Ben Hegwer
can someone tell me the best way to apply forced air to my forge ? Do I add air into my propane line or run air into my forge body itself?
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bigphotog
This is something I’d like some input on too...
the way I was taught when I was a teen was on a traditional coal forge. For health reasons and not wanting to piss off my  neighbors  I’m going gas.

I don’t know on a gas forge but I don’t think you would ad air to the fuel side but after.
I do silver braising/solder and I use regulated compress air and mapp gas through a modified micro tourch.
I do this because  oxy acetylene is to hi of a heat source for what I do. But you have to use reguators a manifold and what is a blow-back/anti spark check valve on both sources.
The air source has to be constant w/o oil or moisture. so taking it directly from a shop compressor is down right a big no no!
also once you use the lines/ regulator for air never use them for O2!!!! 
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Mike Westbrook
You add air to the burner body so instead of it being naturally aspirated it's forced air use large tube leading up to the Venturi and then the propane is injected right before it tapers into the burn tube another and more useful forced air design is a ribbon burner I played with forced air Venturi burners and found they use excess gas make more noise and are harder to tune for not alot of extra  output problem is blowing hot expanding gas into a small box requires an equal exhaust to prevent burner back pressure so most of the heat is blown out the back and front I found it better to use multiple naturally aspirated burners running very gently with a sealed forge that has a small exhaust my three burner is a recycled 30 lb cylinder lined with brick and wool and only has a 1*2 inch exhaust then i have a very large single bottom fired burner into a pile of bricks on a table I use this one for odd shapes just restack the brick to fit the peice neither forge runs higher than 5 psi and a very quiet 
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Ben Hegwer
Thanks Mike for the feedback. I give that a try. Thanks Again Ben Hegwer
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Ben Hegwer
Thanks for the comment. Ben
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Mike Westbrook
No problem any questions just ask I made a lot of failed burners before I figured out the ratios luckily we have a full plumbing selection at work to experiment with but it honestly took around 10 tries or so till I was happy the trick is to get the flame to form just outside the nozzle in the forge chamber so the burner doesn't get cherry hot this is my triple  Click image for larger version - Name: IMG_20180906_224304972.jpg, Views: 5, Size: 154.51 KB
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Ben Hegwer
Is it possible to get a photo of your set up ?
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Ben Hegwer
Soon should have look farther down the page
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Mike Westbrook
There's a few picks under my profile of some of home built junk 😉 like I said feel free to ask questions if you get in a spot 
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bigphotog
Thanks Mike, I built my forge so I could easily make changes so I think I’ll try multiple burners and see how it goes. I got building the burner down...the first  one I made worked great and didn’t bow up. So  I’ll just make more the same way.
if it works don’t fix it😎
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Mike Westbrook
Yep I like to use mig tips for the Jets so you can easily change them out I honestly use the big under fired one the most it's fast and I generally only work small areas maybe 6-8 inches at a time 
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bigphotog
I did use a mig tip. Makes  sense as it allows changing the tips to fine tune. I looked at a lot of designs on the web to come up with my configuration...and the dam thing worked the first time...I’ll take luck any time if it works😆
The end still gets red so I’ll fine tune it so it works likes yours.
Also do you use a regulator for each burner or a manifold with a valve for each burner?
Thanks for your input. 

Dave. 
E5E09640-9B57-4EDE-A75A-25F2A5234EDF.jpeg‘‘This is my latest version. I made it so it’s semi mobile so I can move it outside where I have better airflow. The top bricks are secured by adj brackets that allow me to add and change the bricks. Also the top bricks are compost with the bottom section the softer but more reflective brick mortared with a high temp mortar used in blast furnace construction to a denser harder fire bricks.
ive then bored a hole 🕳 to insert the burner through. So to add a second burner I just bore another hole into the next brick.it’s still a work in progress...
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Ben Hegwer
Thanks Mike and everyone for your input. I can’t seem to get my forge hot enough to make  Damascus.
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Mike Westbrook
Welding in gas isn't impossible but it's not easy either I usually go to coal if I need to weld get some wool for at least the top half of the forge chamber the bricks just don't reflect well and try two layers of brick staggered run it in the dark and look for heat loss I lined my three burner with 2 inches of wool and it reflects so well you can touch the outside metal after hours of use the stuffs not cheap but Amazon sells it just be careful handling it and get a coating and stiffening spray for inside and cure it the wool contains silica and so does many soft refractory bricks not good for lungs 
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jmccustomknives
I weld in gas, a well designed gas forge is plenty hot to forge weld.  I've even red shorted some high carbon billets in mine.  My gas forges, I have two a single and a double burner are both Venturi style.  For knives there isn't a substitute.   The gas forges are faster, less work to operate and in the end more efficient in a work environment.  The advantage of the coal forge, and the only time I ever use mine, is working with true wrought iron and welding said wrought.  The wrought really likes a lot of heat.

Rule #10;  "I can make that" translates to; "I'm to cheap to buy it new."

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Ben Hegwer
Thanks for the info. Just need to figure mine out I guess.
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