Understanding ASME Y14.43 1

[illini8181]

Hello, I am working on the design of a gage. This is the first time I have designed a gage, and it seems as though there is no one in my company who is knowledgeable about doing so. I have read through ASME Y14.43 several times. Each time I read it, it becomes clearer. I have a fundamental question that is spelled out in the attached document. I have been going over and over this in my head, and am pretty stumped. I would appreciate any help! Note that the "fixture" I show is not the actual fixture I am designing. It is just a simplified version for the sake of asking the question.

Thanks!

 

[pmarc]

Okay, but what if preferred size tolerance for pilot portion (as defined in B4.2) was greater than size tolerance for gage portion? I believe this could easily happen if the workpiece hole size tolerance in fig. B18 was tighter. I think you would not like to loosen up the tolerance for gage portion of pin in such case, would you?

And one more argument, according to the chapter about pushpins, the pilot diameter should be of a standard size. In most case this would be very difficult to fulfill with a single diameter pin, don't you think? (This probably boils down to mentioned cost aspect).

 

[illini8181]

Yes, I didn't even think about that. Very true.

Thanks so much for your help. Thanks everyone else also who posted thoughts. I've learned a lot from this thread. Hopefully someday I'll know enough to answer other people's questions.