Adam Seychell wrote:
> Hello,
> I'm wondering it its possible to seal the shaft from a very low
> RPM (< 20 RPM) electric motor (stepper maybe), enough so its
> protected from splashes of etchant. Of course a suitable plastic
> sleeve will be needed on the metal shaft so no metal is exposed.
> A quick google search showed a typical commercial waterproof
> motor will use two shaft seals and design to run ten meters under
> sea water.
> I'm thinking even if etchant doesn't get inside the motor housing
> then fumes might, and so could possible corrode the steel.
> Any thoughts ?
>
No point in over-engineering this, use a $5 stepper and throw it away
as needed. Less than 20 RPM likely won't even matter if the bearings
corrode, and there's little else inside. If you still want some
protection, take a plastic bag of the right type and pull it up the
shaft and it'll stretch and conform to the shaft. You should be able to
get an inch of cover on the shaft this way. Then cut off the rest of
the bag, and pull another piece up the shaft a bit. Tear a hole so it
then rides up the shaft, having a quarter inch or so of plastic pressing
against the shaft and on top of the first piece, and the rest of the bag
goes around the motor. Not exactly high tech but enough that it'll be
likley to outlive both of us.
Alan