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Electropolishing and cleaning stainless steel and aluminum

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  • DigiSnapMark
    replied
    I'll bite... I'm an engineer, not an lawyer, but here's my take.

    The patent system is intended to disseminate new technology ideas... not to hide them. A US patent is a public document, intended for the general public to look at, to gain knowledge of new inventions. There might be some copyright issues with freely copying patents around the place, particularly if you just show excerpts, but they are never intended to be secret!!!

    The original idea was to encourage publishing your inventions, by giving you 17 years of exclusive license to the invention. If not for this system, you'd have most inventions closed up in notebooks somewhere, to keep them secret, and technology advancement would crawl.

    There's absolutely no incentive for any patent holder to sue someone for infringement if you use their idea for your own entertainment, or build 10 for your friends. If you start making loads of money off a currently patent protected idea, and they find out about it, and decide they want to give a lot of money to lawyers, maybe they'd sue, and in some cases maybe even win. It's rather expected that if even if you are 'in the field', you're going to build that invention, play with it, and see if you can work around some of the patent 'claims' to circumvent the patent.

    HSM'ers should never worry about infringing... People who try to make LOTs of money off of a patented idea might.

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  • lazlo
    replied
    Originally posted by Evan
    I just finished supper and am going out to the shop to try some aluminum.
    Evan, the other thing I'm curious about: how does the initial surface finish (on either SS or aluminum) affect the final surface finish? If you were to lightly polish the surface with sandpaper, and then electropolish it, it seems like the leveling effect of the eloctropolish would give you an even finer surface finish, as opposed to a billet finish, where you're leveling rolling hills and valleys in the material.

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  • Evan
    replied
    I just finished supper and am going out to the shop to try some aluminum. I will report later.

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  • jkilroy
    replied
    I am looking forward to trying this on aluminum. Evan how would you suggest protecting threads, in my case blind holes with 3/8x16 thread. Run in a bolt? could this process be used before anodizing without ill effect?

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  • Evan
    replied
    Here is the toasted SS tube test. I cooked the tube on the gas stove until it was dull red heat. After cooling it went in the bath at 24 volts for about 10 minutes, right end only in the image. The foam bubbled up so I had to cut it short but the piece was developing a nice shiny finish at the right end which is closed to the bottom of the bowl. Another 5 to 10 minutes and it will be all shiny for the half that was in the bath. The left half received some cleaning action too because it was covered in charged foam.

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  • Evan
    replied
    Robert,

    Anything with nitric acid isn't similar or safe in the home shop. Nitric is a very agressive acid and can cause very prompt and serious burns. I make sure my chemical recipes are environmentally benign and don't present a disposal problem. We are more acutely aware of that than most since we treat our own sewage on site on this property in a sewage lagoon about 30 feet in diameter. As long as it doesn't get contaminated with things like bleach the bacteria and algae stay healthy and it has a pleasant green plant smell as well as frogs living in it. I would like it to stay that way.

    I haven't done any real tests yet with aluminum. The testing is a slow process because the solution heats too easily. It will need a double bath cooling system the same as I use for anodizing but I don't want to go that far right now.

    Right now I am letting the solution cool for another test, this time a cleaning test of a heat discoloured SS tube.

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  • lazlo
    replied
    Originally posted by Evan
    Here is the micrograph of the faceplate.

    That's pretty amazing. How well does it work with aluminum?

    The standard "Brite Dip" (aluminum electrolytic polish) formula is pretty similar:

    ALTERNATIVE TO BRIGHT DIPPING

    Historically, aluminum has been and is still brightened using the aluminum bright dip bath. This bath consists of about 71.5% phosphoric acid, 10% aluminum phosphate, 10% water, and 2.5% nitric acid. Sometimes sulfuric acid is added, about 6 to 10%. The bath runs at 225 to 240° F. Nitric is a volatile acid and must be added each hour to the bath. Nitric acid also forms nitrogen dioxide, which is a yellow fume that is toxic; therefore, a fume suppressant, such as diammonium phosphate, is also added to the bath to break the nitrogen dioxide down to nitrogen and oxygen. This bath requires a shrouded hood with slots going up to the height of the racks being pulled out of the tank. The parts give off nitrogen dioxide in the air and the fumes must be sucked off into the exhaust hood and into the fume scrubber. There are about 17 variables that have to be controlled each hour to produce bright, pit-free aluminum. Plant corrosion is very bad.

    Originally posted by Evan
    They can start a new thread. My recipe isn't patented so the point is moot.
    I was replying to Tony Ennis' comment that it's OK to copy a patent if it's not for profit. That's definitely not true.

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  • Evan
    replied
    They can start a new thread. My recipe isn't patented so the point is moot.

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  • lazlo
    replied
    Originally posted by dp
    How many pages of off-topic bickering will the herd take this thread? I'd bet it's good for 300 posts just on patent foolishness.
    If you want to kiss Evan's butt some more Dennis, you can do it in the Swine Flu thread.

    Leave a comment:


  • dp
    replied
    Originally posted by lazlo
    They can sue you for the cost of a FogBuster. By building, and using, the FogBuster described in their patent, you have deprived them of $500 of revenue.

    Very unlikely, but if you have a thread with 30 posts, like we had on PM, where everyone was showing their copy of FogBuster's patent...
    How many pages of off-topic bickering will the herd take this thread? I'd bet it's good for 300 posts just on patent foolishness.

    Leave a comment:


  • Evan
    replied
    Here is the micrograph of the faceplate.

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  • Evan
    replied
    They can sue you for the cost of a FogBuster. By building, and using, the FogBuster described in their patent, you have deprived them of $500 of revenue.
    They would have to prove that you would have bought one, They can't. In fact, the fact that you built one is evidence you wouldn't buy one. They can't establish intent on your part and they can't make a case for damages that didn't occur. The only way you can deprive them of revenue is to take the revenue yourself.

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  • lazlo
    replied
    Originally posted by Michael Hall
    There is a good post on rec.crafts.metalworking discussing this very subject, it is from a few years ago. If my link does not work search RCM using "electropolishing recipes" the author is Carl Ijames.

    http://tiny.cc/PAqXj
    That's a great post/recipe! Seems pretty simple -- very similar setup to electrolytic rust removal or electrolytic cleaning.

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  • Michael Hall
    replied
    There is a good post on rec.crafts.metalworking discussing this very subject, it is from a few years ago. If my link does not work search RCM using "electropolishing recipes" the author is Carl Ijames.

    http://tiny.cc/PAqXj

    Michael

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  • Blueskys
    replied
    Originally posted by Evan
    It draws directly from electroplating which goes back to the Babylonians so there is a very large body of prior art.
    I wonder what the Babyloners used for the electro part of the plating
    process. Some kind of chemical/battery reaction?

    Great discussion. A humbling reminder of how little I know/understand about
    so many things.

    EDIT: Persian Batteries made of clay with iron and copper for anode/cathode and vinegar
    for electrolyte? Remnants have been found but some dispute over whether
    they were actually electrical devices.
    Last edited by Blueskys; 11-29-2009, 06:26 PM.

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