Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

Hi all...

Finally got some minutes to make my new etch tank...

It is a simple tupperware container.
the pcb is held horizontally.


I mounted the pcb holder to the lid directly.

It is a stripe of 4mm thick acrylic glass (80mm wide), the ends are bent
up and back.
these ends have two holes through which they are screwed to the lid of the
container.
(this looks like a big C with the opening upwards to the lid) and a long
flat plane on the bottom.

this strip is located in the center of the container now.
there are two more plastic parts, which are simply two plastic angles.
the two angles are mounted with one leg on the flat of the C, the other
leg pointing
down and holding one end of the pcb.

the downward leg has small strips of 2mm cd box material glued to it to
form a
"groove" for holding the pcb. (you could grind that too).


i cut a lengthwise slot in the bottom of the "C" strip in the center.
the angles and the C hold together with a plastic screw each through the
slit in the C and also a little "knob" to prevent rotating further to the
end of the leg.
(the knob rests in the slit).


For adjusting the width of the pcb you undo the plastic screw and insert
the pcb.
then you slide the angle to firmly grip the pcb and tighten the screw.

If you need a big pcb you rotate the angles so that the downward leg is on
the outside.
if you need a small pcb you rotate them so that the downward legs come
together at the center.

So you can make pcbs from zero to the full length with no lost space in
the container.


I do not know if the above description is understandable, the webcam can
not take a picture
which will be better, especially not of acryl glass parts.
i can make a drawing if required.

the holder allows for viewing through the lid (and the acryl glass) if the
pcb is ready.
you can also look through the sides of the container, and through the
bottom would be possible too.
(mirror etc).


The pcb holder is fully contained within the closed cotnainer, no etchant
or vapor can get
out wile in storage or in use, only at putting the pcb in or out.
you can attach a "wiggling mechanism" to the screws which mount the holder
to the lid, the lid
flexes enough to allow agitation...


the operation will be with the help of a plastic hex (ring-) wrench which
ideally will
be used to both spaning the plastic screw and sliding the angle piece.

If it works out there will be no touching of surfaces exposed to etchant.
this means i do not necessarily need to wash the holder (and waste
etchant, and add water).

just undo the screw while the pcb is a cm above the water conteiner and it
will drop out.


I still have a big problem: i do not have the plastic
screws which hold the angles and the C together.
this need to be 2 M8 or M10 screws with nuts.
plastic, stainless is no good in HCl.

I have the screws which hold the C to the lid, these are plastic screws
used
normally to hold together cabinets/shelfs and such stuff. it are plastic
nuts, but with
a steel screw, however the plastic nut has a sleeve which comes through
the lid and
so no steel is inside the container exposed....

I have no idea where i will find these screws, and i also can not find
round stock
to cut them myself.


I have not tested the holder and i can't say if it is good...
But it was a major design goal for me to allow for 100% useage of
container area
and also to allow very tiny pcbs.
This design goal was reached and i am satisfied with it. i hope it is
useable then.


If ther is interest i will maybe make a drawing and any ideas where i may
find plastic screws are welcome.

ST