Matt Bower

Well, the electrodes you mentioned aren't going to harden. But it's an interesting experiment, and if you put blade steel in the middle you might be onto something.

Anvil appearance isn't too important. Too late now that you've done all that cutting and stacking, but you don't need a terribly wide face for a bladesmithing anvil. Maximizing the mass under the hammer (sectional density, really) is the biggest thing. I'd probably have stood that 2" plate on end with the longest axis running vertically, and had at it. Mild steel will do; you can always resurface it.

There are ways to improvise a horn. I wouldn't sweat it too much. I've had some luck using pipe locked down in my leg vise, with a piece of square stock through the pipe and resting across the tops of the jaws.

So you're just running beads of different electrodes, then forging them down and running additional beads? That could be interesting. Are you planning to use this in san mai style construction (in which case you'll still need to forge weld), or are you using hardfacing electrode? Most common electrodes aren't hardenable.

UPDATE: Wait. I guess if you were to start with a core of some hardenable steel, and proceed as you've been doing, you might end up with a sort of built-up, "arc-pattern-welded" san mai billet. Sorta. Is that what you have in mind?

JV,

Most (all?) stainless steels that are capable of hardening will air harden. That's why differential heat treating methods like edge quenching generally (always?) won't work with stainless steels like 440C. The part of the blade that isn't submerged in the quenchant will harden anyway.

David, I've been picturing a tool like that for a long time, specifically for the purpose of putting fullers in blades, but I've never gotten around to building it. Nice to know that it can work!

DJ's pretty much got it right. New pennies (post-1982) are 97.5% zinc with 2.5% thin copper cladding. You can melt them on a stove top pretty easily. And aluminum cans are, er, aluminum alloys, not tin. Some food cans are still tin plated steel, but it's a teeny, tiny little bit of tin; you'd need a lot of cans to recover any meaningful amount of tin from them.

That's not to say that you couldn't make bronze from pre-1983 pennies (or scrap copper wire, or scrap copper plumbing pipe, or whatever) and a tin source.* You could. But by the time you got done hassling with it you'd probably be better off just buying bronze, either as scrap or new.

*Some of the lead-free solders are nearly pure tin, and you can buy tin ingots. But scrap tin in meaningful amounts and anything like a pure form won't be terribly easy to find. Or at least I haven't figured out a good source for the stuff yet. In most of its common uses it's pretty heavily alloyed with other metals.

You'd be horrified at the stuff I've managed to cut with a 4.5" angle grinder. You do what you gotta do.

In answer to the earlier question about whether I found that fork steel was 4140, I don't recall narrowing it down to a specific alloy; I just found references to heat treated, medium or high carbon steel.

Uddeholm -- like most steel producers, if I understand correctly -- is more than willing to do runs of custom alloys. That may be why you haven't found a "standard" chemistry that matches your analysis.

Be careful about making the interior too narrow. It may sound good in theory -- less space to heat means less fuel cost -- but it can cause back pressure, and naturally aspirated burners really don't like back pressure very much. Also, I always make the interior more or less round. I think it helps distribute the heat better and, again, reduce back pressure.

The more insulation you can pack in, the better. Better insulation means better efficiency. I second Doug's recommendation of at least two layers. A castable hotface is a good idea, but don't get too carried away with it. It's a heat sink, and if your forging sessions tend to be short you'll end up wasting a lot of propane (and $) just heating up the castable. (It's less of a concern if you tend to forge all day.)

Steve,

Just for the record, I think if you want to use a refractory crucible to make crucible steel -- which shouldn't require any handling while the metal is molten -- it'll probably work fine. (I don't know how long it'll hold up, but there's no harm in trying.)

Be sure to form the depression in your crucible before you fire it. It'll be easier to form and it'll fire faster, too.

I have a 50 pound bag of Edgar's Plastic Kaolin -- extremely high-firing china clay -- that I've been considering using to make one of those furnaces in the "new way to make steel" thread. But I've also been considering digging some clay out of the bank of the local creek. It's really all a question of time.

Wow. You know I only became aware of you guys very recently, in the interview thread, and your work has very quickly become some of my favorite stuff here on the board. Congratulations! Keep up the great work. I really look forward to watching the video tonight, when I get out from behind the web filter.

Grainger sells Parker furnace cement rated for 3000 F; I bought 10 quarts as they are discontinuing this item and the price was right. One arrived exposed to air and hardened...I was wondering if i could drill out the center and use the result as a poor man's crucible?

I know some backyard casting folks who've had some success making crucibles out of castable refractory. But molten metal is very dangerous stuff, and your mileage may vary. I'd suggest you fire it to at least 2000 degrees F for a couple hours (the hotter the better) before you try to use it. Castable refractories consist of, essentially, ceramics plus binders. At high temperatures the ceramics sinter together; in the end, that sintered ceramic bond is what holds the refractory together. But when it's first poured the green strength is provided by the binder, which uses a hydraulic or chemical bond, or something along those lines. Those bonds will break down before the ceramic sinters. So there's a point in the life of a castable refractory where the binder has ceased to hold everything together, but the ceramic bonds have not yet formed. At that point it'll be pretty weak, and handling it probably isn't a good idea -- especially if it's full of molten metal. So you'd want to get the thing pretty well sintered before you started using it as a crucible.

Not if he makes it himself. I mean, who can't burn wood?

I started with homemade charcoal, and there's a definite opportunity cost. Time is money, and I found myself spending a lot of time hunting down, collecting and transporting wood, preparing it for charring (it works much better if it's all about the same size), and then charring it. That's OK if you have a lot more time than cash, or if you have a convenient source of lots of free wood that keeps the total opportunity cost down. But making it yourself doesn't necessarily make it free. Just my $0.02.

Thanks, Jesus. That makes absolutely perfect sense. How do you keep those flux layers from forming inclusions? Do they just get extruded from the steel during the repeated welding and forging cycles, like much of the slag in wrought iron?

Please forgive a probably dumb question from a guy with almost no forge welding experience. I've seen a number of online tamahagane demonstrations and all of them -- including this one -- contain one aspect that I don't really understand: the iron/steel chunks are covered in scale after the initial smelting/forging process, and that scale doesn't seem to be cleaned off before they're welded up into a billet. Yet apparently they still weld. How does that work? I've always read that cleanliness is really important in forge welding. I realize that the flux in the billet will help remove the oxide layer, and the clay coating (if present) will help prevent further oxidation. Even so, this all seems to fly in the face of everything I've read. Can someone enlighten me here?

What about using a bona-fide voltage transformer like a Variac unit? Would this cause damage to an AC motor?

To my understanding, yes -- again, if it's an induction motor.

I believe the difference is in the type of motor. Universal motors can handle variable speed devices. Induction motors can't. That's why machinery built with induction motors often relies on pulley systems or the like to achieve different speeds. (Multi-speed induction motors do exisit, but AFAIK they're not infinitely variable. They're built with a different internal circuit for each speed -- basically multiple motors in one housing.) I'm sure Delta chose an appropriate motor for your machine.

James beat me to it, but I second the recommendation for old fire extinguishers (the acid type) -- if you happen to find one cheap. But a keg should work just as well.

y'know, you could just cut the track to about 1-1.5' long and with a bit of fun with a plasma cutter and a angle grinder have a traditional anvil with horn an all,

then just fab up a tree stump or stand, put about 5 speaker magnets on the side of the track, wrap it in chain. and off you go.

The problem with converting a piece of RR track to look like an anvil, as you're suggesting, is that it only looks like an anvil. That approach puts very little mass under the hammer, which makes it an extremely inefficient design. Anderson's approach, although more work up-front, would have made for a far more efficient anvil and saved him a tremendous amount of hammering over the years.

Anderson, I'm jealous. I've been looking for a fork like that at a reasonable price for quite a while. Based on my recollections of some research I did a while back, they're good steel. Probably hardenable, if you can find a way to quench the thing fast enough. That'll make a nice, very efficient anvil for you.

Do you mean "hardwood" (as in the opposite of coniferous), or "hard wood" (as in physically hard)? Hickory, white oak and white ash are all pretty hard, as domestic woods go, but generally they're not especially pretty. Osage orange (bois d'arc/bodark/hedge apple) is a big favorite of mine; it's hard, very dense, very strong, and very resistant to bugs and decay. I also like the color and grain, though some may not. But I don't know if it's made its way all the way up to Maine.

Ah, I'm an idiot! I somehow completely missed that you were sealing the entire blade in clay after you added the carburizing mix. (That explains why the thermocouple pic was hard for me to interpret.) I thought you were just adding the carburizing mix to the edges and sticking the blade in the forge, unsealed. I had a couple questions about how that was going to work.

It all makes sense now. Looking forward to seeing how it turns out. Thanks!

How exactly are you planning to proceed? How long do you intend to heat the blade, and how hot? Are you going to do it in the forge?

I've done a carburizing experiment with mild steel, charcoal, bone meal and washing soda, but I sealed it all up in a vessel and left the whole mess in a large, hot fire for about twelve hours. It worked reasonably well. The idea of differential carburizing has occurred to me, but I'd be inclined to try the sealed container approach and use a sort of resist to prevent carburizing the parts of the blade that I wanted to keep soft. t

Matt,

Can you return the burner to your original settings that worked on the previous installation. Then you might be able to turn down the volume of the LP (some type of shut off valve?) not just the pressure, until the fire gets smaller. Then adjust from there, maybe.

 

If you're looking through two open doors, eyeballing the heat may be different than you're used to. Don't know if your burner position is ideal, but I'd watch if debris doesn't affect the incoming flame. I think the Reil site says that your 14 sq in of door opening is enough, so maybe it's not back pressure.

 

Just some thoughts, good luck, Craig

Thanks Craig. Burner settings are easy to adjust; that's no problem. I have a needle valve downstream of the regulator, and that's something I didn't really try playing with (I typically just keep it wide open and adjust fuel flow by varying pressure), so maybe I'll give it a shot. I'll check on flame obstructions, too.

oops

Thanks, Doug. I didn't install the burner on a tangent because a lot of folks don't really seem to think that's necessary, and the vertical design should largely even out the hot spots. However, I do wonder if that decision may be contributing to a back pressure problem. From reading Ron Reil's site, it sounds like back pressure is likely my problem. My T-Rex is a lot more sensitive to back pressure than the blown burner that Don uses, and the doors on this forge are pretty small. So I'm wondering whether adjusting the angle of the burner port would help at all (fortunately I left myself some room to fiddle with that, if necessary) or whether I need to find a way to open up the ports a little more. (Of course I could just switch to a blown burner, too.)

I know that a slightly carburizing flame is a good thing, but this was ridiculous. The forge wasn't even getting hot like it should have. It was just way, way too rich.

I just finished a vertical forge along the lines of Don's, shown elsewhere on this site -- with a couple differences. Last night I fired it for the first time, and I got good-sized tongues of blue dragon's breath coming out the doors of the forge, which suggested to me that the forge was running rich. I played with the burner for a good twenty minutes to half an hour, and I could not tune the problem away. By that point it was very late, so I shut down and went to bed.

What could be causing the problem and, more importantly, how can I fix it?

I mentioned that my forge is slightly different from Don's, so let me elaborate a little in case those differences are important.

1. I think it's slightly shorter than Don's design, overall. I used a 5 gallon bucket as a shell, in order to double the insulation while keeping the same internal diameter as Don's design. The burner comes in at the very bottom (see below), and the doors are probably about 10" above that level.
   
2. As of right now, the burner comes in right at floor level, not elevated off the floor as in Don's example. That was really an oversight on my part, but it is correctable if it's important.
   
3. I'm using a T-Rex burner, for now. I can switch to a blown burner if it proves necessary.
   
4. My doors are a little larger than Don's -- about 2"x3.5".
   

There are a couple other small differences, but I can't see how they could possibly matter for present purposes.

The obvious first suspect would be the tuning of my T-Rex burner, but I don't think that's the problem. First, I ran it in another forge just prior to putting it in the vertical, and there were no problems. Second, as I said, I played with the tuning (fuel pressure -- from near 0 to well over 20 PSI -- air/fuel ratio and even the location of the propane jet) quite a bit in an effort to fix the problem, and none of that really seemed to affect it.