The Craftmans Shop > New from Old
Resurrection of a CFEI 100 KVA Induction Furnace
awemawson:
As you know Graham, it was packed to the rafters, and totally impossible to work in.
. . . Something had to be done !
awemawson:
Today's objectives : Wire up the 415 volt three phase input and connect the furnace body ready for pinging
All very well, but the postman delivered the replacement bearings for my buffing spindle, the motor of which is in pieces on the workshop floor - so re-assemble with new bearings - it's only a 5 minute job.
Blooming thing took literally the whole morning. First assembly, greased the bearings, pressed them home, replaced the motor end bells, spindle locked solid :bang: Slacken an end cap spindle frees up - have I put the crinkle shaft expansion washer in the wrong place :scratch: Pull it apart, no washer in correct place, make sure bearings fully home - reassemble - still stiff - argh, beginning to loose the will to live . Dismantle for third time, examine everything, find a burr on one bearing retainer ring pressing inwards onto shaft - bung it back together, put it back on it's pillar - all OK except I've just lost an entire morning :(
So I didn't get started on the furnace until this afternoon. First thing, pull it away from the wall on the pallet truck and unbolt all the doors - front one has keys, the other three although hinged are bolted shut, and the last panel is just bolted and not really removable as loads is mounted on it.
To get it out of my previous foundry, the main isolator switch operating handle, and the 125 A input socket had to be removed to get it through the door - but where are they? OK found tucked away inside behind panels, and at least I had had the foresight to label the phases :thumbup:
Bit of a pain re-assembling them - one of the Nutsert bushes holding the input socket failed and is pretty well impossible to get at, so it's fixed with three out of four bolts, but OK for now.
awemawson:
So now on to the driver connections to the furnace body. There are four rubber hoses each with a heavy braided copper cable cooled by a water jacket - or they would be if I had a cooler !
Searching around I found that I had made sketches back in 2005 when I got this beast to better understand how it interconnects. Basically there are two coils (actually one centre tapped) with a blockage for water where they join. The coils are wired in parallel and give about 13 micro-henries of inductance.
There are two water circulating paths.
OK how do I connect it - I opened up the back of the furnace body that I moved yesterday and then remembered - as I had two bodies I had a system of quick disconnect couplers, with copper braid jumpering them so that the QD surfaces didn't carry the current. But my short hoses don't have the QDs fitted.
Options -
A/ lug the long pipes over - I think they have the QDs
B/ remove the QDs from the furnace (actually not easy due to the construction around them
C/ use the replacement coil set that I have suitably suspended to avoid human contact (nasty high voltages)
I'm tending to option C/ at the moment but will think it over, meanwhile I've realised that I don't have a spare cable mounted 125 A socket to power the beast up, so I need to rob one from somewhere else.
Time for a cup of tea !
Sea.dog:
I take it that you don't have a Rivnut set? It would be a 5 minute job to drill the old nut out and replace.
awemawson:
I do, and it isn't, as it rotates in the hole !
(The nutsert has pushed through the panel, but the bolt is firmly stuck in it so bolt would need sawing off in situ )
These 5 minute jobs - had one of those this morning . . . . :bugeye:
It can bally well make do with three screws until the fate of the big blue box is decided !
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