Homebrew PCBs

You should be able to do 7 mil or smaller traces with a reasonably 
good cnc. As has been discussed before, the good pcb machines "map" 
the contour of the fr4 to compensate for the waviness. I have a model 
that does not do this, and it really is a problem - sometimes the 
traces are too deep, other times too shallow. This problem is 
especially exacerbated if you use V shaped tools (much cheaper) 
rather than standard ones. As you implied, it is exchanging one set of problems
  for another, but when it works well, you have a finished, drilled, 
two sided board. You can't beat that!

Mark


At 09:59 AM 8/10/2011, you wrote:
>I wanted to rekindle the discussion about using CNC for pcb fabrication. I
>love the toner transfer method, but I hate the chemicals and the drilling. I
>think a CNC would alleviate this.
>
>What I have learned from this group and CNCzone forums is that CNC is a
>whole other rabbit hole, but can be worth the time and effort. My questions
>are:
>
>1. Can I reasonably expect to get enough resolution to create designs that
>use such things as SOIC and even TQFP IC packages from a CNC kit?
>2. Is the fact that the FR4 is not flat (has peaks and valleys) going to
>make it impossible to perform the CNC process of creating boards?
>
>
>What do big board houses do? Do they etch chemically or use CNC techniques?
>I would think they would load a 4 foot by 8 foot sheet of stock and etch it
>all at once.
>
>It would be really neat to just load in some double-side copper cladded FR4
>and have the cad drawing etched and drilled. I remember someone saying that
>small board houses were run out of business years ago because of
>environmental concerns, but I am not sure this has anything to do with it.
>
>
>Chris
>
>
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>
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