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drill size rounding

Posted: Sat Jun 15, 2019 10:28 am
by john611
I found this old post with some drill tolerances

viewtopic.php?f=9&t=7556&p=26234&hilit=drill#p26234

Are PCB drill sizes rounded (eg. 1.68mm rounded up to 1.70mm, or down to 1.65mm) at all?

For example, if my PCB files specify 1.68mm drills, which of the below do I get?

- 1.65mm +/- 0.08mm (1.57—1.73mm)
- 1.68mm +/- 0.08mm (1.60—1.76mm)
- 1.70mm +/- 0.08mm (1.62—1.78mm)
- something else?

I am trying to avoid having drill holes that are too small. I can add a bit to the drill sizes

It seems unlikely that Seeed would keep inventory of many thousands of different-sized drill bits?