Jump to content
I Forge Iron

Newbie Forge...Maybe well built...maybe not.


Recommended Posts

So a guy I work with asked me about two months ago if I could build a forge. He said that he's always wanted to make his own knives. I told him I'd give it a shot but he had to help with the process. I've always been relatively good with my hands and not bad a building things with just a little idea of what I'm doing.

It's amazing the times we live in when you can look up just about anything online and find a good group of like minded people to help you along when you get stuck. I found this forum a little late in the process, most of the ideas are based on what I found on youtube.

We still have a lot of work to do before a hammer strikes hot metal but we are getting there. The body of the forge is a hydronic heating thermal expansion tank, which we got from work, returned to us for a warranty claim. Over all dims are 16" round by 24" long, I know it seems huge but it was free and is a good heavy gauge steel, thicker walled than a propane tank. Given the size we thought that 3 3/4" pipe burners would give us enough heat, I drew my ideas out before the process of building, there's a few things that we winged a little not fully knowing what we are doing but know where we want to go.

The gas train is 3/8" to 1/4" needle valves and gauges to 1/8" to the mig tips.   A question I have here is why doesn't anyone source offices from the heating industry?

Still need to insulate it, still have a few questions on what and how much we are going to need. I was thinking of 3" of kaowool and lining it with layer of castable after the wool.

The picture below is the tank on a cart I made from some leftover pallet rack that I have.


This one is the concept of the gas train, at the time I was still waiting for the needle valves to arrive.


Gas trains and burners complete, just not securely mounted yet.


At this point I think I have everything welded up and mounted, we chose to use tabs to hold the front door on rather that trying to get a hing to work.


Link to comment
Share on other sites

Welcome aboard Buddha, glad to have you. Yeah, that's going to be a typically new guy WAY too big forge. You can't forge more than about 6" at a time and keeping 20" or so above critical longer than necessary just damages the steel. You don't need a long forge to heat treat, you can move the blade back and forth through the chamber and the pass hole in the back of the forge. Three 3/4" burners are going to eat fuel like a dragster likes  nitro.

However, if you choose to keep it long lose all the gauges. One before the manifold is plenty, I put mine right after the regulator where it's easy to see when I adjust the pressure. Needle valves regulate flow, not pressure so there's no point putting gauges behind them. 

I'd shorten the pipe nipples up as much and lose as many as possible so long as I could keep the hose out of the heat. The hose is a trip hazard but they're incredibly tough, you could probably pull a car out of a ditch with one. The pipe isn't, it's susceptible to bending and the tapered threaded ends are weak points, the threads themselves are stress risers. So the real hazard is someone tripping over or dropping something on the hose. The hose and bottle won't care much if any, the bottle might get knocked over and roll around a bit. If you're unlucky it might even get flipped upside down and start dispensing liquid propane. That's REALLY EXCITING but rarely catastrophic. The real hazard is snapping the pipe nipples, there is a LOT of leverage against them when they're that long. Pretty exciting but shouldn't be a disaster though it'll be expensive to replace.

Don't think I take the above fire lightly, it's not too hard to place tanks and hoses where they're at minimal risk. Just NOT under the forge, that's a code violation almost anywhere!

A good way to reduce the volume of a cylindrical forge chamber is by putting a floor in it. Just cut some Kaowool the length and width you like, peal the edges so they feather nicely making a flat floor up to the walls. Rigidize it all as you lay the layers and plaster the floor in with the rest with a good high alumina, castable, hard, refractory. At this time the current consensus for THE hard refractory to use is "Kast-O-Lite 30 li." It's a 3,000f high alumina castable bubble refractory. The "bubble" part refers to all the little evacuated hollow silica spheres in the mix which adds a level of insulation other hard refractories don't. 

About building too large a forge, join the crowd, I have a closet full of those T shirts, you should see my shop forge. It's a beast that I've thankfully only used two of the four burners about 99.99% of it's life. My most recent forge is still TOO BIG. Arghhhh!

Frosty The Lucky.

Link to comment
Share on other sites

On 3/16/2018 at 11:32 PM, Frosty said:

About building too large a forge, join the crowd, I have a closet full of those T shirts, you should see my shop forge. It's a beast that I've thankfully only used two of the four burners about 99.99% of it's life. My most recent forge is still TOO BIG. Arghhhh!

Your two biggest problems are the large forge interior, and where you positioned your burners; they should have been less than 22%--not 45%. By making the interior heavily "D" shaped, rather than tunnel-shaped with a narrow flat floor. For about twenty bucks you can buy tough highly insulating K26 firebricks. This will allow you to raise up the level of your forge's floor, so that your burner flames don't impinge on the forge wall, and shrink the forge interior. You can include a third layer of Kaowool to further shrink the interior, if needed.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...