Thanks for the confirmation, guys, I really appreciate it.
Belanger, as far as the "implied zero" rule applying in this case, the problem I have with that is that the exact nature of the relationship is unclear. Does this mean that only the hole and tab directly dimensioned have to be within...
Hrmm... the linkes don't seem to work in the other posts. I bet the filenames are too long. Try these:
http://files.engineering.com/getfile.aspx?folder=aa8106c9-1e8b-464a-a007-d98962455d02&file=Centerlines1.jpg...
In the drawing attached to this post, I was attempting to use the fact that features given the same datum features in the same order in their true position FCFs are required to be gaged together. However, I'm not sure that I did it correctly. Can you offer any insight? How would you guys...
I'm having trouble convincing my supervisor that the title-block tolerance on angles doesn't apply to the clocking relationship between holes defined with basics/TP tolerance and other features specified with standard dimensions. I have a few examples but I don't know how to post more than one...
pmarc,
Thank you so much for your specific critique of the drawing, that type of detailed evaluation is very very hard to find! :-) I made the changes you suggested to the best of my understanding. Yes, you are correct, my goal was to determine the best way to convey simultaneous requirements...
Ah, was that located in the UK? We have a sister company there that I believe makes some engine parts that go in either the Eurofighter or the Mirage 2000, something like that.
Actually, we're called "MOOG Components Group," a subsidiary company of the international MOOG company which makes a large variety of parts for military and aerospace customers. Our particular branch specializes in electrical, hydraulic, and fiber-optic slip rings for ground vehicles, aircraft...
Hello all,
I worked up a slightly more complete drawing that more correctly conveys the design intent of our actual part as I understand it. Hopefully, I grasped how to properly dimension for surface profiles, I really didn't like the idea of trying to use position on the slots. I eliminated...
Well, I've been learning and refining my programming for the last few days, and I have run into a little snag, not unrelated to this thread topic, so I thought I'd post it - see the example image with this post. The issue is with the curved slots, for the most part: to which bolt-pattern are...
pmarc, that is an excellent point! It didn't occur to me that features other than holes could be part of the pattern, but of course - as long as they had true position tolerances with the same datum references, that would make sense. Good heavens... I don't think our CMMs can do that. I found...
Yes, it would seem so - but the issue is that the drafters where I work have been creating drawings without tertiary datums even when they're technically needed for 40 years, and they're not about to go back and fix them just because I point out they're wrong.
Well, actually, I did this...
Yes, I had noticed that caveat about separate gaging only permissible with a datum at MMC when I was reading the standard. I do have a question for you though: you said, "I think the clocking of the patterns in established once you hit any 2 of the 13 holes; everything else is rotationally...
I can speak for two US manufacturing companies, and say without any reservation whatsoever that 99% of the people I work with, even the ones that produce drawings, don't know how much of the drawing standard works. I even had a senior engineer try and tell me that basic dimensions aren't...
No, there's nothing different about inspection, only limitations placed on our capability by software. The standards are the same, thank goodness. Thank you for the references to the drawing standard, that told me exactly what I needed to know - that essentially, if there is no clocking datum...
Hello all,
I'm a CMM programmer, and at my current place of employment and my last job, I have struggled to find someone who knows the answer to this question. On a circular part with a bolthole circle that has a true position tolerance applied to it, how many datums are required? All the...
ModulusCT: The part in question is actually rectangular with a cylindrical bore. Datums C and D would therefore be circular features of (differing) size at each end of the part.
TheTick: Actually, that was my ghetto shortcut of demonstrating there was a centerline defined between two Datum diameters without resorting to drawing another part view in Paintbrush. Yes, you're right, it is horrible. :-)
KENAT: Thank you for the alphabet soup! I hate having to have...
You gentlemen don't happen to have a direction reference to ASME standard where this is stated, do you? This particular engineer directly stated that "Basic dimensions do not have to be tied to the datums."
An engineer I'm working with has dimensioned a part in a similar fashion to the example provided, where a Datum face is included in a True Position control frame but the basic dimensions giving the position of the hole are referencing another face which has its location relative to the Datum...
Dave,
Thanks for the quick answer! I think the print was drawn by a rookie engineer, and judging by the number of dimensions which were completely omitted in the original rev (added in ECOs later), he probably just needs more practice and constructive feedback. I'll let him know about the...
