitoring the forge pressure, fuel economy etc a doddle.

My little forge would tick over quite nicely at 10psi. But you could crank it up to 20 psi and it would be really roaring!


So there we go, bit long winded but thought I'd share.

All the best
Andy
 
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Jul 24, 2017
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somerset
I know how much coal I use in my forge, but wonder if gas would be better so what size bottles do you use and as an average how long do they last?
 

Everything Mac

Bushcrafter (boy, I've got a lot to say!)
Nov 30, 2009
3,106
78
33
Scotland
I know how much coal I use in my forge, but wonder if gas would be better so what size bottles do you use and as an average how long do they last?

I was using the small 13kg propane bottles just for ease of space. I would get a good couple of weeks worth of forging out of one. But my forge was small and running at about 7psi.
It would really depend how efficient your forge is.

All the best
Andy
 

Everything Mac

Bushcrafter (boy, I've got a lot to say!)
Nov 30, 2009
3,106
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Scotland
Where do you get your Coke from Tom? The stuff I get up here is awful so I've switched completely to Welsh steam coal. It's a bit smokey on starting but once it cokes up and gets going it's much nicer to use.

Anthracite is quite nice too. It's a bit more gentle than coke.

All the best
Andy
 

Tomteifi

Nomad
Jan 22, 2016
294
16
Carmarthenshire, South Wales
Where do you get your Coke from Tom? The stuff I get up here is awful so I've switched completely to Welsh steam coal. It's a bit smokey on starting but once it cokes up and gets going it's much nicer to use.

Anthracite is quite nice too. It's a bit more gentle than coke.

All the best
Andy
Hi-Its a company called Welsh Dragon Fuels and stoves. They are in Ammanford, South wales-quite a way from you. It is brilliant stuff though and very reasonably priced. The last lot I bought was £46 for 4 x 20kg bags. That was in june last year. Their phone number is 01269 842620 for the shop and 850224 for the office. If you buy 12 bags or more they'll do free localish delivery but for you they may reduce price a little. If you've used smiths breeze before you'll know how good it is, if not, I cant praise its attributes enough really. It would be worth an overnighter for a trailer load back home!

ps One 20kg bag of breeze @ £11.50 will last you months of weekend 'smithing!
 
Last edited:

C_Claycomb

Mod
Mod
Oct 6, 2003
5,907
977
Bedfordshire
Looks neat, but how do you control air/gas mix? I see two valves, one looks like it is on/off lever operated, and one needle valve on a black dial for adjusting gas pressure. How is the air throttled?

My experience has been with the Shorty burner from http://www.hybridburners.com/products.html, where I have what looks like the same lever and pin valve set up, but the burner has a sliding collar that allows the amount of air pulled in by the Venturi to be throttled or opened wide.
 

Stew

Bushcrafter through and through
Nov 29, 2003
5,482
505
Aylesbury
stewartjlight-knives.com
Looks neat, but how do you control air/gas mix? I see two valves, one looks like it is on/off lever operated, and one needle valve on a black dial for adjusting gas pressure. How is the air throttled?

My experience has been with the Shorty burner from http://www.hybridburners.com/products.html, where I have what looks like the same lever and pin valve set up, but the burner has a sliding collar that allows the amount of air pulled in by the Venturi to be throttled or opened wide.

It's the knurled silver knob in the centre of the burner.

Having seen some of these in use at hammer-ins, they really are the best way to go in my view.
 

C_Claycomb

Mod
Mod
Oct 6, 2003
5,907
977
Bedfordshire
Ah ha! I see now. Difference between picture 2 and picture 3. Pic 2 shows it screwed down in an "open" position, and pic 3 shows it up near full closed.

Nice. With that explained, I agree Stew, it does look a very tidy way to do things. I got the burner I did only because I travelled to the US and it was relatively easy to pick up and bring back...and it was about 12 years ago, so price was probably lower than now.
 

Everything Mac

Bushcrafter (boy, I've got a lot to say!)
Nov 30, 2009
3,106
78
33
Scotland
Ah ha! I see now. Difference between picture 2 and picture 3. Pic 2 shows it screwed down in an "open" position, and pic 3 shows it up near full closed.

Nice. With that explained, I agree Stew, it does look a very tidy way to do things. I got the burner I did only because I travelled to the US and it was relatively easy to pick up and bring back...and it was about 12 years ago, so price was probably lower than now.

You can see my using the knurled adjuster in the video at 4:44. - It's very simple to use. :)

I've heard good things about the hybrid burners but sounds like you're due an upgrade. ;)

All the best
Andy
 

Everything Mac

Bushcrafter (boy, I've got a lot to say!)
Nov 30, 2009
3,106
78
33
Scotland
Hi-Its a company called Welsh Dragon Fuels and stoves. They are in Ammanford, South wales-quite a way from you. It is brilliant stuff though and very reasonably priced. The last lot I bought was £46 for 4 x 20kg bags. That was in june last year. Their phone number is 01269 842620 for the shop and 850224 for the office. If you buy 12 bags or more they'll do free localish delivery but for you they may reduce price a little. If you've used smiths breeze before you'll know how good it is, if not, I cant praise its attributes enough really. It would be worth an overnighter for a trailer load back home!

ps One 20kg bag of breeze @ £11.50 will last you months of weekend 'smithing!


Blimey. I think I'll stick with the steam coal. I get a tonne for £260 delivered. That's 40 bags so £6.50 each to my door.

Thanks for the info though.
All the best
Andy