Homebrew PCBs

ballendo@... wrote:

> 
> BTW, Some pcb mills DO account for rotation. Which makes for an easy 
> setup. You mount the board, then locate the pin positions, and the 
> sofware rotates the layout to fit where the bd is ACTUALLY located. 
> These are usually high end PCB drills/mills which have vision 
> capability to "find" the pins accurately.
> 


   Actually it is only a few lines of code to translate points through 
rotation, even without using sine/cosine trig, and any milling software 
that doesn't have this is pretty slack.  And you'd be amazed how well 
you can line two corner holes up yourself by eye.  Just chuck a tiny 
bit, lower near the board, center it in X direction over the hole, move 
your head around 90 deg and center it Y direction over the hole.  This 
is then your actual coordinate for that hole.  Do the same for another 
hole on the other corner of the board.  And then again, any software 
that can't work from those two located holes and use their actual vs 
file coordinates to transform all the coordinates is really slack.  It 
is a simple coordinate transform, only mild high school math required 
once to make the software capable.  Suspect the program's math as likely 
faulty in other areas for any program that can't handle doing this too.

   Dealing with the set holes sounds like just as much work as just 
having two corner hole references and lining up on them well by eye.  I 
normally just shift the board slightly to get the hole lined up to where 
the actual set coordinate is, and don't even have the software do 
translation anyway though.  Only takes a time or two of practice to get 
very good at it.

Alan