Homebrew PCBs

On Wed, 16 Jun 2004 18:24:49 -0000, cruizzer77 <atlantis7@...> wrote:

> Hi,
>
> I'm thinking about building a spray etcher. This has been discussed
> here before, but I haven't found an answer to my questions. I want
> to build the centrifugal type so that no pump is needed. Can anyone
> tell me how exactly these pick up the fluid at the bottom? Probably
> a picture? And the other thing I need to know is what speed is
> needed to spin the tube fast enough to spread the fluid.
>
> Regards
> Martin
>
>

the centrifugal force spews out the fluid through the nozzles, this 
creates a void inside
the tube. you need to spin it rather fast i'd say, maybe 5000rpm or so i 
would guess.
(assumption based on small units driven by 12V dc motors).

I suggest adding "propeller blades" in the bottom of the tube if the 
pressure isn't enough.
you could use the plastic blades of a small fan (pc fan, hairdryer, etc..).

I find the probability of fine, highly corrosive, spray and mist not very 
appealing and i can
wait... if i'm in a hurry i pay for it with hydrogen peroxyde.

ST