Do people care that the top of the can and the rest of it are two different types of aluminum alloy?
Do people care that the top of the can and the rest of it are two different types of aluminum alloy?
In this context it doesn't matter much. when they are mixed together there isnt enough non-aluminum to make a ton of difference when it comes to casting. when its added to copper to form aluminum bronze, the aluminum content is low enough that the manganese and stuff in the can tops gets further diluted to trace amounts. Furthermore the stuff people cast in hobby foundries like this arent high stress parts or commercial grade, so minor impurities dont matter much.
Ahhah. I've been waiting on this video. That said, I haven't watched it yet before typing this post, probably a bad call, but I want to write what's in my head while it is still there.
I got the propane burner working!! I'm running into issues after 30-45 minutes but I just posted about that on the avenue and I'm curious as to why.
So today, with the working propane burner, I put my dirty crucible into the furnace and fired her up. I call it dirty because of all the dross and unpoured aluminum from my charcoal experiments.
I dropped some can ingots into the crucible to have a better base to melt into. They took a LOT longer than cans in charcoal did to form a pool, but I dumped a bunch of losalt ontop of the puddle, and started adding in the dross I had from previous castings. I took off a lot of dross, but recovered a butt load of good metal. 4 ingots turned into 8, mostly from my old dross.
This remelted can ingot has made ingots that appear much shinier and to have less defects. I haven't drilled or cut any, but they look better than they did before.
The graphite crucible came in the mail, and so did the tongs. The tongs won't work with the crucible, but they're way better than the stick of all thread I've been using to get dross out.
Now I'm going to check your video out. I suspect my tank is freezing over, even though it shouldn't be, so this will help with it's cooldown time.
Rufledt.. you've mentioned that you had bought petrobond a while ago when it was on sale. Since it's seeming like I need a muller to make good greensand at home, I've been looking at alterntatives.
While I'm not a big fan of the price, I have no idea how much I'd really be getting with a 50lb purchase.
How much did you get? How big is the container? Coffee Can size or rock salt bag size or somewhere in the middle?
Before I start dropping cash, I'm just trying to figure out if it would be enough to fill my flasks.
I got a 30lb bag of it, and it's about enough to fill the flat rate box it came in. I think it's a "Large" size flat rate box. It's enough to fill a small flask easily, but not a larger (12x12x7") flask. A 50lb should be enough, however.
Petrobond isn't as reusable as water based greensand though. The stuff that directly touches the molten metal burns black and I'm not sure it can be reused without a muller and more oil or something like that.
In reply to Rufledt:
You sir, are awesome!!! Thank You!!!
SanFord's keys will be on here as soon as I get back to town.
What kind of wood did you use to make the patterns for the key chains?
Rufledt wrote: I got a 30lb bag of it, and it's about enough to fill the flat rate box it came in. I think it's a "Large" size flat rate box. It's enough to fill a small flask easily, but not a larger (12x12x7") flask. A 50lb should be enough, however. Petrobond isn't as reusable as water based greensand though. The stuff that directly touches the molten metal burns black and I'm not sure it can be reused without a muller and more oil or something like that.
I havent checked into this thread in a while, so I apologize for the late reply, but Petrobond (which is a brand name, interchangeable with just about any variety of oil bonded sand) is absolutely re-usable, moreso than greensand. One benefit of oil bonded sand is that it is more stable between uses than traditional water based "green" sands, because it has almost zero water to evaporate out of the mix. The other benefit is that its much stronger and stiffer than water based sands.
Though the sand does darken when it contacts liquid metal, thats just the oil in the mix being singed - you get some carbon accumulation. This actually helps the sand. The carbon is a small particle that helps make up some of the space between the large grains and the microscopic clay. Having a greater assortment of grain sizes helps improve surface finish of castings - smoother, and less grainy.
Oil based sands do require some maintenance tho - about once every 2 dozen casts or so, I spritz my HOME BREWED OIL-BONDED SAND with a few squirts of 70% isopropyl alcohol. This is a very close substitute for the catalyst used in Petrobond's recipe. Remember I said "nearly zero" water. The catalyst is present to put just a small amount of water into the mix. Its the insolubility of water in the oil/clay mix that gives oil sand the stiffness and strength it is known for. I use 70% alcohol (there are several different concentrations available on the shelf at the typical pharmacy/grocery store) because I find that it has just the right ratio of water. The alcohol helps reduce the surface tension so it can be more easily incorporated into the sand.
I then mull by hand - basically smear and smush the sand against the wall of a 5gal paint bucket with a 6" paint scraper - to mix the alcohol in. This rejuvinates the sand very well, and its ready to go again.
Supposedly, eventually the mix will need oil added, as that carbonizing process I mentioned earlier will reduce the liquid oil component of the mix over time. I have not reached that point yet, with many many castings under my belt.
In reply to RevRico:
Boxwood. It's sold primarily as carving wood for crafts, that's because it carves easily, the grain is very forgiving, you don't get end grain tearing as easily as if you used pine (pine also has noticeable grain lines where boxwood is more homogenous like maple) but its soft enough not to ruin your tools. To me, it feels a lot like poplar, but more consistent color. I bet poplar would work just fine if you want a budget solution.
In reply to Rufledt:
Thanks. I have a plan, let's leave it at that. But I was going to go look at paneling or trim boards today, I'll keep an eye out for boxwood.
In reply to 4cylndrfury:
Thanks for the info! I've been saving the charred stuff in a separate bin, it seems to have lost the ability to stick, but Ill try rejuvenating it at some point. I don't have much burned stuff, I separated it out from the normal stuff after casting.
Quick question, since the burned stuff just feels like normal sand now, can I use it for lost foam casting before I try to rejuvenate it? Just a thought I had.
In reply to RevRico:
Cool, boxwood is usually a craft wood sold with balsa and stuff like that, never seen it as trim. I think any wood works for patterns if you can shape it, but in my experience the open grain of something like oak actually transfers to the casting if you use a fine sand like petrobond. It's kinda neat. Aluminum with wood grain 
In reply to Rufledt:
Regarding lost stickiness, just mix it back in. the quantity of burnt sand vs total is fairly small, especially with aluminum. Bronzes and Cast Iron are different. Also, the ratio of "Stickiness" in new vs burnt is not as great in reality as it may seem, in my experience. It does feel less firm when packed, but its actually not that bad relative to plain wet sand, and when mixed into clean sand, the difference is not really even noticeable.
Regarding using the burnt sand for foam: Can you and should you are 2 different things. Certainly its capable of lost foam molding. Ive actually had a lot of success packing typical cope and drag mold around a foam pattern, and then after gating and such, just leave the foam in there. The result is great, less distortion than plain sand, and less trouble than coating foam with thinned drywall mud or plaster.
The issue for me is that the sand stinks afterward - I think its whatever is left behind after the foam vaporizes, but thats personal preference. Im sure that long term, you could see problems with sand that has been exposed to a high number of foam castings, but intermittent use shouldnt hurt it.
In reply to RevRico:
The Kastolite is in. 
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