I dont' know how to spell it nor do I know if it is the thing I am
thinking of....
There are these machines used for mixing chemicals. You see them in
all sorts of video showing the mixing of chemicals. It is not the
device like you see them place a bunch of test tubes on a spinning
thing, this thing is different.
There is a spinning magnent under the top surface of the machine.
You place a beaker of fluid on top of that surface and turn on the
machine and the fluid spins like crazy - very good fluid agitation
without any mechanical connections or hoses etc. The things look
neat as hell, but I have not idea what they are called or how
exactly they work.
If this could be done with the chemicals we use in this process,
there could be some advantages..
1) you could seal the container during agitation (unless there is
some gas given off during the process of eating away the coppper)
2) the agitation would be very consistant within the container and
it would be a consistant process. The board position within the
container could be a problem though.
3) no hoses to siphon out the chemicals when doing something stupid
(like placing the pump lower than the fluid level)
There are some draw backs too though.
The container would probably have to be round - just a guess
If enclosing the container, a support system would have to be made
that could be kept inside the tank (I think most every hangs the
boards from the top of the tank).
Just a thought on this subject, perhpas there is something there
that is useful.
Chris
-- In
Homebrew_PCBs@yahoogroups.com, "Stefan Trethan"
<stefan_trethan@g...> wrote:
>
> I'm not convinced those slots will be small enough to prevent the
vapor
> coming out when the bubbler is on.
>
> I see what you mean, my idea for the moving tube is because i
would like
> to keep it fairly low in height so the tank mustn't be enlarged
much. If
> one would be able to get a small number of holes working uniformly
the
> length you need to move the nozzles would be reduced. I don't
think it
> much of a problem to make a magnet slide around outside the tank...
>
>
> Anyway, if you make that pendulum, why not attach soft plastic
brushes
> that brush the board? might be more uniform, and the wiping action
surely
> mixes the etchant well enough. If the brushes were moved with
magnets one
> could put a windscreen wiper assy outside the tank, or something
similar.
>
> I'm not gonna try that any time soon, since my setup is just too
simple
> and too well working to change. Even the thought of making a PCB
holder
> that holds the board firmly enough to allow brushing seems way too
much
> work to me.
>
>
> ST
>
>
> On Fri, 23 Dec 2005 13:17:09 +0100, Alan King <alan@n...> wrote:
>
> >
> >
> > But that will require something else to do moving, and rotary
to
> >
> > linear motion.
> >
> >
> > Tank, then a pole on the outside center of the long side of
the tank,
> >
> > that's 2x the height of the tank, so the hinge point is at 1x
more above
> >
> > the edge of the tank. Longer arm to make the sweep at the
bottom more
> >
> > linear. Say a 1.8X arm, with a stone at the bottom, and air
tube to the
> >
> > stone. Driving link and motor attach near the hinge, well out
of the
> >
> > etchant. Use a flat arm, flatten the tube a bit as it passes
the lid,
> >
> > and have a decent raise/lower system for the board, and you can
leave a
> >
> > top on the tank. Just a slot for the arm/tube to sweep, and a
slot to
> >
> > load the board through.. Clear PVC etc on each side of those
slots, to
> >
> > close it except when the arm or board are right there, and you
will have
> >
> > near zero evaporation, and almost never open the container.
Just slot
> >
> > load the board and etch. No tube thing to build, just get a
stone and
> >
> > some line and make a fairly simple pendulum and attach a motor
to it.
> >
> > Can be greatly linearized with a little mechanical mixing, or a
stepper
> >
> > etc could make it near perfectly linear. So simple we should
have come
> >
> > up with it talking about the rotary etcher and other types last
year,
> >
> > duh if a stone is too uneven sitting there then move it..
Obvious
> >
> > concept, just didn't even cross my mind at that time..
> >
> >
> > Wait till you see some video of my little manufacturing plant
for
> >
> > rounding my boards and applying the LEDs, I think it's rather
neat..
> >
> > So nice to have all the flying dust stay inside a ziplock bag..
Now to
> >
> > automate my iron and solder feed and feeding the LEDs, may as
well let
> >
> > it build the board for me while I go have a beer.
> >
> >
> > Alan
> >
> >
>