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Re: Depotting a resin-filled tranny
Original poster: "Jason Petrou by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jasonp-at-btinternet-dot-com>
Main problem with epoxy is that it sets like rock and i'm not sure of
anything that can dissolve it. If you mix 30% concentrated nitric and 70%
concentrated sulphuric acid this will probably get rid of it, but be careful
that it doesnt touch the windings or the case!
----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
Sent: Tuesday, May 29, 2001 7:15 PM
Subject: Depotting a resin-filled tranny
> Original poster: "sundog by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> Hi All!
> I got an interesting delimma. I have a 15/30 and a 12/30 that I want to
> depot. The 15/30 is a tar-potted jobber, the 12/30 is a resin-epoxy
> block. The 15/30 is no problem, a few days in the freezer, short the leads
> and let it run for 1/2 an hour or so, and then gentle use of the air
> will pop it out of it's tar block. Keyword is "gentle", with a cutting
> chisel on the air hammer, not the pointy one, and patience. Knowledge of
> what is where in the NST case helps too.
> But the epoxy resin one...I haven't tried to depot one yet, and despise
> soaking them. The 9/60 took 2 weeks, remained gooey and nasty. I'd
> get as much tar off as I can chipping, then use a pick on the rest and
> re-potting it in a metal container (ammo cannister prob'ly), put it in
> bath of oil or vaseline, and let it simmer!!! Until little blobs of molten
> tar appear. That way I get the potting in where the tar can melt out of.
> So far experimental chipping on the epoxy blocks were not too good. it
> seemed it wouldn't release the windings without trying to take them off
> Soaking the epoxy is out. Maybe apply heat with a heatgun and airchisel?
> The epoxy trannies I had that died all shorted to the case by tracking
> the screw in the HV bushings. The bushings usually cracked when this
> happenend, and the shorts became almost impossible to fix (tried to dremel
> out the charred epoxy, no luck.) I would rather depot the tranny now than
> have to have it fail on me later when I'm tinkering on a coil (and
> an evening of coilin').
> Ideas? (throwing it off the 6 story building I work in isn't an option,