I'm trying to interpret the following mechanical drawing:

enter image description here

However, I struggle with the "tolerances" part. Shouldn't one dimension (like $44$ diameter) have one number attached to it, to indicate that tolerance? In this case we have two numbers, and I can't understand their meaning.

  • $\begingroup$ It could be that it is $44_{+0.220}^{+0.420}$, indicating the extremes. Because this is probably from an exercise sketch which aims to teach how to correct input drawing tolerances, I can't be certain. $\endgroup$
    – NMech
    Sep 22, 2021 at 15:36
  • $\begingroup$ Do you mean that the diameter should be in the interval $[44-0.220, 44+0.420]$? $\endgroup$
    – alexp9
    Sep 22, 2021 at 15:47
  • $\begingroup$ I'd guess it applies to the 25 (basic) ID ?? Is the part a collar? If so, +/+ on the ID would ensure clearance... If the OD had +/+, it would ensure interference -- possible in general, but then the 8/16 side hole feature would become inaccessible... I agree that it ought to be more clear $\endgroup$
    – Pete W
    Sep 22, 2021 at 16:20
  • $\begingroup$ @alexp yes that was the intent of my comment. $\endgroup$
    – NMech
    Sep 22, 2021 at 16:46

1 Answer 1


Generally drawings that have tolerances simply listed and not specifically attached to a dimension are general tolerances that apply to all dimensions, note this would not apply for the thread, as this has it‘s own tolerances.

In this case it‘s a Dimension oversized between .220 and 0.42

Agreeably however this is a poorly made drawing, but as it seems to be a simple set ring you‘d use to prevent movement on an axel, it would make sense to me that the inner diametre to be oversized and the rest of the dimensions don‘t matter as none of them matter if they‘re ‚wildly‘ off being they don‘t change or disrupt the rings function if they‘re wrong. So a lazy designer simply applied the same tolerances to everything.


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