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It's for an NX part. I can't figure out the depths and such. I just know the placement of the 4 holes and that the diameters are 10 mm each.

  • 1
    $\begingroup$ 4 - number 10 bolts "thru" 9.5 mm bdiameter oreholes. $\endgroup$
    – r13
    May 7, 2021 at 18:16
  • $\begingroup$ Standard counterbore depth for a #10 thru hole is .19 in (4.8 mm). Thru hole diameter for a #10 screw is .201 in (5.1 mm) $\endgroup$
    – jko
    May 7, 2021 at 18:36
  • 1
    $\begingroup$ Is #10 not a drill size, rather than a bolt/screw size? (I'm not experienced with inch stuff) $\endgroup$ May 7, 2021 at 18:52
  • $\begingroup$ One thing is for certain, there is not a 10mm diameter in this image $\endgroup$ May 7, 2021 at 18:56
  • $\begingroup$ #10 drill = 0.1935 inch, quite similar to #10-24 UNC thread OD. This is a total coincidence however. drill # decreases with diameter, UNC thread size # increases with diameter $\endgroup$
    – Pete W
    May 7, 2021 at 18:56

2 Answers 2


To expand on comments:

This drawing is a little bit sloppy. As it's a clearance hole, it should just indicate thru diameter and both diameter and depth of cbore. Takes almost no effort in any remotely modern CAD.

When I did some mechanical design, I wouldn't be allowed to do this. Might receive a call from the prototype shop asking me to clarify my intention, might get shot down by the doc control guy in release process.

Most likely interpretation is standard clearance dimensions for #10 screw, as @jko says, but there is ambiguity vs #10 drill per @Jonathan R Swift. By complete coincidence, sizes are similar.

If you can call/email whoever originated the drawing, that might be the way to go.


Rather than a counterbore I suspect that it is a countersink, in which case, I would include the angle. Generally, English hardware uses 82-deg heads whereas Metric uses 90-deg heads. The #10 may just be indicting the English drill size for the through hole, 0.1935-inch diameter (mixing English drill hardware and Metric measurements). If it is a counterbore, then yes, the counterbore depth is missing.


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