Homebrew PCBs

Stefan:
 
I am curious WHY you want to "adjust" these plastic rings, as  they are used 
in professional PCB drilling ONLY to support the bit in a magazine  for the 
automatic bit-insertion step in CNC operations using more than one size  bit, 
AND, as a place to print the diameter of the bit.  That is, the  precise 
vertical location of the ring is not used as any "depth reference"; nor  would that 
"stay", anyway!


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