Old Print/True Postition

[[Me...]]

How do you fine folks go about the inspection of these .008 TP callouts with no datums? Does the old standards how this should be done?

[[Ke...]]

I'm not sure about previous standards, but I would discuss with the customer (internal or external) to determine the fit/function, come to an agreement, and have them sign off on what was agreed to be used.... probably not the answer you were looking for 😃

[[Me...]]

[[Mi...]]

anything in the notes describing a DRF for positional tolerances?

[[Me...]]

No Sir lol, the notes are hand written in as well.

[[Pe...]]

The attached may help some.

These old prints are always fun. Some customers will work with you, as Keith suggested. Others will just say, "some other shop has been making parts to this print without any trouble for 60 years. Why can't you figure it out?" At least that's been my experience.

The datums were "implied" (I think designers often dimensioned to some common feature and assumed you'd know what they meant but never really thought about "datums" like we do today). In your case, if you're on your own without customer engineering support, I'd use the plane as primary, the 3.10 OD as secondary (most of the dimensions originate at the centerline of this OD), and one of the edges as tertiary.

Also, MMC probably applies to everything by default.

Out of curiosity, is there a drawing standard listed anywhere in the notes? Does anything in the title block indicate what year this was drawn in?

GDT Differences.pdf

[[Me...]]

Title block says "INTERPRET DRAWING PER MIL-STD-100" It was drafted in 1979 as well

I do not have this standard.

[[Pe...]]

Also, simultaneous requirements probably apply. The idea was, in a world without CNC, CMM, computers, or even pocket calculators, where math all had to be done on paper, to allow the machine shop a quick and efficient way to inspect the position of holes. There would have been a flat plate with a pocket that the outside profile fit in to and a bunch of MMC pins to check all the holes in that face at once.

[[Da...]]

I asked professor Google about MIL-STD- 100 and found that it references ASME Y14.100M.

[[Ch...]]

Functional wise, I would assume the Counter bores have to be centered or true to the bores and perhaps they were unsure how to specify each bore individually. Definelty check with customer.

[[Aa...]]

Here's a nifty military document that might help you work backwards from the more recent standards.