Propane Forge Build

johnnyjump

johnnyjump

Well-Known Member
Getting ready to build a new propane forge from an air-tank I recently purchased (see photo). The dimensions are 21" long by 10" wide. According to the online calculator, this yields a volume of 1650 cubic inches.

I plan on using a 1 3/8" Goede Stainless Steel Foundry/Forge Burner, (https://www.amazon.com/dp/B019X6E7L...olid=1DFYE0KTHE6CE&psc=1&ref_=lv_ov_lig_dp_it) I am thinking this will require 2 burners and wondering if anyone would like to comment on my plan so far.

As far as design, I really like the plans I picked up from a man named Reece at his website: https://althoffwoodshop.com/building-a-propane-forge/. Wondering what your thoughts are on this design for knife making. Thanks!
 

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Well, your volume will be significantly reduced with 2" of insulation and refractory. Figure your BTU per cubic inch and shoot for over 450. How many BTU is the burner you linked?
 
Here is a WIP from Ed. Even if you do not build one exactly like it, you can get some good tips going through the WIP. If you use your search function, there are a few more forge builds on KD. Look for the search function in the upper right hand corner.

New Welding Forge WIP

I have repaired ALL the images in this thread! It took a while to find/upload/post them, but everything is back the way it should be.....before Photobucket messed us over! :) Its time to build a new welding forge..... for several years I've been using a KaWool insulated welding forge, mainly...
knifedogs.com
 
Just my opinion, but I would highly recommend building a single, properly sized blower type burner over the venturi model you listed, especially over multiple venturi burners. It will make your life far less frustrating when it comes to using the burners/forge..... you'll spend your time forging versus trying to get multiple burners to work correctly.
 
I will agree with Ed on this one - build a blower type forge and think how easy it is while forging. I looked at the link of the forge build you linked to. I very BIG caution with that forge. The flame is going down directly on the metal billet you're forging and it WILL have hot spots. You'll need to constantly move the metal back 'n forth to help evenly heat. I just finished a forge shown in this thread: https://knifedogs.com/threads/new-forge.50681/

With the burner coming in from side about 1/3 from front, angled back and upward the flame hits the forge hits the wall around 1/3 from rear and around the 1 to 2 O'clock position allowing the flame to circle/swirl inside. In my first test run I had a 12" long rod laying on bottom, and it was an even red/orange color the full length - that's without moving the rod, just laying there.

My first two forges where with venturi burners - they worked good, but nothing like the forced air burner. They don't get as hot and are more finicky to adjust. A forced air burner does require electric to run the blower. I used a $78 shipped blower off Amazon.... Oops, just checked and it's no longer available.

edit: The Ed's forge build that Dennis linked to is a REALLY NICE forge, and designed for somebody who's going to be using it lots every week. Definitely the best forge compared to the forge I built. BUT, for part time use, my forge a much simpler build - and pretty cheap with the free tank.

Have fun.
 
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I will agree that a blown gas forge is superior to a venturi as I have built and used both types. I have not used a ribbon burner forge so I cannot give an informed opinion but I have run into videos on YouTube about building them and they seem to be a lot more involved but how much more involved is going to depend on the equipment that you have and the experience you have in fabrication.

Doug
 
Well, those are all vey helpful ideas and suggestions, I need to do some more research on blower type burners. Any plans you could point me to? Thanks.
 
Blown burners are dirty simple compared to most venturi burners. The biggest thing is using the CORRECT blower. DO NOT use a common "squirrel cage" type blower....those are not designed for any level of back pressure, and will quickly overheat the windings and burn out. You want a blower built specifically for a forge..... the one I use is from Blacksmith's depot: https://www.blacksmithsdepot.com/products/forge-fan-fuel/blowers.html/forge-blower-3.html (on sale right now). I think Ken is using one from Amazon.....https://www.amazon.com/dp/B07C935P3...olid=2248A579TI2AQ&psc=1&ref_=lv_ov_lig_dp_it

The rest is a matter of sizing black iron pipe to fit the forge body you're building. REMEMBER THIS..... you can always turn down a blower that is a bit too large for the application.....but if your burner is too small, and you reach it's upper limit....you're hosed. Only option then is to build/buy a new/larger burner(s).
 
EdCaffreyMS said:
Blown burners are dirty simple compared to most venturi burners. The biggest thing is using the CORRECT blower. DO NOT use a common "squirrel cage" type blower....those are not designed for any level of back pressure, and will quickly overheat the windings and burn out. You want a blower built specifically for a forge..... the one I use is from Blacksmith's depot: https://www.blacksmithsdepot.com/products/forge-fan-fuel/blowers.html/forge-blower-3.html (on sale right now). I think Ken is using one from Amazon.....https://www.amazon.com/dp/B07C935P3...olid=2248A579TI2AQ&psc=1&ref_=lv_ov_lig_dp_it

The rest is a matter of sizing black iron pipe to fit the forge body you're building. REMEMBER THIS..... you can always turn down a blower that is a bit too large for the application.....but if your burner is too small, and you reach it's upper limit....you're hosed. Only option then is to build/buy a new/larger burner(s).
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Hey, I really appreciate all the good information and links. Thanks!
 
Ed's got it right - forced air blowers are easy to build. The two blowers he listed, I think the one from Blacksmith is the best one. The Amazon blower works good, but requires max speed and full open for sufficient air. Note the specs, for $100 you get 125 CFM 260 watt (about 2 amp) motor. For $150 you get 180 CFM and a 370 watt motor (more like 3 amps). Doing over again I might spend the extra $50.
 
Thanks for all the good information. I think I've been persuaded to go with a single blower burner as opposed to two venturi type burners, which leads me to my next question: How many cubic inches will a single blower burner heat sufficiently for forge welding? The air tank I will be using is 21" long by 10" in diameter, with poured castable refractory bringing the inner diameter down to 5", and a volume of 412 Cubic Inches. I am assuming one blower burner will be sufficient to heat this build? On another note, I've been searching for the best price on castable refractory. I've been told I will need approximately two 50# bags of at least 2000 degree castable refractory. Anyone aware of a good, reasonably priced source? With that much weight, shipping could be as much as the cost of the cement. I live in NW Arkansas, and have been looking for refractory supply stores in my area to no avail. Thanks again!
 
johnnyjump said:
I will need approximately two 50# bags of at least 2000 degree castable refractory.
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100# of refractory? What are your plans for this forge? Do expect to be using it several hours per day, everyday of week? OR, like myself for a few hours each week, then perhaps a rest for a while? You might check on using the ceramic fiber blanket like I used. https://www.ebay.com/itm/201588565559 with this stuff you'll need a few lb of refractory to coat the fibers really good. I'd think Kast-O-lite 30 LI Insulating Castable Refractory from the hightemptools link above would be a good source. 20 lb would more than provide a good coat for the ceramic fiber. hightemptools also has the ceramic fiber for insulation http://www.hightemptools.com/inswool.html and a tad better price. Folks say you should use the ITC-100 to "paint" the inside of the forge, 1/4 to 1/2 pint should do it. http://www.hightemptools.com/itcproducts.html

Looks like you could order everything from hightemptools, ceramic fiber (5 ft $36), 20# Kast-o-Lite ($48), and even the ITC-100 (1/4 pint $27) for not much over $100 shipped. pick up an old 30 lb propane tank from local propane distributor (free) and you've got a forge for $100 or so not including the burner.
 
Another thing to consider for refractory cement, Kao-Wool, Fire brick etc... is a local ceramics shop. I didn't realize this till after I bought my Fire brick thru the mail. For 2 of them because of shipping were $27. Bought more and picked them up at local shop for $4.03 each.
 
I don't see why you would need more than about 20# of Kast-0-Lite, 3' of Inswool and a pint of Metrikote.
Again, I suggest that you
Check out the Build a Gas Forge and the Ribbon Burner attachments on the Forge Supplies page at www.WayneCoeArtistBlacksmith.com.
Let me know if I can help you.
 
Hey gang..... before you go off the rails about too much refractory....look at the dimensions...... he's pretty much on point for the amount needed....keeping in mind that castable needs to be A LEAST 3" thick to be/meet it's effective rating. Even if he is a bit over.....its a far better thing to be over by 50lbs then under by 2lbs!! Anything left over, provided it's sealed, will last indefinitely, and....sooner or latter every forge is going to require repairs are relining/replacement......that's just the nature of the beast with forges....they are a "consumable". Personally, I'd be looking for Cast-O-Lite 3000+. A person COULD do all kinds of "hybrid" things, but when it comes down to longevity, a pure castable forge is the way to go.

Once cured out, a light slurry coat of.... https://hybridburners.com/new-ordering.html go down the page to: HYB-UV - Infrared reflective coating ..... it's the best product I've found for reflective forge coating next to ITC100..... at about 1/4 the cost.

Not sure where to direct you in NW Ark.... but when I lived in Blytheville, AR, I would make a run to Memphis,TN, to a refractory supply there. It's not easy to find the stuff just anywhere...... here in Montana, I have to travel at least 3 1/2 hours to get to a store that handles refractory.....and the last forge that I did with Cast-O-Lite 3000...... it all had to be shipping in from Spokane, WA...... at an extra $150 shipping charge!

Sometimes just just gotta bit the bullet and spend the money.....or save it up....then spend it. ;)
 
Hey I appreciate the good suggestions. I think I’m going to use castable refractory cement and pour into a form creating a 5” inner core of refractory cement 5” thick. I’ve used Koawool coated with refractory cement before with mixed results and think I’d like to use this recommended approach this time.
 
EdCaffreyMS said:
Hey gang..... before you go off the rails about too much refractory....look at the dimensions...... he's pretty much on point for the amount needed....keeping in mind that castable needs to be A LEAST 3" thick to be/meet it's effective rating. Even if he is a bit over.....its a far better thing to be over by 50lbs then under by 2lbs!! Anything left over, provided it's sealed, will last indefinitely, and....sooner or latter every forge is going to require repairs are relining/replacement......that's just the nature of the beast with forges....they are a "consumable". Personally, I'd be looking for Cast-O-Lite 3000+. A person COULD do all kinds of "hybrid" things, but when it comes down to longevity, a pure castable forge is the way to go.

Once cured out, a light slurry coat of.... https://hybridburners.com/new-ordering.html go down the page to: HYB-UV - Infrared reflective coating ..... it's the best product I've found for reflective forge coating next to ITC100..... at about 1/4 the cost.

Not sure where to direct you in NW Ark.... but when I lived in Blytheville, AR, I would make a run to Memphis,TN, to a refractory supply there. It's not easy to find the stuff just anywhere...... here in Montana, I have to travel at least 3 1/2 hours to get to a store that handles refractory.....and the last forge that I did with Cast-O-Lite 3000...... it all had to be shipping in from Spokane, WA...... at an extra $150 shipping charge!

Sometimes just just gotta bit the bullet and spend the money.....or save it up....then spend it. ;)
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Thanks Ed! Looks like our paths have crossed a bit. We used to live in Memphis before we retired here in Bella Vista, AR. I’ll have to see what’s available in Memphis.
 
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