Matt Bower

Aliens!!!!!

But they are kinda cute, in a weird way. They take me back to the robin that Dad and I raised and released when I was a kid. (It was a bit further along than that bunch when it fell out of the nest.)

Surely enough. My polarity got backwards somehow. Sorry about the massive confusion.

Whew! Glad we got that figured out.

I assume you have somehow reversed the polarity without realizing it.

In electroplating, the work piece is the cathode (negative electrode). The electrolyte donates metal, which is plated onto the cathode, and is then replaced by metal stripped from anode. If you don't believe me, look it up.

Electroetching is the reverse of electroplating. Therefore, the work piece must be the anode (positive electrode). Metal flows off the anode and onto the cathode (or the fiber pad connected to the cathode). This is how the etching process removes material. Therefore, in electroetching the work piece must be the anode, and the etching pad must be connected to the cathode (negative terminal).

Alright. Another question.

 

Which would be better:

1 inch of inswool + 2 inches of castable refractory

or

2 inches of inswool and 1 inch of castable refractory.

The one with more inswool will heat up must faster and will be more fuel efficient. Two inches of castable refractory (measured along the radius) is a lot.

I can get 15lb bags (and more) of castable refractory locally.

Well then that's probably the smart way to go. It's a waste to pay shipping if you don't have to.

So just grab whichever is cheapest? (Satanite or castable stuff)

That's what I'd do. Darren Ellis sells both Mizzou (high density castable refractory) and Satanite in small quantities, and five pounds of either one costs the same. (Mizzou is a little cheaper if you buy more than five pounds.) I'd personally be inclined toward Mizzou, but it probably doesn't matter. I only say I'd be inclined toward Mizzou because mortars typically are meant to be spread pretty thin, so I'd be afraid that Satanite might be inclined to crack if you lay it on a little thicker than intended. But that may not be a real concern, especially if you don't plan to lay it on very thick.

If you can get ahold of castable refractory locally, there are many, many others that'd do just as well. In my experience, the problem with buying locally is that they want to sell you 50 or 100 pound bags.

I just picked up a 7gal air tank that I plan to build the forge in.

 

What if I were to line the inside of the tank with inswool and then pour in castable refractory on top of that(with an inner-spacer tube of course)? Then coat the castable refractory with ITC-100. Would that still be efficient enough to heat up quickly? Or is the inswool-satanite-ITC100 still the better way to go?

Satanite is technically a high temperature mortar, but for current purposes it's not significantly different from castable refractory. So as far as your two proposals, it's pretty much six one, half-dozen the other.

As far as how fast it'll heat up, Doug is exactly right: it depends on thermal mass, and thermal mass will largely depend on how thick your dense layer (mortar/castable) is.

Interesting thought on the preheating of air... Lionel suggests that due to density at temperature, cooler air actually burns better. I know I don't preheat my forge air, and it gets screaming hot. I wonder if oil preheat is what's making the difference in your setup.

 

As for the coaxial oil flow pipe, I like it, and it's a thoughtful approach to cleaning up the assembly. That goofy right angle gas line is just... goofy. He's right about a right-angle, and could easily position it much further back.

 

I'm not convinced a full 18 inches is really required, I think 12 would do just fine. It would get hot, no doubt, but not hot enough to hurt anything on the assembly. For the space-constrained like me, that's important. Of course I could just put it outside the shop...

I'm not sure I agree with Lionel on the air preheat. Generally speaking, recapturing waste heat always boosts performance. (If it's good enough for steel mills, it's good enough for me.) I haven't sat down and tried to figure it out mathematically in this case -- not sure I'd know how, anymore -- but if you look at the recuperative forge that Rob Gunter developed at Sandia Labs, the whole principle of the thing is that it preheats the incoming air. It's suposed to be both hotter and considerably more efficient than a similar forge without the preheat. Different fuel, yes, but I don't think the underlying principles depend on the fuel.

Preheating the oil certainly helps for a number of reasons, not the least of which is that hot oil is less viscous and atomizes better. (In this design the atomization is crude at best.)

My fuel line and tuyere/injector pipe are much shorter than the ones shown at the link I provided you. There's really no big advantage to the long pipes, that I can see. This isn't like a propane burner, where the fuel and air need to mix thoroughly before they hit the forge/furnace chamber. In this design that all takes place inside the chamber. If you were running a heat exchanger, the extra length will provide a place for the preheat to occur. I think that's about the only potential advantage.

Chris,

I've built two oil burners. The first was almost identical to Lionel's "Brute" (Lionel being the "guy over at backyardmetalcasting.com"). The second was a simplified version that employed a fuel line coaxial with the tuyere. (I used a T fitting with the air coming in the side and a plug in one of the orifices. The plug is drilled to accept 3/8" copper tubing, which is the oil line.) Both are capable of getting almost scary hot. So no, the fuel line doesn't need to come in at an angle! Here's one that a guy over there posted just a couple days ago; it's almost identical to my simplified "Brute," except that I used 2" pipe and fittings: http://home.comcast.net/~moya034/burner/

These oil burners work better if you preheat the incoming air. The first one I made had an elaborate heat exchanger arrangement to preheat the air (and consequently the oil, since the hot air flowed around the fuel line). It got just plain ungodly hot.

My chief problem with this style of burner has been achieving regular, consistent fuel flow. That may be in large part due to my mediocre fabrication skills.

I'm just down the road from you. Shoot me a PM if there's anything I can do to help you. I haven't been playing with the injector style oil burners much lately; I'm stilll chasing the Holy Grail, i.e., an oil burner that burns oil from a cold start. I'm just starting to fool around with a Babington design. But I'll be happy to help in any way I can.

I mostly lurk here, because I know so little compared to so many others. That said, Scott MacKenzie has more than once recommended Hougton on Quenching as a good primer on quenchants and how they work. So a while back I downloaded and read it. And one point that comes up several times in Houghton on Quenching is that the properties of oil quenchants change with use. For example, viscosity and flash point can both change -- and viscosity, at least, is very closely related to how fast a quench oil removes heat. Don makes basically the same point somewhere on his main site -- I can't find it right now -- when he mentions that flaming quench oil wears out quickly. The same process happens over time, even with good quenching practice; it just doesn't happen as fast.

As I think I've said over on PP, John, it's all the creative detail in your work that really gets me. Great stuff.

Keep looking and eventually you'll find wrought iron. If you're in a hurry you can buy it from Darre Ellis: http://elliscustomknifeworks.hightemptools...roughtiron.html If you want the full experience, pop over to the Bloomers and Buttons forum here and start learning how to make your own. The Rockbridge Bloomery site is also very informative: http://iron.wlu.edu/

I can't make up it to Maine for a five-day class, but my family and I vacation about 60 miles from Auburn for a week every summer. If a one-day lesson of some sort were possible during that time, that'd be fantastic.

They have been eating their siblings that did not make it.

Of course! Shoulda known. When I was a teenager I spent many hours one summer hunting crickets in our (big, old, unfinished, turn-of-the-century) basement with an air pistol. I quickly learned that crickets are cannibals, and the corpses of my most recent victims made the best bait. By the end of the summer I'd pretty much wiped them out -- and had become an almost superhuman point-shooter with that air pistol.

Wow. That's wild. It's hard to believe they start out so tiny. I wonder what they manage to kill and eat when they're that size.

I had one weird incident a couple of nights ago when McAfee went absolutely nuts over this site, but that was the first and last time it happened.

Park says the working range of #50 is 50F to 120F. I warm mine up just a little, to around 100 degrees.

Park also says the working range of AAA is 100 to 180 F. I've never used AAA myself.

Am I the only one who's ever tried drywall plaster? I used it on 1075, and darned if it didn't seem to work. Yes, it came off in the quench -- but it stayed on long enough to leave a visible hamon.

Caveat: I've only done a handful of clay quenches, so I don't have a lot to compare it to.

I have no experience with hydraulic presses myself, but someone who does recently told me that they're often louder than power hammers. Hydraulic pumps can really scream. This surprised and disappointed me. I'm in the same situation you are, and I had been considering an hydraulic press as a quieter alternative to a power hammer. Apparently that's not necessarily true, although I'll be interested to see what other folks who've worked with both have to say.

You might also consider a rolling mill. http://www.anvilfire.com/bookrev/mcdonald/...olling_mill.htm This design looks simpler to build than a press, and apparently they really are extremely quiet. A fly press would be good, too, though it's not the sort of thing that's feasible for most people to build from scratch, and it won't do everything that an hydraulic press would.

Oops, just remembered you were asking about a treadle rather than a power hammer. But I guess my point still holds.

Not sure I followed all that, Jake, but my understanding is that the Vikings mostly -- if not exclusively -- used side-blast forges.

Sam, one difference is that in a side blast forge the clinkers don't tend to collect right over the mouth of the tuyere.

Those are some of the nicest homemade lifting tongs I've seen -- certainly as nice as most of the other backyard metal casters' tongs that I've seen. You should accept that crucible failure is inevitable, sooner or later, if you mess around with casting long enough. Plan so that when the crucible does fail, it won't hurt anyone or endanger any property. And as long as you've done that, don't sweat the tongs too much. They look pretty darned good to me.

Pottery suppliers sell very pure silica sand and flour. Higher purity = higher melting point, if that's important. It's cheap. Not as cheap as play sand, but cheap enough.

And have you forge welded with that combination? (Burner and forge, I mean.)

I built my first Reil style burner recently with a 0.035" tip in a 3/4" tube, and I'm finding that it runs a little rich. Have you noticed any such problems? I'm planning to try a 0.030" tip and see if that helps.

Thanks for that, Sam. It's just about what I' envisioning, and having that one to look at makes some things clearer in my mind.

I do think I can make mine even simpler, though.