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[STorres]

I am helping a friend design a new furnace and wanted to hear some outside discussion on the pro's and con's of either type of furnace.  The machine will be a 19" ID the rest is yet to be decided.  Please post your opinions and suggestions.

Thanks,
Steve T.

[Iron Guild]

CUPOLA VRS CUPOLET
Both are the same in most respects from the tuyeres down. The cupolet is short and has a lid to maintain pressure and heat inside the furnace. The cupola has a tall stack and no lid. The operation varies mainly in how the furnace is charged and slagged.
The Cupolet is a batch melter. The iron charge is bashed very small and the full amount of metal to tap can be charged at one time. When charging be sure not to let the coke bed get too low. If the tap is 100lbs you can often charge the full amount all at one time or as much as will fit in the furnace. Watch the tuyeres as the iron rains and when it stops its time to tap.

The Cupola is charged in smaller amounts in sequence. If the tap is 100lbs then charge 25lbs iron then 5lbs coke then iron then coke etc. (one starts to get a handle on how much iron/coke to charge after a few runs. I have found that much less coke is needed than it appears.) To know when to tap keep time with the charges it usually takes 7-10minuts to melt a batch if you have things running smoothly.
Mark the time of the first iron charge and watch the tuyeres for the first drops iron. This will give you an idea of how fast you are melting. The slag hole is often used to determine when to tap. As the well fills with iron the slag will run. When iron runs from the slag hole the well is full and the furnace is taped. Conversely cupolets don’t always have a slag hole. After a few taps the tap hole is left open to run off the slag, some folks call this “Power slagging”. Be sure not to over fill a furnace with no slag hole or iron and slag will pour into the wind box.
A cupola is fast! It can be hard to keep up with at times. It can melt and melt and cast dozens of molds in an hour. A 19” one can do tons and tons and have a 200lb tab and be an unstoppable beast. A cupolet affords you time to get yourself ready while your batch of iron melts. But you can also over fill it and slag can become an issue. At times the sparks and flames that shoot out from the lid on the cupolet can be a pain, especially if you are casting for a while.
Josh
The Iron Guild

[STorres]

Thanks Josh,

I will pass this info along.  Right now we are leaning towards a cupola, but I am hoping for a few more post to confirm that it is the right choice of tool.  I'll check to see if they have enough crew to keep up with the current design and not have the furnace run the crew into the ground.

Steve T
FeSU

[Iron Guild]

http://picasaweb.google.com/ironguild/IronCupolaCatalog#

take a look at this. there a number of great furnaces out there.
a cupola can be run just fine with 4 people. 3 if they are good. 2 can run a cupolette.
josh

[STorres]

Thanks for the link Josh.

You actually have pictures of 4 of the furnaces I have previously built, and I even found a picture of myself in few.

Thanks,
Steve

[Iron Guild]

which ones are they?

[STorres]

I worked on the TWO4 at Florida State. Which we ran at sloss in '05 (images 65, 201, 202, 203, 267, and 284)  There is my lid melter "the Super Sport" which also ran at sloss in '05 in the small cupola contest (image 175).  My smallest furnace "the microwave" which was donated to UNF (where the pictures were taken) (images 289, and 290) and finally the P.I.G. furnace "Reagan" (images 170, and 274 thats me putting the bottom in)

Steve

[Iron Guild]

the smallest one "the microwave"? what are the specs on it? id, od, tap, # of slag holes....
my small furnace "the wee Beastie"  has a 8"id   12" od .  1, 2inch tuyere. 3 slag holes and taps 35lbs in 6-10 minutes(first slagger) 45-50lbs in 10- 15 minutes(last slagger). we cast 500lbs with it this last Sunday.

its great to find a furnace maker! the cupola catalog is sort of my hobby. i try to find descriptive pics of the furnaces. i thought perhaps someday it will come in handy to a fellow metal head. i sure could have used it when i was trying to figure this stuff out.

Josh
IG
207 475 6669

[STorres]

My little guy runs about the same.  It has 4, 1.25 inch tuyeres though.  I only ran it once myself, then built the 10" for the small cupola contest.  UNF has put several thousand pounds through it at 65#+ per tap (which I think is a little rediculous) but they have built a bigger furnace now and the microwave is being retired again.  I generally like to work bigger.  We ran over 6k lbs last week out of the TWO4, I think it is a lot less work, we get to the beer drinking quicker that way.  Will you be attending Sloss this year?  I'll be there the whole time, don't think I'll be working any furnaces or pouring, gonna try to focus on my buzz and seeing old friends.

Steve