GD&T: Calculating Max Axis Separation, Coaxial Features, RMB & MMB (Calculating Datum Shift)

Have you ever wondered how far the axis of a cylindrical feature at MMC can be from a coaxially datum feature referenced at MMB?

[@muscleweb]

Honestly the best explanation on datum shift I’ve seen so far. Most stop short of the actual mathematical mechanism of the shift. Thank you.

[@RDeanOdell]

Thanks so much! I agree, I think a lot of content whether video or written presents these topics in the same way. I try to explain things a little different and take the concepts a little further.

[@gt31187]

Hi Odell,Thank you very much for your videos which is presented in a very nicely and easy explanation....It helped me a lot to understand the concepts & finally I passed my GDTP senior examination....

[@RDeanOdell]

Congratulations! That is a serious accomplishment. I’m thrilled my videos could help in your studies!

[@Funny-qo8gt]

I respect the men like you so much, thanks for sharing. Hope you see my comment.

[@RDeanOdell]

Thanks so much! Thanks for watching!

[@denizkoc2100]

Hi Dean, your videos are really helpful to understand some of the gray concepts in ASME. I really much appreciate that efforts. Can you please also make a video for the concept described in ASME Y14.5-2009 Fig. 4-16 (determining the correct MMB)? Thanks in advance.

[@cocoapebbles13]

Great video! Thanks for putting this together!

[@RDeanOdell]

Thanks so much!

[@elsakay2660]

best teacher thank you so much

[@rezajabaruti4139]

Awesome

[@KANNEGANTIGOPINATH]

Good example Odell Thank you can you pls provide example with LMC and LMB conditions.

[@C777-q3w]

Ahh makes so much more sense now thank youuu!!! Question though; what's the difference when MMB is applied to different datums when theres three or two called out in a FCF? In this video you gave a simple example of MMB applied to only one datum, however i get prints at my job where MMB is applied to a secondary datum or both a secondary and tertiary datum and nobody knows how to apply this principle at inspection. Do you add them together? Also, can you add a video to this where you are applying the MMB principle on the surface plate?? How is this not the same thing as bonus tolerance? I understand you aren't gaining any size, but isn't the added shift in axis in a way the same thing as a "bonus" so to speak? Thanks again for your videos!!

[@hugorodriguez6835]

MMB & LMB can only be applied to Datum features of size.

[@C777-q3w]

@hugorodriguez6835 yeah I understand that part I just don't know the difference when more than one datum is used

[@shaunmcnamara4756]

Hi Odell, Your videos are very helpful! Thank you! Might you be able to help me with an alignment issue? I'm trying to set up a program to run a part that needs to be flipped but will not be in the same location after its flipped, so I need a manual alignment for the 2nd side, hoping to get all the info on one report. So far I have program that works, but I have to do the manual align for the second side every time. I set up the manual align for the second side by going to the "Measurement plan editor" then "Man cnc mode to chose the second side alignment features. That seems to work but I still have to do the manual align each time. I have to think there is a better way. Again thanks for your time and your helpful videos! Shaun

[@tidwelltidwell5308]

Hi, I need to report ok / nok results for attributes in the report. Is it possible with some formula in the result element or some other way in zeiss calypso? Thank you

[@vanzz3863]

Hey Dean, thanks for this great and very particular video, there is very few content of MMB out there. A colleague asked me about this topic today and I am glad to say I was able to help him because of this great explanation. However, I was left with the question, this is a ASME modifier which I haven't seen (or found at least) in the ISO GPS standard, do you happen to know if ISO uses this as well? If so, do you know in which standard? (the MMB principle) Sorry if this is a big request, appreciate your help!

[@designerd77]

Can the Primary Datum of a datum reference frame for true position of a hole be a datum which is NOT perpendicular to the axis of the Hole being defined? Every textbook example I have seen has a datum Normal to the Hole Axis as the primary datum. For example if a hole is machined into a surface which is perpendicular to datum A, can Datum A be used as the primary datum in the datum reference frame and if not why?

[@designerd77]

Can you do a video on how to simulate a Hole Pattern as a datum at inspection? Specifically a 5 hole pattern where there are no obvious center planes of the pattern itself and the holes are not on a radial pattern.

[@RDeanOdell]

Do you mean an inspection on a granite plate, or a CMM inspection?

[@designerd77]

@@RDeanOdell On a granite plate preferably but either would be good to know. (or both :) )

[@MA-ns5ov]

This is cool info. Thanks.

[@RDeanOdell]

Thanks so much!

[@emregungor2969]

you ar giving the efforts, thanks but really not catching the most important points. should be posted again reviewing again i guess so.