Homebrew PCBs

David McNab wrote:
> Can someone recommend better ways to do the tracks, using inexpensive
> and easily available materials that don't need specialised tools to
> deploy? Preferably materials which can be easily sourced in a small city
> without 8 hours searching the Yellow Pages?

Yes, I'd use sections of 1/2" steel drill rod which
can be found at machine tool suppliers (ENCO is a
good example) and they are likely cheaper than the
AL angles you are using.

Using the drill rod as a "ways" I'd use HDPE as
a bearing material.  If not readily available I'd
grab the cutting board from the kitchen.  You
can mill/drill out the bearing as a "clam shell"
from two mating pieces of PE relieved to encase
the drill rod.  You probably want to preload the
clam shell bearings to the rod to remove play.
Something like a strip spring should work well.

Depending upon the length of the drill rod used
you may need intermediate support.  If you keep
the profile of the support narrow relative to
the parallel axis of the drill rod the clam
shell bearing should be able to easily clear the
supports.  The supports ideally should mount to
the drill rod by threaded connection into holes
cut into the rod's bottom which do not penetrate
clear through the rod's diameter.

-- 
uhmgawa@...        www.gnu.org