MattBower

Any chance it's beryllium copper (a.k.a. beryllium bronze)? If so, be aware that the dust and fumes are toxic. http://www.industrialheating.com/Articles/Column/85877f0c9dd79010VgnVCM100000f932a8c0____

Why not sell the scrap copper and brass and use the proceeds to buy yourself a couple big pillow block bearings from Surplus Center? Whole lot easier, and the final product is likely to be significantly better. You'd probably have money left over to by other smithing toys, too. :)

Well then, I put this down to blacksmiths' bad habit of calling steel "iron." :)

Fascinating PDF. Thanks for that.

Nah, I'm sure it's not HF if it's made in the USA. It's still not likely to be ductile iron, which is the only kind that I'd be willing to beat on much.

Reread what I wrote, Steve. I said there is more ("lots more") carbon in cast iron than there is in steel. Which is correct. I did not say CI has "lots more carbon than iron." That would be incorrect. But I meant what I said. And don't worry, I already know about white iron. And malleable iron. And ductile iron, &tc. :)

That's a much bigger question than I care to take a stab at in a single forum post. The fundamental difference is the amount of carbon they contain. Elemental iron is just that -- an element. Steel is an alloy of iron and carbon (and usually a few other things). Cast iron is also an alloy of iron and carbon, but with lots more carbon than steel. The mechanical and thermal properties of ferrous metals typically have a huge amount to do with how much carbon they contain.

Go ahead and do it if you want, but that HF anvil is not tool steel. It's cast iron.

I know they can get there; I'm just wondering if the more traditiona venturi shape of many commercial burners makes them more efficient, and better able to handle back pressure.

Firing temps for these types of very pure ceramics tend to be extremely high, though.

O1 has ~1% carbon and plenty of carbide formers like chromium, tungsten, and sometimes vanadium. Traditional slow-cool annealing from above critical in something like vermiculte or wood ash is likely to get you grain boundary carbides that can make it very hard to drill, even after "annealing," and which are likely to remain -- causing unnecessary brittleness -- after hardening and tempering. (If you look at industrial recommendations for annealing O1, it's a sub-critical spheroidizing process.) O1 also needs a proper soak to get all the carbon into solution before quenching, because the alloying elements get in the way. I have made knives from O1, and they certainly got hard when heat treated with simple methods. They were also very difficult to sharpen, even after tempering. (Knowing what I now know, I suspect that was because there were big, nasty, extremely wear-resistant carbides in the matrix.) I have since learned enough to realize that the microstructures of those blades probably are far from ideal. I second BGD's comment that O1 is a steel that should be heat treated with proper equipment in order to get close to its potential. I have quite a bit of O1 stock that I will not touch again, at least for knife blades, without a proper, temperature-controlled heat treating furnace.

In an oxidizing atmosphere, yes. In a reducing atmosphere, we'll get steel with an ever-increasing proportion of carbon, until it becomes cast iron. Cover fluxes (e.g., crushed glass) are normally used for this reason.

Silicon carbide has exceptional thermal shock resistance. Graphite is even better. Unfortunately they're both susceptors -- i.e., induction will cause them both to heat directly, which could be a problem. They'll both also contribute carbon to any ferrous metals you melt. Still, they might be worth a try. But please do this over a bed of dry sand large and deep enough to capture the results of any failures. Molten metal plus concrete is a very dangerous combination.

John's suggestion is a good one. Or just dress your not-quite-square punch with a file or grinder until it is square.

The last three are refractories or refractory mortars that can provide some (or at lot of, depending on how much you apply) mechanical protection to the blanket. ITC is an IR reflective coating. It's normally applied quite thin (it's expensive), and won't do anything to prevent mechanical damage. I'm sure the last three will also seal in the blanket fibers, which is a safety thing. I'm not sure about ITC. It's sometimes used for sealing, but I don't know how well it actually works.

I have played with homemade castables from ceramics. I found the experience very frustrating. The problem tends to be getting them hot enough to vitrify properly in situ in a forge or furnace. The outer layers generally don't get hot enough to fire, and that creates all kinds of internal stresses. But all castable refractories are basically ceramics, so if you overcome the firing problem (and the tendency to crack as they dry) there's no reason they can't work. Good luck. I'll be interested to see how it goes.

Seems like ability to handle back pressure ought to be a consideration. Burners that look great in free air don't necessarily perform well in a forge or furnace. Also, for want of a better term, tunability in a forge environment? You said 0-30 or 60 psi, so I guess that covers turndown ratio, which was going to be my other suggestion. I think that's related to the "tunability" issue. And how could we quantify the amount of heat you can pump into a forge of a fixed size from a burner, until you start losing unburned gas out the front? I'm sure the combustion gurus have a term for this. I don't know what it is.

Thanks. I know what blown burners can do. Right now I'm kinda specifically interested in venturis, though. ;)

Hot as the sun, ounce of fuel an hour? But seriously, that'd take some thought. Gotta think about that. I grew up ~90 minutes east of Valpo. Some of my high school friends went there. No engineers, though.

I happen to have a T-Rex, so just now I went down and pulled the injector assembly and started examining the inside with a flashlight. I couldn't tell if it had a necked-down throat (Rex makes it hard or impossible to remove the back end of the burner), but my flashlight was almost the exact diameter of the burner tube at the business end, so I turned the burner upright and dropped the flashlight down there. It slid all the way through to the intake ports. No restriction there worth mentioning. It's basically a straight pipe.) By the way, I know turbulence is good for mixing, but is it good for the induction ratio? I know Mike Porter mentions several times in his burner book that he's trying to promote laminar flow. And I'm pretty sure the T-Rex is just a commercial version of MIke Porter's burners. You definitely want intimate mixing before the mix enters the body and ignites. From what I can tell, a "short," fast, efficient burn lets you pump more heat into the furnace before you get to the point where any extra fuel comes out as dragon's breath. Forcing the fuel/air mix into a bunch of tiny streams rather than one big one seems to be a way of promoting that kind of burn. I think that's why the Gibersons and ribbon burners work well.

Sounds like a pretty good idea. Wish I knew some engineering students! If we're talking home built burners, the budget probably wouldn't have to be very big. Of course it looks like this book should answer just about any burner question one might have. Lots of tantalizing stuff in the preview. Too bad I can't afford it. It'd take months to digest. http://books.google.com/books?id=cCJ_YyAEqnQC&lpg=PP1&dq=industrial%20burners%20handbook&pg=PP1#v=onepage&q&f=false

Check. More speed, lower pressure.

When I say "semi-naturally aspirated," I'm thinking of using a small, high pressure compressed air jet shot down a venturi -- an eductor/injector/aspirator, or choose your favorite term -- in place of a blower, and introducing the propane somewhere downstream, as on a typical blown burner. BTW, although I've never studied fluid dynamics, I did wonder if a straight, relatively narrow pipe doesn't create extra drag. There's also the fact that the pressure in front of the restriction on a more traditiional venturi -- where the flare is -- actually goes up, compared to the pressure in the necked-down area. Not sure if that's important.

Oh, I know some of these designs work really well. I'm just wondering if they max out on efficiency. I'm asking this because I've kind of got the idea to try to build a semi-naturally aspirated cross between a Pine Ridge style ribbon burner, and a Giberson ceramic burner head. I suspect a venturi has to be very efficient to work with those sorts of burners. (Pine Ridge says their ribbon burner needs forced air, but Joppa Glassworks typically pictures the Gibersons in use with Ransome venturis.)

I've been messing around with naturally aspirated burners lately, which I haven't done in quite a while. In the process I've been looking at all the common designs -- the Michael Porter/Rex Price "T-Rex" type, Frosty's t-burner, Ron Reil's stuff, the Zoeller sidearm, etc. I've also been looking at commercial naturally aspirated burners for kilns, glass furnaces, etc., like Ward and Ransome burners, and even the venturi burners on things like commercial turkey fryers. One thing I have noticed is that the successful blacksmith burner designs involve a larger area intake necked down to more or less a straight pipe, which then runs straight to the flare. In contrast, the better commercial burners seem to use a more traditional venturi shape -- large intake area followed by a short, necked-down section to reduce pressure and increase speed of the air/gas mix, then a long, gentle flare -- after which they finally straighten out again at a diameter close to that of the intake. In fact I've seen it said it's wrong to call most blacksmith burners "venturi" burners, because they really aren't venturis. I'm not sure that's exactly right, because they do operate on the basic principle of a venturi, but it's at least true that most of them don't use the full, traditional venturi shape. I'm wondering if the full venturi shape offers added efficiency over the straight pipe burners. Anyone have any firm ideas about this?