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New forge got some questions and need assurances


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Ok so here is my forge. Started curing the inside today. So first fire up happened today. I believe i have an issue with how the gas is delivered into the airstream. I need to fix that and get the gas closer to the airstream. Ill handle that tonight. 
 

Now i have 2 1” layers of kaowool that have been rigidized and then i put a 1/2” thick layer of kastolite 30 on top of that. I have some metrikote i have to add as well but was waiting until the kastolite is cured. Anyway i only ran the forge for about a minute or two. It got nice and hot on the inside but the outside also got quite hot. Uncomfortable to touch. Ive been reading people saying the outside of their forges dont get hot like that. So im worried about that. Other than those two issues anyone got any constructive criticism on the forge. 
 

i know its larger than most but its what i wanted. 
 

oh and excuse the mess. 

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What is the issue with the gas line?  For blown burners all you need is the 1/4-turn shutoff for safety and the needle valve for control.  Oh, and the regulator at the tank, but still, the gas should just be dumping into the air line with little restriction.  I knew a guy who didn't even use a regulator or shutoff, just a needle valve at the tank and a 1/8" copper line straight into the 2" air line. Not the safest setup, but that's how simple it can be.  

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Just now, Alan Longmire said:

What is the issue with the gas line?  For blown burners all you need is the 1/4-turn shutoff for safety and the needle valve for control.  Oh, and the regulator at the tank, but still, the gas should just be dumping into the air line with little restriction.  I knew a guy who didn't even use a regulator or shutoff, just a needle valve at the tank and a 1/8" copper line straight into the 2" air line. Not the safest setup, but that's how simple it can be.  

So the gas line dumps into that little horizontal chamber before the vertical pipe because i couldnt find the proper T. So i used a nipple and a cap but there is like 4-5 inches the gas has to travel to get to the airstream. 
 

i am getting some stuttering in the flame and i am feeling like it is from turbulence in the gas flow into the airstream because of the distance it has to travel. 
 

question so i have a pressure gauge at the regulator. I hear people talk about running a certain psi of gas. How exactly is that measured? Do i read the pressure gauge at the regulator and then when im opening the needle valve look at how much the pressure drops and thats the pressure im running? If not whats the proper way to measure psi coming from the needle valve?

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Pay no attention to the gauge pressure.  People who talk about running at 7 psi and welding at 20 are using venturi burners which rely on pressurized gas injection to create the gas/air mix.  You are relying on the length of the 2" pipe to mix the gas and air, and you may be right about that nipple with the bell reducer making it a little less than uniform. That's a big space for gas to pool where the air can't entrain it properly.  Try just threading the needle valve directly into the 2" pipe in the same location. That may solve your problem.

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6 minutes ago, Alan Longmire said:

Pay no attention to the gauge pressure.  People who talk about running at 7 psi and welding at 20 are using venturi burners which rely on pressurized gas injection to create the gas/air mix.  You are relying on the length of the 2" pipe to mix the gas and air, and you may be right about that nipple with the bell reducer making it a little less than uniform. That's a big space for gas to pool where the air can't entrain it properly.  Try just threading the needle valve directly into the 2" pipe in the same location. That may solve your problem.

Thank you. Other than that does the forge look alright? Anything i could of done different?

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If your forge hasn't cured completely yet, and from your description it most likely hasn't, you will be driving off moisture from the castable for a while yet.  The steam created will definitely heat up the forge skin and may even interfere with a stable flame.  Unless you want the castable to crack, you need to heat it very gradually.  You might even want to drill a small hole in the bottom of the skin as a "weep" for the steam generated.

 

I would switch the locations of the needle valve and ball valve in your gas train assembly.  Ball valve is for quick emergency shutoff, needle is for metering the gas flow.  Note that the burn will be more stable once the forge gets up to heat and the flame front speed is better established.

 

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3 minutes ago, Dan Hertzson said:

Note that the burn will be more stable once the forge gets up to heat and the flame front speed is better established.

 

My blown forge has always puh, puh, puh'd a minute or two until the forge starts glowing, then it smooths out. It drove me crazy when I first built it, but now I just fire it up and wait for it to get good and hot before I adjust anything.

 

My forge body gets pretty hot too. I don't think it's anything to worry about as long as the heat isn't traveling to your valves.

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What Dan said.  I forgot that's new refractory.  It has to cure a LONG time at low heat.  If you have a mechanic's work light, leave a 40-watt light bulb in there for a few days. That low and slow heat will greatly reduce the cracking and spalling.

 

And don't worry too much about the heat, all forges will get pretty darned hot on the outside.  Since you used rigidizer on the wool, there will be a lot of steam trapped in there between the hard face and the shell.  A couple of little holes will help let that out, again as Dan said.  He's a smart guy! 

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Awesome guys thank you. And yeah i only ran the forge for about a minute just to heat everything up. Definitely dont want anything to crack. I will drill some small weep holes didnt even think about that. This forum is great. I will update again after the changes are made. 

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Forget the gas diffuser!  Just follow the instructions in the attachments on the Forge Supplies page of my web-site.

That is the way I did it 10 years ago and it has worked perfectly ever since.

 

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3 minutes ago, Wayne Coe said:

Forget the gas diffuser!  Just follow the instructions in the attachments on the Forge Supplies page of my web-site.

That is the way I did it 10 years ago and it has worked perfectly ever since.

 

Hey Wayne so your site is where I took a lot of the stuff that I did from. But towards the bottom reading of the comments it talks about a gas diffuser so I figured I’d add it I can always take it out if it’ll be detrimental but you tell me is it something that is good to have or does it not matter

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I'm sorry Jon,  I just looked over the attachment that John wrote.  I had added some notes from my early research.  If it was not in a PDF and a problem to remove I would delete all of the notes beyond John's original article.  I used his original article and then wrote the other Ribbon Burner attachment.  I kept it as simple as possible and still get the desired results.  I will soon try to delete the extraneous text.

 

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1 hour ago, Wayne Coe said:

I'm sorry Jon,  I just looked over the attachment that John wrote.  I had added some notes from my early research.  If it was not in a PDF and a problem to remove I would delete all of the notes beyond John's original article.  I used his original article and then wrote the other Ribbon Burner attachment.  I kept it as simple as possible and still get the desired results.  I will soon try to delete the extraneous text.

 

No need to apologize man. I appreciate you getting back with me. I will remove the diffuser then. Will report back when i install the new coupling. 

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Small update the union with the street elbow solved the issue. Nice and steady burn now. Tonight was the 3rd heat. I drilled  some small weep holes in the bottom of the forge and let her run for about 5 minutes floor of the forge was a dull red shut of forge could see steam escaping. Gonna let it cool and check for cracks and such tomorrow morning. 

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yet another update here. Fired it up again to get it hotter this morning. The one thing i didnt do that i now feel like i should of done is put an opening in the rear of the forge. Once i turn up the air and the gas it starts to sound like a jet engine and as shown by the picture the rear of the forge doesnt heat evenly with rest of the forge. 
 

not sure how i can put an opening in it now that the castable has cured. But my flame is stable and she gets hot quick! 

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Yeah, you need a back door.  A hole saw with get through the shell, but you will make a ragged hole through the castable.  Just patch it with more!

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41 minutes ago, Alan Longmire said:

Yeah, you need a back door.  A hole saw with get through the shell, but you will make a ragged hole through the castable.  Just patch it with more!

Ok i will drill a hole with a hole saw then. The thing starts to sound almost like a pulse jet engine when you really crank it up. 

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"My forge doesn't get hot on the outside when its running."  I also read that comment years back when I was researching building my own forge.  Made me think the same thing that I've got bad wool, but I do have the wrong hard refractory in it.  However it has served it's purpose and protected that soft wool.  My venturi gas forge was made from a large diameter pipe with no doors accept hard fire bricks.  When it runs, the outside shell gets hot, hot enough that I would not dare touch it.  However it does cool off pretty quick.

 

The bricks however, they were a quick easy purchase that I learned to regret. 

 

 

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Alrighty hole is drilled takes care of the pulse jet engine sound. But a new problem came up. I dont think this blower is sufficient. I purchased the green amazon blower that Wayne links to on his site. With gate valve all the way open i can only open my needle valve about a 1/4 of a turn. 
 

The way i understand it is the proper settings will not produce “dragons breath”. So granted im still learning heat levels in steel and comparing to a color chart i think its in the 2200-2300 degrees. Maybe less. Granted its super thin but i threw a piece of band saw blade in there while it was running. It got to that orange-gy yellow but more yellow than orange color quick but just kind of stayed there. I know my burner is 8”x3” instead of the 6”x3” thats shown on waynes sites also my burner has 29 holes in it which is not a whole bunch more than a 6”. 
 

i want to be able to reach welding temp obviously and ive read thats described as a brilliant yellow almost white and the steel will like smoke when pulled out of the forge and also spark. So is this an issue with my blower not providing enough pressure? If so what are some other options for blowers that are not super expensive. I saw one the other day that was $800 thats way to much.  

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Well, if your steel sparks then you managed to get it too hot lol.  Colors look differently to each person and can vary greatly depending on the ambient lighting.  If you want to know exactly how hot your forge is getting I would spend the $80-$100 and put together a thermocouple/PID setup.  There's a couple of threads on doing it in the Tools and Tool making subforum.  Otherwise, try taking some plain old laundry borax and put it on top of a piece of steel.  Stick it in the forge and see if you can get the borax hot enough to liquefy and come to a rigorous boil.  The boiling happens right around the welding temperature for common simple steels and can be a good indicator that your welds are ready to set when forge welding.

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19 minutes ago, Alex Middleton said:

Well, if your steel sparks then you managed to get it too hot lol.  Colors look differently to each person and can vary greatly depending on the ambient lighting.  If you want to know exactly how hot your forge is getting I would spend the $80-$100 and put together a thermocouple/PID setup.  There's a couple of threads on doing it in the Tools and Tool making subforum.  Otherwise, try taking some plain old laundry borax and put it on top of a piece of steel.  Stick it in the forge and see if you can get the borax hot enough to liquefy and come to a rigorous boil.  The boiling happens right around the welding temperature for common simple steels and can be a good indicator that your welds are ready to set when forge welding.


yeah i want to do a thermocouple setup for sure. I will look for the threads. Thank you for that. I know colors looks different to everyone so it makes it difficult for sure. I will try the borax i have plenty of it on hand. I still need to put the metrikote on. Thats gonna happen tonight maybe. I can get 4.5x8x1 firebricks for free, they are the heavy ones not the super light fragile ones, so i figured since they are free i will use them as a floor in my forge just need to level the forge floor out a bit more. So the metrikote may wait until after i do that. 

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Do not use those bricks as a forge floor.  They are just heat sinks that will make your forge take up to an hour longer to hit welding heat than it should.  The Kast-o-lite is more than flux-resistant enough.  The Metrikote will give you another couple hundred degrees of reflected IR.  You can use the bricks as doors, they work well for that. Just consider them a consumable, they'll eventually crumble.  

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1 minute ago, Alan Longmire said:

Do not use those bricks as a forge floor.  They are just heat sinks that will make your forge take up to an hour longer to hit welding heat than it should.  The Kast-o-lite is more than flux-resistant enough.  The Metrikote will give you another couple hundred degrees of reflected IR.  You can use the bricks as doors, they work well for that. Just consider them a consumable, they'll eventually crumble.  

Ok fair enough i will not use them as a floor thank you. Good info to know. I think i remember reading that somewhere else. Is it the soft bricks that are super brittle that dont act like heat sinks? 

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