--- In
Homebrew_PCBs@yahoogroups.com, Matthew Smith <matt@...> wrote:
> You want either a magnetic drive pump (polypropylene would probably
be a
> suitable material) or a peristaltic pump (actually a positive
> displacement pump - a set of lobes on a rotor squeeze a plastic tube to
> push the fluid along.)
I used a magnetic drive pump on an etcher some years ago. The etchant
slowly ate the magnet material, eventually ruining the pump. I made a
pump out of Plexiglas that ran at a low speed, and was driven by a
long Plexiglas vertical shaft that ran down through the fluid sump to
the pump. This was seal-less. The impeller bearing was a piece of
Plexi bar stock in a piece of Plexi tube, with a spiral groove on the
bar to work fluid through the bearing, to prevent heat buildup. It
actually worked quite well. I held the pump pieces together with a
bunch of nylon screws and was astonished that the FeCl2 etchant would
turn the nylon brittle and the screws would pop their heads in a
couple minutes.
These weren't "in the soup" but just got drips and splashes on them,
but that's all it took.
I eventually got a discarded Kepro "bench top" etcher which uses two
Little Giant brand pumps. I suspect these pumps have titanium shafts,
and the rest of the lower section (impeller, impeller housing) are
some blue plastic that seems to hold up remarkably.
Jon