Homebrew PCBs

Thanks for your replies!

I tried the one with the propeller, mounted a small cpu fan 
propeller on the bottom of the tube and the upper part of a half-
liter fanta bottle over it to form a kind of funnel. The rotating 
direction was correct but there happened _nothing_ when I sped it up 
to 5000 turns (I used water to test it). By the way I simply used a 
drill with a flexible to drive it. The problem is that I'm using a 
KRH M20 electrician's installation tube with an outside diameter of 
20mm which is too small to fit any propeller inside. But the idea 
with the 3 holes sounds interesting, I imagine that the holes are 
drilled with an angle. What diameter does the tube approximately 
have?

Regards
Martin



--- In Homebrew_PCBs@yahoogroups.com, Markus Zingg <m.zingg@n...> 
wrote:
> >Hi,
> >
> >I'm currently building my own spray etcher of the rotating 
> >perforated tube type. The most difficult problem is to get the 
fluid 
> >up that tube. Does anyone know what kind of mechanism commercial 
> >spray etchers like the ones from Bungard use?
> >
> >Regards
> >Martin
> 
> The one I have is having a small plate that basically would "close"
> the tube but this plate is having three holes in it. Can't tell 
from
> memory wehter these are just holes or if they are drilled with an
> angle to form some sort of propeller as Stefan sugested. 
> 
> IMHO it's not too important as long as some fluid can get in. The
> plate moreover seems to serve as a way to even limitt the amount of
> fluid that otherwise would go up the tube. The problem here is that
> yuo need a surprisingly powerfull motor to drive the tube and I can
> imagine that having no plate there would simply make the tube 
rotate
> less quickly leading to a less intense spray effect. These are just
> speculations on my end. I never did eny experimenting yet.
> 
> Markus