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Author Topic: Fun project, hopefully a moneymaker!  (Read 13196 times)

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Re: Fun project, hopefully a moneymaker!
« Reply #10 on: September 14, 2013, 01:59:35 PM »
Adprinter, I forgot about the comment on the MDF. Yes, I was surprised how well it stood up to the heat. It was a Lead Alloy that melts at about 550F, I take it to about 600F to pour. It barely scorched the MDF, I think I could have cast a few more without trouble. If it had failed, I was going to try to cast it with Bismuth. It still has to be about 550F to cast. I wish I could afford some Woods Metal. I just don't have any Cadmium. Woods Metal melts at about 160F, that would be pretty neat to try.
I have had a few failures, metal shooting out between the flask, melted through what I thought was a thin steel plate, turned out to be Tin. That was fun, molten Aluminum everywhere. I want some petrobond for brass, it likes to spit and pop out of greensand. Glad I have good PPE.
Re: Fun project, hopefully a moneymaker!
« Reply #11 on: September 15, 2013, 03:27:41 PM »
Adprinter, I forgot about the comment on the MDF. Yes, I was surprised how well it stood up to the heat. It was a Lead Alloy that melts at about 550F, I take it to about 600F to pour. It barely scorched the MDF, I think I could have cast a few more without trouble. If it had failed, I was going to try to cast it with Bismuth. It still has to be about 550F to cast. I wish I could afford some Woods Metal. I just don't have any Cadmium. Woods Metal melts at about 160F, that would be pretty neat to try.
I have had a few failures, metal shooting out between the flask, melted through what I thought was a thin steel plate, turned out to be Tin. That was fun, molten Aluminum everywhere. I want some petrobond for brass, it likes to spit and pop out of greensand. Glad I have good PPE.
Jammerm, what device do you use to measure temperature of the molten? I have a laser thermometer, but it will only measure up to about 500 degrees F. My foundery oven is a charcoal-fired design, using an old heat gun (aka glorified blow dryer) to air blast the charcoal. I have since learned that my scrap pieces of left-over oak (from my CNC carvings) yields a hotter burn (20 minutes from lighting, to molten vs 30-40 minutes using charcoal). Yes, it burns up faster than the charcoal. But it does the job (and since I already have it, the price is much cheaper than buying charcoal). My biggest problem, is coming up with a trivet to hold the crucible pot which will withstand more than a couple of firings. I have tried many designs. Including a disc brake rotor, with threaded rods casted in the same mortar mix used to line the furnace with, as the legs of the trivet. But the ends of the rods were exposed to the heat, and the threaded rods melted, and ran out of the mortar castings, which then crumbled and broke off. You mentioned the greensand spits and pops. I have learned, that the more vent holes you put in the sand mold, the better. Just be sure that you don't plunge your wire any closer to the pattern than about 1 inch. Also, before assembling the cope to the drag, go over each with a blow torch (I use a Mapp gas torch for this). It will improve the spit and pop problem. And it will save time (with failed castings) in testing whether or not your mold is durable enough to hold up for the casting. I.E.- if the torch causes it to crumble, you have just learned that the mold wasn't actually ready to use for a casting, because it would have been a failure anyway. Much easier to just re-mix the sand, and re-ram the pattern in the sand, without the need to also re-melt the useless blob of aluminum that would have otherwise resulted!
Re: Fun project, hopefully a moneymaker!
« Reply #12 on: September 15, 2013, 04:51:24 PM »
This is a little kiln pyrometer I got from ebay, I think it was $75. I use it for Aluminum and for small brass melts. I submerge it in Aluminum but not brass. Mostly I just read the furnace temp.

This is a little electric furnace I built, it worked great. That's Brass in the crucible, I think it's 85-5-5-5. I got it too hot and the Zinc started burning when air got to it during the pour. I don't remember what I was casting. This was too hot for the elements, when I tried a second brass pour they broke and I'll have to replace them.

I was able to get a lot of fire bricks from an old foundry. I cut one of the 1" ones into triangles and use them for a plinth blocks. They have held up very well. I've also made some with refractory that has worked well.
I've got a mix of graphite and alcohol that I spray on the greensand and then light it. The alcohol burns off and heats the sand and the graphite makes a smooth surface. That's a good idea with the torch, I need to get a rosebud tip for mine.
This is my small gas furnace, it runs on propane with a blower attached. It uses a high pressure regulator and puts out a lot of heat at 5 to 10 pounds pressure. This is lined with commercial refractory rated for up to 3200 F. I don't have anything that can read that high of temp, but I think I've been close to 2600 F a couple times, especially when I used a waste oil burner. This little guy didn't survive the move from Ohio to Tennessee.  
Re: Fun project, hopefully a moneymaker!
« Reply #13 on: September 18, 2013, 12:14:19 PM »
This is a little kiln pyrometer I got from ebay, I think it was $75. I use it for Aluminum and for small brass melts. I submerge it in Aluminum but not brass. Mostly I just read the furnace temp.
What material is the sensor on the Pyrometer made of? I can't image submerging anything into molten metal, without it resulting in the sensor itself becoming a part of the molten metal. Thanks for responding! I could not recall the word used to describe the mortar material I used to cast legs for the trivet- "Refractory". Your little oven looks very similar to mine, except that mine was constructed from an old hot water heater tank, instead of a freon tank. It stands about three feet tall, and will accommodate up to an 8" diameter  crucible pot. I have actually used the freon tanks, sawed in half-as crucibles placed inside my oven. Yes, the steel crucibles do burn holes thru them after only a couple of firings, such is life for the financially challenged! I have not yet tried melting brass, but I have a cast iron dutch oven I have been saving for this purpose. Do you have any experience with crucibles other than the carbide graphite variety? I have used stainless steel (of the dollar store salad bowl variety), plain steel (of the freon tank, or LP tank variety), also stainless steel pressure cooker pots, as well as cast iron cookware. Experience has taught, that the steel pots can be used as crucibles, but great CARE must be excercised, when stirring the molten, and spooning the dross. (So as to not poke a hole thru the bottom of the pot, which is usually in a near-molten state itself!). What experience have you had, with cruciibles? What material were they made of? Where did you find them?

Offline khalid

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Re: Fun project, hopefully a moneymaker!
« Reply #14 on: September 18, 2013, 12:55:02 PM »
show us a brief video..unable to believe MDF can be a mold for melted metal pouring..
Re: Fun project, hopefully a moneymaker!
« Reply #15 on: September 19, 2013, 11:34:55 AM »
Well, I didn't have a video and everything is still in storage. Again it was a lead alloy and was less than 600 F at the pour. If it would have been a heaver casting with thick areas that would hold heat, I imagine it would have burned the MDF. This is thin and cooled very fast. I was surprised how well it worked.
I haven't made any money, my son isn't much of a salesman. He took it home and hung it in his bedroom. I'll have to get with the local cruise ins here, there's one about every month.

The thermocouple is the usual bi-metal wire with the end welded with Nickel, I believe. The it has ceramic insulator on the outside. I have used just thermocouple wire twisted together, or clamped with a steel connector. Too much of a chance to get false readings with a set-up like that. I've also got a couple of these old temp controllers, they look like something from a Steampunk set-up. they work but don't do well over 1000 F. The one I have used is 1800 F max, this one in the picture I picked up at a flea market for $18, it's not working but they are pretty simple, I think I can fix it.

Offline Chaoticone

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Re: Fun project, hopefully a moneymaker!
« Reply #16 on: September 19, 2013, 11:50:46 AM »
show us a brief video..unable to believe MDF can be a mold for melted metal pouring..

Do a search for evaporation foam casting. You would be surprised if you have never seen it I think.

Thanks,
Brett
;D If you could see the things I have in my head, you would be laughing too. ;D

My guard dog is not what you need to worry about!
Re: Fun project, hopefully a moneymaker!
« Reply #17 on: September 19, 2013, 12:04:49 PM »
I like doing lost foam casting, it just stinks.
Drain Cover in blue foam

In Aluminum