Homebrew PCBs

James Newton wrote:

>Perhaps the thing to do is NOT convert it to a linear system but 
>instead work within the constraints of the rotary coordinates. You 
>may be interested in this page:
>http://techref.massmind.org/techref/idea/lccam.htm which is a redux 
>  
>


  Well that works fine enough for the table part, and really not that 
hard to convert to X,Y from the polar.  But even for that, after looking 
at it the rail system I made wasn't much harder to do and had the more 
standard X,Y..

  Can't just leave it rotary for Z though, at least not for a drill if 
you don't want to snap bits.  But it's close enough as is as long as the 
circle is large enough and you only use a small arc out of the circle.  
Easiest way to make it more linear is to move the hinge point further 
away, it just gets very unwieldy very fast.

  Actually there is a simple way to make it linear now that it hit me, a 
scissor jack type of arrangment that looks like an accordion.  Similar 
to this scissor gate:

http://www.concordelevator.com/Gallery/Infinity%20Fixtures/gate-scissor.jpg

  While linear these aren't very dimensionally stable esp when extended, 
but with a little thought they might be made so.

Alan