Homebrew PCBs

On Thu, 22 Jul 2004 12:33:59 -0000, cruizzer77 <atlantis7@...> wrote:

> Well this is interesting. The original patent paper clearly states
> that the etchant is pumped up the tube using a sprial mounted inside
> the tube. This sounds reasonable to me but unfortunately will be
> close to impossible to fabricate such a spiral. Somebody who has at
> least a middle-sized lathe could probably try to turn it out of a
> plastic bar, similar to turning a thread. I think I'll try the 3-
> hole type next.
>
> Regards
> Martin
>

I believe it should work without the spiral.
What we missed with the pumping thing was only the simple "it will go out 
the bottom".
You must restrict the bottom to a lower outer diameter, otherwise 
everything you
pump inside the tube goes away the easiest route - straight back out the 
bottom.
I'm sure if you put a "washer" on the bottom restricting the inlet to half 
the diameter
it will work. the centrifugal force is very strong on the heavy water, 
therefore
the pc fan didn't work because back out was still more "energy efficient" 
than up.



ST