Removing sharp perforation edges on stators with ferric chloride - Page 2 - diyAudio
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Old 3rd July 2007, 02:07 PM   #11
oshifis is offline oshifis  Hungary
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Bigwill,

In your place I would not do it with my precious stators. Just try with a piece of aluminium sheet in a plastic (!) tray with well diluted NaOH. NaOH is still more "friendly" than FeCl3, that is a killer material, etches everything. You realize too late that your dress has holes on it. Do it in open air, the gases released make you cough strongly. But the result will be a rough tarnished piece of junk, not a nice shiny metal sheet with rounded edges what you wanted. Countersinking sounds more safe, alhough time consuming... Flexible sandpaper disc in a drill, just to make the surface flat is not enough?

Laszlo
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Old 3rd July 2007, 02:32 PM   #12
bigwill is offline bigwill  United Kingdom
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Hmm yes maybe I will just countersink and sand afterall then. I'll need some extremely fine sandpaper to remove the little sharp lips of metal countersinking leaves but yes I think this is actually more sensible.
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Old 3rd July 2007, 02:37 PM   #13
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The Audio Amateur had a electrostatic speaker project back in
maby 1972. As I remember the author did use a warm sodium
hydroxide solution to debur his aluminum. Then he had them
annodized.
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Old 3rd July 2007, 03:29 PM   #14
Few is offline Few  United States
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Electropolishing would probably be the ideal technique for removing the sharp asperities. I'm not sure it's very diy-friendly though. You'd certainly end up working with a large quantity of nasty chemicals (usually acids). Perhaps it would be worth looking into a local commercial electropolisher. You could be confident that your stator wouldn't be dented or kinked by your mechanical polishing efforts.
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Old 3rd July 2007, 05:08 PM   #15
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I have made some experiments with little perforated sheets of aluminium and sodium hydroxide. Its possible to remove the burr, but you don't get round edges. In another forum electrolytic polishing was recommended, but I have no experience with it.
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Old 3rd July 2007, 05:47 PM   #16
bigwill is offline bigwill  United Kingdom
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I wonder if it's possible to electropolish alumium in hydrochloric acid? Any chemists here?
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Old 3rd July 2007, 06:15 PM   #17
Few is offline Few  United States
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I'm a physical chemist but I haven't tried electropolishing aluminum and so can't speak from experience. The site I mentioned previously includes aluminum in their list of suitable metals, so I take it that it can be done. You do have to be careful, though, because the various aluminum alloys behave quite differently in electrochemical processes. For example, I've found when anodizing aluminum that the results depend strongly on the alloy used. I do think electropolishing holds more promise than simply dipping the stator into a corrosive bath. I would anticipate extensive experimentation being required as you try to figure out the details of the conditions that yield the desired results. If the pros can do it for a reasonable cost, relying on them might be the better approach---even though it isn't fully within the diy spirit.
Few
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Old 3rd July 2007, 07:42 PM   #18
bigwill is offline bigwill  United Kingdom
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I found this site about etching aluminium in lye for asthetic purposes

http://www.mailleartisans.org/articl....cgi?key=18133

It seems to leave a nice finish!
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Old 6th July 2007, 09:29 PM   #19
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This is silly.

Take a small piece, place in the solution of your choice, TEST.

Consider a small piece in a "ziplock" plastic bag.

I say properly done the "lye" will do the trick. The sharp edges will react more than the flat edges, the result should be deburring.
Agitation may help.

Temperature plays a role too.

Once the aluminum forms an oxide, or if it forms an oxide layer, it will cease to react.

BE SURE TO WEAR EYEPROTECTION AND RUBBER GLOVES whenever you work with chemicals like these!! It is also a good idea to wear clothes that fully cover your body.

DO NOT POUR LYE DOWN YOUR DRAIN!!!


Have a mild acid on hand (citric acid based is good) like vinegar or similar and a hose to clean off any splashes or spills. Especially on your clothes or skin.

Shiny alumininum should not be the prime criteria - working panels should, imho.

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Old 7th July 2007, 02:35 AM   #20
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Default Perforated Al ESL stator prep

First post- Back in the 70's, Sanders etched his aluminum stator panels with lye (sodium hydroxide). Ferric chloride is a real stain pain.
The panel should be first wet sanded with 4-600 grit "wet or dry" emory paper. Use a soft rubber sanding block. This may be enough to knock down the ridges.
If you feel the urge to use the NaOH, as a follow up, wear eye and hand protection. The stuff will blind you and eat your flesh!
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