Electronics Forum / CAD / April 2005

Hi Keith,

Don't know of any published table but drill sizes up to around 1.8mm are
normally used/available in 0.05mm increments.

Larger than 1.8mm in 0.1mm increments.

Above 5mm they are regularly routed.

Keith,
   While I couldn't tell you about specifics in the UK, I would
think that any size you can think of would be available within
reasonable tolerances. Remember that you must allow tolerances.
   On most smaller holes (<0.050", <1.25mm) I typically allow
+/- 0.003" (0.08mm), from 0.050" and up I apply a sliding scale
typically up to +/-0.005"(0.13mm). If a hole can be even looser
then I allow more tolerance. With the tolerance and the initial
drill verses finished plated size, most any hole spec is possible
at most fabricators.
   In N.A. I find that typically anything above approx. 0.125"
(3.175mm) tends to be routed these days.