The Shop > Metal Stuff
I bought another deader
ddmckee54:
Kelly (Al203 - over on thehomefoundry.org) has built a couple of electric furnaces. I believe that he has posted a link to an on-line calculator for winding your own heating coils. Nichrome may not be the best choice, don't think its' max temperature is high enough.
If you just want to do small parts, these electric jewelry furnaces are pretty cheap, you can pick them up for USD $200-$300. If you are electrically inclined, you can pick up non-working furnaces at about 1/3 of that cost. My first unit cost me less than $100. It was a non-working factory return, all I had to do was flip 2 wires around and I had a working furnace. They had the polarity of the 12VDC signal to the solid state relay backwards. This unit I got for less than $70. It had 2 issues, they had a crucible failure and a mystery metal dribbled down into the control guts of the furnace, and the heating coil burned out. I got the mystery metal removed and it didn't cause any serious damage. I've got a replacement heating coil on the way, it was less than $50.
When I get that coil replaced I'll have 2 working furnaces for a little more that $200. I plan on turning the 2nd unit into a burnout oven for lost-wax and/or lost-PLA casting.
Edit: Corrected some spelling errors. Spell-chequer isn't all ways rite.
tom osselton:
Ok thanks what are they like for brass do they Handle it well another thing I see is them being either 120 or 220 volts I’m wondering if it is for the North America verses European power supplies or if it affects the melt time.
( in a pinch I could fire up the kiln if push came to shove during the winter. )
ddmckee54:
I haven't done any casting with mine yet, still getting things set up to do that.
Myfordboy has made a number of castings using an electric furnace that is very similar to what I've got. I think he's done brass, aluminum(Or aluminium depending on your side of the pond), and ZA12 - but it might have been a different zinc alloy. The size of some of the castings that he has been able to pull off using that little jewelry furnace surprised me - as in bigger than I expected.
Because they are temperature controlled I would think that you'd get less zinc burn-off when doing brass by keeping the set-point as low as possible.
tom osselton:
Yes I watch Myfordboy and have seen the things he makes I think it’s the smaller gates and risers that help out or I have a spring loaded centrifical casting machine I bought off of Kijiji for $50. ( Can ) out here that’s itching to be used.
ddmckee54:
I got the replacement coil about a week ago, I think I got this damned cold about that time too. I'm going to try and get the coil replaced this weekend and see if I can get some heat out of the furnace.
Then I need to figure out how I can turn the furnace into a burn-out oven. On HMEM, Foketry is building a scale model of an Italian 18 cylinder aircraft engine. He casts some of his parts and in his build thread provided a link to an Arduino based controller for a burnout oven, I'll have to take a look at that again.
Don
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