Homebrew PCBs

Your suggestion about sealing metal parts with polyester resin 
was useful nevertheless. I should of mentioned that I wanted to 
run a stepper motor inside the etch chamber to drive the conveyer 
assembly directly. The motor will be housed in a sealed PVC 
enclosure (made from section of 90 mm diameter PVC storm water 
pipe and a press fit end cap) The motor's plastic shaft will exit 
one side of the PVC enclosure and pass through two rotary seals 
before being exposed to the chamber atmosphere. I bought a couple 
of oil seals (Nitrile rubber, 8 mm ID) to try out. You are right, 
about etchant mist. When I tested the nozzle and pump I used a 5 
liter bucket and directed the nozzle to the bottom. When it was 
running a fine aerosol of etchant was forming all around the 
bucket, and you couldn't stand near it or you'll choke :)

The only reason I'm trying to put the motor inside and mounted 
directly on the conveyer assembly is because it will greatly 
simplify its design and construction than trying to drive it 
externally.




mpdickens wrote:
> --- Adam Seychell <adam_seychell@...> wrote:
> 
> 
>>I'm thinking even if etchant doesn't get inside the
>>motor housing 
>>then fumes might, and so could possible corrode the
>>steel.
> 
> 
> Adam, 
> 
> For whatever reason I did not read this part of your
> post. I think you are guaranteed a fine micro mist of
> etchant (Just like in a hot shower) inside the etching
> machine. The only answer that I see as viable (But not
> practical...) is to totally disassemble the motor and
> apply protectant to every part that is suspect. If
> possible, I would attempt to figure out how to mount
> the motor outside and away from the etchant.
> 
> Best regards
> 
> 
> Marvin Dickens
> Alpharetta, Georgia  USA
> 
> 
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