GD&T Most Important Symbol Explained

In this video I discussed the most important symbol in ASME Y14.5. This is the MMC symbol that has three meanings depending on where it’s used as I discuss in the video.
1. As a concept maximum material condition is a convenient way to distinguish between the maximum size and the minimum size of the gap between mating parts. If we compare the maximum size of external feature and the minimum size of an internal feature, we will know the minimum room, and the maximum room between those two parts at assembly.
2. The next use of MMC is in the feature control frame with the tolerance value. In this case it means that the tolerance applies only at the MMC size of the feature or features being controlled by the feature control frame. At any other size, additional or bonus tolerance will be available.
3. The next use of the MMC symbol is in the feature control frame with the datum references. If the datum feature is a feature of size, then a material condition applies. The default material condition is regardless of material boundary (RMB). If we add the MMC symbol we are creating a maximum material boundary (MMB) which allows fixed gaging when setting up to inspect a part with feature of size datum features as I discussed in the video.
#engineering #drafting #gdt #cmm #metrology #symbols

[@ceasarjones]

Just wanted to chime in as a Deaf CMM programmer that's a life-long learner for all things relating to GD&T; thank you for adding closed captioning! Please continue doing this.

[@RDeanOdell]

Thanks so much for the feedback! It takes a little extra time for me to do it. It’s mostly automated, but I have to go in and fix what the software gets wrong. I’m more than happy to do it going forward.

[@nathanshepherd7607]

These uploads are great. I will be sharing them with my college students.

[@RDeanOdell]

Please do! Thanks

[@najmaul7830]

I've been working in aerospace part manufacturing, i'm used to using micrometer, dial test indikator, profile projector, keyence, swiftpro and cmm. I've a question that till now i have not the answer yet. What's formula to calculate position tolerance when use polar coordinate/ angle and radius ? It's so easy when using cmm, is there another way to calculate manually instead prior convert it to cartesian coordinate? Thanks

[@bobmrcs]

Great video! I really appreciate your clarity on all things GD&T. I have been a student of GD&T for over 30 years and and I look forward to watching and still learning from your videos. Thank again!

[@BigAlz11]

Abbreviation was correct. Acronym is when an abbreviation makes a word. FBI-abbreviation NASA-Acronym
Keep up the great videos. They help.

[@yousefabdelsamie5983]

Thank you very much, these videos are relay helpful.
One suggestion would be using different tol values to avoid confusion.

[@marcob.2756]

About the MMC/LMC dinamic action to a feature dimension, for example in interaction with a concentricity, it seems then it can be automatically used in such cases even if it's not mentioned in a drawing, from the functional point of view, because most designers in companies don't use it but it can be quick set by yourself that condition to save false scraps, is it correct?

[@asaholey]

If i have a 10mm+- 1.0mm plate, the datum A is the bottom. I want to add 1mm depth hole on the top of the plate, Do I need to add the dimension from datum A which is 9mm? What if the plate is made at the minimum thickness which is 9mm, what will happen to the hole?

[@jthewarrior]

Fantastic explanation. Subscribed.

[@jonathonpashukewich7608]

Good stuff 👏

[@RDeanOdell]

Thanks so much!

[@alfaradbean]

Very interesting video

[@Stocjon1985]

Great explanation.

[@RDeanOdell]

Thanks so much!

[@ariel59864470]

🏆number one🏆

[@mikee4430]

Dope video 🫡

[@manassehsusairaj182]

Thank you

[@vickiemickie23]

One suggestion, maybe add more pictures and use more simple terms. Leave the talk of datum shifts and complications in a later video. By removing that topic out, you have more room to talk about the MMC concept that applies to holes and shafts. That way, you can talk about MMC fully. I do like how you had an example for the 3 applications that you would use it

[@RDeanOdell]

Thanks for the feedback! I do sometimes use pictures added in post, but I want to avoid it feeling like a PowerPoint presentation, so that’s why I keep it to a minimum.

[@CharlesLogstonInTexas]

MMC might be an initialization 😅

[@ManishGupta-gv4kk]

please consider diffrent numbers as tolerance

[@ManishGupta-gv4kk]

please remove background music. its distracting

[@RDeanOdell]

Thanks for the input, but I like the music. Plus the video is free to watch.

[@QwertyCanada]

Not distracting at all, I barely notice it.

[@Jordan.Vaughn]

No, leave the music, I like it. Feels like I’m at a GD&T party

[@bobmrcs]

Can't please everyone.... wouldn't even try. Your videos of great!

[@silkroad3442]

25 years machinist, i do not understand this!!