MattBower

Fortunately, the piece of leaf spring that I dropped into the slack tub had not yet absorbed a lot of time and effort. :)

I don't see how it'll really be a big problem as far as heat. You could burn yourself, I suppose, but learning not to touch hot stuff is part of blacksmithing. However, one of the big advantages of setting the brake drum into a large steel drum is that it provides you with a table on which to store coal, place tools, and so on. Your plan eliminates that advantage.

All I was trying to get at is that most cutlery stainless (at least that I'm familiar with, and since I lack the means to properly HT stainless, this is entirely theory for me) is hardened and quenched, usually by air or by contact with heavy steel or aluminum plates, then tempered, in a manner very much like that used for conventional steels with sufficient carbon to harden significantly. The times and temperatures are different, and the process is much more exacting, but it's basically the same. If you look around for heat treating info on something like 154CM, ATS34 or 440C, it won't look dissimilar to the typical quench-and-temper process that you're probably familiar with (except that tempering stainless often involves a cryo step). But if you look at what's involved in age or "precipitation" hardening, that's a very different process. It increases strength but doesn't give knife-level hardness, and it's only applied to specific steels -- usually very low carbon alloys, which generally isn't what you want for a blade. You seem to be operating on the belief that precipitation hardening is how all stainless steels are hardened, and to my understanding that's not the case.

If Ric Furrer is around he can speak up on this, but an acquaintance of mine learned pack carburizing from Ric, and he uses thin-walled tube as the carburizing container for just this reason. He uses ~1/4" bars as the material in the pack, and carburizes up around 2200 F. The tube is considerably thinner than the bars. If the tube turns to cast iron and melts, it's time to quit. It's sort of the canary in the coal mine.

Dragon blood, too. :P

It depends what you want to make. Auto springs, both coil and leaf, are pretty reliably tough, medium carbon, oil hardening steel that will make decent or better edged tools. They can have hidden flaws from their former lives as springs. But that's the breaks when you use scrounged steels.

An hour in a fire isn't going to do much in the way of pack carburizing unless it's a blown fire at near welding heat.

What you need to understand is that some grades of stainless steel cannot be hardened by thermal treatment. Period. They are austenite -- the soft, malleable phase of steel, which we normally achieve by heating steel in a forge -- at room temperature. 304 is one of those. In fact it's similar to many non-ferrous metals in sense that heating to around 1850 and cooling it rapidly will anneal it. You can harden 304 some by cold working it. And aging is not a process that would apply to cutlery steels. Stainless steels that are capable of hardening are hardened like non-stainless tool steels, except that they're air hardening, and the temperatures generally are higher and the soaks longer. There are dozens of high quality stainless steels that are very suitable for cutlery, ranging from 440 to 154CM to S30V to 12C27 -- the list goes on and on. If you want to make serious knives out of stainless, you're going to need to buy one of those. But they are expensive, hard to work (they're usually not forged), and have very particular heat treating requirements that you will not be able to achieve with a simple forge. You'll need a pyrometer of some sort and a heat treating oven, high temp salts, an old kiln, something that'll allow you to achieve and maintain an exact temperature (within say 10 or 15 degrees) for a half hour or more. An alternative would be to send your blades out for professional heat treating. If all you want to make are more or less edgeless cheese knives and table knives of the variety you can buy cheaply in any big box store, you can use 304. Don't bother heat treating it. As someone else mentioned, if you're serious about corrosion resistance you should look into passivation.

You can also buy 'em brand-spankin' new from McMaster-Carr and probably many other places, though that's not nearly as cheap.

Yeah, sorry man, but not all steel is created equal. I don't know what a "grss cutting hockey" is, but if it's mild steel you're pretty much out of luck If you want to heat treat steel you're going to have to find a way to get the whole blade up to around 1500 degrees F. A charcoal grill ain't gonna do it. (With real charcoal it could probably do the job for smaller blades, but not a sword.) A simple ground forge can do just fine, but building one takes a small investment in time and work, and very minimal parts. Somehow I suspect that's going to prove to be too difficult for you, but if you're serious about making a functional sword, resign yourself to spending at least a few years learning all about this craft. There's a lot to know. Sorry. If it were easy, everybody'd do it.

Read this:

The fan would certainly help, but if you look at fume hoods they're typically much larger, and a much different shape, than a kitchen sink. If you're going to use a bathroom fan you'll need to make sure it draws in a lot of fresh air to cool the exhaust before it gets to the fan.

Ah, good. Then I think you may be onto something. I still suggest claying the whole thing (1"-2" on the bottom should give you a good fire pot depth and enough protection), and using firebricks or clay if necessary to adjust the interior dimensions of the pot to an efficient size. As far as attaching the forge directly to the wall of the shop, as long as the wall is all steel I'd think it would be fine -- just make sure it can support the weight. (I think I'd add some legs to the front of the forge, just to be sure.) It sounds like there'll be air circulating around the back of the forge no matter what, due to the corrugated walls. And the clay will insulate things some. The other sink half may or may not work as a hood. It may need some modifications. The chimney is pretty important even if your shop isn't air tight. Homoglobin likes carbon monoxide -- CO -- much better than it likes oxygen, and once the CO is in your blood it stays there for a good while. So you can certainly poison yourself in a non-air tight structure. And there's lots of other nasty stuff in coal smoke, too. So proper ventilation really is important. Use a big enough chimney -- a lot of folks here seem to recommend 12". 8" seems to be an absolute minimum, and many don't think it's big enough. (I don't actually know what sizes we have on the coal forges at the shop where I do most of my smithing. Two of the forges have masonry chimneys, and the other two are large, but probably double-walled.) By the way, I'm envisioning a side draft chimney. That's what I'm familiar with. If you're thinking of an overhead hood, I think it'd have to be much larger than sink sized.

I think you'd want to clay the whole thing, both to protect it to and to shrink the sink down to something a size appropriate for a firepot. Most kitchen sinks I've seen are way too large (and too deep) for that purpose, unless you're planning to do a lot of very large work. But that much clay will make it darned heavy. Are you planning to attach a chimney of some sort that vents outside the shop? I ask only because you mention the shop not being airtight, and I'm not sure exactly what you're getting at.

Hmm. Probably not. But they'll do for this purpose.

I find it much easier to work on hardy tools that fit the hole reasonably well. Too loose wobbles around and makes your job that much harder. You can upset thinner stock to make it fit, but it's easier to start with something that's the right size to begin with. What're you planning to do for a collar or shoulder on the tool?

I once read somewhere that soaking hammer helves in antifreeze (after the head is mounted) will help keep them from shrinking, causing the head to get loose. I tried it on one of my hammers. I'm not sure if it worked, because I've forgotten which hammer it was. :lol:

I'm very pleased to know that I'm not the only one crazy enough to have had this thought! And with an air hardening steel you could probably braze and heat treat at the same time. This would be a good anvil to experiment on.

I like Tempilaq, rather than the crayons (Tempilstiks). Tempilaq you just paint on (each bottle has a specific melting point), then watch until it melts. You don't have to pull the piece out of the fire and poke at it with a crayon. (It's losing heat while you're doing that, which may or may not be a problem. It's not such a big deal in large cross-sections.) The only drawbacks are that you have to let the work cool enough to paint on another coat, if you're doing something that requires multiple heats to a given temperature. And a solid fuel fire can tend to scrape off the paint, so you're best-off building a cave in the fire for heat treating, or using a "muffle" (a piece of pipe in the fire), so that you're not dragging the work directly through the coals. Tempilaq is supposed to be good to +/-1% of the rated temperature; i.e., 1500 degree Tempilaq melts between 1485 and 1515. Close enough for me. I think the maximum temp for the paint is 1600; above that I think crayons are the only option. I would not choose higher carbon steels like O1 and most of the W1 and W2 steels (although carbon content can vary in those) for struck tools. Heat treating is a little more finicky, and if you do it wrong they can tend to be brittle, which you don't want in a struck tool. For struck tools I'd prefer something inherently tough, in the medium carbon range. 4140 and 5160 both qualify. So do the 10xx steels from 1040 through, well, really up to about 1075. So do S7 and H13, which are both extremely tough and stand up well to heat (H13 far more so than S7). I expressed my concerns about heat treating S7 and H13 in the other thread, but guys like Grant have actual experience with them; my opinions are based solely on what I've read. I've never taken the plunge and actually bought any of either of those steels.

Are you trying to slit thin metal? And are you doing it over the hardy hole?

I suggest that you stick with something relatively simple like 4140 or 5160, as Phil and others have suggested, until you have considerably more experience. Tool steels are more expensive (much more expensive, in some cases), and the requirements for properly heat treating steels like H13 and S7 are much more complex. No, your 4140 and 5160 tools won't hold up to hot work like S7 or H13, but you can work around that by cooling them regularly during hot work, and you can fairly easily rework and re-heat-treat them when the need arises.

The one edge I can see looks a bit rough, but nothing that can't be worked around or even (carefully) ground out, eventually. Looks like the face is intact, and in decent shape. Horn looks good, too. I don't think you'll regret buying it at that price. You are going to be stunned at what a difference it makes in your ability to move metal, compared to a flat, thin anvil that puts no mass under the hammer (i.e., what you've been using up to now).

I notice that Budget Casting Supply sells expensive phosphor copper shot for degassing. (Phosphorous is mentioned as a degasser in the link in my previous post.) But you can buy copper phosphorus brazing rods quite cheaply. Hmm. Same alloy, or close enough? I don't know. But it's a thought.

I don't think so either. The typical deoxidizers for copper seem to be pretty scary-sounding chemicals. Zinc is probably the most benign of them. It doesn't take much, either --I've read that a couple percent by weight is enough. Edit: Here's far more than I ever knew about degassing copper.

Here are the Google Shopping results for "IR safety glasses": http://www.google.com/search?q=ir+safety+glasses&hl=en&rlz=1I7GGLL_en&prmd=ivns&source=univ&tbm=shop&tbo=u&sa=X&ei=n7cdTrjYFY7fgQfKqKz4CQ&ved=0CIABEK0E&biw=1024&bih=536 Some are very inexpensive. Caveat emptor.