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Well start off by checking backyardmetalcasting.com
In the lab links check out #91.
Paul
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Does anyone know if it would be possible to use kitchen stove elements in a home-built kiln/furnace? Melting & heat treat aluminum (possible HT some steel components)
I would be using a fire-brick lined chamber, backed up by castable, with an outer wrap of Kaolin wool to insulate it as much as possible.
I would prefer to use these elements if possible, rather than the wire elements due to their outer layer which makes them less prone to stretch and break from heat cycling. Not to mention at $20-30 a piece and being able to order all of the other components (connections and relays) from several local & online vendors, replacing them would be alot less time consuming.
Well start off by checking backyardmetalcasting.com
In the lab links check out #91.
Paul
Yeah I'm familiar with Lionel's Lab...but where in the hell is Link #91? He doesn't have his page layed out that way.
Scratch that...found it. Must learn to actually LOOK before opening my mouthThanks! Again...another mistake. Lionel's Lab is a different page I was thinking of. Don't know what my deal is today. Anywho...that link looks good, but those aren't commercial stove or oven elements...those are coil elements like you can find at a kiln supply type place. I'm just wondering if the commonly available kitchen stove/oven variety elements would hold up in a well insulated box, or if they would go beyond oxidizing temp and break.
Any new input for this thread?
It wouldn't be that tough to test, just turn one on for three hr in a well insulated heat resistant chamber and find out. An oven goes up to 500 degrees or higher and they run constant y during the self cleaning cycle, or broiling for quite a long time.Originally Posted by 307startup
Scratch that...found it. Must learn to actually LOOK before opening my mouth
Just my 2 cents, Mike.
Warning: DIY CNC may cause extreme hair loss due to you pulling your hair out.
307startup,
Most self cleaning ovens sustain almost 1000 degree's Fahrenheit for three hours without any problems.
Jeff...
Patience and perseverance have a magical effect before which difficulties disappear and obstacles vanish.
Hi all, if you get the stove top spiral elements (in tubular form) they run at red heat on high.
The point to remember is the dissipation of the heat otherwise they just get hotter and hotter till they burn out.
On a stove top the elements are exposed to the air or bottom of a pot so they get rid of the heat that way, but in a furnace with insulation to contain the heat they might just go critical and simply melt, that is unless you have a thermostat control switch or one of those simmerstat switches that switch the power on and off on a mark space ratio principle.
What you are working with is about 1000 watts of power, (240 volts at 4 amps) and it's got to go somewhere.
The simmerstat switch will allow the element and furnace internals to come up to temperature without self destructing from being in a confined space.
I once saw a simple furnace that was simply a 1KW stove hot plate with a clay flower pot upside down on top, used to melt lead for fishing sinkers.
Ian.
I just use a hotplate with a castiron pot to melt lead for sinkers. Most of my lead is an alloy and has lower melting point, but I've melted pure lead, too. Up to 25 pounds at a time.
I almost melted Magnesium or set it on fire, I thought it was Aluminum until it started shooting little white fireballs. I've since learned how to tell the difference.
I hadn't seen this thread when it first started.
Stove elements melt aluminum? Yes, just forget to put water in an aluminum pot and turn the stove on High.
Stove elements heat treat steel; doing the intitial hardening step may be pushing it but they are fine for tempering.
Did you ever get anything built?
An open mind is a virtue...so long as all the common sense has not leaked out.
I've been using a toaster oven for tempering small steel parts. Basically using a MAP torch and oil quenching and tempering in the oven. I found that commercial thermostats have a lot of hysteresis which can be problematic. The oven I currently use overshoots it's setpoint by about 40F on it's first heatup and seems to ring around +/-25F so I let it get to temp before putting my work into it. I monitor temp externally with a K type thermocouple setup which is more precise than you need for baking a flan.
I also found that you need to put in some shielding so you don't get direct radiative heat from the elements. Nothing fancy just a couple sheets of steel above and below the rack supporting your parts. Direct radiation can boost your surface temps significantly and in unpredictable ways. You only want the warm air to heat the part which is another nice reason to have a convection oven. Red hot coils radiate quite a lot of heat. Coradiation from a radiatively heated steel sheet that isn't glowingly hot isn't as harsh. I think the surface area of a radiatively heated sheet ends up sinking to the air so you get much less radiative heating of your parts.
If you're more temperature picky, you can modify a conventional oven or toaster oven by adding an Omron process control. They're floating around Ebay from time to time. Some are very easy to configure and offer auto tuned PID functions which significantly reduces ringing and initial overshoot. At my previous job, we modified a stove to do lower temperature tempering and strain relieving. We didn't take it all that high (600F max) but it was high enough for age hardening I think. The temperature controls were sensitive enough to also do low temperature work (120F) which doesn't do much for metals, but is very handy for curing cast rubber or prototype plastic parts.
Stove coils go up to around 1000F when they glow bright red just fine. They radiate like crazy so you definitely don't want them radiating close to your parts. It's not immediately obvious, but most of the heat transfer between a coil and a pan is radiative. The contact between a pan and a coil is really quite bad (try wiping some blue onto your coil and see how it touches the base). Almost all of the heat transfer in electric range cooking is radiative because there's so little contact and convection just sucks at moving heat because air is fairly insulative.
You'll definitely need some firebrick and insulation if you want to maintain this temperature for any length of time without exceeding the RPM specifications of your electrical meter. I'm not sure if K type thermocouples are good for this temp range. You may need to go to something higher like an R type thermocouple for temperature monitoring. 1000F is higher than the ignition temperature of lots of organic materials like paper and will probably destroy any gasketing materials or organic binders used to hole an oven door together or prevent air leaks. I think for this temperature range industry moves to firewool as a gasketing material. Think about where the hot air will go when you open your door. 1000F exceeds the ignition temperature of many flammable items like paper and will probably can burn your skin. It would probably be safer to shutdown and let the oven cool instead of opening it stinking hot.
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