Thanks very much for the help, I've ordered 75, 90 & 100 jets so I have something to experiment with and see how they get on. I'm betting 90 will work given everyone seems to use them but figured having some others might be interesting. I'll have a play next week when they get here. 

finally got half an hour this afternoon to put the new jet in and fire up the burner. MUCH better. put it in the forge and you can see that it looks like it'll work. This is with zero tuning, just turn on the gas and light it. 

Now need to rebuild the forge because it's twice the size I actually want for a ¾" burner so I'll try and fix that this weekend.

Thanks so much for the help and guidance so far.

On 3/5/2026 at 5:34 PM, Hefty said:

Hopefully someone like Mikey or AFB will be along shortly to confirm, but in my opinion the greenish primary, and long purple and orange tertiary flame envelop in your photo suggests that your burner is not inducing enough air even when it's outside the forge, so when you put it in, the extra backpressure is slowing that induction even more and you're getting super-rich flames. I can't see from the photo: what sort of adjustment is there for air intake, or gas orifice distance from the mixing tube? You need a larger air intake area, or a bigger distance between the gas orifice and the beginning of the mixing tube so that the speed of the gas stream has space to entrain more air.

As to the flame appearance, Hefty is correct. As to commenting on Amal burners; I don't go there; they have a good reputation among their users, but their dynamics are foreign to any design I have built.

Good Morning Third,

The picture above must have been taken just after starting. There is no reaction in the Brick, from Heating in the Fire-Box. When I start a Propane Forge, cold, I have to adjust the pressure at the regulator richer/up. Leave a strip open at the bottom of one end of the Doors, Close the other end. After the brick gets hot, you will find that you can adjust the pressure down and still keep a Roar. Be careful not to bump the Bricks, when Hot.

In the above picture, you either have the regulator turned down, or too small of a Jet. 

Learning and keeping track of your changes. Change one thing at a time, jot down the change in your Book. What is the reaction/result? Is there someone near you whom you could ask for assistance/mentoring?

Good Luck, Neil

8 hours ago, SafetyThird said:

finally got half an hour this afternoon to put the new jet in and fire up the burner. MUCH better. put it in the forge and you can see that it looks like it'll work. This is with zero tuning, just turn on the gas and light it. 

Yes, this is waaaayy better.

10 hours ago, swedefiddle said:

Good Morning Third,

The picture above must have been taken just after starting. There is no reaction in the Brick, from Heating in the Fire-Box. When I start a Propane Forge, cold, I have to adjust the pressure at the regulator richer/up. Leave a strip open at the bottom of one end of the Doors, Close the other end. After the brick gets hot, you will find that you can adjust the pressure down and still keep a Roar. Be careful not to bump the Bricks, when Hot.

In the above picture, you either have the regulator turned down, or too small of a Jet. 

Learning and keeping track of your changes. Change one thing at a time, jot down the change in your Book. What is the reaction/result? Is there someone near you whom you could ask for assistance/mentoring?

Good Luck, Neil

Hi Neil, thanks very much for the hints and suggestions, I'll go through those when I next fire things up. 

You're correct in that the photo was just after I turned on the burner in the forge. It was only on briefly to check that it held that shape of flame and then I turned it off. I'll rebuild the forge to a more suitable volume and then start setting things properly and making notes. I have the other jets to try as needed so should be fun to experiment. 

I haven't looked for anyone local yet, there's no-one I know at the moment but I'll see what I can find out.

Good Morning Third,

Don't change anything!!! The Forge HAS TO COME UP TO TEMPERATURE, FIRST!! Everything changes when the Fire-Box is at temperature (maybe a yellow colour of the bricks). ONLY Change ONE Thing at a Time!!!!!  If the Fire-Box doesn't get up to HOT, then try a Jet Change, NOT BEFORE. Make sure your End Doors are in Place. For anything to go into the Forge, you MUST have an Exhaust Path!!!!  The Doors will retain the Heat Inside the Fire-Box. After it is HOT, you will see that you can turn down the pressure at the Regulator and maintain a good burn with less fuel.

This is all new to you. Take Little Steps!!!!  Document what every change is and what result you have after the Change!!!

Neil

Good Morning Third,

The B.A.B.A. is big in the UK, British Artist Blacksmith Association. They have history going back to 1600-1700, maybe further. Some have moved to N/America (not just USA), as well as wherever Feet will Travel,

Neil

Hi Neil, thanks for the info on the BABA, I'll look them up.

As to the forge size, it's twice the size needed for the burner. I originally thought the burner was 1" but it's actually ¾", so I built a forge with about 700 cuin volume when it should be 300-350 from everything I've read. I think I'd be better served building something the correct size that it should be easily able to bring up to temperature rather than trying to heat up a much larger volume? Would you agree?

Good Morning,

I think what you have is totally Fine. You NEED to get the Fire going so you can start to Learn, pay attention to what goes on. There is no such thing as a 'Forever Forge'. I don't know how many I have and how many I teach in at the Blacksmith Association. Probably, over 30 different Gas Forges. One Gas Forge is a Pipe Tee!! Works Great!!  I have 2 AMAL Burners, exactly like you have. They can work in a small Forge or a Larger Forge, you can adjust it for what you Need. Don't let the tip of the Burner Nozzle stick inside the Fire-Box, always sucked back a bit. There is no such thing as 'It Has to be this Size, or it won't Work'. Use your Noodle that the Good Lord gave you, the one that holds your Ears to your head. Try it and See!! MAKE NOTES!!!!!

I was asked to Hammer Texture 3/4" solid square bars, started out 10 feet long. Hammer Texture 4 sides. I did it in a single Burner Brick Forge. Yes, I had made the Burner, it was 2" pipe with Flow Straighteners, it has a single speed Fan with a Gate Valve to control the Air Volume. I did it in 3 sections, almost 3.5-4 feet per heat. 120 Bars. They were 11-11.5 feet, when done and straightened. The builder was making Security Bars, for a Fancy Motorcycle Shop. I visited him about 15 years later when he had to move. He said "Here, this is Yours", he had made a fancy high back Chair with the left over short pieces. Sometimes, you just can't say No!!

Neil

 

thanks Neil, I'll give it a go with what I have then and see what it does. I'll report back with the results.

little diversion first to make a stand for my anvil that I'd been meaning to get round to.

Cut a length off an old oak log I have lying around. Cut one end flat and notched it as my barn floor isn't remotely flat so this should stop it wobbling too badly.

Stacked it on a paving slab and wedged it so the base is flat then 3 bits of 2x4 make a guide for the chainsaw.

Then knock off the remaining bits of bark and finally jet wash it.

Then roll it across the barn to where the anvil is.

However, I can't lift it on my own so it's sitting there for now until a friend comes round. Mind you, have to tidy that section of barn up so it has some space designated for blacksmithing. 

Right then, time to fire up the forge.

It lights up and seems to be happy so I might as well shove a bit of steel in.

Seems to be getting hot

It's just sitting on a workmate for now, I'll make a better stand at some point once I finalise the forge size.

I grabbed a hammer and started hammering the first bit of hot metal since I was 13 and doing metalwork at school, which is 47 years ago, where the hell did half a century go past so quickly.

After 10 mins I turned the needle valve down. It had been running at 10psi but I turned it down to 2-3 once it was hot and it seemed to be happy heating the metal, although the flame went from full blue to blue and orange. No idea yet what the flame should look like so it's an experiment.

and this was the forge just before I turned it off.

and finally, a bit of pointy metal, which was great fun to make.

The flames in your photos look just fine. As to rebuilding that forge, I would simply add more bricks to raise the floor level.

Good to know and thanks, good idea

Raising the floor level with more bricks sounds like a solid plan for rebuilding the forge

On 3/5/2026 at 5:34 PM, Hefty said:

Hopefully someone like Mikey or AFB will be along shortly to confirm, but in my opinion the greenish primary, and long purple and orange tertiary flame envelop in your photo suggests that your burner is not inducing enough air even when it's outside the forge, so when you put it in, the extra backpressure is slowing that induction even more and you're getting super-rich flames. I can't see from the photo: what sort of adjustment is there for air intake, or gas orifice distance from the mixing tube? You need a larger air intake area, or a bigger distance between the gas orifice and the beginning of the mixing tube so that the speed of the gas stream has space to entrain more air.

Totally correct.