I stopped watching after 34 seconds when he did not identify an axis as a possible datum. ASME Y14.5-09, 1.3.13 Datum : a theoretically exact point, axis, line, plane, or combination thereof derived from the theoretical datum feature simulator.
I don't think your statement is fair. (1) This is Lesson 1. (2) An axis is a type of line. (3) Mr. Odell is trying to communicate a general concept. Teaching is an art. I really appreciate the way Mr. Odell is teaching. Quoting "the law" directly from ASME Y14.5 (like you have suggested) when one is just starting out in one's GD&T journey may not be the wise thing to do from a pedagogical point of view. (4) Mr. Odell, please proceed.
If you quit listening at 34 seconds, it is your loss. Great intro video.IMHO. When I teach GD&T in my ENGR 1304 class, if I can get students to understand these four concepts, I feel I have done a good job.
Stopped listening because you thought you were better right? He actually explained what you're just saying. If you need to learn, you need to be patient.
I'm studying GD&T as fast as I can to prepare for new job position. Going from civil engineering to mechanical engineering. This is very helpful! Thank you for sharing these videos.
@@sophiapappa849 All the jobs I saw were pretty hyper specific. You need to narrow down what you're looking for and then study what they list in their job description.
Dean, I come to say thanks to you. I just passed the GDTP Senior and certified in the 2009 version. Appreciate your generous videos, these really help me lot. I come from China where the RU-vid is forbidden, anyway I come to share you the good news. And best wished to you! You are the man!
That’s why I made it! I remember years ago looking for good GD&T content for myself on RU-vid and not being able to find anything useful. I’ve tried to provide the best I can with the tools I have.
Im about a year along my 3d printing hobby and didnt really need this stuff. As Ive been diving more into design,I found myself here and Im hooked. This is just the nerd food my brain needs. all jokes aside I learned a lot, probably need to watch the video a few more times but the instructions are clear even if they are a bit over my head for now. Kind of shocked this video only has 133k views.
3:34 That is absolutely 💯 correct. Datums whether it could be ABC or XYZ or 321 are basically an absolute common ground or a foundation or a reference where a designer, manufacturer and quality inspector come together to speak of & understand the same concept without leading them to any incorrect interpretation.
Dean Odell, thank you for your post. I appreciate what your doing. The Gd&t Subject can be a little dry for many engineers and designers. I like how you add your own twist to the subject and make more interesting.
Thanks so much! I try to explain things in my own way, and not just read off what is in a book. Sometimes I make mistakes, but I think explaining is more important than presenting information.
Dean, wow this "Straight to the Point" is so beautiful and is so easy to understand. Thank you for this powerful easy to see approach. I will look out for more of your videos
Thank you for going with this approach to explaining things. I wish I could have you as one of my instructors. Up to this point, I've had struggles with understanding GD&T in my Print Interpretation class. I'm pursuing a CNC Production Machinist Technical Certificate. I'm glad I found your channel and I have better confidence with the concept of GD&T. Again thank you
This is simply outstanding! As an EE, I’ve dreaded learning this, but this is so practical and explained so clearly, I wish I started sooner! I really lucked out finding this channel.
Your explanation over the feature control frame has helped me understand the concept so much better now. Glad I was able to find you before I started my GD&T class this semester.
An intuitive way to think of the difference between MMC and LMC is to think of the part as a balloon filled with air. MMC is the over-inflated condition and LMC is the under-inflated condition.
Great Explanation Professor. Is it possible to make a video on inspecting the position tolerance of the washer explained in 19:44 with datum A and B at RMB. Or even explain how will we use gauges in calculating the deviation.
Thanks for the video. I subscribed and plan on viewing all the videos in the playlist that you created. In your video, you had mentioned MMB and LMB for Datums: 1. Do they have anything to do with Datum Shift? 2. How to calculate Datum Shift? 3. What are some applications for their use?
Great video Dean. The only part that was a little confusing is that you seemed to be drawing the Right Hand View for parts to the left of the front view in your samples. So that when you had a datum reference it seemed to be picking up the opposite intended surface? See for example your Views at 19:33 in your video.
Thanks for your teaching video Mr. Odell. Would you make video to show 1/ how to lock a slot if it's 3rd datum and 2/ how to inspect its true position if it's called out its width and its length separately. THANKS.
Question regarding the MMC and LMC pin example at 18:00: 1. For MMC pin example, does machinist tends to machine the pin to the lower end (0.98, 0.99) to give themselves more room for error (shaft deflection from lathing etc...) in straightness? 2. For LMC pin example, what is the practical application?
Awesome content! I have to work with both Imperial and metric tolerances for the automotive industry. I may be able to show you a real world fixture for the concepts you are illustrating in the round for measuring tolerances.
Hi Dean, great content as always. Would I be correct in saying that for the drawing produced at 22:47, there is nothing controlling the tolerance of the 2.00 dimension until you add the profile tolerance at 23:20? In other words, is the drawing incomplete or "incorrect" until the profile characteristic and tolerance is added since there is no feature control frame associated with the basic dimension 2.00?
Hi, thanks so much! You are correct! According to Fundamental Rule “A” ( I made a video about it last year ). Every dimension must have a tolerance. As you pointed out, that surface dimensioned with a basic dimension does not have any associated feature control frames. This would make the specification incomplete. Adding a profile would be the best course of action in most situations.
Hi Dean, thanks for the video. I'm little confused about LMC. How the tolerance increases when the dimension move from LMC to MMC. When the pin gets bigger there will be less space to move around and thus less tolerance right. Please correct me if I'm wrong.
This is the first video I was presented when trying to learn about GD&T, and im impressed about how good you are at teaching. I thank life and the algorithms for letting me learn from you! Greetings from Mexico!
So...if we are considering a thru hole in a block...at mmc the hole will be smaller with limited tolerance to its axis(considering position gtol)....and if the hole is.larger then the hole axis can bend or have more.slantness?
Basically, yes. If the hole is toleranced with position and the MMC symbol is present, the hole gets more position tolerance if it is made a larger size within the size tolerance. The additional position tolerance is called “bonus tolerance” although this phrase is not in ASME Y14.5. The bonus tolerance is the difference between the actual size of the unrelated actual mating envelope and the MMC size. This can be added to the specified position tolerance and is known as the “allowable” tolerance. The axis is always straight, but can exist at any orientation or location within the tolerance zone.
Hi Dean, Your contents are very informative and helpful to learning GD&T for fresher engineers like me. Thank you for this initiative. I have a question actually for you. Let's say datum B (That you have shown in your video 10:25 ) is the main mating surface in case of an assembly, but you have said to consider the largest surface in case of choosing the datum A. So my question is should we consider just like you in this case or there is an exception?
Hello professor, thank you for the explinations, please what do you mean by : - basic dimensions terminate of 30 thousandths ? - position is almost applied with the directly tolerance dimension that applied to a feature of size in 8:27 - this surface is parallel to 5 thousands in 5:53 and why you said for datums it can be A C B, then it should be A, B, the C ?
Thank you for your great educational videos on GD&T. A couple of questions: There is a confusing note under feature control frame on the drawing at 19:30 . It says "MMC=VC=1.98". The hole feature size is only 1.00 +/-.02 shouldn't it be 0.98 at MMC? Also, does departure from MMB/LMB when used on datum in feature control frame affects other tolerances of feature size or geometric tolerance?
In this figure the smaller hole is an internal FOS, and you should know that for hole the MMC size is the smallest size of dia which is 1.98 and there is no geometrical tolerance are given for MMC ,that is why VC=1.98
Let's say we have a position tolerance exactly the same as given in time 8:00. What would be the situation if we defined datums as only B and C (cancelled datum A restriction)?
Great question! Without datum A, the axis would have no perpendicularity requirements. So the hole could be at an extreme angle and still pass a position check on one side of the part or the other.
@@RDeanOdell Thank you for the response. Your videos are so helpful. So, if we cancel A, we inspect the hole at just one circle in terms of the position according to B and C, one of the two sides of the part, right? And if we include datum A, we inspect it throughout the hole.
Hi. It sure could be measured that way! The idea with the feature of size definition in the ASME standard is that you need opposing points, while the depth gage is measuring in the same direction. This isn’t a law of nature or anything, so your instinct is not wrong. The ISO standard allows some different concepts like position on surfaces where the ASME standard says that is against the “rules”.
@18:00 How could additional tolerance be gained by moving closer to MMC from LMC? If your alignment pin is getting larger or hole is getting smaller, by default you are losing positional tolerance for those features. In what type of situation would you actually be gaining tolerance like stated in the LMC description?
I have to disagree about not reporting Basic dimensions unless you are in a strict pass/ fail situation. In the shop, the machinist nearly always wants to know where the center of the hole is, especially if the feature is out of tolerance.. Reporting .01 position can mean many different things, especially if you have multiple holes in a pattern. Having all the holes in a pattern drift towards 2:00 o'clock is a very different thing than having the holes moving randomly. If the holes are drifting about the same amount and in the same direction then that is very likely a setup issue. If the holes are moving randomly then something may be loose in the setup. I do like your videos and wish I had something like them back in the dark ages when I was first learning this stuff.
Hi, thanks for the great feedback. I understand your disagreement completely. I think this is always going to be a sticking point between manufacturing and inspection. My view on the design and inspection side is that drawing requirements are pass/fail. No room for interpretation *if* the drawing is prepared correctly. I hope most companies have a feedback mechanism where inspection can include important data on actual locations from basic dimensions so that manufacturing can fix errors.
ASME Y14.45-2021, titled "Measurement Data Reporting" has a solution for this issue. For position tolerance data, Y14.45 specifies that "Location components" are a standard item that can be (should be in most cases) included along with a position value. Location components are the X, or Y, or Z locations of, for instance, each end point of the axis of a hole. If the position tolerance is applied to a center plane of a slot or tab then only one location component may be needed. If the position tolerance is applied to an axis of a shaft or bore then two directions of location components, possibly at each axis end point (if the feature has enough length/depth to make this practical) are needed. If the position tolerance applies to the center point of a sphere, then three location components, X, Y, and Z will be needed. As you may already be thinking, if X, Y and Z location components are to be reported, then an explicit set of coordinate axes that represent the applicable datum reference frame must be shown on the drawing or model when location component reporting is desired. There are several conceptual and practical reasons why basic dimension cannot be reported (it's more than just that they should not be reported), but location components, relative to an explicit set of datum reference frame coordinate axes provide a good way to provide clear data the shows where the feature is. A similar type of additional data that clarifies data reporting for profile tolerances is also specified in Y14.45-2021. "Surface deviation" values for each measured point, or a sampling of measured points can be reported along with the profile value.
on your last example, you have dia.03 in the feature control box. how does this relate to the part holes' size tolerances? it would still be MMC 0.98size + .06 to get back to 1.04, correct?
@RDeanOdellHVCC Thanks for all the video explanations you have put up! Really helpful! Can you answer this: if the part comes in at exactly at Upper Spec Limit (USL) 1.02 and MMC is not applied, then 1.Form tolerance applied will become zero zero, or 2.Will it be 1.02 USL + 0.02 form tolerance
