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Re: Copper Machining Question

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  • kwolson2002
    Larry I think mostly what s occurring in this electrolytic rust removal process is as follows: Electrolyte perks through the porous rust layer until it reaches
    Message 1 of 31 , Aug 1, 2005
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      I think mostly what's occurring in this electrolytic rust removal
      process is as follows:

      Electrolyte perks through the porous rust layer until it reaches
      solid metal after the work is plopped into the bath.

      The electic current is applied to the cathode and anode, separated by
      the electrolyte bath (12 VDC, <6 amps, because that's what my battery
      charger supplies).

      Gas bubbles form by electrolysis at the solid and conductive metal at
      both the anode and cathode; however, the bubbles on the work begin to
      gently lift the rust away from the good metal.

      The process continues until the current is removed, with somewhat
      haphazard progress due to the lack of control of the location of the
      electrolytic action on the surface of the work.

      I'm pretty sure the majority of the action is happening by this
      mechanism, rather than in the fashion seen in an ECM process.


      --- In taigtools@yahoogroups.com, "Larry Richter" <cattaraugus@e...>
      > I started using electrochemical processes because I didn't want
      strong acids
      > in the house. I had children, and there was an awful accident in
      the town I
      > lived in because acid was stored in a coke bottle, up high,
      supposedly out
      > of reach, and a little girl recognized the bottle.
      > It's been a long time ago, but aside from working in it, I got
      > on the rare and arcane possibilities from a government study of
      > unconventional machining processes that served the space program,
      and a then
      > standard text named something like The Handbook of Electrochemical
      > Processes. And, from some months of more or less formal
      experimentation. The
      > main result of that was not new processes but the realization that
      > listed parameters in the literature were mostly based on cost
      > not absolute results, and that you could do things a commercial
      shop could
      > not do if you didn't stick to the limits recommended, and did so
      with some
      > wit.
      > The processes were also strongly responsive to little changes, with
      > opportunities to discover trade-secret type information--or be hurt
      by it.
      > Bright plating baths, for example, self-polishing, were supposed to
      > been the result of chance discoveries when chicken sandwiches
      > fell into a tank, and I knew people who regularly received health
      updates on
      > the progress through life of the "exposed class" of people that they
      > belonged to because of the later use of some of the additives
      modeled on the
      > supposedly accidental discovery.
      > There are any number of coatings used to stop electrochemical
      action, tars
      > and asphaltums to rubberized paints. Waxes are usually a mess. I
      tended to
      > want to cut metal rather than restore it, and a pinhole in any of
      > liquid based coatings tends to produce the same current
      concentration that
      > an antenna does, with resulting pits and disasters. 3M was making
      > world-beating adhesive tapes at the time, and that is what I
      > substituted for "liquid when applied" resists, and all that class of
      > problems went away. But the workpieces I used were new material,
      > usually to start with, and of a size that would be about right for
      the Taigs
      > we use, not big, old, and irregular. The exposure times at the
      > levels I used were seconds and minutes, not hours or days.
      > 3M also does not now make exactly the tape I favored, a truly heavy
      > waterproof tape then used for library book repair, but the world is
      now full
      > of other high-stick clear plastic tapes at lower prices.
      > I sometimes used vinyl film sealed with tape when the object was
      > irregular, but the realization that came from that was that
      ordinary paint
      > store and hardware quality vinyl sheet was produced then with a
      number of
      > pinholes too, and not better than the paints and stripping enamels
      in terms
      > of leaks and pitting.
      > I've also heard of electrolyte being held against work in sponges,
      sort of a
      > shocking idea with the electrode being a plate on the back of the
      > but had no reason to try it.
      > Nitric acid has worked fairly slow on steel for me, but can cause
      > and dangerous changes in organic materials, and I've seen things
      happen with
      > Sulfuric acid and steel that were genuine disasters. Strong acids,
      > cyanides, which have also been used in cleaning, are where " no,
      no, bad"
      > starts as far as I'm concerned.
      > ----- Original Message -----
      > From: "kwolson2002" <kwayneolson@h...>
      > To: <taigtools@yahoogroups.com>
      > Sent: Sunday, July 31, 2005 1:17 PM
      > Subject: [taigtools] Re: Copper Machining Question
      > > Larry
      > >
      > > Art's link will tell pretty much the whole story, at least all I
      > > know. My electrolyte has been mixed at one tablespoon of washing
      > > per gallon (yes the kitchen math gets hairy with a 30-odd gallon
      > > trash can). I tried using a stainless steel wire spatter guard as
      > > sacrificial electrode; the setup "cooked" pretty well at first,
      > > the wire rotted out quickly and the current dropped on my battery
      > > charger's ammeter. I substituted a stainless grater (lots of
      > > area cheaply, though less than the spatter guard); the grater now
      > > some light rust showing, but still was drawing pretty well at the
      > > of cleaning up the jack. My first attempt actually used a piece of
      > > scrap angle iron for the sacrificial electrode. It worked, but
      > > if I regularly wire brushed or ground the rust and "gunk" off of
      > >
      > > I've spoken with Industrial Archeologists locally regarding the
      > > refurbishing of old machine tools. They use various acid solutions
      > > when cleaning up artifacts; I think they said sulphuric and
      > > but I don't recall for sure and don't know the concentrations, so
      > > you decide to try it out, "suture self". To me, the washing soda
      > > seems safest - when you've finished, just pour it on the lawn, no
      > > harm done.
      > >
      > > There are a few experiments I'd like to do to determine whether
      > > how) the rust removal action can be limited to certain areas,
      > > with a resist (perhaps wax, as light oil can be removed by the
      > > washing soda's detergent action) or by some other means. It
      > > frequently occurs that one area or another of an old tool is more
      > > heavily rusted, frozen, etc. It would be handy to be able to clean
      > > that area more than surrounding areas. Also, some machinery is so
      > > large that the electric current per unit area would become
      > > ridiculously small, slowing progress to a crawl (and requiring
      > > olympic swimming pool sized baths). If the reaction could be
      > > confined, small areas could be cleaned up singly, one after the
      > > other. Additionally, some machinery has brass, babbitt, aluminum
      > > other unknown bits. It might do irreperable damage to these parts
      > > be subjected to electrolytic action, depending on where the metal
      > > in the galvanic series, and so would be nice to protect them.
      > >
      > > I've used this method to put some "hopeless" cases back into
      > > order. Mostly it requires patience (besides the obvious equipment)
      > > and is certainly the gentlest method I know of.
      > >
      > > Kevin
      > >
      > > --- In taigtools@yahoogroups.com, "Art" <t2b1r3@y...> wrote:
      > > > Hi Larry
      > > >
      > > > Have a look at the following for a quick intro to the process.
      > > >
      > > > http://antique-engines.com/electrol.asp
      > > >
      > > > Only rusty thing left around here is me <G>
      > > >
      > > > Regards
      > > > Art
      > > >
      > > >
      > > > --- In taigtools@yahoogroups.com, "Larry Richter"
      > > <cattaraugus@e...>
      > > > wrote:
      > > > >
      > > > > Always interested in electrolytic processes and restricted
      > > > > electrolytes, if that's what this is. It's a new one to me:
      > > > you give a
      > > > > clue as to strength of solution and voltage levels and
      > > orientation.
      > > > You
      > > > > seldom see sacrificial stainless electrodes, though you see
      > > as
      > > > > workpieces.
      > >
      > >
      > >
      > >
      > > To Post a message, send it to: taigtools@e...
      > >
      > > To Unsubscribe, send a blank message to: taigtools-
      > >
      > >
      > >
      > > Let the chips fly!
      > >
      > > Yahoo! Groups Links
      > >
      > >
      > >
      > >
      > >
      > >
    • Art
      ... Whoops - url should hopefully be http://tinyurl.com/9olcw Art
      Message 31 of 31 , Aug 1, 2005
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        --- In taigtools@yahoogroups.com, "Art" <t2b1r3@y...> wrote:
        > Hi Larry
        Whoops - url should hopefully be http://tinyurl.com/9olcw

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