MattBower

Maybe. Some folks have made decent looking tongs out of rebar. But it's unpredictable stuff. Sometimes it'll break with little or no warning, particularly if you've quenched it from above critical. (Yes, some rebar will harden.)

Yeah, Ken's a very good photographer, Makes me feel slightly ashamed of the terrible pics I take. :angry:

Some steels are so high in alloys that it's difficult to grow the grain. That's true. (S1 has quite a bit of chromium and a bunch of tungsten, for example, both of which inhibit grain growth.) But in line with what you're saying, Thomas, those tend to be steels that most of us lack the capacity to HT properly, anyway. (E.g., the recommended hardening procedure for S1 is, "Heat slowly. Preheat at 650 C (1200 F). Austenitize at 900 to 955 C (1650 to 1750 F), hold for 15 to 45 min, then quench in oil.)

An excellent demonstration by a couple Internet buddies of mine: http://paleoplanet69529.yuku.com/topic/47099/Normalization-Grain-Size-Control-Experiment-----normalize

I wanted a propane burner to fire a very small casting furnace or forge -- something with more "oomph" potential than the handheld propane torches, but smaller than the typical 3/4" Reil/Porter/Price style induction burners. So I scaled one down. I started with a version of something called the mako burner from another forum, but ended up with a scaled down version of one of the burners from Michael Porter's book. Although "measure twice, cut once" is always excellent advice, I didn't heed it in this case and ended up paying for it in the end. It's running OK now, but it still needs tweaking. So far, it's gone like so. 1/8" brass pipe nipple. Length of 1/4" OD copper tube. 0.030" MIG tip. The MIG tip was brazed shut. The tube was chucked up in a hand drill and polished with 150 grit abrasive. Unfortunately the chuck crushed the end of the tube, which required cutting it shorter than I originally planned (seen later). I should've started over with a longer piece of tube, but I got in a hurry -- to my later regret. Tube soft soldered into the pipe nipple (then pickled with ferric chloride, which is why the solder looks dark). Tube trimmed. And since the pipe nipple was a leftover from an earlier burner, the small hole in the side was soldered shut. Tube ID reamed to 7/32", then tapped 1/4-28. MIG tip and tube end pickled in ferric, fluxed, threaded together and soft soldered. Checking out how far the orifice will protrude into the burner tube. Starting to come together. The burner tube is 1/4" NPT, joined to the orifice assembly with a 1/8"x1/4" coupler. Orifice drilled with a #75 drill in a pin vise. (My drill press routinely breaks tiny drills.) That took a little while. I don't have any more WIP photos, but I will describe the rest of the process. The next step was to cut "gill slits" (air intakes) into the burner tube. Since I wanted to keep the slits as close as possible to the tip of the propane orifice, and the orifice didn't initially end up protruding as far into the burner tube as I had wanted, I cut the slits quite close to one another, as near to the orifice end as I could get them. The consequence was that I could only make two rows of slits, diametrically opposed to one another. Since my burner was going to be much smaller than the original, I tried to get away with cutting the slits with a hacksaw, which proved inadequate: the burner couldn't draw enough air and ran very rich. I later enlarged the slits with the edge of a big mill file, and the discrete slits turned into two larger, rectangular openings, as seen in the video. I also drilled two 3/16" holes near the front of the burner for supplementary air, similar to the original. I now suspect that was unnecessary. During my initial test firing the burner ran stable but very rich. tI wasn't drawing enough air. One of the solutions was to enlarge the air intakes, as described above. But I also suspected that part of the problem was that the orifice wasn't seated far enough into the burner tube, for reasons already mentioned. To fix that, I ended up reaming out the pipe threads on the side of the reducer coupling that the injector assembly (MIG tip, plus copper tube and brass pipe nipple) had formerly threaded into. That allowed me to insert the injector assembly much deeper into the burner, at the cost of simplicity: I could no longer just thread it into the coupling and be done with it. So I ended up inserting the injector assembly into the burner tube as deeply as I could (the non-working end of the burner tube ended up butting up against the end of the 1/8" pipe nipple, which kept the injector from moving beyond a certain depth). That gave me enough extra depth to fix the problem, but I had to resort to JB-welding the injector into the coupler, which cost me adjustability. There's a better way that I could've done that. Prior to the second test run I also chucked up the entire injector assembly in a drill and used files and abrasives to put a nice, rounded taper on my MIG tip. That should let the burner breathe more easily. If you use the TWECO tips that are usually recommended in these sorts of tutorials, they're pre-tapered. The next test firing didn't work very well because I had not quite gotten the orifice axially aligned with the burner tube when I epoxied it in place, and I didn't yet have even a temporary flare; I used an unattached piece of scrap square tubing as a flare, which only kinda worked. Fortunately the copper tube that the orifice is mounted in is reasonably bendable, so a little judicious pressure through the air intake slots got the alignment problem fixed. I also attached a 1/4"x1/2" reducer coupling as a temporary flare for R&D purposes, and I inserted a piece of metal window screen across the opening of the burner tube where it enters that coupling, to serve as a flame holder and hopefully help a little with mixing the propane with intake air. The screen shouldn't be necessary, but I figured it couldn't hurt. Here's the result so far: My apologies for the bad videography, All I have to take video with is a phone, and I shot that at night because it was my first opportunity. I'll get something better when I have a chance.

Yeah, it's working very well for me. Fairly slow going, but I could be babying the drills a little more than necessary. Either way, it works!

This is an excellent WIP. Thanks for taking the time to document it.

That's zinc oxide. Inhaling enough of it is what causes metal fume fever. I'd clean it out. A damp rag will probably do. It makes good sunscreen and diaper cream! Just kidding. (I mean, it is used for those things, but I'm not suggesting you should do that with the stuff in your forge.)

If anyone in the northern NH/southern Maine area is interested, I can tell you where you can probably find a sawyer's anvil similar to this. It's at an antique shop in Wells, Maine, or was as of early August. I didn't bother asking about the price, since I didn't really need a sawyer's anvil and, judging from his prices on other stuff, the proprietor of that shop isn't particularly interested in giving good deals.

That's a fair point, Jeremy, but he did get several answers to his question.

Great resources there, Glenn. Thanks. Woody's Blueprint was especially informative.

That certainly wasn't direct at you, Rich. That's basically how the first warning to the OP was phrased, and I really don't agree with that way of doing things. But there's nothing wrong with telling people they'll probably be much better off if they don't burn zinc. Smoking? You go ahead and take that one. lol

I agree making people aware of dangers. I don't agree with effectively lying to them concerning what we know about the dangers, in order to scare them beyond what the facts support. I have lost friends to car accidents; it does not mean I will tell people that, "IF YOU DRIVE, YOU ARE GOING TO DIE!!" I can find exactly ONE example of a death that may have been caused by burning massive amounts of zinc in an enclosed space (a stupid thing that I would never advise anyone to do, and never have), and that was a man with emphysema, who ended up coming down with double pneumonia. As far as I can tell from what's posted online, that -- pneumonia - is what finally killed him. And frankly, I'm not sure that large amounts of any fine particulate might not have have caused pneumonia in someone which such severely compromised lungs. (I would note that fumes from many other metals can also caused metal fume fever. Zinc is just a particularly common culprit because it's used a lot, and because it has a relatively low boiling point).) The question concerning long-term effects of inhaling zinc oxide is completely legitimate, although it may or may not be relevant that zinc is not like many so-called "heavy metals" in that it is necessary for life and your body does excrete it. (I'm not certain how inhaled zinc oxide relates to ingested metallic zine.) But if we are going to speculate about the possible dangers of long-term zinc exposure, there is no reason we should not also be equally vocal about the possible -- or sometimes even well-established -- long-term dangers of cadmium (more common than you may think, and clearly much more toxic than zinc), flux fumes, various alloying elements in certain steels (manganese, chromium and lead come to mind), ceramic wool fibers from our forges, silica dust from foundry sand (if you cast), clays, and castable refractories, carbon monoxide -- there's just a whole long list of dangers inherent in the things we do. And that's just the respiratory stuff. Cataracts from long-term IR exposure? Sure! It goes on and on and on. Warning people about dangers, and recommending ways to mitigate those dangers -- e.g., by dissolving zinc off the surface of galvanized materials before exposing them to high heat -- is the right thing to do. I absolutely agree with that. But I also think it's downright wrong to in essence lie to people -- adults in particular -- because you've decided it's for their own good. "If you burn galvanized you WILL DIE" is a claim that appears to have almost no support, at least in the short term. One guy may have gotten that result, but thousands upon thousands of others have been exposed to ZnO fumes and NOT gotten that result. In fact we have several of them posting in this thread. That does not mean it's a good idea to burn zinc, especially without taking any precautions. It isn't. But it's a bad idea mostly because it'll make you feel awful for a few days, and because we're not sure what the long term effects may be -- not because it provably *WILL* kill you, no matter what. At least give people enough respect to lay out the known facts, to speculate responsibly about dangers that may not yet be fully understood, and to let them make up their own minds about how much risk they're comfortable with. People who aren't willing to accept any risk should not be involved in blacksmithing. Or life, for that matter.

On the other hand, I've had non-galvanized rebar behave badly under the hammer, too. Maybe that's the problem.

That could be. A metallurgist once told me that it's a bad idea to use molten tin to heat steel for hardening (I was wondering whether it'd work as a substitute for molten salts) because the tin gets into the grain boundaries and causes problems later.

It isn't, or thousands of welders and brass founders would be d-e-a-d. But it'll make you feel like crap, so it's still a very good idea to dissolve the Zn with an acid before you heat any galvanized material

A drywall mud pan might do -- one of the longer ones.

I hadn't really paid much attention to the testing angle on this blade until just now. I'll be shocked if it fails at the ricasso since, as Phil suggested, that's probably the strongest part of the blade -- and the stress is going to be concentrated further down the blade, where it's thinner. Speaking of that, how thick is it? Remember that longer and thinner is more flexible than shorter and thicker. On the question of wanting to test what you like to make, I would add a couple things. First, I think that's fantastic! But, second, you seem to assume that if "what [you] like to make" can't pass the ABS test, that means you're doing something wrong. And that isn't necessarily so. My understanding is that even the ABS does not claim -- anymore, at least -- that a soft-backed, hard-edged blade that can cut a 1" free hanging rope in one swipe, chop twice through a 2x4 and still shave hair, and bend 90 degrees without cracking too badly, is the ideal blade for all purposes. The test is supposed to assess your ability to design and heat treat a blade to perform to a particular standard, not to establish that standard as the universal measure of blade quality. My point is that in the real world nobody is ever going to use one of your knives by locking it in a vise, sticking a cheater bar on the handle, and bending it 90 degrees. So if you do that to one of your blades and it fails, that doesn't necessarily mean it wasn't an ideal blade for the purpose(s) for which it was intended to be used. Depending on the blade, that might be a little like testing 200 mph sports cars by taking them offroading and, when they fail, concluding that they're bad sports cars. Y'know?

I think you're well on your way.

Nice job. You did get a bit lucky on the steel, maybe, but still. I concur on tempering at 400ish a couple times.

That's a good thought, Frosty. Thanks.

Ah, dang, I know what I need! Engraver's pitch.

Something slightly less permanent would definitely be more convenient. I dunno about beeswax. When I get to hogging off material with draw-filing I use plenty of pressure, and the blade gets pretty warm to the touch.

Well then, have fun. Just be extremely safety-conscious when you take it out and test it. Good luck!

I agree with Phil. If you're doing a soft(er)-back draw, why not do it immediately after the oven tempering, before you invest all that time and energy in sanding to high grits?