GD&T Lesson 2: Form Tolerances

[@HaloWolf102]

I appreciate the free education Mr Odell. This will enable me to be prepared for a up and coming job interview. People like you make the world a better place.

[@RDeanOdell]

Thanks so much!

[@JPeezyWeezy]

@@RDeanOdell I'd like to echo that comment. Thank you for the series!

[@bassmechanic237]

Thank you kindly for these lessons. I just became a machinist after 46 years as a mechanic. You are a God send as these lessons are wonderful.

[@RDeanOdell]

Wow, thanks!

[@theunfrailhale]

Gotta say, your content is top notch. Thanks for all this work!

[@RDeanOdell]

Great to hear! Thanks for the support.

[@rizalardiansyah4486]

Just leaving a mandatory comment for the algorithm. Thank you for sharing this course with us!

[@RDeanOdell]

Thanks so much!

[@stevedeprospo8617]

Thanks, I'm starting a new job tomorrow at an aerospace company and this helped me brush up on my gd&t

[@irfanulbhuiyan7958]

at 7:19 it takes up 1.06 and violate MMC? should it be 1.05 instead?

[@RDeanOdell]

Looks like I misspoke. MMC of 1.04 + .01 GTOL is 1.05 virtual condition.

[@rocketscience777999]

Great Video. The pros and cons of each GD&T feature were very well explained. I have been a chief engineer in the gas turbine industry for over 15 years, and I haven't met any two engineers or machinists that can look at a drawing and interpret it the same way.

[@RDeanOdell]

Thanks so much! It’s tough to generalize about the applications of various tolerances. There is always an exception or industry that uses some obscure concept in the ASME standards more than everyone else. I really appreciate your feedback.

[@mikejankowski6321]

That is a travesty and speaks to the poor state of education in this subject. The whole point is to have an unambiguous language that is NOT open to different interpretations. Don’t get me started on bad writing by the designers!

[@juanluengas2417]

@@mikejankowski6321 are you actually disrespecting Dean and calling him names or are you talking about GD&T?

[@mikejankowski6321]

@@juanluengas2417 I am disrespecting everyone who mangles GD&T applications and leverages the few opportunities for ambiguity into a vast field of muck in Product Definition, and while I am at it all the folks downstream who cannot read and understand! For instance, I have seen Surface Profiles to diameter Tolerance Zones and at MMC. Bad Datum designations, etc. Not enough space here for a full diatribe nor do I have the time at present. Dean is doing his best.

[@sourabhbhalke]

Better than some paid content. I'm surprised! Thank You!🥰

[@chemingwu]

At the timestamp of 10:50, you mentioned that the gauge to check the flatness tolerance applied to feature of size is 1.06. I am wondering if the functional gauge size should be 1.05 (1.04 is the MMC + the flatness tolerance of .01)

[@RDeanOdell]

You are correct. I misspoke on the video. The virtual condition is always the MMC plus the geometric tolerance for an external feature. I’ll make a note in the description. Thanks for letting me know.

[@zuhairsras5047]

I believe the same point applies at 7:22.

[@pablogriswold421]

I was wondering about that. I'm glad you cleared it up!

[@GasparinPR]

Thanks!

[@RDeanOdell]

Thanks so much!

[@shadab630]

Mr. Odell please make more videos on cmm, I am a quality engineer and it will help me a lot to make programs for different components of engine🤗

[@yogabrindha5640]

You saved my life... Thank you so much for giving us elaborate explanation❤️❤️❤️

[@deepakpatel2292]

Hi Mr Odell, you mentioned the gauge size should be 1.06 inches to check the flatness for the example with derieved median plane. I think it should be 1.05 In : 0.04 size and .01 flatness. Am I correct? I am referring @10:45 sec of your video.

[@RDeanOdell]

Hi, I appreciate your feedback. I did misspeak in this example, it should be 1.05. I’ll have to remake this video.

[@deepakpatel2292]

@@RDeanOdell Thanks sir for posting indepth high quality educational videos. Love your content! 👌🏻

[@sbahr]

I was scratching my head until I saw this conversation! thanks :D

[@studdruppo]

You mentioned watching another video at the 7:25 mark about MMC boundary and straightness tolerance but I don't see the link. Could you please list it.

[@jeffersonsong9593]

Pls help clarify. At 6:41 shouldn’t it have .08 straightness tolerance at 1.00 diameter because it’s .04 mmc plus the .04 difference?

[@AlfraRed]

Why can it take up 1.06, not 1.05. I thought the MMC is 1.04" dia + .01" of bending? Can anyone explain please?

[@MattRoberts-t8g]

How do circularity and cylindricity form tolerances compare to runout and total runout?

[@elcidcampeador9629]

You may want to move the chapter marker back to 7:40 for flatness

[@susanthompson9259]

can someone explain again around the 2:29minute mark why it is 1.08? If I understand video 1 and I do the tolerances that at 1.00 size dimension there is .08 tolerance and we are selecting that because the dimension is 1.00? Confused but trying hard to understand. And we chose that 1.00 dimension because there was no MMC indicated correct?

[@susanthompson9259]

is there also perhaps a video that can explain the comment around the 7:23 min mark. Guess I'm not very good at this trying to help my kid in a class that has no instruction just reading. Thanks for the videos I wouldn't have any clue without them.

[@RDeanOdell]

Hi, this is the video I was referring to: kzbin.info/www/bejne/p57MoXyIe5Z-qMU

[@RDeanOdell]

So I think I showed that in a misleading way, the idea is that the .08" of variation exists in that direction, but I drew it in a way that looks like it exceeds the MMC boundary. It should be entirely within the MMC size.

[@a.c.estudio2432]

thanks for the knowledge Dr 🙏

[@RDeanOdell]

You’re so welcome!

[@zamree69]

Hi, Almost all of the time, the datums specified in any component drawing are the features available inside that drawing...A...B...C...you can find them inside the drawing itself. I will call them localized or local datum...it is part of the component. Now what if i were to use centralized datums...for example...i took one point with coordinate of xyz on a car as my 0,0,0.....and use that point to control all applicable symbols in all related car component drawings. The side mirror, the tail gate, even the plastic panel covering...all refer back to my origin (xyz). Is that allowable? And is that not more hassle for manufacturing and assembly pov? Thx. Now...what if

[@RDeanOdell]

Hi, That’s a great question and I shot a video today to address it. I will edit and put something out next week. The short answer is that datums are normally applied to parts or inseparable assemblies because those are inspected as one. According to ASME, drawing requirements only apply at the level they are specified (I made a video about that). It is the designers job to make sure parts on detail drawings will fit correctly at assembly with a minimum of additional inspection. If there is inspection at the assembly level, those dimensions could override detail drawing inspections and cause extensive rework. Thanks for you question.

[@mikejankowski6321]

Go touch (0,0,0) to start your measurements and get back to me! This is a classic that I have had to address from time to time.

[@robertmartin85]

Nice video. I have two questions. 1, what version of Y14.5 are you using? Flatness isn’t allowed to apply to a FOS until 1999. 2. In regard to Circularity, you said it is checked on V-blocks, but those would be datum simulators, which would allow for form deviations of the contacting surfaces to effect the circularity reading.

[@RDeanOdell]

Hi. Thanks for commenting! I used 2009 for this video. I occasionally reference 2018 or 1994. You are correct that using V-blocks to check circularity would affect the readings. I would argue that you could accept a feature checking it this way, but you would not be able to reject the part if it failed inspection on a V-block. A specialized machine for checking circularity or a CMM would be ideal, but I want to make these topics accessible.

[@robertmartin85]

@@RDeanOdell That makes sense. I've been a designer studying GD&T for over twenty years. There always seems to be a disconnect between what ASME says and what inspectors do. It comes down to cost. Pure ASME would be very expensive and time consuming to build/buy the tools for each feature of each part. Understanding things like being able to inspect a part on V-blocks in the hope of passing the part under this higher level of scrutiny makes sense. Adding that info to your video would be helpful to everybody who watches. Thanks.

[@lucasc1212]

@@robertmartin85 thanks for the comment. I am also a mechanical engineer trying to learn GD&T concepts. I always feel that metrology teams don't inspect the part as ASME idealizes.

[@mikejankowski6321]

@@robertmartin85 The task of inspecting in a plane perpendicular to the axis stumbles when you start determining that axis. Invoking a Datum would turn it into a Runout tolerance. Fortunately, the parts I deal with don’t require such surface quality refinements so I don’t have arguments about these nits. I would expect that for practical purposes any reasonable derived axis would be equally acceptable. The “good inspector” would set up a favorable axis and a “bad inspector” would find an unfavorable one. It would be interesting to see a disagreement between two such people. Get the popcorn. 🍿😂

[@Invisibleman956]

Love the Tie Clip

[@RDeanOdell]

Thanks so much!

[@cvdh876]

For a conical shape, would you use circularity and straightness? Also, would it be easier to gauge calling out circularity and straightness rather then cylindricity? Or do they use the method to measure both? Anyway, love your videos.

[@RDeanOdell]

Hi, great question! Yes, you could use circularity & straightness of a line element to control a conical shape with a plus/minus size tolerance. Depends on the size of the feature and tolerance when it comes to inspection. I don’t think that a hard gage would be applicable to reject a part with these form tolerances. Profile is another option to control a conical feature, and kinda simplifies the requirements because of basic dimensions. Also, there is an obscure use of position where you can have a conical tolerance Zone, but this would not control the form of the surface.

[@mikejankowski6321]

Circularity and straightness can be used with different values if the requirements support that approach. Profile controls both aspects to the same value over the whole surface and will likely be easier to verify. Similar to using Straightness in perpendicular directions vs. Flatness, can a functional case be made to have meaningfully different values?

[@ashwinkrishna6361]

Excellent video Thanks

[@arundaniel6127]

Thank you👍👍

[@InvestingExplained1]

Great video

[@RDeanOdell]

Thanks so much!

[@sozanje3316]

Great thank you❤

[@rajatsingh10]

awesome

[@sangeethkumar4506]

At 2:05 u have made an mistake in explaining, you have applied .01 tolerance straightness to a surface,but while explaining tolerance zone u are explaining the size tolerance .08, If even applying straightness tolerance .01 , size tolerance controls form means that tolerance .01 doesn't make any sense.

[@evahoney4976]

I think the background music is distracting

[@mikejankowski6321]

I think any discussion of GD&T should begin with Darth Vader’s theme.

[@studdruppo]

It's a matter of focusing.

[@bimalrajk7]

nice dress.... tutorial too

[@nureservationdesk5550]

your videos are great but hairstyle is bad