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PetrifiedWood
07-05-2011, 05:10 PM
I wanted to try building a little propane forge today so I called around and found a place that sells fire bricks. After chipping at them a while I think they are not actually the soft insulating bricks, but rather the harder fireplace bricks. In any case, I was able to drill a hole in one of them using a 1/2" steel tube with notches cut in the end.

They are soft enough to work with, anyhow. I made a little rig to hold an ordinary propane torch positioned in front of the opening, and stacked the bricks to make a little cave inside. After a good 10 minutes or so there was a glowing orange circle on the inside opposite the hole, but the outside of the brick was not hot to the touch. The rest of the little cave did not heat up, and it didn't look like it was going to.

So here are some pics of the setup. I can't figure out what I'm doing wrong. If you have any suggestions for changes let me know.

http://i1238.photobucket.com/albums/ff485/ThePetrifiedwood/IMG_0379.jpg
http://i1238.photobucket.com/albums/ff485/ThePetrifiedwood/IMG_0380.jpg
http://i1238.photobucket.com/albums/ff485/ThePetrifiedwood/IMG_0381.jpg
http://i1238.photobucket.com/albums/ff485/ThePetrifiedwood/IMG_0382.jpg
http://i1238.photobucket.com/albums/ff485/ThePetrifiedwood/IMG_0383.jpg


The one brick on the side with the hole in it has a slight depression in it. I was originally going to try to make a "2 brick" forge but after chipping and scraping for half an hour I decided it wasn't worth trying to do that with the wrong kind of firebricks. I've never seen the soft kind or the hard kind so it's possible these are the soft firebricks but I'm just not sure.


Would a larger torch hole do the trick? Perhaps putting the torch hole off center instead of right in the middle of the brick?

Rudy Joly
07-05-2011, 05:44 PM
Those are not the soft fire brick.
They look like the fire box liners for a conventional fire place. You're trying to heat up too much mass. I know for a fact that the torch works but those bricks have no reflective properties, they'll just keep absorbing the heat from your flame. Get in touch with Wayne Coe (sub forum), he's got what you need. With two soft bricks hollowed out, that torch will get you started. I used to forge and heat treat with this one.


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Good luck,
Rudy

PetrifiedWood
07-05-2011, 06:05 PM
Thanks. I guess the local brick guy i went to didn't know what he was talking about. :34: At least I'm only out $20 for the ten bricks I bought. And I can probably still find a use for them.

The main reason I wanted to do this is that I've got a heat treat oven on order that will take some time to be manufactured and delivered. I wanted a quick way to heat treat a knife so I can put some handles on it and see how it turns out. :D

Rudy Joly
07-05-2011, 06:16 PM
You could use those bricks as a shell for the soft bricks if you had them.
If you have any ceramic wool, you can make a coffee can forge. In case it crossed your mind....I tried to heat treat with a propane torch years and years ago. Don't waste your time, it won't keep the blade heated evenly, even for an edge quench. I never had any success with it.

Rudy

PetrifiedWood
07-05-2011, 06:25 PM
You could use those bricks as a shell for the soft bricks if you had them.
If you have any ceramic wool, you can make a coffee can forge. In case it crossed your mind....I tried to heat treat with a propane torch years and years ago. Don't waste your time, it won't keep the blade heated evenly, even for an edge quench. I never had any success with it.

Rudy


You mean using the torch to heat the blade directly? I can still use the torch to heat a refractory brick forge though, right?

Rudy Joly
07-05-2011, 06:44 PM
Yes x 2,
Sorry if that was unclear. The whole point is to contain and reflect the heat into your blade evenly. Trying to heat the blade directly with that torch is almost impossible...you're always chasing a cold spot from one end to the other. Maybe Murph will post a pic of his brick set up, I know it's here someplace. Just heating the blade would work with a oxy-acetaline set up though...more heat.

Rudy

PetrifiedWood
07-05-2011, 06:54 PM
Ok, cool. I was a bit worried my torch wasn't going to work for a forge! :D

Any thoughts on the size of hole for the torch flame? And, would the set-up in the pics I posted have worked if I had the right bricks?

Rudy Joly
07-05-2011, 08:50 PM
The hole for the torch can be as tight as possible, the torch head creates it's own venturi action from the holes drilled in the side. That set up should work with the right bricks but I'd try and avoid a square or rectangular chamber so the flame can swirl inside instead of blasting the flat opposing wall. Try using the minimum chamber size required to do the job, use whatever that torch can do to it's maximum. Keep the tip of the torch out of the chamber....they DO MELT.

Rudy

PetrifiedWood
07-06-2011, 12:22 AM
Ok, thanks for the advice!

EdCaffreyMS
07-06-2011, 07:23 AM
I agree with Rudy. This issue here is that your trying to heat way too large a chamber with way too small a burner. A propane torch like that MIGHT be able to get about a 1 1/4" X 3-4" long circular area (like a hole drilled into a soft firebrick) hot enough to forge, but that's about it.

PetrifiedWood
07-06-2011, 03:50 PM
I agree with Rudy. This issue here is that your trying to heat way too large a chamber with way too small a burner. A propane torch like that MIGHT be able to get about a 1 1/4" X 3-4" long circular area (like a hole drilled into a soft firebrick) hot enough to forge, but that's about it.


Thanks for the advice. I looked around town again for the soft refractory fire bricks and apparently they can't be found locally. So, I guess I'll just wait for the kiln to come in. I was trying to get a head start heat treating, but if I have to order soft fire bricks online and wait for them to ship I might as well just wait for the kiln instead of spending more money on bricks and shipping, etc.