Order arrived from the Opel GT supplier in the US. My shopping cart had a few hundred worth of stuff during their Covid sale, but it paired down to $58 by the time I ordered. I expected shipping for 1lb of little things from the US to be like, $10 at most.
I guess I wasn't really thinking, I don't need any of this stuff now and the savings from the Covid sale (after I pared it down) were completely swamped by the shipping costs of ordering now.
Even combining shipping with someone else local, a 4lb box was $48 (US) shipping + $18 CAD in duty. $80 CAD to ship 4lbs to Canada. At least we saved money by splitting that to ~$40 each, but, ugh. This is why many Canadians just ship to the border and then go pick it up themselves. If you don't mind the drive, even small orders cost as much as a tank of gas.
Anyway, mmmm, the smell of new rubbers:
- Steering boots
- Master cylinder reservoir seals
- Master cylinder tube
- Door and hood bumpers
- Transmission output seal
Also, I did a little comparison between the window regulator motors for Honda Civics vs. Dodge Caravans.
If you exclude the bearings and the end caps and all that and compare the actual motor (where it gets its power), the Caravan is about 150% the power of the Civic. So I might swap civic ones for Caravan ones (or any other cable-driven regulator, those are just the two vehicles I've been taking apart lately).
This might also mean it's geared differently and just moves faster rather than more powerfully, but, meh. Either was, beefier motor.
Aluminum Coupler:
- Now that I'm trying to pour a beer-can-sized amount of metal, (verus the golf ball sized amount of copper before), I can't just use firebrick.
- That's annoying, because I don't want to order a graphite crucible just for this little project. I need something cheap that'll hold together above aluminum melting temp.
- I settled on a stainless chaffing tray. This kind of thing:
- I melted some aluminum into it, but the metal was so thin, every time I accidentally bumped the sides with the torch it burned a pencil-sized hole through. Also it had trouble holding temperature. I ran out of battery juice before I had much melted.
- I made my first green-sand mold by mixing sand and ground up kitty litter, packing it into a flower pot around an aerosol can for the shape, and then set my plaster spline at the bottom. Wait, is aluminum heavier than plaster? Is the plaster thing just going to bob up through the metal like a cork? Hmm. Too lazy to anchor it with a bolt.
- I called up my fire extinguisher guy and asked him if he ever has old extinguishers for disposal. He said sure and dropped off a handful. The steel is thick enough that it makes good crucibles.
- I chopped the slimmest extinguisher in half and set it into a coffee tin, filled the sides with sand. Hopefully to give it enough thermal insulation to hold the heat. Melted a bunch more aluminum, but still ran out of juice.
- I noticed the can took like an hour to get hot, so I thought, what if I pre-heat the whole can/sand/crucible on a stovetop for an hour or two first, so that it's pre-heated and won't drain batteries. So I did that.
... and it worked!
Sort of.
Problems:
1 - Normally in a combustion furnace you have gas, or CO2 from the burnt fuel. This sort of replaces oxygen. That's good, because oxygen bonds to the molten metal and creates dross, a waste that has to be scraped off before you pour.
Also, the temperatures are low, 3600'F max for propane (and less by the time it touches anything). The hotter the temperature, the more aggressively oxygen will bond to it.
Also, with a combustion furnace you heat the vessel, not the material, so if a layer of oxide forms above the pool, that's okay.
Also, you heat from the bottom up, so it all melts.
With a carbon arc torch, you have regular air everywhere. You have 36,000'F (!) plasma. You heat the material itself, by conducting through the material, the surface of which is already corroded and doesn't want to conduct so the arc keeps going out unless you poke or stir it, oxidizing a bigger and bigger surface scab of waste material. And, heat has to work its way down via conduction, so the bottom is solid and the top is liquid.
All this adds up to mean that the amount of material wasted is like 30% of what you want to pour. You have to scrape it off right before you pour.
2 - I didn't realize how vacuum-packed sand would get around a smooth steel crucible. I used up every last bit of energy in the batteries melting as much material as I could, to as high a temperature as I could. Finally I'm ready to pour, I scrap the dross away, grab the crucible with pliers... the whole coffee can lifts up. I can't shake it loose.
I end up having to stab the sand with a screwdriver a dozen times to make it let go of the crucible. Meanwhile the lid is off and it's rapidly cooling.
I go to pour, and it's just barely at the melting point now. I dump it into the mold, which boils off a little steam inside the liquid metal, cause it to belch upwards to vent. The top of the molten metal collapses down after the air releases, then belches again. Up then down. A third belch... and it only goes part way back down. The metal is solid.
I tried to add more, just so the weight of the incoming metal would pop the bubble and fill the void, but, the bottom 1/3 of the crucible had turned solid.
The casting filled the mold pretty much to the brim, more than it needed to.
So, I broke out the casting and inspected it. Somehow I never took pics of this. I could tell the balance point was almost exactly at the end of the gear splines, which meant the air bubble on the "solid" half must have been almost the size as the whole splined area.
I cut the top off the "solid" end and revealed...
:/ Yep.
Giant air pocket.
I don't think it's a good idea to just pour more metal into that hole, I think you generally have to cast everything at the same time. You can even see there's a couple layers on top where it burped and froze.
Not bad for a first attempt.
Flipped it over cut the rough sandy texture off, and had a good look at the splined side:
... not bad!
The edge needs to have a taper filed into it, it's still got the saw burrs.
Measuring, it's about 0.003" smaller than the motor shaft. Meaning... must still have some crust on the edge interfering with my calipers, or, it's actually slightly small.
I was able to hammer it on 1/4" pretty easily, letting the motor splines shape the coupler's splines a little bit, but I'd rather not be hammering on the motor.
As a proof of concept, I'd call that a success. This looks to be technically possible to do with aluminum.
...
Zamak Coupler:
- I hate aluminum. It's scummy, surface is crummy, it oxidizes badly, it's weak. It melts at a high temp. I don't want it.
- Die-Cast Zinc/Zamak is as strong as cast-iron, surface finish is great, it pours well, it doesn't oxidize badly, and it melts at stovetop temperatures apparently.
- I rounded up every bit of die-cast zamak I could find. Conduit couplers, bathroom towel rod holders, some V-pulleys from a treadmill CVT, some plumbing fittings, a 2-hole punch, railing brackets, chainlink fence toppers, etc. I might barely have enough zamak to make this work. Hard to find, it seems with improved technology, lots of stuff is cast aluminum these days.
- Bought a cheap fried-egg-sized cast iron pan for a crucible and tested whether zamak actually melts at stovetop temperatures.
- Just barely... barely... on my little portable electric burner, but it does. I test-melted as much zinc as I could fit in that little pan (about 1/3). Seems to work.
- Dumped the zinc into a steel pan to make an ingot for the next time I melt. Zinc is 3x as heavy as aluminum so, I don't trust the plaster spline thing to not cork up without being anchored.
...
Next up, more sand, another mold, and an attempt at a zinc coupler. I'd like that to work instead of aluminum if possible.