Matt Bower

Thanks, Steven. Nice design, but I'm already pretty well committed to ceramic wool (with a hotface) for the lining. (I already have the wool. ) What sort of burner are you using? Naturally aspirated, or forced air? If it's natural, is it a Reil or something else? And what size orifice are you using? 0.030" MIG tip? Or did you drill one yourself?

That's functionally identical to v.1.0 of my oil burning forge. What do you consider "slow" and what is "heat" (as in, how long does it take to get to the temp you want, and what is that temp)? Do you have any kind of hotface, or just a ceramic wool lining? And are you preheating with anything other than a couple charcoal briquettes?

I'm betting you don't have a hotface, and you're just using a couple charcoal briquettes. In which case I think you'll find that a thin Satanite lining and a much more robust preheat (a serious propane burner for 15 minutes, or a good quantity of wood or charcoal with an air blast) will make it run a whole lot better. Oil doesn't burn easily, and it takes more than a couple charcoal briquettes to get that forge hot enough to digest serious quantities of oil (and thus produce serious amounts of heat). Ideally you want the entire interior of the forge at at least a red heat before you cut in the oil.

Having said all that, oil burners are NOT the thing to use for a quick heat-up and short forging sessions. If you want fast and simple, use propane. Oil burners are good for generating pit-of-Hell levels of heat for hours on end, cheaply. I have melted stainless steel in mine (unintentionally).

Another couple words of advice: get those air bubbles out of your fuel line, and elevate the fuel tank more. It'll run much better that way.

Thanks, Ken and Geoff.

I soon figured things out so I didn't immediately sqwack.

 

K

I wish I'd been that smart.

I've done very little forge welding, and so far it's all been in a charcoal forge. I'd like to build a dedicated propane welding forge for making billets and cable damascus. Can those of you who do a fair bit of that sort of work recommend some appropriate internal dimensions? I'd like to keep the forge reasonably small to economize on fuel and materials, and I don't see why welding up billets should require a lot of space. But I don't want to get too carried away and end up making something that turns out to limit me in ways I didn't anticipate. So I thought I'd better get some input from folks with more experience.

Well, today I received my drive and tracking/tension wheels from Rob. And as I was examining the tracking wheel I realized that the bore of the wheel didn't look concentric with the bearings; there seemed to be a good 1/16" offset. My initial read: the bearings sit in countersinks, and the countersinks aren't concentric with the bore. Which I thought was really weird, considering that Rob CNC machines these wheels: you'd think that after producing probably thousands of wheels like this one those sorts of problems would be pretty well ironed out.

So I shot off an e-mail to Rob about the "misalignment" between the bore and the countersinks, and he immediately wrote back and very politely explained that what I was seeing between the bearings was a spacer, not a bore machined directly into the wheel, and that I could move the spacer around with a pencil or whatever to line it up with the centers of the bearings. So I grabbed a pencil and, sure enough, I can.

It's been a long time since I felt this stupid.

I unfortunately have been playing catch up in the real world ... so I haven't gotten the pictures posted.

 

I looked at the last post, and this steel looks nothing like that piece McKenzie found. I will do my best to get pictures posted tonight.

I know the piece you're talking about, and it, too, is a rail anchor just like McKenzie's. They're just different designs. Both do the same job.

There are currently two rail anchor manufacturers in the United States. Both use proprietary steel recipes. I exchanged e-mails with one of them a while back, trying to find out something about the metallurgy of rail anchors. They told me that anchors run between 40 and 60 points of carbon (theirs are on the higher end, their competitor's are on the lower end), with more manganese than a typical AISI 10xx steel. That's about all I can tell you.

How do you etch logos onto the blade? Is it an electric arc-etching pen or do you use an acid?

 

I've got a touchmark but it's kind of imprecise.

Anyone care to inform me on this?

To me, electric "arc-etching" would mean electrical discharge machining, or EDM. I imagine that'd work fine for logos, but it'd be big-time overkill.

Electrochemical etching -- probably the pens you're referring to -- just uses electricity and an electrolyte solution to cause steel to rust very fast. You can buy one of the little commercial systems or make your own fairly simply. Google around for plans. Good templates are the hard part.

Acid etching would certainly work, but as far as I know it's slightly more dangerous and a bigger hassle.

Please tell me this is going to be an annual event.

I use Park #50, but a lot of people like experimenting with homemade quenchants for, probably, the same reasons that a lot of people will spend hours making tools they could've bought relatively inexpensively. There's a sense of satisfaction in doing things for yourself. It may not make strict economic sense, but there it is. Who am I to question it?

In fact to me this whole bladesmithing game is a hobby. So from a purely economic POV, none of it makes any sense. A look at the knives I've made, and the time/money/effort I've invested to produce them, would suggest that I'd be much smarter to spend that time working a part-time job. Then I could take the extra money from that job and use it to buy much, much nicer blades from some of the pros who hang out here. That would make the most economic sense. But it wouldn't be very satisfying. So I continue doing it the hard, expensive way.

Of course you're not the only one that has actually done this. Wayne Goddard has actually done it! It should work fine, though I suggest you take all the safety advice these fine gents have given you. And I wouldn't expect it to perform as well as steel.

If the edges of this slab of yours are square, you'll want to radius (round off) them off on the working face. If you leave them square they'll be a real shrapnel hazard.

Rick,

You probably know this, but just to be clear: the biodiesel you can get from the pump is generally B5 or B10, occasionally B20. The number tells you what proportion of the fuel is biodiesel. The remainder is straight petrodiesel. So B10 is 10% biodiesel and 90% petro. That'll make a big difference in your flash point, so just keep it in mind.

If you want pure biodiesel (B100) I imagine you'll have to make it yourself, or find a local homebrewer who's willing to sell you a couple gallons.

On the other hand, though, you might be able to cut your veggie oil with plain old petrodiesel. But I'm not entirely sure how the combined flash point would work. Does a relatively homogeneous, 50/50 mix of diesel (flash point ca. 125) and canola (flash point ca. 600) give a combined flash point of 360 ish? Or does the diesel just start burning off at 125, leaving the canola behind? I'm not sure..

"If so is the general consensus Silicon Carbide as there is no carbon to absorb . . . "

Uh, the chemical formula for silicon carbide is SiC. If you recall your periodic table, "C" is carbon. In other words, there's plenty of carbon in silicon carbide crucibles. And while I can't speak to this from personal experience, I'd be somewhat surprised if molten Fe couldn't suck up that carbon (and the silicon, too) fairly easily.

The thing to experiment with for homemade steel crucibles is probably magnesium oxide. It seems to be the main component of most of the refractories used in commercial steel mills. As a starting point, various acids can act as binders for MgO.

Thanks for the thoughts, and the good advice. You may be right that it'd be worthwhile to spend a little more now. I've been down that road before.

But what's wrong with welding? I like welding!

I'd like to put together a very simple 2x72 belt grinder using Beaumont Metal Works wheels. When I say "simple" I envision basically a drive wheel direct mounted to the shaft of the motor, an idler wheel, and a short platen. (Short enough to leave some space for slack belt work.) Very much like this belt sander by Rob Frink, but made of steel and probably oriented vertically, with a work rest: http://www.metalwebnews.com/howto/sander1/sander.html I can upgrade later if the spirit moves me.

I envision powering it with a 3/4HP 1750 RPM motor (because that's what I have).

My question is what two wheels to start with. What size drive wheel? 4" or 6"? And for the other, a 2"x2" idler, or the tracking/tensioning wheel? Or could I get away with a contact wheel? I e-mailed Beaumont these questions and they referred me to their website, which unfortunately doesn't answer my questions. (I had already looked at the website. That's how I knew that they make a 2x2 idler, a tracking/tensioning wheel, and 4" and 6" drive wheels!) Kind of disappointing.

I haven't tried it, but it has occurred to me. It dawned on me a while ago that petro diesel would probably have a lot of good qualities as a quenchant if its flash point weren't so low. Biodiesel has (or can have) a much higher flash point -- at the cost of being somewhat more viscous.

Try it and let us know how it goes.

Yeah, I've seen that. Never liked it. I think they usually use carbide scrapers that I cannot believe would produce a durable edge. Even assuming you used stones, and even if it worked - each stroke sharpened the blade a little -- it wouldn't do enough sharpening to keep up with any real use. To me, this sort of gimmick is usually a sign of poor quality.

Sent mine yesterday as well. It wasn't a lot, but I hope it helps. Nowhere on the Net have I learned more about the craft of bladesmithing than right here. Thanks so much, Don, for making this resource available.

Hi Rick. I didn't know you'd found your way over here as well.

I'm looking forward to seeing the blade -- once I get home. Photobucket pics are blocked by our web filter here at work. Grr.

I would guess that the sand isn't easily reusable. Once linseed oil hardens it doesn't really un-harden, to my knowledge. The advantage of Petrobond and similar oil sands, and greensands, is that they can be reused repeatedly with occasional topping off with fresh oil or water/clay. The recipe you have there looks very much like one for cores.

What sort of furnace are you thinking of for the cast iron? I'd love to build a cupola, but I really don't need the capacity to produce large quantities of cast iron.

Ah, that's a different kind of oil sand. It's using oxidized linseed oil as the binder. Can it be reused?

Daniel,

With regard to backyardmetalcasting.com, don't just read the main pages. Go to the forums, read and ask questions. You'll learn a great deal there.

Pottery suppliers are the backyard hobby caster's best friends; I'm fortunate to have a couple good pottery supply shops within 20 minutes or so of my house, and I've bought lots of stuff from them (most of it for things other than casting). They carry all kinds of stuff you won't find too many find other places: clays, useful chemicals , ceramic fiber, firebrick (both hard and insulating), alumina, very fine silica sand, etc. Yes, the clay mentioned on BYMC was dry, powdered clay. For greensand, which is casting sand bonded with clay and a little moisture, bentonite is a commonly used clay. (You'll fine recipes on the Internet if you look around. Southern bentonite, western bentonte, various proportions of both . . . ) Proper oil sand normally uses organo-bentone, which is bentonite clay that has been chemically altered so that behaves in oil the same way that regular clay behaves in water; i.e., absorbs the oil and becomes sticky, which is what binds the sand together. Mixing oil with regular bentonite clay won't give you real oil sand; it'll just give you an oily mess.

I haven't quite figured out where to buy organo-bentone, yet, so I haven't tried making my own oil sand.

Jewler's supply shops sell high quality investment, carving waxes, etc., if you want to get into investment casting. A lot of folks do investment casting using Plaster of Paris grogged with silica sand, but it's somewhat iffy and I'd be very hesitant to try it with higher-melting metals (brass, bronze, silver, etc.)

Ceramic shell investment casting is a great method for fine detail and great surface finish, but it's fairly expensive and time-consuming, and you have to know what you're doing.

Jewler's supply shops can also sell you very fine, oil sand-like material that I believe is actually made from clay. You use it like regular oil or green sand, but it provides a very fine surface finish. Delft Clay is one kind. It's not cheap, but it is reusable.

By the way, I'm not a very skilled caster; I've just read a lot about it. (I've done some rather crude castings, but I haven't had the time to really get into it. Someday . . .)

Thanks, Scott. I may give them a call. Haven't been able to find any good discussions on the web of what industry uses for pots or pot linings.

Howard, thanks. If oxidation from the heat source is the problem, some of the ITC products that are designed to protect steel from oxidation in high temp environments may help.

I've been reading up on high temp salt pots, and I have some questions for folks with relevant experience.

1) Does the extra longevity of 316 stainless for the pot justify the extra cost? Is it true that 304 doesn't last much longer than black steel pipes?

2) What is it that causes SS high temp salt pots to degrade? Scaling away from the outside, corrosion from the inside, or both?

3) Has anyone here ever considered a ceramic pot? I suspect that the right ceramic tube would be more or less impervious to both oxidation and chemical attack. From what I can tell, industry often uses ceramics for this application. Even if I'm right, I'm not sure what the right ceramic would be. But I know where to get slip-cast, close-ended alumina and mullite tubes greater than 3" inside diameter. The cost is something like twice that of comparable SS, but they might make up for it in longevity. I'm just not sure. (The same place sells some more exotic ceramic tubes, including zirconia, but they're even more expensive.)

4) Anybody ever tried ceramic coatings like the various ITC products to improve the longevity of their SS pots?

Steve R,

Unpublished applications are meaningless. I could file an application for the previously mentioned thermal chunkification of water process tomorrow; that wouldn't mean you couldn't still make ice cubes in your freezer. If that's all "fluffy" has, it's as Ken said: he's got nothing. He probably knows that. That doesn't prevent him from making threats, though -- or possibly even from filing a frivolus suit, if it comes to that.