Homebrew PCBs

well, john, you said you are willing to discuss pcb mill here.
so what i ask you to discuss maybe it the quality of rail surface.

i saw some of your designs (and the designs of others) use some sort
of common pipes or steel profiles.

especially i saw gass pipes at your page... i wonder which surface quality 
they have.
I have lots of pipes and sqare stock here, but i have no idea how smooth 
and plain the surface needs to be.

obviously professional machines only use precision ground surfaces. but how 
much is needed for accurate milling?

it is hard to describe a surface quality, maybe you can find a way.
how looks it when you put a straight edge against these pipes? is there 
light shining through?
are these welded pipes?

the european pipes may differ from your pipes, and there are lots of 
different surfaces available.


have you ever had problems with these rails? i mean precision problems.

thanks

st

(by the way - don't you use a car for some reason? i mean you write a lot 
about walking here and there and so on..?)