Homebrew PCBs

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