Author Topic: Resurrection of a CFEI 100 KVA Induction Furnace  (Read 36591 times)

Offline hermetic

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Re: Resurrection of a CFEI 100 KVA Induction Furnace
« Reply #750 on: February 20, 2021, 02:52:05 PM »
Jammy dog, I had to pay 17.95 for mine!!
Man who says it cannot be done should not disturb man doing it! https://www.youtube.com/user/philhermetic/videos?

Offline awemawson

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Re: Resurrection of a CFEI 100 KVA Induction Furnace
« Reply #751 on: February 21, 2021, 06:13:45 AM »
They are only a tenner iirc anyway Phil.

So not being able to get on with the hearth itself due too lack of materials I decided to re-make the coupler that joins the torch gas lever valve to the torch flexible hose, but incorporating a choke or jet to reduce the gas flow. As it was, if the gas was fully on a dangerously long yellow flame was produced. The 1/2" BSP lever valve  presents a female socket, and the original adaptor was a short stub of 1/2" pipe threaded both ends with a slight socket boring into one end to receive the 60 degree male cone on the flexible pipe. A bit crude and of course 'full bore' at 1/2".

I made one from a bit of hexagonal steel which gives the advantage of flats to put a spanner on when tightening. Jet end drilled 3 mm, female cone end drilled 6 mm then bored to give a good area of 60 degree taper with a big centre drill (BS7 3/4" Body).

Now if lit with cocks fully opened at least the flame isn't stupidly large and can still be controlled by the lever valve on the manifold and the knob on the torch itself.

Andrew Mawson
East Sussex

Offline awemawson

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Re: Resurrection of a CFEI 100 KVA Induction Furnace
« Reply #752 on: February 24, 2021, 09:16:07 AM »
Well Flamefast came up Trumps :thumbup:   (cards that is not politicians !)

Were I to make a donation to a nominated charity they would pop some bits in a box and send them to me - a refreshing way of doing business ! That was Monday afternoon, today (Wednesday a box arrived containing 5 kgs of rather special 'RCF Mastic', an 18" square of 4 mm pretty solid Kaowool blanket,  Two face masks, two pairs of nitrile gloves AND the proper propane jet  :ddb:

A bit of careful marking out and cutting and the kaowool was reduced to a 12.5" disk with a 7" hole in it ready for use as a thermal barrier between the ceramic tile and the metal plenum chamber.

I then 'caulked' the joint between the plenum chamber and the quadrant tiles with the RCF mastic forcing it as far into the joint as possible as it is this seal that had previously been leaking.

Then fitting the Kaowool disk with the perforated tile on top I caulked all round the tile forcing as much as possible down into the gap. Having got as much in as I could with a putty knife I then forced it further in with a wooden lath cut to size. Another two  trips round the tile with the putty knife pushing the mastic in as far as possible followed by smoothing with a wet trowel and a damp cloth. This seal HAS to be good or the whole rigmarole that I've been through will be a waste of time.

Asking how long to leave the mastic I was told that in the factory they hit it with a gas torch, make it sweat, and then it's ready ! OK I used the forge torch to dry the surface then put the ceramic chips back in and lit the forge, reasoning that hot chips are no different than a darn big gas flame to dry and cure the mastic.

Initially clouds of rather nasty smelling steam then after about 5 minutes things began to clear and the chips started to glow. After ten minutes I'd swear it's hotter over a more even area than i can ever remember it. So with much of the bulk of the ceramic chips glowing white hot I turned it off in the interest of conserving propane  - I'm sure that the mastic will now set nicely.
« Last Edit: February 24, 2021, 10:36:15 AM by awemawson »
Andrew Mawson
East Sussex

Offline awemawson

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Re: Resurrection of a CFEI 100 KVA Induction Furnace
« Reply #753 on: February 24, 2021, 09:23:50 AM »
Comparing the 'original' propane jet that was in the forge when I got it to the one sent by Flamefast convinces me that someone has altered the holder from 1/2" BSP to M 12, but what is important is the hole for the gas - how big is it?

My currently installed one is 3.5 mm as that was as close as I could get to a #28 drill. I'd been told recently by Flamefast that the jet should be 3 mm, but NO! This jet actually measures #29 (yes I now have a set of number drills!) or extremely close to 3.5 mm so I'm not going to change anything.

« Last Edit: February 24, 2021, 10:40:26 AM by awemawson »
Andrew Mawson
East Sussex

Offline hermetic

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Re: Resurrection of a CFEI 100 KVA Induction Furnace
« Reply #754 on: February 24, 2021, 02:38:18 PM »
Another useful peice of kit brought back to life Andrew! There is nothing worse than finding a job you have to do and then saying "this would be easy if only X was working" And now it's Perfick!!
Phil
Man who says it cannot be done should not disturb man doing it! https://www.youtube.com/user/philhermetic/videos?

Offline Pete.

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Re: Resurrection of a CFEI 100 KVA Induction Furnace
« Reply #755 on: February 24, 2021, 05:26:27 PM »
"May cause cancer by inhalation" - that can only mean it's the GOOD stuff :D

Offline awemawson

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Re: Resurrection of a CFEI 100 KVA Induction Furnace
« Reply #756 on: March 30, 2021, 09:59:57 AM »
So there was I melting the greenhouse . . . . . .

. . . . . OK let me explain, some years ago we had a greenhouse that was a bit of absolute imported rubbish - it didn't last the first winters storms - and for several years now there have been bits of green anodised aluminium channel section getting in the way and being tripped over in the horticultural area. Time to sort them out (I was told).

Now no point in chucking it out, turn it into ingots and save it for later use. Cut up with the band saw into convenient 'crucible lengths' today was it's appointment with doom. I even welded up an extra ingot mould as there was 3 kgs in the bundle.

All put in the pot, coolant water from the borehole circulating, 110 kva generator purring away . . throw the switch Igor  :bugeye:

Wound it up to 50, then 60 then 75 kw - channel section sinking nicely into the melt - hang on - what's that burning rubber smell ?

Now there had been flames off the channel sections, not unexpected with the dross of years on the surface but this was distinctly burning rubber - what's going on and why are there flames down there among the various driver hoses ?

It turns out that one of the driver cables that is enclosed in 'Brewers Hose' for water to circulate to keep it cool, was resting against the 'air hose' (actually braided hydraulic hose that I'd used for robustness), and there must have been enough electromagnetic coupling from the driver hose to the metallic braiding to heat it up and set the rubber sheath on fire !

Turn off the furnace driver, give the hose a blast from the CO2 extinguisher and the flames subside - move the hoses apart - tentatively tilt / untilt the furnace (which uses this hose for the pneumatic cylinder) - OK still working - turn the furnace driver back on while the crucible is still hot, and pour the ingots (second one looks lousy quality)

. . . the good part of this is that it has only cosmetically marked the Brewers Hose (which is darn expense) - OK the air (hydraulic) hose is toast (literally!) but I have miles of that so it's not an issue.

OK Greenhouse melted, domestic demands satisfied, just need to swage up a new hose !
Andrew Mawson
East Sussex

Offline mattinker

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Re: Resurrection of a CFEI 100 KVA Induction Furnace
« Reply #757 on: March 30, 2021, 10:39:40 AM »
Andrew,

I know you are fortunate enough to be able to analyse your metal content! Extrusions are usually pretty pure Al. Did you add any Cu? I find 4to 5% Cu makes a harder more easily machinable alloy!

Cheers, Matthew

Offline awemawson

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Re: Resurrection of a CFEI 100 KVA Induction Furnace
« Reply #758 on: March 30, 2021, 12:34:54 PM »
Matthew it's still in the ingot moulds. I made my judgement on how horribly it poured but as you say extrusions are usually LM2 or similar.
Andrew Mawson
East Sussex

Offline awemawson

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Re: Resurrection of a CFEI 100 KVA Induction Furnace
« Reply #759 on: March 31, 2021, 06:11:34 AM »
Added to today's tasks was of course making good yesterday's damage :bang:

Taking the hose off and duplicating it was easy, as I had the crimp ends and 1/4" hydraulic hose in stock, and I also have the proper 'Parker' crimper. It's a bit of a fiddle to manipulate but good solid kit that gives a nice reliable result.

The second air hose running along side this one had suffered a bit of collateral damage but I judged it safe to use - mainly cosmetic scarring.

Now having put it all back together the obvious question is how to avoid the problem in the future  :scratch: I had left the four Brewers Hose power feed cables unstrapped to give more movement flexibility but it occurred to me that these are basically a transmission line (well a pair of transmission lines) and they avoid radiating by the fields of parallel conductors cancelling out (i'm assuming here that the damage WAS stray energy radiation from these leads inducing large currents in the braid of the air hose) so the first thing that I did was Ty-Wrap them into pairs.

However watching the action of the crucible assembly raising and lowering (it tilts) in the down position the power cables press firmly against the air hose which is less than desirable from many point of view. However stopping this is by no means simple. I need the hoses to emerge at a different angle from the base of the tilting assebly.

If I can source some brass 3/4" BSP cone connections that are at 45 degrees then that might be a possible solution but I reckon that they are probably as rare as hens teeth !

Andrew Mawson
East Sussex

Offline chipenter

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Re: Resurrection of a CFEI 100 KVA Induction Furnace
« Reply #760 on: March 31, 2021, 09:59:44 AM »
Would two ninety's have enough room to be set at any angle you want .
Jeff

Offline awemawson

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Re: Resurrection of a CFEI 100 KVA Induction Furnace
« Reply #761 on: March 31, 2021, 11:15:15 AM »
Jeff that certainly is a possibility, though the whole structure is becoming rather cumbersome. (Remember that these carry thousands of amps as well as the cooling water)

I'm wondering if I can construct a non conducting (but heat proof) gently curved shelf over the air lines to keep the power cables a fair distance when it comes down.

I also want to conduct an experiment with a bit of the braided air hose held close to the power cables when the furnace is at full tilt to see how far away is 'reasonable' - presumably the inverse square law applies. But that is a two person job to be safe as one needs to keep an eye on the generator / cooling system / furnace driver while the other dangles bits of hose and and measures how hot they get!

Andrew Mawson
East Sussex

Offline WeldingRod

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Re: Resurrection of a CFEI 100 KVA Induction Furnace
« Reply #762 on: April 01, 2021, 10:36:19 PM »
Zip tie scraps in place with wood spacers?  If the zip tie melts you know it's too hot ;-)

Sent from my SM-G892A using Tapatalk


Offline awemawson

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Re: Resurrection of a CFEI 100 KVA Induction Furnace
« Reply #763 on: July 25, 2021, 02:46:53 PM »
You may recall the problems that I had with the roof of my foundry - lots of leaks, lots of repair attempts etc, it ground on like a cracked record.


Well today we had an absolute deluge in a short space of time. My rain gauge has recorded 43.4 mm in the last 24 hours but a lot of that happened in about 20 minutes.

Hearing how poor old Graham (Seadog) has suffered with his workshop roof leaking badly I thought I'd better go out and see how the foundry was fairing.

Delighted to say just a minor (tolerable) damp patch in one corner, so it looks like the big issues are solved - fingers crossed)

Andrew Mawson
East Sussex

Offline Sea.dog

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Re: Resurrection of a CFEI 100 KVA Induction Furnace
« Reply #764 on: July 26, 2021, 05:47:04 AM »
Good news, Andrew. I think that you now can be fairly certain that the foundry is water tight, to all but downpours of biblical proportions, that is  :clap:

Offline edward

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Re: Resurrection of a CFEI 100 KVA Induction Furnace
« Reply #765 on: July 26, 2021, 09:47:26 AM »
One thing that comes out of these rather excellent threads is that I find out about things I never knew I needed - I've had one of those rain gauges since you mentioned it, alongside my existing 'weather station' on my bedside table.

Now I don't even need to get out of bed to see if it is raining or not :-)