Building a forge, need some opinions

O

Okie405

Joined
Sep 29, 2017
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I'm about to build a small propane forge. I'm either going to do it out of a 40gal propane tank or a square box with fire bricks. Still have not decided which yet. Building it to heat treat a whole bunch of 1084 I just bought. I've read that 1084 is easily heat treatable for a rookie like myself. Eventually I will start pounding on stuff though :)

1. What do the real knifemakers here use, round forge or square forge?

2. I have decided to go with forced air burners over venturi burners. Should I do a normal flared end or a brick ribbon? I read that the brick ribbon burners use less fuel by running at lower psi and are able to get hotter and are just plain better.

I got good plans already found for both styles of forges. I'm just looking for opinions from you fellas on what you think is better. Thank you.
 
If you're going to use it for HT, I'd recommend a round forge so your gas swirls around the chamber. You'll get a much more even heat than a box. I made one from a 30 lb tank and it works great.
 
KnuckleDownKnives said:
If you're going to use it for HT, I'd recommend a round forge so your gas swirls around the chamber. You'll get a much more even heat than a box. I made one from a 30 lb tank and it works great.
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Thank you Sir. Can you fit longer blades in that 30lb'er? Say like a Bowie knife or a big chopper? Was thinking the 40lb at 30 inches would be better than a 30lb at 23 inches. I already got 2 20's, 2 30's and 1 40 I could use. I know that seems excessive but one can never have too many propane tanks. some for the grill, some for the camper, some for the fish fryer, you get the point. What I don't know is will a single forced air burner with a flared end or a forced air brick ribbon burner be enough to get all of a 40lb'er heated up?
 
Was "I'm about to build a small propane forge..." sarcasm? :eek: I reckon very few of us have forges the size you're describing, though I know some may. (horizontal ones anyway, my vertical is about that size)

Round, vertical forges with a single forced air burner (no flare required) are popular for making damascus because they can reach high temperatures very evenly (and allow a cast floor for flux resistance). When I started down the path of building a bigger, forced air forge I planned for a ribbon burner, and scrapped the idea. While I'm sure they are nice it's not necessary. A blown burner pointing at a tangent to the interior wall gives excellent heat distribution in a round chamber. I did that to upgrade from the square forge I built, and I will never build another square forge. I've used mine, and a Mystic, and there is simply no comparison to a round forced air forge in my opinion.

I don't think you need a forge longer than 20-24" honestly.

If you have a 20" forge with an 8-10" interior and a blown 1 or 1 1/8" burner with a good swirl, and block off the ends to only the openings you need, it will absolutely be enough to heat the entire thing to welding heat, evenly.
 
Scroll down a bit and check out the thread "virtual BBQ building a 2 brick forge" the people that made it build excellent mini forges that people seem to love. They also sell a torch that puts out 30k btu and gets hot enough to forge weld with. So that's the route I would go. Because thats exactly what I'm doing lol just ordered the fire bricks last night
 
kuraki said:
Was "I'm about to build a small propane forge..." sarcasm? :eek: I reckon very few of us have forges the size you're describing,
Click to expand...
What size do most makers use?

valknut said:
Scroll down a bit and check out the thread "virtual BBQ building a 2 brick forge"
Click to expand...
I saw that and thought it might be bit too small for future pounding on metal use. I think it would work just fine for heat treating 1084 though. I should probably decide if I want to go that small just to HT the steel I have now or go a little bigger for future projects

Thank you everyone for your replies. This site and the people on it are outstanding !
 
At my local dump site they let you take the old propane tanks that people drop off for free.
I think they are a nice forge body dimension
 
30" length is a HUGE forge. You're looking at around $12 per hour to run it at welding heat. My little forge runs around $1 per hour and will work for 95% of knives you'll forge. Yes, you'll eventually want something bigger, maybe, but you'll appreciate a smaller, more efficient forge that is quick and portable.
 
Only thing left is to line the forge with the MEECO’S RED DEVIL 611 Refractory Cement. Straight out of the bucket this stuff is like peanut butter with sand in it. I used it like a mortar between all the bricks and it was difficult to work with to say the least. My questions is does anyone have any experience with this stuff in coating the inside of a cylindrical forge? Can I thin it with water? If you don't thin it, how do you go about getting a nice even coat on the inside?

I don't want to mess this part up cause these bricks are not cheap and I don't want to have to order and wait on shipping again, thus delaying my HT'ing even longer.

I went with the smaller forge but instead of a two brick one I did my own 4 brick one. made the hole 4 inches instead of 2. Burner is a venturi style, I got build instructions for off of youtube. It works great, already tested it. It fires like a darn jet engine :)
I Will share pics when I get it all done.
 
I figured out the Refractory Cement from my last post. Got the forge all done now and it is working great except for one small issue. I have some minor cracking but I am going to put some of the steel wire mesh around it like that other atlas forge thread does. Probably should have done that to begin with but honestly I forgot about it. Here are some pictures of me building it from start to finish and it working. I plan to do my first heat treat on my knife and my sons knife this weekend (if we are done with them by them):


























Both me and my son should have a fully completed first knife to share with you all after this coming weekend.
 
Yes, you can thin most mortars with water. Careful though, the bricks will absorb the water and be more likely to crack. They will crack no matter what you do, it's just the nature of them. The cracks may not be visible, but it's an unavoidable result of the modern alumina-based bricks today. The older Babcock/Wilcox process allowed them to chip rather than crack, but they weren't nearly as high quality.

FWIW: I never mortar the bricks together. With the machined surfaces, there just isn't enough heat penetration in the gap to bother with.
 
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