The Shop > Metal Stuff
I bought another deader
tom osselton:
There are some articles on this site about converting a kiln into a programable oven.
tom osselton:
Well Black Friday got me and I picked up one of the furnaces along with a Resin Printer, Resin and Wash and Cure Station! Wish me luck! lol
ddmckee54:
Good luck Tom, let us know how it goes.
I finally got around to cracking the top half of this thing open last weekend, and the coil is definitely dead. I don't know if I'm going to be able to save the ceramic furnace liner / coil winding guide or not. I'd like to save it as the ceramic liner seems to be in good condition. After they wound the heating element on it they smeared some type of goop over the coil on the outside of the liner. It MIGHT have been a refractory compound of some type, but as cheap as these things are, I doubt it was a proper refractory. It's cracked pretty badly so I doubt it was rated for the temperatures it actually saw. It's probably just plaster and sand, but since it's been smeared over the heating element the coil is acting like rebar. I'm going to try chipping that crap off the liner, but I'll probably just have to get a new liner - they are less than $50.
Or I may just get some decent castable refractory and make my own liner, the size I actually want it. I've got to make a new top and bottom for the oven anyway. This is going to be a burnout oven, not a foundry furnace so it won't be seeing metal melting temps. I've got 3D printers, I can easily print the molds to make a liner.
Don
ddmckee54:
At first glance, this ceramic liner doesn't look too bad.
As a jewelry furnace this one is definitely dead.
That is the remainder of the heating element that I can't get off of the ceramic liner, all the rest of it came off with a little persuasion.
This stuff refused to let go, it's like it's fused to the liner.
There seems to be some of the mystery metal mixed in with the heating element, and I've got no clue what the purple stuff is. All I know is that it DOES NOT want to let go of the liner.
Here's a look at the hole from the inside of the liner.
It looks like whatever happened to that liner started from the inside where the crucible would be, and went out towards the heating element. Anybody seen a failure like this before?
Since I've already got a new heating element, I think we'll be going to Plan B and casting my own liner.
Don
hermetic:
Problem is some of that stuff fused to the former will be conductive. This is what mine was like, albeit to a lesser extent, when I stripped it. The problem on mine was that the ceramic wool insulation appeared to be in small peices, and had been forced into the gap between the element former and the outer case so that some areas were under more pressure than others and some more insulated than others. When I tried to order a replacement I was told that there was no UK stock of spares, and eventually got a kiln element maker to wind me a new element. He queried the dimensions and diameter of wire,saying that for this wire and loading, the coils were too close together, and would cause itto overheat and fail. The element he supplied was a comprimise, having a slightly lower loading and wire coils further apart, and after winding it onto the former I wrapped a completely new ceramic blanket around the whole former and element until it was just over the diameter of the outer case and slid it into the casing. So far so good. I think the chinese element wire, and quality of assembly may leave something to be desired, although it was used at the upper setting to melt copper, and that is at the very limit of what Kanthal wire will stand. Interesting project, good luck with it!
Phil
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