Homebrew PCBs

> Robin Wrote:
>
> I doubt if there is an absolute need for the
> vanes at the bottom of each rotating tube
> <SNIP>

Early versions didn't have vanes.

They had startup reliability problems.

The vanes fixed the startup issues.

The BEST solution for the bottom is
a radial that is a conical shape with
a very slight axial inflow.

I knew people would complain about
needing a lathe.  I didn't want to
make an impeller that needed a 5
axis CNC machine to make :D

(The toy wheel was something to make
it easy for the average person to do)

> <SNIP>
> Likewise, I doubt that the three vertical
> strips you glued inside the tube would be
> necessary
> <SNIP>

Without the strips you do get banding.

I think it was Alien Relics here that tried
to make his tube with a spiral of holes
and found his banding was the exact distance
of the spirals.

RoelCNC made his tubes with a bottom bearing
and it does not have such banding. (even
without the dams/strips)

This indicates to me the out of round
condition is causing the issue.


> <SNIP> 
> I didn't see any lower bearing.  Do you
> have the end of the rotating tubes rubbing
> against the lower plastic framework?

No lower bearing.  Thats why care is needed
in the building to keep it round.

> <SNIP>
> I think the problem of evenly distributing
> the etchant on the PCB might be solved to
> some degree by cycling the speed of
> rotation.

I have done this speed modulation and it did
even out the banding.

I have also used a gear head motor to slowy
cycle the PCB holder up and down.

Neither is now neccesary now I have the
banding issues sorted at the source.


> <SNIP>
> went to my
> brother's place for lunch.  Lo and behold
> he had some of the same plastic containers
> in his pantry!  The were made by Icon:
> 
>   http://www.iconplastics.com.au
> 
> near Melbourne.  He recalls he bought them
> at Bunnings.

Yes the one I used was "icon" brand from
bunnies (where lower prices where just at
the begining)