New forge design

After playing around with home made castable forge body I decided that they suck. Going on the assumption that the Inswool liner was doing all the real work I made a wire basket and lined it with two inches of wool and painted the whole thing inside and out with Satanite. I was right - it works great and holds up better than the castable stuff I used and has a total weight of about 8 or 10 pounds. I can move it around without worring that I'm gonna damage it. I't has an inside diameter of about 8 inches, Outside 12 or thereabouts and is 24 inches long. I ran it up today and melted a pre 1982 penny (mostly copper - melt point 1940 degrees fahrenhiet I think) and could probably get a couple hundred degrees hotter if I wanted to. Only complaint that I have is that it still won't heat the whole chamber to a uniform temperature. Guess I'll have to add a second torch closer to the front to do long blade heat treating. Here is a picture of it: http://home.comcast.net/~greyangel1/AngelStation/pics/newforge.jpg
GA

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I wanted to respond to that number before but didn't have all the facts ready... still don't. :/ Can't find the information I'm looking for, and that's the alloy content of pre 1982 "pennys".
You tell me the alloy content and I'll tell you the melting point. ;)
I don't know where I got it (can't re-find it) but remember it being 99%Cu and 1%Sn. That measly 1% would drop the melting point to about 1900F.
5%Sn would drop it to about 1750F.
(fig 13-13, page 441;)
Nickel's are 75%Cu and 25%Ni. (that one I can find;)
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Looking forward to checking out the picture. :)
Alvin in AZ

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The US mint http://www.usmint.gov/ lists a bunch of penny compositions (on a page they call fun facts, and they try to set a cookie, but show the page anyway if you refuse it). From 1962 to 1982 the composition was 95Cu + 5Zn
US Nickels are 75Cu + 25Ni melting at 2201F (MP from a jewellry book - the mint does not mention melting points...
US Silver coinage (1964 and earlier) (like you'll ever find that outside of coin collections these days) is 90Ag + 10Cu (from jewelry book also)

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Thanks for looking that up, it's a pain for me to get on the internet search engines, I was searching through my books and couldn't find it. (wrote it down, thanks;)
95%Cu and 5%Zn? I was all wet, I thought for sure it was tin (Sn). :/
Anyway 5%Zn (balance Cu) is -a- "red brass"- Red brasses ...percentages and their names- 5%Zn = "gilding metal" 10%Zn = "commercial bronze" <- wierd huh? ;) 15%Zn = "rich-low brass" 20%Zn = "low brass" (page 433, Metallurgy Theory and Practice;)
Salesmen for the actual producers of brasses and bronzes, have swapped the names brass and bronze around so much, they don't mean much anymore. :/ Specifics are needed to know what it is.
Page 432 (MT+P)... My guess is the old pennys melt at 1940F. Isn't that what "GA" said to start with? :/
The alloy has a slushy state tho, between two temperatures, with what looks like a 20(?) degree spread.
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I know-ed that one. ;) (page 447) (except for the melting point which I wrote down, thanks:)
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I know-ed that one also. ;)
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dogs, beer, jerky ...and knives and guns and pickups ;)
Alvin in AZ ps I say-> do yourself a favor, if you're working with metals, get a copy of "Metallurgy Theory and Practice" by Dell K. Allen 1969 :) ISBN: 0-8269-3500-1 pps- Tell you what, get it, only if, GA or Bill H also sez to get it :)

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Best five bucks I ever spent ;-) Right handy book with a lot of good information. Got mine off Amazon from a used book dealer. Had some neurotic students name all over it. Spent five minutes just blacking all of them out ;-)
GA

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Got mine the same way! Was more than 5 but didn't have any writing in it.
-- Bill H. [my "reply to" address is real] www.necka.net Molon Labe!

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of
It was the writing inside I wanted anyway ;-) I was prepared to spend more so I considered it a steal at that rate.
GA

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All I got is hearsay. I was told by somebody who usually knows what they are talking about that pre- 1982 had about 1% zinc and post 1982 about 1% copper over a zinc body. I'm told the old pennies are a more reliable copper specimen than most of what's out there.
You know Alvin, I'm rotten at remembering the chemical designators for all these materials - If you use the whole name now and then I'll get a lot better - I promise! ;-)
GA

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Ok will do, but there are only 2(?) dozen of them that we'll use here. (page 16 and page 18 ;)
I like looking up words etc about their meaning it's looking up words to find out how to spell them, that bugs the heck out of me. Like, work with no pay off.
Something that threw me early on is metallurgy's use of the original name for Niobium Nb, for some reason they prefer Columbium Cb. (it acts like V;)
Alvin in AZ

Looks great, Greyangel. I bet it heats up lots faster than the castable, too.
For comparison, I built a forge 10" ID/14" OD, 24" long (just a little bigger than yours) and I put three burners on it. It was pretty uniform, but it sure chewed up the propane. I think the best setup is to have a big one for when you are doing large items, and a little one for what will fit in it.
You'll probably do ok with two burners.
Steve
Greyangel wrote:
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Just for kicks I made a mini version about 12 inches long and about four inches ID. tried it out on my bench top with a mapp gas burner and It worked ok. Figured I needed something less drastic for the occasional small stuff. I think I'm gonna pack it inside with a bit more wool to reduce the length. Took a while to get hot on the test run and Its still a bit larger than what I had in mind.
GA

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Hey GA,
I have a piece of pipe that is 6" ID and about 24 inches long and was thinking of cutting that length down to about 8 inches and then lining the inside with 1" durablanket. That would give me about 4" ID and 8" long. You mentioned that it took a while for yours to get hot at 12" long. Have you packed the inside your your little one with the extra wool to get your length down from 12". Just wonder how long it needs need to be able to heat quickly and evenly for knifeblades?
Walker

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Haven't played with it again. Been trying to get an even heat source going for a small-sword that needs to be heat treated. What your talking about doing should work ok. If I can get mine hot enough to heat treat smaller stuff then reducing the volume will make it that much easier. Just a note though - I've learned that long and narrow won't get good results. Tends to heat up more near the flame and leaves the farther area cooler. Reduce the length and leave the diameter alone for radiant reflection. Sealing it up as much as practical is a good idea too. My new larger forge is capped at both ends and coated with Satanite with just the torch port and a sqare opening in the working end and it holds the heat pretty well. Still had too much varience from end to end though so since I had the large burner near the back end I tried making a small port hole near the front and just adding the mapp gas torch at that end and it worked pretty well. What threw me was that between the two torches it was impossible to keep the temperature down where I wanted it. Not really a problem but the overall temperature was a bit past the upper phase change and in order to treat my long blade I'm gonna need to just heat it up and quench instead of soaking it at the lower temperature range like I would prefer.
GA

Regarding your comment that you will "have to add a second torch"----
I don't want to get into a heated dialogue about burners, but the type of burner makes all the difference in both ultimate temp. and propane usage. I like the Hans Peot burner, which uses a small fan. Gas forges made with this burner can forge weld mild steel easily in a forge like yours and about 18 inches long. After I get mine up to temp, (5 to 10 minutes, at most), I cut back on the propane pressure quite a bit and back off on the air, too. So, I assume there's plenty of Btu's left to heat the additional 6 inches of your forge. You should be able to find how to build one by going to the www.ABANA.org. Or go to my webpage: http://www.spaco.org/bk.htm and click on the gas forge link. As you will see, the direction of the heat into the forge body is pretty important.
Pete Stanaitis
Greyangel wrote:
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I agree that the burner can make a lot of difference. A friend of mine built a forced air burner. It works pretty well for pushing heat and has a fair adjustability range. I suspect that the forced air style would tend to push the heat around the chamber more, given optimal interior geometry. I've been trying all along to stay with naturally aspirated variety since I don't have the luxury of a dedicated forge space. I'm trying to keep the apperatus to a minimum for easey setup. Had miserable success building my own burner and ended up buying one of Rex Price's burners. I love it and don't see any compelling reasons to use anything else. I don't think I have a problem generating BTUs - just getting a uniform heat over longer blades. With my original forge design, I just poked the burner in one end at an angle and I got more heat in the middle with both ends cooler. Probably had something to do with not having a tight seal on either end. This new forge has the burner opening near the back and poking in at a slight angle toward the front but the ends are well sealed with the exception of the work opening. As I said, it gets cooler toward the front end (away from the burner). I've got my original end result from my burner building experiments that I could push in nearer the front end with a bit more plumbing for the gas hookup.
GA

Forges like this have been around for several years at least, probably longer.
I would be concerned about using something as flexible as wire cloth to support the refractory wool, however, because that wool eventually becomes brittle. Better to have a steel shell to prevent flexing of the wool.

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While it *can* be crushed, what I find is that because it's light weight, it's easier to handle and move around and "be in control" of it while doing so. The whole thing is coated in Satanite and it really is a lot tougher and stablized than I expected when I started. No, it's not indestructable but it doesnt flex at all with normal handling. It was really easy to build, cheap and convenient. I figure if I need to haul it around im my car, I'll build a wooden box for transport. Time will tell but it didn't cost me much in time or money and it's *definately* more durable than the castable that I made first and if this one lasts me a couple of years then I got my use out of it. I figure my next forge project will be 55 gallon drum unit, but I'm tickled silly with this one for now.
GA

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FWIW, The steel ring rolling mill where I used to work had 12 (IIRC) furnaces for heating billets up to 1 X 2 meters to 2300 degrees F. These had a 10-foot X 10-foot X 10-foot heating chamber each.
All of them were open I-beam and angle frames filled in with expanded steel sheet and lined with 330 mm of ceramic wool insulation batts. They seldom had any leakage of hot gases and were seldom damaged, even when hit by our forklift driver who most often drove by ear. Of course, we didn't try to carry them around much. :)
Ceramic wool is pretty strong stuff once supported. Stiffened as GA has noted, it's pretty unlikely to break or crush if handled with reasonable care. Ideally, I'd like to build another forge similarly to the furnaces at my old job, a little tougher frame than GA's, but a whole bunch lighter than the 10-inch well casing my present one is based upon. :)
IIRC, Jay Hayes offers rolled sheet steel tubes in various sizes, which seems like a good compromise. I'm thinking of a two-burner design with burners entering the tube on opposite sides and spread apart about 6-10 inches. Should develop a good swirl with plenty of turbulence to minimize cold spots?

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Mmm, maybe one high and one low and angled from back to front? They should reinforce their current flows that way.
GA

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Holyshit I got just the thing in piled up in the back of my pickup right now! Wierd but true. They are stainless steel water softner sleeves to protect the fiberglass re-enforced "resin cylinder" from light (for two reasons).
Some attract a magnet and some don't.
Call all the water softner outfits in your phone book and ask about them. The ones I have are "throw aways" but were saved by an "insider" for posible water softner use or at least scrap. For some reason they can't or won't sell used ones even tho they clean up nice with ShowerPower or CLR.
There are at least two diameters... I have the larger(?) ones at 10+1/2" and I have two lengths... 44+1/2" and 47+1/2".
I suppose a used commercial soda can (9" in diameter) is too small?
It's got both ends sealed in stainless steel. ;) I use the bottom 2/3's of one for a quench tank. Got it at the scrap yard, cut the top off, then later, after I'd collected enough other non-magnetic stainless, sold it back to 'em. :)
Mine has a real good looking rubber bottom/stand still, most don't, the top was screwed on mine tho.
Can't say, but the top has threaded holes that might be useful on a forge?
A certain scrap yard I go to almost always has a pile of old commercial soda cans. YMMV.
Alvin in AZ