When the projected tolerance zone system is not used, it is required to select a positional tolerance and clearance hole combination that compensates for the allowable out-of-squareness of the part thai contains the fixed fastener. The following formula is applicable:
7', = positional tolerance diameter of clearance hole r3 = positional tolerance diameter of tapped or tight fitting holes D = the minimum depth of engagement of threaded or tight fitting member P = maximum projection of fastener
EXAMPLE: Given that the fasteners in Fig. B-2 have the maximum diameter of 6.35 (F), the positional tolerance of the clearance hole is 0.2 (7*,), the positional tolerance of the tapped hole is 0.4 (7"2), the maximum thickness of the plate with the clearance hole is 12.0 (P), and the minimum thickness of the plate with the tapped hole is 8.0 (D), find the required clearance hole size (H).
+ 0.2 +
Was this article helpful?