Ron,
The Elements you use are the same thing I had. (I say had `cause my pot had a blowout on my last melt, and shorted out the element!) Anyway, the controller is homemade and uses 2 SCRs that are rated at 600V / 70amp. This is tied into a Lutron dimmer switch. The switch comes with a very low rated triac so that was replaced with one rated for 400v.
After thinking it over I really don't think it's the controller so much as I am just losing heat from the seams between the base, body, & lid. Most likely it is between the body & lid. I've ordered a new heating element & should have it in by the end of the week. I plan on installing it this weekend, and running it at night. Kill the lights out side the shop & see what I can see.
As for the refractory we once had a foundry here in Louisiana (that was knocked out by Katrina). I got two 5 gal tubs of high temp cement from them for nothing, and used that for the base & lid. The body has an inner wall of fire bricks that have been notched for the heating element, and between that & the outer metal shell it was packed with more refractory. Short of making another lid I was considering using that ceramic blanket you showed in your post to help seal the gap between the lid & body like a gasket. I've also been considering building the Gingery charcoal foundry with the remaining refractory I have….but than again….
Anyway, thanks for all the help
Brian
--- In gingery_machines@yahoogroups.com, Ron Thompson <ron@...> wrote:
>
> On 9/11/2011 10:50 PM, confed2001 wrote:
> > Am I to understand that you are using this to control the temperature
> > of an electric foundry such as the Gingery "Little Bertha"? I got a
> > set of plans for an electric foundry from this site:
> >
> > http://www.dansworkshop.com/aluminum-foundry/homebuilt-electric-melting-furnace.htm
> >
> > It works & I have been using it for several years, but despite what
> > the plans say it does not get hot enough to melt copper much less
> > brass. I constructed the controller as described in the plans, and am
> > using the heating elements stated, but aluminum is the best I can get
> > out of it. If this controller will raise the temp of a small electric
> > foundry than I need to get one.
> >
> > Brian
> The controller will not raise the temperature of a foundry. It will
> regulate it and help the elements live longer due to the Pulse Width
> Modulation (PWM). This is easier on the elements.
> I bought Dan's plans years ago, but have lost them. What kind of element
> wire and controller does it use?
> One thought is your elements may be too long. Do they glow bright orange
> under full power?
>
> Another thought is the refractory. Maybe it isn't insulating enough and
> loosing too much heat. Is the outside of the furnace hot to the touch?
>
> I am using 2 Kanthal elements from here:
> <http://www.ebay.com/itm/170641989014?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649>
>
> This will be for 220V operation.
>
> I intend to use this ceramic blanket refractory:
> <http://www.axner.com/superwoolfiber-1thicksoldpersqft.aspx>
>
> Axner is local to me, but they do ship. I am going today to pick it up.
>
> I still need some heater duct for the shell and for the solid state
> relays to arrive from China.
>
> Oh and I need some small ceramic insulators to hold the elements in place.
>
> --
>
>
> Ron Thompson
> On the Beautiful Florida Space Coast, right beside the Kennedy Space Center, USA
>
> There are two kinds of posts on newsgroups.
> 1. This is what I have done...
> 2. This is what I think...
> Be aware of the difference!
>
> http://www.ourcadguy.com/
>
> http://www.plansandprojects.com My hobby pages are here:
> http://www.plansandprojects.com/My%20Machines/
>
> Visit the castinghobby FAQ:
> http://castinghobbyfaq.bareboogerhost.com/
>
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