what does four 8-32 holes on a 50mm bolt circle mean here?

the link to the website is here:https://www.ampflow.com/motors/highPerformance/threeInch/

that drawing I think is the front of the motor, the shaft is in the center, the 4 holes around it are presumably threaded for mounting, but what diameter are those?

thank you in advance


1 Answer 1


The diameter of those four holes is specified by the designator "8-32" which means standard screw diameter #8, threaded to 32 threads per inch. This is the usual way threaded holes are called out, rather than by saying the actual hole diameter in decimal inches and then saying the thread pitch.

So the machinist who has to make the part knows what drill bit diameter to use to make a hole and then tap it to 8-32 by looking it up on a chart, and the engineer who wants to buy the part knows exactly what mounting screws to use to attach it to another machine part.


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