gas forge ?

[leroyk]

high guys: i am building a gas forge for welding damacsus billets. It is about 9 in high and square and about 18 in long. It has an angle iron frame. I will hold it together with threaded rod. My? is this, will expansion of the bricks be a
problem? Maybe i should spring load the rods holding it together. I will appericate and info you can give me. Thianks, Leroyk

[Grant]

Good Morning Leroy

I do not believe brick expansion will be a problem. Take a look at this site gasforge | iron | iron-to-live-with

-grant

[Frosty]

What you can do is drill matching holes through the brick for the lid and string them on rods that hang from the frame. That way you can leave a little room for thermal expansion.

The walls and floor can just have a little space to move.

Frosty

[Grant]

Frosty

It is good you jumped in here and corrected me.

Also, did you work out the cross for your "T" burners. I read in an earlier post where you thought you would try the cross for the four burners in your variable volume forge. I beleve it allowed you to drill the jet holding port without a lathe and allowed jet to be moved further out of the burner tube intake junction. However I see from your pictures that you are using the the T.

tks grant

[Frosty]

Grant:

I'm using the "T" burners. I ended up trimming the mig tips a little to get them tuned for the 3/4" tubes. The jet needed to be proportionally a little farther back from the throat than the 1" burners.

I didn't have much luck using the cross in the 3/4" burners and went back to drilling the "T"s in the lathe. It wouldn't be hard to do with a nice square (drill bit perpendicular to the table) drill press using a jig and measuring carefully.

The VV forge is working well for me, it's now my main shop forge. I'm rethinking using insulating firebrick for the walls though, they're really fragile, even thermal shock is breaking them up. Coating the 3,000f split brick floor with ITC-100 makes them come to heat almost as fast as the sidewalls so I may try hard brick next.

Frosty

[Grant]

Grant:

Coating the 3,000f split brick floor with ITC-100 makes them come to heat almost as fast as the sidewalls so I may try hard brick next.

Frosty, will you replace the full size insulation bricks in the sides and cover with full size 3000F hard brick or use some combination using split brick and the 2,300f insulating castable refractory.

-grant

[Frosty]

I haven't decided yet Grant. No matter what I do I see potential problems so I'll probably try different things till I get something I like. Or at least don't hate.

Backing split brick with castable or rammables is problematical as they don't stick so well and there's the hassle factor of curing and firing the things.

Full 3,000f hard brick will work but even with ITC-100 they're real heat sinks.

I may just cast my own; the local EJ Bartell sells some pretty high end refractories, I just have to catch them when it's in stock. I'd need to make molds and go through the whole curing and firing routine though. Still, it may be better in the long run. I could try casting a high temp hard refractory for the fire contact face and back it with something insulating. IF they'll stick, don't react badly, etc.

I just don't know. What I do know is the soft brick is really vulnerable. I'm being idiotically careful and discover broken brick frequently. I'm surprised the ones in the lid haven't broken up and fallen out by now.

Frosty

[divermike]

Man Frosty, it's too bad we are not closer, I got a buttload of firebrics for free, the hard ones, I 'm using them as edgers for my pond for now!!

[Grant]

I may just cast my own; the local EJ Bartell sells some pretty high end refractories, I just have to catch them when it's in stock. I'd need to make molds and go through the whole curing and firing routine though. Still, it may be better in the long run. I could try casting a high temp hard refractory for the fire contact face and back it with something insulating. IF they'll stick, don't react badly

Frosty, what is the fire contact area? I assumed in your case it was your forge floor (the part the burner was pointed toward) and that it is already protected with the split brick. The complete inner chamber? Also, are you suggesting that one could cast or have cast an insulating brick with one hard protective face?

I see, now that you have pointed the way, an advantage to a forge that can be optimized for volume even with some compromise in efficiency - whether you can change it on the fly or not. These Zoeller forges look like subsections of your forge.

firebrickforge

One could add half bricks (bottom forge) to each inside wall and narrow the area, move the back wall to the end of the 9" bricks and/or add another complete section with an additional burner for length and open the back wall. This is the way I envision your VV Forge working only on the fly.

-grant

[Frosty]

I call anything that gets fire on it directly the fire contact area or zone, basically the inside of the forge chamber. Not just the parts that are getting hit by the burner's primary flame.

The floor of mine is split brick over 2,300f insulating castable. The two didn't stick even a little bit when I poured the castable so I don't have much hope I could make them stick for a free standing app like the sidewalls.

Yes, that's exactly my thought. Use something very high temp and hard like Missou or Pyramid Super AS and mold it simultaneously with an insulating castable. Hopefully if you do it before either has set, they'll bond. At least a little, hopefully enough.

I'd ram the hard inner liner as hard as practical, then score the contact face before pouring the insulating refractory. I'd probably make the hard liner between 1/2-3/4" thick. 3/4" has worked fine for more than a decade in my old pipe forge.

What I built is kind of like what Larry shows, but more like Ralph Sproul's design. We brainstormed the idea some years ago and he started building them then. I only recently had time and space to start building my version.

And yes, you have the idea. You can change the volume and shape of mine while it's running pretty easily. The lid lifts on a scissor jack and once the weight is off the sidewalls you can move them easily. Lower the lid back down and the sidewalls are held in place.

I didn't know how likely it would be to want to change the shape and size of a forge on the fly but it's already come in handy a few times and it's only been operational since last June.

I can set the thing up for two or even three different forge chambers if I want. I COULD go four chambers but it'd be really crowded near the jack handle side.

So far I'm really happy with how it works. Most of the time I don't need a very large forge, 200-300 cu/in is plenty but all to often I need one that's 2 or 3 x that size and all I have to do is mve or pull a sidewall or two and light more burners. Best of all I don't have two or three propane forges laying around in the way, too valuable to get rid of but a trip hazard most of the time. It's sweet, I like it.

Frosty

[Grant]

Frosty

This is as far as my current understanding of these things will let me take this. Thank you for your thoughts. Obviously, update me/us if you have a break through.

grant

P.S. How about Shuttle Tiles?

[Frosty]

To be honest, I've been speculating for the last couple posts myself, though I have some experience to base the guesswork on.

Shuttle tiles have been suggested before and I'd dearly LOVE to get hold of enough to try building a forge. The main problem I see off the top is they're almost pure silica which is extremely vulnerable to caustics like molten borax. They would dissolve faster than Kaowool if hot flux hit it.

I think cost might be a factor too.

Lastly, never underestimate the value of a good question, I've had more new avenues opened for me by questions than all the "good ideas" I've heard. It's why I enjoy teaching the craft so much, I learn more than the student.

Frosty