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Cleaning a dirty chassis




 
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Author Topic: Cleaning a dirty chassis  (Read 12189 times)
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Todd, KA1KAQ
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« on: June 22, 2005, 11:16:00 AM »

One of the most rewarding parts of using old gear for me is the restoration process. I'm not a concours-collector-minded type, but a clean piece of old gear is a sight to behold. It's almost like stepping back in time to the day when the new owner put the piece of gear on the air for the first time.

Getting a dirty chassis clean can be a pretty big challenge. Over the years I've found some little tricks that work fairly well and might not seem all that obvious.

Before starting with any cleaning solutions, I usually try to blow off the chassis first with a compressor. This removes a lot of crap that would otherwise turn into mud as soon as you apply cleaner. If you have a large compressor, be careful as a strong blast of air can actually do damage. Even my small compressor is capable of this. To aid in the removal of loose dirt, try using a variety of soft paint brushes to loosen the dirt.

When it's time to move on to the cleaning fluid part (Windex, soap and water, whatever flicks yer switch), put away the paint brushes and try an old toothbrush. And for those really tough, deep areas between transformers, IF cans, or whatever else - those gray sponge disposable paint brushes work great. I use the small size for most applications. They are bevel-cut at the bottom and also have a stiff piece of plastic inside to lend shape and support. This is handy for getting into cracks and cervices, but be careful. As the sponge wears away, the plastic can become exposed and is capable of marring aluminum. Q-Tips work well for the areas you can easily reach, and most drug stores have the long, wooden swab version for deeper places.

I'm not a fan of the dishwasher or hose approach for anything but the most extreme cases where you really have nothing to lose and everything to gain. But I do try to rinse the areas cleaned before drying the chassis in the sun or with some source of heat. Be careful of getting liquids into transformers and coils, of course.

There are plenty of other tools for certain situations. #0000 steel wool is good for polishing away surface damage, but should be used with care or you can do more damage than good. Same thing applies to cleaners, of course. I reserve use of 409, Fantastick, or other heavy duty cleaners for extreme cases as they almost always remove the luster of paint, if not the paint itself.

I'm probably preaching to the choir here, but maybe someone will find a tip in there that will help out in a restoration. Even better, I hope to see more helpful comments that I can learn from as well. Cheesy

~ Todd,  KA1KAQ
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k4kyv
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Don
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« Reply #1 on: June 23, 2005, 02:26:05 AM »

Quote from: Todd, KA1KAQ
I reserve use of 409, Fantastick, or other heavy duty cleaners for extreme cases as they almost always remove the luster of paint, if not the paint itself.


They also remove the lustre of bakelite, and it can never be fully restored.  It dissolves  the "skin" of the phenolic, exposing to the surface the filler, which may be anything from powdered mica to plain ol' wood sawdust.
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« Reply #2 on: June 23, 2005, 06:51:54 AM »

Don, see my post on this subject:
http://amfone.net/Amforum/index.php?topic=4883

I agree it probably can never be *fully* restored, but you can get awfully close.

73 John
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Todd, KA1KAQ
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« Reply #3 on: June 23, 2005, 01:21:33 PM »

John -

I wonder if you could polish bakelite back to a decent level as you outlined, then spray it with a decent, durable clearcoat? Obviously the surface would have to take the coating, so any residue could prevent this. Overspraying after simply cleaning and removing the coating would yield shiney crap-brownish black knobs, though. I recall reading an article in ER (I think) some years back about a guy who used black shoe polish and a buffing wheel.

Somewhere amongst the piles of 'stuff' I'm sure there are some borken old knobs to experiment on. If I don't find time for it in the next year(or month), would anyone else care to try?
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« Reply #4 on: September 11, 2011, 01:38:03 AM »

The only method that I have used and do not recommend is a kiln method using a programmable ceramics kiln. You must gradually heat the bakelite piece to nearly its surfaces melting point, then very gradually cool it down. You must watch it continuously and you can certainly destroy the piece very easily.

Not recommended.
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K1JJ
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« Reply #5 on: September 11, 2011, 11:55:10 AM »

Fantastic!

Back in 1966 I acquired a used HT-37 and cleaned it up like any good JN would. Using Fantasdick, (or was it 409?)  I started cleaning the panel meter. After 30 seconds the plastic lens cover turned a frosted white and I could barely see the meter needle. The cleaning solution literally melted the surface of the plastic!  I couldn't believe this was happening - like a ham nightmare.

Later, I carefully sanded the meter cover with fine sandpaper and then polished it. The meter still looked slightly frosted and barely readable.

A few months later I traded the rig in. No one noticed the fogged meter at the ham store. Somewhere out there there's a slightly frosted HT-37.. Embarrassed

T
 
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« Reply #6 on: September 11, 2011, 01:06:28 PM »

Using Fantasdick, (or was it 409?)  I started cleaning the panel meter. After 30 seconds the plastic lens cover turned a frosted white and I could barely see the meter needle. The cleaning solution literally melted the surface of the plastic!  I couldn't believe this was happening - like a ham nightmare.

Yep, clear plastics are very susceptible to surface corruption from a lot of solvents used in 'cleaners'.

Rather I always try and polish them out with Meguairs' plastic polish, and it usually will give great results without changing the optical qualities.

It also does a pretty good job on metals that aren't rusted or corroded, just dull looking or full of fingerprints.

73DG
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