Matt Bower

All we need to do is arrange a time on a weekend at the BGOP shop, Chris. Doesn't matter if your membership has expired; mine is still active. And I probably know a couple guys who'd jump at the invite.

One note to add is that recalescence (the opposite effect on the way down) happens at a cooler temperature than recalescence. So you really need to catch it on the way up. If you catch it on the way down the blade is cooler than you want it for quenching.

When I first read this over at IFI, I couldn't quite get it to register for just the reason you mentioned, Alan. Just Friday or Saturday he'd mentioned something in a post that I spent an hour or so this weekend trying to look up. I meant to ask him about it. Grant knew so much about so many things that we'll never really know everything he took with him. There was an update on the NWBA site last night that mentioned it was an aortic aneurysm.

I've tried DIY mixes, and none of them are as easy or as pleasant to work with -- or probably as durable, for that matter -- as the commercial stuff. Portland loses its bonding power at high temps as it dehydrates. The offgassing of steam can cause explosive spalling, although it won't necessarily do so -- e.g., if the Portland content is low and the matrix is porous. Still, beyond a certain point it isn't contributing any bonding power, although it may help flux the surrounding ceramics to get them to sinter at a lower temp. Too much Portland will cause serious fluxing problems and reduce the melting points of your ceramics too far, to the point that your "castable" turns into slag. Commercial castables use bonding agents like calcium aluminate cement, which is much more suitable for high temps. If you don't have something along those lines, you're left with basically just ceramics, which are difficult or impossible to fire properly, through-and-through, in situ. If you don't fire your ceramics properly, they're liable not to be nearly as durable as you'd like. And the sorts of ceramics you'd want to replace a castable would have high pyrometric cone ratings (making them difficult to sinter) and would be very resistant to thermal shock. Most aren't, and a lot of the interesting ones (like mullite) that do resist thermal shock really well tend to form at extremely high temperatures -- so again, you have a problem of how to fire it properly to get what you want. Most common ceramics also contain a lot of silica, which undergoes phase changes at various temperatures, accompanied by sudden volume changes which can cause cracking. (Google "quartz inversion.") Alumina doesn't have that problem -- but once you start looking at high alumina ceramics with minimal silica, you discover they're not all that cheap.

Thanks, Greg. Those are interesting links, and some of those threads contain other interesting links as well. The pic at the top of the last link you provided looks very similar to this knife in terms of overall shape, the shape of the blade, the decorations on the brass, etc.

Thanks for the tip, JD. I sent Mr. Levine an email. And yeah, I noticed that it's pretty navaja-like.

This knife has been in my family for a long time, and this weekend I finally got around to taking a few photos. My grandfather looked into the history of the blade a bit, many years ago, but unfortunately no one wrote down what he found. I have a vague recollection that he decided it was probably made in Philadelphia in the late 18th or early 19th century, but I could be mistaken about all of that. I'd welcome any info that any of you folks can provide, particularly if anyone recognizes the maker's mark. Please don't ask why I didn't take a pic with the blade locked fully open. I have no explanation for that. The scales are horn, and the brass is thin sheet wrapped around the horn. The tips of the scales are broken off, so the point of the blade extends just a bit beyond the handle when it's closed. The spring is intact but doesn't snap into place anymore, so if you want to lock the blade you need to manually press the spring down into the notch. There appears to be a pin missing on the left side scale (the hole is visible in the second pic), but I'm not entirely clear what its function was. There doesn't seem to be a corresponding hole on the other scale, and the pin couldn't have run all the way through both scales or it'd have prevented the blade from closing.

You can get 1000 grit from ceramics suppliers like Bailey. I don't know where you'd get 1500. I'm sure it's out there somewhere, though. Good luck.

I was sorry to hear of this. Growing up during the late Cold War, I considered men like Vaclav Havel and Lech Walesa heroes. Perhaps a little crazy, I thought at the time (now I realize "very brave" would have been a better description), but certainly heroes.

You could grind one straight edge on it, a couple inches long. That'd probably do. It wouldn't require too much work with an angle grinder, and you wouldn't have to (or want to) flatten the side of the anvil for its entire length -- you'd only need to grind a couple inches down from the face. A longer straight edge would be more convenient, but you don't have a lot of material to play with. Upsetting the face and squaring it by forging would probably work well, too, but it'd be a lot of work and you'd need at least one helper (human or machine). I don't know if you could successfully harden the face, but if it were me I'd probably give it a try. A deep charcoal or coal fire with a good air blast should be able to do it, although I admit that the largest stock I've worked in a coal forge was 2.5" (6.35 cm) in diameter. You wouldn't need to heat the whole piece to austenitic -- just the first few inches back from the face. Definitely don't cut the steel in half lengthwise and lay it down flat. It'd make a miserable anvil that way. The most reasonable way to use that piece of steel as an anvil is upright, just as you're using it now. A piece of steel that size should weigh around 43 pounds (19 kilos), not 60 kilos!

Unless you're going to be running your burner outside the forge, you generally don't need a separate flare. Just build the flare into the forge itself, as Brian suggested.

The breaker hammer bits that I have are within the range for 1045, as Alan said, and as described in that link above. Grant Sarver suggested they might be something like 15B40, which is .4% carbon with a tiny amount of boron to improve hardenability. (He used to make these bits and had a bunch of his competitors' products tested.) That could be; the boron content in 15B40 is so low that it might have been written off as "trace" on the test results I got. (My bits don't have enough Mn to be 15B40, but they could be a similar proprietary alloy.) For $5 each, they're probably worth buying. With the Mn and possibly B, I wouldn't expect them to make good hamon. (Is "hamon" the plural of "hamon"?) But you could use them to make tooling, small hammers, etc.

Pretty sure lots of folks here use them. I just recently bought one and am likely going to be trying it out very soon.

If I had paid for that, I would be annoyed. The workmanship is crude, the design frankly doesn't look very efficient and, to top it all off, it was defective! (That probably relates back to the crude workmanship, but there's a difference between "crude but effective" and "crude and dangerous.") It might not be a bad idea to pressurize the orifice assembly in a sink or basin full of water, to check for any other leaks. (You could use air rather than propane.) You can also do it by brushing on a soapy water solution.

I don't know if I've ever seen that kind of flame out of a propane burner. Like a couple others before me, I'm wondering if your regulator is providing enough pressure. And do you know (or can you find out) what size the propane orifice is?