MattBower

OK, I might need to get with you on your technique for that. I have a project in the works that's going to require a metal sheath. I was also thinking of starting with copper. Very nice!

I've used a 5 gallon steel bucket with a steel lid. Now I use an old soda-acid stainless steel fire extinguisher body, but I'm mainly doing blades. Wall thickness isn't really important, as long as it doesn't leak.

Oops, you noticed that? :P

So, Grant: aluminum fly press frame?

I defer 100% to Grant on this. But DTOM, what's the practical significance of the question? How do you plan to cast that much aluminum in one go? (I won't ask where you plan to get it, since getting that much aluminum for free would be feasible, given enough patience and hustle.)

Charred wood, i.e., wood with all the volatiles burnt out in the absence of oxygen. It's light, hard, dry, black, makes a tinkling sound when the pieces rattle around -- and it looks like pieces of wood! It's mostly carbon with minimal impurities. You can get it at Lowes or Home Depot, although you'd be better off buying bulk from someplace like GFS, as Phil suggested. Here's a quick rundown on lump vs. briquettes.

OK, I did misunderstand the problem. You're having trouble getting the cross exactly symmetric. Could you make a sort of bending jig to help you adjust the arms to exactly ninety degrees?

Sorry, Ric, I wasn't very clear there. I was actually talking about the KA150. :)

If I had that machine and you had a feather....well, nevermind. But we'd both be tickled. :D

Sorry, I missed this question at first. Aim for about four liters of quenching oil per 500g of steel. Generally speaking, a lower viscosity oil will be a faster quenchant than a higher visosity oil. If you were quenching shallow hardening steels you'd want to stay away from viscous oils. (One reason we normally preheat quench oil is to decrease the viscosity.) But 5160 does not require an especially fast quench. As I said in an earlier post, I suspect its popularity for blades may have something to do with the fact that it will harden reasonably well in relatively slow quenchants (which describes a lot of the junk people sometimes quench in). As best I can tell, sunflower oil is probably a pretty fast quenchant. Cutting it with mineral oil will slow it down some. For 5160 that might not be such a bad thing.

I got that from Scott MacKenzie, who's the technical guy (metallurgist) for quenchants at Houghton. But I'm sure I've also seen it in writing elsewhere. In any event, Scott's a very reliable source. The bottom line is that you want sufficient volume of oil to prevent an excessive temperature rise during the quench. Apparently a gallon per pound is usually enough, though I typically use more. (I have a three gallon tank and I rarely quench anything that weighs three pounds.)

Maybe I'm not understanding the problem correctly, but why can't you punch a hole, drift it out with a slightly undersized, precisely made square drift (drift and punch could probably be one, in fact), then finish with a little filing?

As long as you're using at least a gallon of oil per pound of steel (which appears to be the standard recommendation in the industry), and letting the oil cool back to a proper quenching temp between uses, I don't see any reason to get wrapped up around flash point. Most commercial quench oils seem have flashpoints in the 280 F to 450 F range. Your quench tank should be metal with a fireproof lid, so you can snuff out any flare-ups that do occur, and it should be something that won't tip over easily. That said, although a little surface flare during the quench isn't uncommon (or a lot of surface flare if you're into edge quenching -- which BTW is very hard on your quenchant), it'd take some pretty severe abuse to get a full tank to sustain a burn. I personally don't let flash point drive my decision making about quench oil; my first concern is whether it has the right cooling characteristics. Obviously I don't use materials with absurdly low flash points -- gasoline might have a great cooling curve, but obviously that's just not gonna work -- but anything in the ballpark of 300 F or up is OK with me.

Good point.

Satanite isn't going to insulate any better than the hard bricks. In your position I might think about whether it'd be possible to pull the hard bricks on the sides and top, replace them with wool, and give them a light coat of Satanite. Or it might be simpler to use insulating firebricks, or something like Insboard, rather than the wool

Real charcoal, though, not that briquette garbage.

My point was going to be that if your forge is lined with hard firebrick it's going to be slower to heat. If it's solely hard firebrick, with no superior insulator (ceramic wool or insulating firebrick) surrounding it, that'll limit the temperatures you can reach. Insulation is important, and hard firebricks don't insulate for squat. Before you start messing with the burners you may want to make sure your forge is adequately insulated. If it isn't, even the best burners will struggle to get it to a good welding heat. Ideally you want a hard, durable, flux resistant interior (hard firebrick or castable refractory), not too thick, surrounded by a couple inches of a good insulator.

Yes, I've often said that, as a rule of thumb, a steel that'll make a good spring will probably also make a decent blade. But it may take some experimentation. Leaf springs do have a reputation for being 5160. I took a set from the dumpster at my local spring shop (with permission) and had a piece analyzed. It actually was 5160. But that doesn't guarantee anything. I really can't say what other steels might be used even in the U.S., let alone in another country!

Phil's right. You don't need coal. Tonight I needed to knock out a couple quick forge welds and couldn't get to the shop, so I threw together a simple forge in my back yard from firebricks, with lump charcoal for fuel and a heat gun for a blower. Problem solved. Charcoal is excellent forge fuel. In fact I almost overdid it making one of the welds; the steel got just a tad sparkly. But buying charcoal can get a little expensive; I suggest you learn how to make it. Free scrap wood is pretty easy to come by.

What Phil said. The T-Rex is a great burner and definitely gets hot, but there's nothing magical about the design; it's just better made than a Reil or the like and that amounts to better performance. Smooth flow is more efficient than turbulent flow, the angles are optimized, etc. Yeah, mine has the sliding choke. When you say ceramic blocks, do you mean soft firebrick? I'm just looking at the weights on the NC Tool forges online, and wondering if they're using hard firebrick on the interior.

Frank's absolutely right. When it comes to scrap steel there is no "usually." Not in the sense that you can reliably know what sort of steel you have just by the type of item you have. I've had a dozen or so scrap steels tested with a spectrometer, mainly to prove the point that these scrap steel charts and the like don't necessarily correspond to reality. For example, demolition hammer bits? The charts will tell you S- series steel. Hah! The one I had tested was 1045. I've had two large auto coil springs tested, and both were basically 5160 (though one had some vanadium). But that doesn't mean your coil springs are 5160. I've not heard of 1095 being used in coil springs as a routine thing, though.

A couple extra points about water quenching. (1) Don Fogg has an excellent discussion here by Randal Graham, who apparently can successfully water quench just about anything. (2) A thin clay coat very likely increases the speed of the quench (counterintuitive, I know), but also probably makes it somewhat less severe than water on bare steel in terms of uneven cooling and risk of cracks. In other words, the clay coat may actually help improve survivability in a water quench. I always thought it seemed really odd that the Japanese apply the clay coat even on the edge they want to harden; seemed to me like it'd insulate the edge and reduce hardening. Apparently, though, it may have just the opposite effect. BTW, where'd you get your coil springs? The auto coil springs I've had analyzed were 5160.

Frank is giving you good advice, but let me recommend that you do some serious reading on the bladesmithing forums (here and at other sites -- there are some outstanding ones out there). The nature of your questions suggests you don't have much background in this, and frankly no one's going to take the time to fill in all the background info you need in order to completely understand the answers to your direct questions. Quenchant choice first and foremost depends on the steel you're using. I don't off the top of my head know any bladesmiths who use water for quenching anything other than 10XX and W-series steels. Even with those, water hardening is riskier; you'll lose more blades, though people who really know what they're doing do seem to have pretty good success with water on the 10XX and W- steel. I don't think I know of anyone who quenches 5160, O1, or other deeper hardening in water. (I've heard of using water for heavier cross sections of deep hardening steels, but I'm just talking about blades.) 5160 is designed to be fairly deep hardening; there's no reason you'd need to water quench it, especially in blade cross-sections. Doing so vastly increases your chances of quench cracks, and I know of no advantage. 5160 also is not a steel you'd choose if you're looking for a nice hamon. It is too deep hardening. The martensite will creep up under the clay lines and wash out the visual effect to a certain extent. People do manage to get hamons with 5160, but they're nothing like the ones you can get get from shallower hardening steels. Not all oils are created equal for quenching. Some are fast, some are slow, some are in the middle. Ideally you'd like to marry your choice of oil to the steel you're using: fast oils for shallow hardening steels, slower oils for deep hardening steels, medium oils for medium steels. Fast commercial oils include Park/Heathbath 50 and Houghto-Quench K. Warm canola is also quite fast. Some folks get pretty spectatular hamons in shallow hardening steels using these fast quenchants. You can quench some deeper hardening steels in these fast oils, but it's probably a little risky. McMaster-Carr's 11 second oil is roughly a medium hardening oil. So are Brownell's Tough-Quench (Houghto-Quench G) and Park AAA. McMaster's 28 second oil is fairly slow. The medium oils would probably do great for 5160 and most of your other deeper hardening steels. They might not be quite fast enough for 10XX and W-series steels, but if you Google you can probably find some specific discussions on that. I don't think I'd bother with the slower stuff like Mcmaster's 28 second oil for blades. It would probably harden a lot of the deeper hardening stuff -- I suspect one reason 5160 has been so popular with bladesmiths for so long is that it's sufficiently deep hardening that you can quench it in all kinds of junk and still get a decent result. But it might be too slow for some, and it certainly would be too slow for the shallower hardening steels. As for your many junkyard oil concoctions -- your guess is as good as mine. [Edited for rotten grammar!]

https://dg.box.net/shared/static/s3pjhjalji.pdf This design is by Daniel Gentile, a very talented Swiss bladesmith, toolmaker, machinist, etc. I own a T-Rex. The T-Rex is similar to any venturi style burner (not sure venturi is quite the right word, but that's the common parlance), it's just better made and they did quite a bit of experimentation to optimize everything. As best I can tell this design is pretty much the same as my T-Rex. Of course Daniel uses metric measurements, so you'll have to convert everything. Sorry about that. By the way, how's that NC Tool forge insulated?

Yeah, OK. That does it for me. Out before I even got in. Too bad. http://offer.ebay.com/ws/eBayISAPI.dll?ViewBids&item=200468167147