The year is mandatory. The example I give my students is dictionnaries. There is a dictionnary I had in high school back in the early 90's. Wi-Fi, Internet, youtuber were not in that dictionnay. The definition of cellular was there, but it didn't have anything to do with phones.
Definition...
Thank you all for the replies!
@3DDave, I was preparing an example in what a good GD&T drawing should look for my students and, like @Bunrunduk said, I didn't want to overkill my dimensions but i don't like leaving things ambiguous: I first learned GD&T from experimenting with bad parts made...
Hi,
IF I OVER SIMPLIFY There are two approches to dimensioning : one for feature of size and the other on for the rest. Feature of size are feature with two opposed surfaces. hole depth, in that sence are not feature of size. direct tolerancing on the dimension is used on FOS dimensions...
I am trying to reply to the essence of your question, which is WHY people model their parts at MMC. I can't say I completely agree with it, but here are the arguments.
The reason I got from designers that use that approach is simple: to be able to locate interferences. When drawing at nominal...
Suds,
What I teach my student is
You can't do real GD&T on a part without it's assembly, because it depends on the situation. in your case you show the mating part in red I beleive so good.
Ideally, when practical, your datum should be in contact with another part. A surface that touches...
Cup909
Technically speaking, you should inspect the part per drawing. What I worder is if engineering selected either the datum correctly of the tolerances correctly.
I came across long shaft (aerospace engine shaft) that needed precise runout. usually, the Datum should, when ever possible...
Thank you all for your replies. Honestly, they're all quality answers.
3DDave, as usual, you demonstrate excellent comprehension of the standard.
mfgenggear, jassco, and, well, everyone else, I don't remember reading replies from you before, but you make very valid points, and I thank you...
Thanks for your input, mfgenggear.
As a teacher, my job is to take existing experiences and summarize them so that students don't start from scratch. My predecessors used to teach GD&T symbols and their meanings.
I try to teach them the effect of GD&T on practical cases: I don't want them to...
I agree with Burunduk. Don't forget that Datum are mathematical models. The way I can explain it is with cad. imagine scaning a very crooket part and importing it in your favorite cad. lets assume that the order of precedence is A then B and then C.
For datum A
You would create a plane (P1)...
Hello all,
As some of you might know, I am teaching GD&T at the college level. I was wondering if there was a rule of thumb about the value to give for datum tolerances. I got a tip about that a few years ago from someone in the aerospace industry. The rule of thumb was to make the datum 10...
Burunduk, 3DDave,
Thank you for your answers! It confirms my original theory.
I am trying to mix GD&T Design theory and Metrology in the same course in order for future designers to understand how the GD&T work and will be inspected and make the subject more "real".
As I said, I understand...
Blue33,
I would add the following information. In ASME Y14.5 2018 the profile tolerance explainations are better and there are new ways to control the location. The way profile controls the location vary depending on your datum selection and if you use all around or all over. It made me better...
Hello All,
Following thread1103-507627 that has been closed since, I had additional questions on the evaluation of the run out when two datum with two diameters are called in the drawing. I understand the limitation of using V-blocks to setup the inspection. This being said, when calculating...
