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Old 9th December 2006, 09:21 PM   #1
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Default Unstacking a transformer...

OK, need some help from the pros.

What's the easiest way to unstack the laminations of an EI transformer core that has been dipped in varnish?

Want to keep the damage to the laminations to a minimum so it can be reassembled later.

TIA,

-- josť k.
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Old 9th December 2006, 09:33 PM   #2
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If you are not keeping the windings heat it up so all the glue burns off. The oven works but use a open window and a fan. Not many chemicals will work, try acetone before oven.
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Old 9th December 2006, 09:43 PM   #3
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I second the suggestion for acetone. Dunk it in a tub of the stuff, make sure it's fully submerged, and leave it in there for a few days. I've taken apart many smaller transformers because the varnish tends to turn into more of a gel with the acetone. I've also read that nasty solvents like toluene and xylene could work but honestly I'd avoid them.
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Old 9th December 2006, 10:02 PM   #4
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Use of a retractible knife and cleave the lams like sheets of mica. Relatively fast.
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Old 9th December 2006, 10:14 PM   #5
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Quote:
Originally posted by Geek
Use of a retractible knife and cleave the lams like sheets of mica. Relatively fast.
Acetone makes this a lot easier. What worries me about having done this is that the razor might scratch the insulation off from the laminations. I've read that it's important for each lamination to stay insulated from the others, so do this at your own risk.
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Old 9th December 2006, 11:58 PM   #6
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Quote:
Originally posted by sorenj07
I've read that it's important for each lamination to stay insulated from the others, so do this at your own risk.
It is, but when you restack, use nail polish. Never restack them dry anyway since you'l have a pretty noisy transformer.

I've been doing this for years with the knife and polish, no failures yet
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Old 10th December 2006, 12:04 AM   #7
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what's the procedure for restacking it wet?

thanks,
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Old 10th December 2006, 12:57 AM   #8
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Just a little stripe of polish on the surfaces, lay down the next layer of E and I. It doesn't have to be spread too thick, when you squeeze it later with a clamp, it'll spread quite evenly.

As ou near filling the stack, use a Quick-Grip clamp with the rubber pads removed to give a squeeze on the exposed faces. You can install the rest. Give a final squeeze, rub off the nail polish that squeezes out and you can use it right away, or if the smell bothers you, wait a couple of days to dry (the heat from an operating transformer will cure it all the way through in a week).

If you have a few lams left over (3 is typical), no worries. It takes practise

I just use the el-cheapo clear enamel that's 50 cents/bottle. It's easier to work with. The expensive stuff never quite hardens and is too thick for this job.
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Old 10th December 2006, 01:08 AM   #9
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Default just found your webpage...

http://geek.scorpiorising.ca/windingtransformers.html

Good reading.

-- josť k.
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Old 10th December 2006, 01:15 AM   #10
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Default Re: just found your webpage...

Quote:
Originally posted by korneluk
http://geek.scorpiorising.ca/windingtransformers.html

Good reading.
Thanks!
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