"New" Forge Idea

[John Frankl 0]

I say "new" because it is new to me, not because many others out there smarter than I may not have already done this. But I haven't read about it, so I''ll share.

 

I really like the idea of making an ovular or elliptical shaped forge for damascus. More length with less area to heat, while still getting the vortex effect. Most people cut a pipe in two, top to bottom, weld in panels, and go from there. Well, I have to have a pipe rolled and welded, so I am not about to then go cutting it in half. Besides, I'm a pretty bad welder So I came up with an idea for getting the shape without any cutting or welding.

 

I am going to line an 18" pipe with 2" of Kaowool--pretty standard so far. Then I am going to cut two pieces of Kaowool board and slide them down into the forge to make the shape I want. Then I will stuff the empty spaces between the wool and the board with all the old wool trimmings I have been saving from other forge builds. Then Satanite or something similar to cement everything in place, etc. This should give me the shape I want on the inside, while providing a bunch of additional insulation. (For what it's worth, the wool and board are pretty cheap here in Korea, so the extra $$ there are negligible.)

 

Thoughts,

 

John

 

p.s.

 

I have another modification I'm considering.

 

I may try pouring castable right up to the bottom of the door. From there I will use wool. This will eliminate the great majority of flux problems, while also making the portion of the forge that actually needs to be hot come up to temp rather quickly. Of course I realize the castable will suck some of the heat from the wool until the temps between the two equalize, but I still think this may represent a good compromise between an all wool vs. all castable forge. Also, the Koawool board panels on the sides will run the entire height of the forge, making it come up to heat even quicker, but not coming into contact with flux.

[DFogg 9]

Phil Baldwin use to make his forges spherical by casting them around a beach ball. They were quite interesting to see.

 

The eliptical should work fine. Please post pictures when it is finished.

[John Frankl 0]

Here is the shell of my welding forge. The castable (1600 C) is curing in the bottom now. I will try to do a "forge building" thread as I build it as described above.

 

 

The front door is 4" x 4" for larger billets and cannisters. The rear door is deliberately smaller. It is precisely the size of a soft firebrick, with which I will plug it when welding, but still plenty large to pass longer billets through. It also has a large shelf in front for firebricks, preheating, etc.. Finally, you can see the angle/tangent on which the burner will enter.

 

More to come,

 

John

[John Frankl 0]

I've finished the first forge--I am actually building three with slightly different designs for friends, and to see which design works best.

 

Here are some process pics.

 

 

 

This shows the forge body, with channel welded to front door to keep flux off of the wool. Of course it will deteriorate somewhat rapidly, but it is only tack welded on and a lot easier and cheaper to replace than relining a forge. It also makes a great platform for resting work on.

 

 

This shows the unfinished interior of the forge. I used the 1.5" pipe both to cut the exact sized hole in the wool, and to serve as a "mold." It will be removed, but the hole will be "air tight" when my burner is inserted. This, for me, is the key to keeping my burner tube cool, as it keeps flames from searching for oxygen in the burner port. The wet looking stuff on the wool and floor is Kaowool rigidizer. It's a bit less messy than Satanite, and is made for this exact application.

 

More to come,

 

John

[Matt Gregory 6]

I'm a new guy (both on this forum as well as to bladesmithing), and this post could not have come in a more timely fashion! I have plans (and all the stuff required) to assemble a comparable forge... in fact, so comparable it's kind of freakish.

MY forge will be made of a section of schedule 40 stainless steel pipe 18" long and 12" in diameter... I'll be doing 2 layers of 1" ceramic wool with the inner side of each treated with rigidizer, then I'm planning on inserting a 6" diameter piece of PVC and pouring castable around it, giving me an approximately 1" thick layer of refractory cement with a 6" diameter forge atmosphere.

 

I would LOVE to see your progress on this, as it will greatly assist me in my own quest. I'm planning on documenting my progress as well, so I'll be sure to post links as I venture forward.

 

Again, thanks for sharing!

 

Matt

 

PS-My crummy diagram isn't to scale, so please use it as nothing more than a point of reference!

[John Frankl 0]

Glad this is helping someone. I'm away from home for a few days, so additional pictures will have to wait.

 

I can say, however, that I thought about doing what you are planning. One concern I had was with the amount of water that the Kaowool might absorb from the castable, possibly making both less than optimal. I would try to find a way to form the castable separately (cardboard concrete tubes?) and then slide the finished product into place.

 

A second concern is that the wool around the doors will still be exposed to and damaged by flux. You should probably incorporate something into the design to keep the flux off the wool where they are most likely to come into contact. I think the idea of needing castable comes from horizontal forges, in which the entire floor is potentially exposed to flux. In a vertical forge with a castable or other hard bottom, only the area around the doors really takes abuse.

 

Finally, with only a 6" interior, I am wondering if you are planning to use this as a welding forge. If not, you really don't need the weight/durability of castable, and you could easily get away with just one inch of wool.

 

Other than that, I think you have a great idea.

 

John

Edited August 15, 2006 by John Frankl

[Matt Gregory 6]

 

 

Finally, with only a 6" interior, I am wondering if you are planning to use this as a welding forge. If not, you really don't need the weight/durability of castable, and you could easily get away with just one inch of wool.

 

John

 

Not really sure if I'll ever do any forge welding or not, but I hate doing stuff twice. Also, it's in my nature to grossly overcomplicate things!

 

I was hoping the rigidizer would offer enough resistance to the water in the cement mix to keep it from saturating into the Inswool... is this not the case? Your idea about casting the entire thing ahead of time is most likely the right idea... think I'll start looking for 2 pieces of concrete forms that will fit my needs. This way, I'll be able to cast the entire opening for the forge with castable, now that I think of it! Just have to get creative with the construction of the form, I guess.

 

Thanks for the input, and I can't wait to see more of your forge!

[John Frankl 0]

More pictures soon, but I would start with one inch of wool and rigidizer. You will save money in both construction and fuel.

 

John

[John Frankl 0]

Since at least one person seems interested I'll continue with my forge building thread

 

Here is the forge, all insulation done. I am preparing to weld on a work rest.

 

 

 

This next photo is with the work rest welded in place, lid on. The rest may appear cumbersome, but it can easily be removed, leaving only two very short pieces welded to the body of the forge. I find it very, very useful for heavy billets when one does not want to sit in front of a 2,000+ degree forge waiting for steel to come up to temp. The hook is for keeping heavy billets from taking a dive into the forge.

 

 

Finally, a picture of a billet soaking in the forge.

 

 

Thanks for looking, more to come.

 

John

[Greg Thomas Obach 3]

sweet... looks like you got a production line goin on there...

 

very nice forges...

 

did you use only one layer of wool?

 

 

Greg

[Chuck C 0]

very nice work how's it working so far?

[Matt Gregory 6]

Hey John,

How big of a blower are you using with these setups? Obviously you're running them hot for forge welding, but can they be regulated to lower operating temps if you just wanted to use it for normal forging work? I'm guessing that, just like any forced induction system, you'd just cut the gas and air back... but is that a problem with a forge this big?

Also, how are you insulating the top? A layer of Kaowool with ITC-100 or something?

 

Please continue, this is of great interest to me!!!

[John Frankl 0]

Thanks guys.

 

Yes, it is sort of a production line. I was asked to build one for a friend, and we are also thinking of starting a small bladesmithing school here. Also, each has a slightly different internal configuration, and I am trying to see which works best.

 

One layer of wool, yes. But it is 2" HTZ wool. I feel this will hold up better under the constant high temps. OTOH, check Ed Caffrey's forum for some pretty convincing evidence that a single layer of 1" wool is plenty. I've read Randall Graham saying the same thing. I didn't use ITC-100. Never have. I bet it would improve efficiency, but I have never had a problem with getting Don's forge designs hot enough. I usually have problems keeping the temps down, they work so well.

 

The blower I am using is exactly the same one sold by Grant Sarver and Kayne and Sons. These are made over here in Korea--they are cheap here --and I am using the smallest one they make--1.5" opening. It is more than powerful enough. (See the picture below of my burner setup.) I only run this forge hot. I have a separate one for forging. It is essentially the one Don outlines on his site. I find it the perfect size, though it too runs pretty darn hot. I may switch to a T-Rex burner, which I am using now on my Drum Forge (thank again, Don), and is infinitely and easily adjustable.

 

Here is my burner setup.

 

 

It is 1.5" pipe (don't worry, I burned the galvanizing off the part that gets hot). The only differences from the way Don describes building his burner are as follows: No drilling and tapping. I used a T-fitting and a bushing instead; No bell reducer on the business end. I have it embedded half way into the wool lining and find it unecessary. I tried it outside the forge but couldn't keep it sealed so that flames came out and it got too hot. This way works better for me. It also allows me to lock it in place with four bolts. Finally, I like having it all sit on my table, rather than having it suspended somewhere/how. This puts the air and gas controls right in my hands, and keeps them steady.

 

My old forge and burner looked like this.

 

 

As you can see, with the bell reducer I had to jury rig a mounting system, as well as stuff the hole with Kaowool to keep flames from seeking oxygen/heating up my burner tip. I also had the gas and air controls backwards. The blower flap was facing away from me, and the gas was in my left hand. I didn't like either of these, so I reversed them. Finally, my forge was made from a drum. Some people like this, but I find inconvenient because they are way too thin to weld on burner holders, work rests, etc.

 

All in all, my new forge is much better. Evolution is what it's all about.

 

John

[DFogg 9]

I think you will find that packing insulation around the burner tip will only serve to trap the heat at the tip and it will quickly get red hot cause the flame to ignite in the pipe. You need to have air space around the burner tip to keep it cool. Everything looks good to me though.

[John Frankl 0]

Thank you, Don, for this and all the very good information you have been generously providing for the last several years.

 

That makes perfect sense, and it is what I do on my little forging forge and my HT drum forge. But for some reason I get the opposite effect when running a forge at higher temps. When I leave air space around my burner tips, and I am running a reducing atmosphere, I have flames shooting out my burner port in search of oxygen, just like my front and back doors. This is what really gets my burner tip red hot. When I can seal everything off, things stay relatively cool.

 

John

[DFogg 9]

Hi John,

 

If you are getting that much flame out the burner port you need to make an adjustment to the fuel air mix. Probably too much of everything or you don't have your doors big enough and it is choking the fire.

[John Frankl 0]

Thanks, Don. That makes good sense.

 

FWIW, I usually start with my propane at 5 lbs. and my burner wide open. I cut it back to about 4 and half open, but I will play with 3 pounds and see what happens.

 

John

[Doug 0]

John,

 

5lbs should be OK, make the adjustments with the needle valve. You may be getting too much air. It takes time to dial them in, nice looking forge. It's me in my on the road persona.

 

I am at Sierra Fire and Forge in sunny Exeter, CA. What a nice facility, for those of you on the West coast take a look at what they are offering.

 

Don

Edited August 24, 2006 by Doug

[John Frankl 0]

Here is the latest info on/modification to my welding forge.

 

I find it will run very hot on even about 2.5 lbs. of propane. It will also run on fumes (literally, I found this out simply leaving it on with the air choked way back when one of my propane tanks was running out) and still stay in the forging range.

 

I also installed an "air knife" or whatever you want to call it. Like Don's muffin fan, it certainly keeps handles and faces a lot cooler. Mine is a blower for which I had no immediate use. I hooked it up to some 1.5" pipe, U-bolted the pipe to my work table, after squishing the opening to make a more concentrated blast. Works great.

 

 

 

John