Forging With A Kiln?

[Mcgyver]

Murphy, really good points about the oven. how feasible would a 9x9x9 or thereabouts up to 2000F be? Any plans out there that you know of? how do the electrics work - ie how do you spec, find & control the heating element? thanks for your insight and help

[murphy625]

BAhahaha..

That's a TOY !!
Don't waste your time building it.. It would cost more to build it than to just find an old used Lindberg or something...
Here you go:
Item number: 7515890138
I was thinking more like 3 feet x 3 feet or larger.....

2000 degrees is easy.. Just about any grade of ceramic will do that and then some.

For that size oven, electric would be fine LOL.. <<<Changed my tune eh?

The electrics are controlled using a few different formats.. The new ones are very high tech using power transistors (SCR's??) to power the elements.. (Sorry, cant help you with this one).. I think the one in your picture probably has a rheostat to control power to the elements. The other way is to pulse the element on and off.. When full power is needed, the element is on, as the controller senses it closing in on the target temperature, it pulses the element on and off.. (several times a second).. The element stays as hot as it needs to keep the temp stable. Gas works by variable butterfly valve position which varies the number of btu's being burned..

For something that is less than a cubic foot in size, I would just buy it..

Murphy

[Mcgyver]

lol, 3x3x3 !! I picture you coaching someone through building a cubic yard electric furnace, dimming the neighbourhood lights and going at a 1000lb heat - then what?

the one in the picture is 600 US, so with tax close to 1000 cdn - too much for something that would be used infrequently at home to be cavalier and just buy it….or I’ll just keep waiting and one day pick up a used one for a few hundred bucks.

Usually I'm go big or go home on equipment (its a home shop) but the rare times I need to heat treat something beyond what i can do with a propane torch, its usually some small piece that would fit in a 9x9x9. If I was doing melts, as you suggest, it would be in a cylindrical gas top loading furnace, so the contemplated use is annealing, case hardening & stress relieving. 3x3 would be handy once every couple of years to normalize a large fabrication but would just take up (limited) space in the interim

Thanks for the info - any idea where to source the heating elements?

[TinkerDJ]

Deciding on size can be an issue, with the propane DIY fournace sizes its upto you. Mine has two bricks one on each side that come out and i can stick a piece of metal into the holes through the fournace. I built mine to handle a crucible that is 5 inchs round and 9 inches tall. It works for what i wanted it for and it cost me less then 100 dollars canadian. For just starting out you can use alot of diffrent ideas to have a fournace or a forge design. If your set on electricity you can get the heating elements for kiln's from online and likely a local source in large city's. After that all you really need is the main oven heat control from older ovens. You can get this free if you look around. But its a matter of application. Dans design is all electric and he does have a contoller idea.

The best aluminum scrap to use is from pistons. They have the highest quality aluminum and silicone. The silicone makes casting easier. After that all other engine components. Then last is all the other aluminum like ladders, storm doors that stuff. Pop cans are made up of 60% paint. So they really do not work well for the home caster.

It all comes down to how much you want to do and how much you want to spend.

[mik32176]

on my cnc milling machine, im not sure how usefull this would be. am Im pretty good with some minor sheet metal work. harbor freight powder paints said do not use in a gas oven. fumes?maybe. I had no idea about the hot gas cloud. very useful info since I have low ceilings and that would have been a bad day. ok everybody says go gas so Ill try it, I could do a 3'x3'. so what do I do first. where do I start this adventure.I have a sheetmetal supplier close by. but what about the other stuff? gas unit?refractory? fire department?etc

[murphy625]

Here you go,
ITEM NUMBER 7514718724
$40 bucks and your in business..

But have you thought about maybe building a plasma arc furnace?? I hear these can melt down anything and they are easy to build if your going to keep it real small..

Anyhow, to build what you want, just remember to keep it simple.. all you need is a steel box that you insulate with a few different types of material.. IE FireBrick on the inner most wall, Ceramic cloth behind that, and maybe Fiber Wool behind that if you want a "Cool-to=touch" outer case..
You will need to find a gas fired burner.. The kind that go into a home furnace, or a radiant tube heater box would do it.. You will also need a thermocouple and process controller that you can find used very easy for less than $100.

Hope this helps,
Murphy

[mik32176]

what size could I build? and oh yea I would love to build one. now your talking. any websites about it? and I see you wrote ITEM NUMBER 7514718724 for the other furnace but where is that for?

[murphy625]

Originally Posted by mik32176 what size could I build? and oh yea I would love to build one. now your talking. any websites about it? and I see you wrote ITEM NUMBER 7514718724 for the other furnace but where is that for?

http://cgi.ebay.com/ws/eBayISAPI.dll...tem=7514718724

Bidding has ended.. no one bought it.. would have made a nice shell..

Plasma Arc furnaces have to be small unless your the owner of a nuclear power plant.
You can build one out of a simple Arc Welder and a couple of electrodes..(I saw it in Popular Science magazine...
You can also mix iron oxide and aluminum powder.. Done right, you can get 6000 degrees or more out of it... All kinds of ways to melt stuff eh? LOL

Check ebay.. Shhh!!! dont tell anyone about the big secret..

Murphy

[TinkerDJ]

Problem with alot of the stuff that comes up like that on ebay is the weight. 300lbs would cost alot to have shipped from CT to say Alberta Canada. I watched a herburt turret lathe go for $1.67. It needed some work as it had sat outside under a tarp for some time. 3 phase motor was a draw back. But the guys dad had it, he died so it had to be moved that weekend. Weighed 2800lbs, only one bidder. For the 40 bucks that fournace would do everything and more, most likely you can pm the seller and get it for the minimum price or have him put it up for auction again. But those deals for some of us, unless its real close to were you live it is a definite no go.

[murphy625]

Ya.. I agree.. Shipping is a major drawback..

I drove 1700 miles to pick up $200 piece of equipment... New cost was $3800.

The idea is to find something located within reasonable driving distance. (reasonable of course is defined by the savings)

Murphy

[Arnie]

I've built lots of pottery kilns. The first was in mum's front yard using gas bottles and a pile of fire bricks at the ripe old age of 13. I tried lots of different configurations and sizes. It was fun and I learned a lot about what works and what doesn't. Didn't cost much and with light insulating bricks was firing stoneware from early on. (That's around 1300 centigrade). Look for old pottery books in the library on kiln building.

[2ndgear]

Originally Posted by murphy625 I'll jump in again.. (but remember I know very little about this stuff) As for the quality of the finished product, I would think that is going to almost completely depend on the quality of the mold. Also, your comment about heat treating steel in an electric setup is correct.. But it can be done with a gas setup also.. It's all up to how stable you can get your temperature and how well you can control it. "Heat Treating" is a very wide term.. Kinda like saying your getting into the Painting business.. It doesnt denote what your treating, or for what purpose your teating it.. Heat treating anything means bringing the temp up to a specific point within a specific amount of time, holding it there so long, and then lowering to a specific point within a specific amount of time and sometimes repeating the process. (sounds complex but just about any common programmable temperature controller can do this. (Sometimes called process controllers). Your working temperatures and accuracies needed will dictate to you the type of thermocouple you will need.. (IE Type K, Type J, RTD, etc etc). As for building a furnace or kiln, I can help you out to a point with design work.. I have build several ovens that could swallow a pickup truck with temps ranging from cure (300-600 degF) to temps ranging in the burn-out areas (600-1400).. The burn ovens are built with a fireboxs that are much like any furnace I suppose.. The temps I designed for are around 2800 deg F as there was direct flame impingment in these areas. I used a ceramic fire-brick and ceramic cloth that was backed by a "Fiber wool" type material called FBX2900. As for what kind of aluminium grade, I would start off with whatever scrap I could find.. Of course, if you think about it, perhaps it doesnt matter.. Its not like you cant melt it back down and use it again if you mess up.. Murphy