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REMOVING ENAMEL COATING
From: Michael Coslo on Thurs, May 29 2008 6:02 am:
AF6AY wrote: From: (Dave Platt) wrote on Mon, May 26 2008: In article , W3CQH wrote: I wonder if items such as Strip-X became obsolete due to changes in insulation composition, i.e. not working on new types of insulation. But I do agree about the folk who would protect us from ourselves. Strip-X was pretty innocuous stuff. As far as I could tell from communications with General Cement, it was FEDERAL REGULATIONS that was the issue. GC already had over a hundred products in its catalog so they weren't going to suffer any real loss in income. They've been making 'radio' chemical products for over 75 years. Did you by any chance try some old style enameled wire in your experiment above? "Experiment?" The only experimentation I did was well AFTER my last bottle of Strip-X was used up, residue dried out. Strip-X from GC worked for me the first time I tried it long, long ago. That experimentation I wrote about was to find a possible substitute for GC Strip-X. GC Strip-X has worked on enamel-coated magnet wire, PolythermalEze (a trade name), different kinds of wire-wrap wire. It didn't work on the surplus Teflon-coated #25 AWG magnet wire I got surplus from a transformer maker (#25 is an odd gauge, heh heh, but the transformer makers use practically every gauge in the AWG table). Tetrafluouroethylene is pretty inert stuff so few chemicals will affect it. Teflon also abrades easily compared to other insulations so it is relatively easy to strip with a knife. The acetone issue is a strange one. Acetone is one of the safer solvents out there, heck our body even produces some acetone. I think that should be 'acetyls' in the human body, not acetone per se. shrug Acetone won't strip off enamels or other polymers used on magnet wire. I tried that, too, also toluene. Acetone as a solvent was dropped from the model hobby industry chemicals once gas-powered models started using "hot fuel," the methanol-based stuff for glow plug engines that took over from real spark plug ignition model gas engines in the late 1940s. Methanol softened acetate-based paints, whereas the 'ordinary' gasoline used in spark ignition engine fuel did not affect acetone-solvent lacquer commonly called "dope" in model hobby industry jargon. For years Testor Chemical Company, also in Rockford, IL, had lacquer paint bottle labels of DOPE in all- capitals, something you just CANNOT DO in today's restrictive society. Building model airplanes was fun, the "dope" smelled very nice, so the blue-noses made all kinds of bad noises about the "evils" of having fun in a hobby. Sigh. Digression: The first small two-cycle gasoline engines used real spark plugs of very small size. I still have two Champion brand spark plugs in a storage area...less than a half-inch long...and those are for the big class C and D engine displacements. I learned to solder wires properly by making the spark ignition packages for gas-powered models. The "spark coil" for those was a tiny one that was picked up by the first electronic flash units for camera use in the 1950s...ideal for igniting the Xenon flash tubes that replaced the one-shot photoflash bulbs. Yes, I was emitting "spark" RF in the late 1940s with those spark-ignition engines, all without being licensed to do so. So were other gas-engine modelers and just about EVERY running automobile of that time! :-) My late father-in-law was a polymer chemist. He died in 1977 so can't help me. I just hope that some chemist could come to the aid of us hobbyists using coated magnet wire and provide us with a GOOD product like Strip-X was. Meanwhile, it's back to being VERY careful with a sharp X-Acto knofe and scraping coatings. With #34 AWG that requires Zen-like calmness... That is an understatement1 8^) I have to make sure I am in a good mood, and no coffee for me that day before I attempt that sort of thing. Coffee calms me down. Always has. Makes for good moods. :-) Actually, I use a fine emery finishing paper to strip fine gauges of enamel-coated wire. I've used X-Acto hobby knives for the heavier gauges. Emery paper (easy to get at do-it- yourself stores) allows a gentle stroking of a folded emery paper over the wire. I find it works better to draw the emery paper over the wire rather than pulling the wire through the paper. Less nicking than with a knife blade for #28 to #34. I just finished a few small toroid inductors using #34 enamel-covered last week. Not recommended for beginners. :-) PATIENCE (in all-caps) is needed to make toroids of the T37 size (about 3/8" OD), drawing a very-carefully-folded wire bundle through the center hole in a toroid core. :-) THAT is the "Zen" thing. Good self-control is absolutely necessary, can't use slap-dash hurry-up behavior. By the way, don't use "Q-Dope" for coating finished inductors, any type. Despite what the ads say, it does NOT enhance the coil's Q. Trials of before-after measurements on a Q-Meter haven't shown goodness. ALL coatings degrade inductor Q. I've found that oil-based 'maritime' clear varnish to result in less degredation of Q than other coatings. I've used McCloskey "Gym-Seal" brand with good success on making inductor coatings that adhere to windings for years. It is available nationally in do-it-yourself stores. Q-Dope (originally acetate-solvent based, now probably using toluene solvent) will "lift" from smooth surfaces within a year in climates with only moderate humidity. Q-Dope only adheres well to all-polymer-based surfaces, won't get into fine pores. 'Maritime' varnishes NOT polyurethane based DO grab porous surfaces. I've tried various polyurethane- based varnishes with mixed results; the makers of those apparently have a rather large variation of ingredients. Varnishes take 2, 3 days to properly cure if used on coils. That's the down-side of using the stuff in hobby applications. However, on a Q-Meter the characteristics of 'maritime' varnish coated inductors don't change much after it has reached a tacky state, roughly 12 hours after application. It ain't for 'weekender' projects started on a Saturday and 'finished' on Sunday. 73, Len AF6AY |
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