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Resurrection of a CFEI 100 KVA Induction Furnace

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awemawson:
That's a hard one to answer Steve as things don't stay the same size. The ring and the crucible alter as they heat and cool, and getting a 'good place' is a bit hit and miss. I aimed for 'sort of 2/3 rds up'  but you do have to be rather careful. Some designs have a hook over the rim of the crucible to prevent tilting but they are difficult to use as the hook is a loose piece.

You can adjust where the crucible sits by putting a few turns of soft iron wire round the ring of the shank.

Sadly we are so soaked here that my two bonfire sites are untenable. The one in the field is under a few inches of water, and the one in the veg patch is so soft you sink in up to your ankles !

hermetic:
My old metalwork teacher would wander past when I was "adjusting" a piece of metal in the vice, with a big hammer, and whisper "All cold blacksmiths go to hell" God bless you Spearmint Jim Wrigley for passing on to me an undying love of metalwork!
It looks good enough to me Andrew! I am in the same boat with my forge, I am going to have to rejig the flues in spring.
Phil

vtsteam:
Hmmm, I don't think that expansion of the ring and crucible probably make much difference to the slipping problem as the crucible will settle to wherever it needs to maintain a slip fit . Yup I do know the fit can be adjusted.

For me the question still stands: where should it properly be located when making one? Is it half way up, two thirds, etc? I wish Ironman still visited here, as I wouldn't doubt that he has a useful opinion on it.

And also I, like you, Andrew, have made shank rings out of round bar and about 2/3 up which felt right as a mere guess. But I experienced the problem and ruined a pour. I do wonder if round bar contributes to the slip out problem. Would, for instance, square section bar be preferable? Or even flat stock? Would it be an advantage if that were shaped to a cone segment? Much to ask about this particular topic!

I suppose a shank could be tested in advance over a padded surface to protect the crucible. That might have been smarter of me than finding it out during pours. Also to mimic the real action maybe a few largish ball bearings poured in the process to mimic the molten iron emptying out and shifting the balance.

I should confess that I eventually gave up on ring shanks altogether and just poured directly with the tongs I made. But I'd still like to know the solution to the problem.

Edit: Okay, I'm going to throw out a new (for me ) guess, that actually the ring should be located nearer the bottom end of the crucible than its balance point when on its side. Theory, mind you, not necessarily reality.....

millwright:
Andrew,
 is the chip forge an ex schools flamefast one? a single or a double one?

Phil,
the term i heard often as an apprentice was, cold iron blacksmiths go to hell. I had a chap working with me on a job outside on a very large steel dust cabinet that filtered the air from our shot blast unit, a very large one. The job was to open up the cabinet and remove the filter bags and fit new ones, the problem being that they hadn't been changed for too long, the 4 cabinet doors were bolted up on 1/2 bolts at about 12" spacing and the doors about
 6ft X 4ft absolutely rusted solid, quickest option knock them off with a hammer and cold chisel, i started on the first one with John watching me before he stopped the hammer on my backswing and told me to sit and watch, he said he couldn't stand and watch me doing it with hammer in my wrong hand, i'm left handed, most of the bolts he got off in one hit and the doors were off in no time without him breaking into a sweat.  it was after he had finished i found out he had been a blacksmiths striker, his wrist and arms were twice the size of mine.

Sorry Andrew, carry on.

John

mattinker:

--- Quote from: vtsteam on February 02, 2021, 11:18:04 AM ---
Now I have a question re. ring shanks I've never seen answered -- and I've read a LOT of the available lit about casting and done a fair share it over the last 20 years myself. And that question is this:

How far up a crucible should the ring fit?

The reason I ask is because I have had crucibles slip out of the shank onto the mold when pouring the last of the melt. Not always but sometimes. And that is always an occasion for using words I'd prefer not to.

--- End quote ---

Round sections are much easier to make, but flat, conical rings with the same angle as the crucible will hold better. Two thirds up the crucible, with the ring near the beginning of the bulge. Cheers, Matthew

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