Re: Casting Aluminum: Making an electric furnace dirt cheap.

Mike Scouty McScoutington /

That is pretty fantastic

Re: Casting Aluminum: Making an electric furnace dirt cheap.

for inspiration, dude goes through all the steps start to finish designing and casting his own cylinders for a kawasaki.

http://www.alloyavenue.com/vb/showthread.php?11802-Air-cooled-2-cycle-motorcycle-racing-cylinder

Re: Casting Aluminum: Making an electric furnace dirt cheap.

Blaine- The artist formerly known as Plumber Crack "(OFMC)" /

Thanks guys. That's an awesome link Lee. A lot of details covering the entire process. I wish i had that kind of free time. I guess I'll have to stick to just buying kits from treats. :)

I would have liked to put a gas hood strut on the lid that would have let the lid down gently by itself but it probably wouldn't like the heat. The springs take away a lot of the weight of the lid so hopefully the lid bricks won't break, should the handle slip from the hand while closing the lid.

I'm really pleased with how the action of the hinge turned out. There's less than 1/8" clearance on all 4 sides of the lid. I needed it to lift up 2" before swinging rearward, without hitting the back wall with the bottom of the lid. By raising the pivot point of the lifting arms an inch above the pivot point on the lid, the lid moves forward slightly until it is half way out of the hole. This minimized the amount of clearance needed. The following arm that keeps the lid level throughout it's travel is adjustable to allow fine tuning the action.

It tips the scale at 98 pounds. Pulling around 17 amps, so over 4000W of power. And no more tin can crucibles. Schedule 80 pipe crucible for aluminum and an A2 graphite crucible for doing copper. I need to finish up the controller wiring and assemble it into it's box yet and make a set of lifting/pouring tongs and everything will be completed. Hoping the double wall brick will allow me to hit copper temps sooner.

It's been a fun journey from junk space heaters to a purpose built foundry, and i'm looking forward to many casting projects. And at 4000W, it also doubles as a kickass space heater. :)

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Re: Casting Aluminum: Making an electric furnace dirt cheap.

Blaine- The artist formerly known as Plumber Crack "(OFMC)" /

I chose the largest graphite crucible that would fit in the furnace. Unfortunately the crucible wasn't perfect. The lid made contact with it for about a 1/3 of it's top rim. After about half an hour of grinding on it with my 6" belt grinder to remove only about an 1/8" of it, my belt was roached. It wasn't a new belt, but it's some hard stuff to grind.

Re: Casting Aluminum: Making an electric furnace dirt cheap.

copper melts at 1085C but you can alloy it with zinc. this is brass and you can drop the melting point to under 900C and still have a usable brass alloy, and it's much more castable.

A good bronze (alloy w. tin) is also lower melting and more castable and usable than Cu.

Even the Ni Cr should be good to 1200 though so you need to fit in some kinda thermocouple and control your overtemps better and you'll have the melt under control

As far as ceramics the cheaper and more impure the lower the melting. anything with glaze or glassy surfaces will help melting too.

at least for most artist ceramics they're fired to a cone rating (slump T of orton cones, with 6 being a typical high fire and that being around 1200C

so low fire clays aren't gonna survive it. porcelains should, earthenware probably wont. depending on your temperature control a flowerpot might work, old unglazed pottery and bowls etc. you can also make your own castable cements out of fire clay and basically fire them solid while firing the furnace

I saw a thing not too long ago where a dude was using carbon electrodes from the big 6V lantern batteries as arc elements (doesn't last long but actually pretty similar to what they use industrially) and powering it off of a microwave oven's transformer.

Most knife sharpening rods to my knowledge are alumina but used for hardness, where most ceramic knives are zirconia.

ceramic tubes are not particularly common by themselves, theyre used as supports in a lot of refractory builds, like putting together butcher block

It's partly a cost thing but also it's easier to manufacture a tube and it's lighter for the same strength, lotsa good reasons.

theres a dude called bill bolt who sells refractory, and zircar sells refractory also, both will do industrial grade stuff at hobby quantities.

The 999C limit on your controller you can apply correction factors so it just reads half the temperature of actual or something. make sure you've got the right thermocouple type for it and check it in boiling water that it reads exactly 100C as a calibration check (or if you're at half T, 50C)

I imagine it's a simple controller that's switching on/off. if it's having trouble maintaining a temperature or set for a narrow temp band it'll switch frequently and you'll wanna fan cool the controller.

Also 999C is OK for brasses and bronzes which are more castable anyway. but depends on your end goal I guess.

Re: Casting Aluminum: Making an electric furnace dirt cheap.

sorry I stopped responded too early, didn't finish

the settings on the PID are how many points it averages over and what it's responses are. basically it controls % time on for the elements and you can change settings that let it heat up faster but are more likely to overshoot for example. like tuning the curve as it approaches the setpoint T.

Re: Casting Aluminum: Making an electric furnace dirt cheap.

Blaine- The artist formerly known as Plumber Crack "(OFMC)" /

Thanks for your input Willd, but i've pretty well addressed the issues i've run into along the way. Instead of using ceramics to support the coil, i cut strips of fire bring to build a shelf for the second row of coil to sit on. I went with kanthal wire which has a higher operating temperature potential. The first pid controller i bought had a large portion of the settings locked, so i was unable to change many of the parameters. I am using high temp type K thermocouples, so i'm good there.

I did my homework and purchased another pid that would do what i needed and had no lock on it's functions. There are quite a few functions and features that i could research to better understand things that i might want to change, but for the most part, it remained full on until it got close to the set temp and then started cycling on and off like it should. It's currently set to a "self tuning" mode, but i've only used it 2 or 3 times just to verify that it worked.

I had planned on making some brass with the many pounds of copper that i have. I imagine i'd still need to hit copper temps for the copper to melt and mix with the zinc. Maybe i'll experiment by melting the zinc first and add copper to it and see what happens. If it'll work that way, i'd rather run it at the lower temp of brass. That few hundred degrees difference makes a huge difference in the heat that radiates out when you open the lid.

It's strange how some things work. Many brass alloys melt at a higher temp than zincs boiling point, yet the zinc doesn't boil out of the mix, or does it? Hmmm.

Pic of my zinc collection.

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Recipe for Yellow Brass

2 cups of copper

1 cup of pennies(post 1982)

2 tablespoons of boric acid

Heat until bright yellow, stir, spoon of nasties, then pour.

Re: Casting Aluminum: Making an electric furnace dirt cheap.

zinc does absolutely fume out somewhat

that's why you have (or will have) a good white ring by the exhaust (and a brutal headache and nausea if you're not careful)

it's a cool project

there was a sweet dental furnace at a local industrial surplus at 14"w X 17" X 13" inner for only 400 bucks. crazy deal, kanthal too so like 1200C

Re: Casting Aluminum: Making an electric furnace dirt cheap.

Blaine- The artist formerly known as Plumber Crack "(OFMC)" /

I had a few hours today to spend on this project to wrap up the controller and test things out. I stuffed the PID in to 3 junction box extensions and tack welded a blank cover plate on the back to mount the SSR's on the inside and their heat sinks on the outside of the back.

I mounted a double gang switch on the front. One to turn the power on to the controller and the other switches the control wire to the SSR's so the heating element can be switched off while feeding more metal in to the crucible. I welded a pair of 5/16-18 "legs" under the front to angle the box up for an easier view.

Plugged things in and set it for 1400F and loaded up some chunks of a Silverado throttle body and shut the lid. The PID remained on continuously until it got within maybe 40 degrees of the set temp, at which point it started to cycle on and off as it gently worked it's way up to 1400F. I was able to get enough aluminum in the new crucible to pour 5 muffins, and the stainless crucible didn't oxidize and flake off like the steel cans i had been using. I'm looking forward to some fun projects with this thing.

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Re: Casting Aluminum: Making an electric furnace dirt cheap.

Cool.....

Its as if you are preparing to mass produce something of great importance for the world....;)

Re: Casting Aluminum: Making an electric furnace dirt cheap.

Andrew Squiggman /

Pacer Racer Wrote:

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> Cool.....

> Its as if you are preparing to mass produce

> something of great importance for the world....;)

metal muffins. How's your electric bill Blaine?

Re: Casting Aluminum: Making an electric furnace dirt cheap.

Blaine- The artist formerly known as Plumber Crack "(OFMC)" /

I do have a few ideas i'd like to try. I just wish i had more free time. My friend has been on binge investment casting skulls recently using aluminum and brass. I'm not sure what you do with them though. I guess as long as he's having fun, that's all that matters.

The electric bill wasn't too bad last month. Unlike that month of experimentation of shoving 240v up the ass of anything i could. Smoke was a rollin'. Had to open the garage doors several times to air out the shop. I thought i really fucked up one day.

I have a crucible i made from a 5" piece of schedule 80, about 5" deep. I use it in my potbelly stove that i get kickin' cherry red around the bottom on about 5 pounds of anthracite, full draft. I just sit the cruible right on top the coals.

I scored a pair of solid aluminum BMW(?) lower control arms that were a bitch trying to cut up in to 4" pieces with the band saw to melt in the electric, so i just cut them in half so i could stand the pieces up in the potbelly and let them slowly melt into the crucible.

Now each of these control arms have a ball joint that is like molded into the arm or some shit. It doesn't just press out, so the plan was to just melt the aluminum off of it like i've done with plenty of shit before. As it was melting, i was periodically checking to make sure that the control arm was just sinking into the pot, and not falling over and into the coal.

All was going well. It got down to basically the huge chunk that contained the ball joint, and i gave it a poke to position it just right so it would all make it into the pot as it melted, and just around this time, the grease inside the joint was really starting to smoke a lot. I put the lid back on the potbelly and as i was reaching over to hang the handle on the nail, a hellaciously loud explosion blew the lid of the potbelly into the air and bounced off my 12ft high ceiling and landed on the floor aside of me, and at the same time, ashes and hot coals blew out of the bottom of the stove.

The smoldering gases from the grease had ignited. I've had similar but much smaller blasts like that when adding a few shovels of coal to the fire. When you first add fresh coal, it gases off, and if there's no open flame to burn the gases it can accumulate and then explode when it does ignite. This is why i will shove a piece of wood into the hot coals that starts burning almost instantly, then i add coal. You have to have a blue flame dancing around on top of the new coal. If you add too much coal too quickly, it smothers the blue flame. The stick of wood cures that problem.

About a year ago at work, my co-worker had a ball joint type sway bar link that the nut had completely rounded off on him when he was trying to replace it, so he used the fire wrench to cut it off. About 10 seconds after it had dropped to the floor, it exploded and the ball end took off thru the shop one direction and the socket end went the other.

The ball and socket were loose, but once it landed on the floor, hot as hell, the grease inside it was boiling and just the way it landed, the joint had sealed up enough and made pressure until the socket left go of the ball. It was loud as hell and then you could hear the pieces bouncing off of stuff throughout the shop and everyone in the shop turned and all of us just looking at each other wondering what the fuck just happened.

At first when the potbelly exploded, that's what i thought had happened. But then i remembered how badly it was smoking and that there were no open flames to burn off the gases.

The last one is about the size of a shifter knob. Getting a smooth surface consistently has been a challenge for him. One time will be smooth, while the next one might be so rough that it looks like it came from a totally different mold.

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Re: Casting Aluminum: Making an electric furnace dirt cheap.

Pretty cool skulls.

Reminds me of the movie The Phantom with Catherine Zeta Jones.

So when your friend gets done playing can I bring my truck full of catalytic convertors over to melt down??

Re: Casting Aluminum: Making an electric furnace dirt cheap.

Blaine- The artist formerly known as Plumber Crack "(OFMC)" /

^ You're going to need a chemistry set, not a metal furnace.

Re: Casting Aluminum: Making an electric furnace dirt cheap.

Blaine- The artist formerly known as Plumber Crack "(OFMC)" Wrote:

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> ^ You're going to need a chemistry set, not a

> metal furnace.

Yeah I kinda figured after looking at some videos about gold and platinum.

Re: Casting Aluminum: Making an electric furnace dirt cheap.

Blaine- The artist formerly known as Plumber Crack "(OFMC)" /

Fired up the furnace today for a quick lost foam casting and thought about this thread. Just wondering is anyone has cast anything cool lately.

I made a thingy for my friends jack. It somehow went missing.

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Re: Casting Aluminum: Making an electric furnace dirt cheap.

Blaine- The artist formerly known as Plumber Crack "(OFMC)" /

My friend that does copper and brass just made this thing. Pretty cool.

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