Author Topic: Resurrection of a CFEI 100 KVA Induction Furnace (Read 143352 times)

awemawson · « **Reply #675 on:** January 30, 2021, 10:11:49 AM »

So I tried the Plasma Cutter - just a trial to see how it went.

It has absolutely no problem cutting the required thicknesses, but I found visibility through a welding mask quite hard due to the huge amount of glare from the cut. Also I had to stop a few times and clean the consumables as presumably 'stuff' had lodged inside, also it was quite slow.

I had hoped to be able to use my Startrite "18V10" vertical bandsaw with a suitably coarse blade, however it seems that 18V8.5 would be a truer description as the throat is indeed 18 inches, but even stripping off the swarf blower assembly the greatest depth of cut that I can set it to is 8.5" unless I remove the upper blade guide, which would not be safe. - hmmph !

So it looks like it's the Plasma Cutter when the time comes.

kayzed1 · « **Reply #676 on:** January 30, 2021, 02:36:50 PM »

JCB bucket i think

vtsteam · « **Reply #677 on:** January 31, 2021, 02:05:15 PM »

Andrew, I would think either a big gas welding torch or a Sawzall would do the job After all, aluminum can be welded with a gas torch -- the only problem is it's easy to melt through! Neutral flame though, not oxidizing. The other benefit is no arc re, optical filter type.

I have softened aluminum automotive bell housings outside in a wood fire and broken them up with a hammer, but it's dangerous.

vtsteam · « **Reply #678 on:** January 31, 2021, 02:36:34 PM »

Thinking about it.....I think the sawzall would be my go-to for those wheels or heating over an open fire and breaking up. That last would probably be the quickest for all 4 wheels, otherwise it's a lot of cuts no matter what tool you use.

What are you thinking of casting, btw? Project(s)?

awemawson · « **Reply #679 on:** February 01, 2021, 05:10:16 AM »

Steve I agree about the Sawzall - I had intended to try my old one Sunday morning before I saw your post, but I got diverted onto other tasks. However this morning I dug it out, a cheap and cheerful copy branded 'Power Devil' (Screwfix I think) that I've had for at least 15 years, it has only seen occasional use as I always found it under powered.

Anyway this morning it got it's own back on me - I thought that it smelled a bit odd as I got it out of its case, and sure enough once plugged in and fired up it erupted it a shower of sparks terminally

OK it was still crawling round but it's bin fodder - no point in even opening it up as it was always pretty useless !

So I've splashed out on a (hopefully decent ) Bosch GSA1100-E 1100W corded job due for delivery on Wednesday. Even if it doesn't work for this task it's a useful tool in the armoury !

I don't think gas cutting would be very good - cutting steel, the steel itself is the fuel and burns intensely in the oxygen as the steel has relatively poor thermal conduction whereas cutting aluminium alloy the thermal conduction is so high that the alloy can't be maintained at burning point. I'm sure it would melt it's way slowly through but not as a proper cut.

vtsteam · « **Reply #680 on:** February 01, 2021, 11:49:58 AM »

I agree that the torch method for steel depends on oxygen to burn the steel and that isn't applicable for aluminum. But I was thinking a large welding torch rather than a cutting torch, and no excess oxygen to form aluminum oxide.

But I also agree that I think the Sawzall would be a better bet -- of course the right blade will also make a big difference there.

And then there's the good old wood fire outdoors and club..... caveman method. Quite effective and cheery on a winter's day. Just don't hit yourself with a bit of shrapnel.

awemawson · « **Reply #681 on:** February 02, 2021, 06:43:50 AM »

I've decided to use an intermediate crucible when it comes to mould filling - pre-heat a crucible, fill it from the induction furnace, skim etc and pour.

So I need a pouring shank - all mine got given away. So make one - that was this mornings task.

1/2" Black bar perfectly adequate for these small crucibles but my blacksmiths hearth is not set up - how to heat it

. Not too convenient to use oxy-acetylene on long bars - although possible. Start off in the induction furnace - rapidly becomes impossible as the curve is formed. Shove it in the pottery kiln - ridiculously expensive in electricity.

Hang it - bend it cold!

So cutting an exact length of the bar to be the circumference at the height that I want the shank to sit, if I can get its ends pointing at each other and weld them firmly I should be able to bash it into a tolerable circle. It didn't come out too badly - be so much easier just to toss it in the hearth and do it hot, but you work with what you've got!

Once the ring was as good as it was going to be, I squashed it flat on the 60 ton press then welded a handle and a pivot - job done. The idea being that it will sit in a triangulated frame in front of the induction 'body' where I can tip the melt and do my stuff skimming etc.

Still need to work out how I'm going to pre-heat the crucible as I doubt that just putting it on top of the heating induction pot will be enough - damn the efficiency of induction melting !

mattinker · « **Reply #682 on:** February 02, 2021, 08:59:56 AM »

Have you got a weed burner? They aren't very efficient, but I've seen them used as raku Kiln burners!

awemawson · « **Reply #683 on:** February 02, 2021, 09:25:38 AM »

No Matthew - I did have but it's long gone.

But I had thoughts of resurrecting my Ceramic Chip Forge - not only could I have heated the ring up but it would do for pre-heating crucibles, and being gas powered with no coals, just ceramic chips, it's relatively quick to turn on and off. Currently in the depths of the tractor shed - I'll try and dig it out over the next few days.

vtsteam · « **Reply #684 on:** February 02, 2021, 11:18:04 AM »

Looks good to me, Andrew.

I'm a cave man type so, if faced with that task, I would probably just build a wood fire outdoors from limbs I wanted to get rid of anyway, bring a couple of potatoes wrapped in foil, The steel goes in the glowing embers, and the potatoes go nearby in the cooler ashes.

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.

awemawson · « **Reply #685 on:** February 02, 2021, 11:44:46 AM »

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 · « **Reply #686 on:** February 02, 2021, 02:34:01 PM »

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 · « **Reply #687 on:** February 02, 2021, 02:59:59 PM »

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 · « **Reply #688 on:** February 02, 2021, 04:59:57 PM »

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 · « **Reply #689 on:** February 03, 2021, 03:50:36 AM »

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.

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

awemawson · « **Reply #690 on:** February 03, 2021, 05:28:37 AM »

Matthew yes some of my previous ones were made from flat bar of about 1" x 1/8" and bent on a taper which is easy to form if you have a forge and a big enough blacksmiths cone. My cone would 'just' be big enough for that particular crucible but useless for the big ones I used in my pit furnace.

John, the ceramic forge IS an ex school single burner one. It along with my coke forge were of course buried deep in a corner of the tractor shed and I'd thought it was going to be a major pain extracting it, but in practice I just had to move two tractors and I was able to move it to a more accessible place where I can get the forklift at it. Not doing it today as (naturally!) it's pouring down and has been all morning and there's no point in soaking it (or me!)

Let's hope that it still works. It's gas regulation is odd in that it uses a strange 'zero demand' or maybe 'zero pressure' valve - I don't remember which but I know that it gave issues 15 years ago and I had to replace it as it had jammed from lack of use sitting idle for too long.

Anyway the new Reciprocating Saw is due for delivery in the next hour, so I have a date with some alloy wheels !

awemawson · « **Reply #691 on:** February 03, 2021, 09:35:24 AM »

The rain slackened just before lunch so I decided to fire up the fork lift and shift the DS130 ceramic chip forge at least into the stable, and if possible as far as the foundry (fork lift won't do the 90 degree bend up to the foundry so the last leg is 'push power')

Well with the very high humidity the propane engine of the forklift was extremely reluctant to start. I did eventually get it firing on two cylinders so putting a bit of heat into it and after about ten minutes off we went.

Having just got it running reasonably the delivery of the Bosch Reciprocating Saw arrived so a quick trot across the farm yard with the DS130 loaded up, and I popped it down at the far end of the stable. By this time the rain was back

Never mind, the show has to go on. Quickly returning the fork lift to the Tractor Shed and locking up it was a case of man handling the DS130 up the slope and over the threshold strip of the foundry where it now sits. I did manage to prove that the blower fan still works and the pair of solenoid vales at least click when powered so there is the possibility that it works !

After a quick lunch (Welsh Rarebit) I was back out to try the new toy. I have to say that it performed very well. It came with a nice 'progressive' coarse metal cutting blade (S123XF must order some more!) that slices nicely through the rims though it does take kindly to a squirt of WD40 as a lubricant going through the thicker bits.

It's definitely the way to go (Thanks Steve for jogging me!) and far less mess than the plasma cutter or bonfires etc. It also allows me to store the alloy as rims and cut off what's needed for a particular job.

Time to put the old dead Power Devil one in the bin !

vtsteam · « **Reply #692 on:** February 03, 2021, 10:52:52 AM »

Great to hear about the forge and rim cut successes, Andrew.

Quote

Two thirds up the crucible, with the ring near the beginning of the bulge. Cheers, Matthew

Unfortunately, Mathew that's the fit I had during a few crucible drop outs, at least with a round sectioned ring.

The problem seemed to be that, as I turned the ring past vertical the crucible was able to pivot within the ring, due to the taper, and then slip out. So there were two movements. First a pivot in the ring, and second a slip out of it. I'm now wondering if maybe it was a result of different shaped crucibles that I tried. The bilge was not always as pronounced, nor was the taper the same on all I tried. That was pouring iron, btw.

Hmmmm, I might have to do some experiments and revisit using ring shanks. I'll stop cluttering up your thread here Andrew and open up a new one if I do.

Pete. · « **Reply #693 on:** February 03, 2021, 11:03:17 AM »

This guy carries and pours his crucibles with a claw-type effort that grips the rim of the crucible. Around 17 minutes in.

awemawson · « **Reply #694 on:** February 03, 2021, 11:19:34 AM »

That's a dangerous way to carry a crucible. A friend (George) of mine and myself were casting bronze years back, and with an 'unconventional' way of carrying the crucible we did something similar with tongs. A big chunk came out of the wall of the crucible, we dropped the lot and the bronze went everywhere

By one of those co-incidences a huge amount of it flowed round and under that very same ceramic chip forge - very fluid stuff bronze - and I had the devil of a job extricating the base of the forge from it when it had cooled.

Fortunately we both had heavy leather boots on at the time and no one was hurt, but not an experience I'd want to repeat.

(I know Iron Man says crucibles are very tough - I'm sure some are - then there's the others !))

hermetic · « **Reply #695 on:** February 03, 2021, 01:42:21 PM »

I cannot claim any experience in this area, but would it not be possible to weld a flat bar with a small turn on the end to the outside of the ring, in such a way that the ring could be sat at a slight angle, the crucible placed in it, and then the shank lifted at an angle until far enough up the crucible for the turn to slip over the top of the crucible as the shank came to its stopping point on the crucibles taper. Am I explaining that well enough to get the idea across?

awemawson · « **Reply #696 on:** February 03, 2021, 01:54:35 PM »

A hook loosely pivoted on the ring outer diameter and lifted over the edge of the crucible once it's in the ring works well to stop the accident that Steve had. But in my experience fiddly things like that are bound to go wrong 'in the heat of the moment' when you've just lifted the crucible and are manipulating things without help. Different matter if there are two of you and you rehearse things properly before you start.

vtsteam · « **Reply #697 on:** February 03, 2021, 02:29:47 PM »

Agreed Andrew, I'd not like to flip a hook on an iron melt -- there's time pressure as well when doing relatively small home shop iron melts (A6 size in my case) because cooling is rapid. Also you're trying to slag it then, and I can imagine tangling up with a hook, or getting slag all over the mechanism while doing that.

I just think that this should be a simple matter of figuring the ring problem out for myself -- rings work for others, there was obviously a slight difference for my setup at the few times it happened for me. I just have to figure out what the actual cause was. Again, also, it happened maybe 3 times total, and only during Iron melts -- I don't use a ring shank otherwise.

I do think just trying it with a cold crucible over a cushion, and/or with sand in the crucible will reveal the cause and probably a solution.

hermetic · « **Reply #698 on:** February 04, 2021, 02:36:07 PM »

yes, I have seen the hinged version, and various other methods of retaining the crucible, all looked time consuming and dangerous to me. what I am suggesting is a fixed hook, welded to the outside of the shank ring, so that the crucible does not touch it when the shank is at an angle, but the hook naturally falls onto the top of the crucible as the shank gets to the stopping point. If I had a crucible I would make one! I could do with one anyway to reduce my alloy collection to usefull ingot size in the forge. Maybe I should order one?
Phil

vtsteam · « **Reply #699 on:** February 04, 2021, 04:58:27 PM »

Opening a separate topic re. ring shanks in "Metal Stuff" section of the forum.

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Author Topic: Resurrection of a CFEI 100 KVA Induction Furnace (Read 143352 times)