Homebrew PCBs

>Do you all weld with a special welding shoe or someone with a round
>nozzle only? i really expected slow speed welding to work (As described in 
>the
>pdf, but i couldn't get anything useful so far (i admit i have no tried 
>enough maybe).

I definately use the special welding shoe. I would not want to try
differently.

>What are the ideal plastics to try with?
>i only know ABS was a complete failure, it got charred and blistery and 
>still
>did not really fuse.
>PVC did work a bit better, but still not perfect.
>
>i expect polypropylene to work well, it is shaped nicely by heat.
>What about polyethylene, the PE shrinks under heat strong, or is this
>only true for the bottles and stuff? i would expect it to be problematic 
>to weld?

In my experinece it all depends on the welding rod material and the
shoe. Again, I don't use rod's that one can buy but cut off stripes
from the sheets I'm working with. Like this you never have the wrong
material.

>Is there any surface preparation to do?

No

>i have this acryl/plexiglas here that gets really soft (like soft rubber),
>but it does not fuse with the welding rod of the same material,
>if i heat more it charrs.

I doubth it's really the same material then. 

Markus