GD&T Tip - Stop Using Datum Shift as a Bonus!

[@vladislavanchoukov3153]

the only clear explanation of MMB in the entire Internet! I mean it! Huge respect!

[@axeonhand]

best video on datum shift ever. well done

[@prashanthshastri2720]

Thanks for beautiful demonstration of datum shift and why it can not be considered as bonus. When the size of the boss is 11.7 as explained, the reduction of .6 from MMC in boss size will add to perpendicularity tolerance and It can make the related AME to maximum of 12.3 and there is absolutely no clearance available for shift. Therefore shift available can be anywhere between 0 to .6 depending on how far the axis of unrelated AME of dia 11.7 is tilted. Minimum Shift available is 0 when axis of unrelared AME of dia 11.7 is tilted by .6 Maximum shift available is .6 when the axis if unrelated AME of dia 11.7 has got no perpendicularity error. Please correct me if i am wrong.

[@throughtube8693]

You're correct that MMB shouldn't be treated as a FoS bonus because it doesn't benefit the virtual condition of the boss feature. However you made it sound like MMB doesn't give additional positional tolerance to pass. I think that's where a majority of the confusion comes from in this video. Very thought provoking, I appreciate the visuals.

[@Frank_The_Tank22]

That was an incredibly well presented video! Thank you for sharing!

[@wxyz885]

This is indeed the best demonstration video, as many others have commented. Is the shift only allowed in the same plane (or parallel to) as the datum?

[@pravinshewale5235]

I like the way to demonstrate it. So simple to understand. Thank you for tips.

[@levike111]

What about - Maximum material boundary (MMB) = MMC size plus the applicable geometric tolerance. Primary datum MMB is just the MMC size and does not include the geometric tolerance. The secondary datum MMB is the MMC size plus the orientation tolerance and the tertiary MMB is the MMC size plus the position tolerance.

[@harikumar4757]

Helpful presentation. Is it permissible to make feature B to maintain dia at 11.7, also by keeping hole dia at 12

[@stuartpilling2643]

So if there is no bonus allowed if datum feature B was 11.7, would you have to replace the sleeve with one that is virtual condition 12.5 - 0.6, to make the gauge useable and check the other feature hasn’t tipped more?

[@tjvanderloop1686]

A Datum Shift is always present with a datum feature of size (like a pin) ; it allows for a datum shift. Nice graphic explanation by TEC-EASE. Your organization is awesome. T J (Tom) Vanderloop, Author, Technology-Instructor & Consultant, ATEA, AWS & SME Leadership

[@tjvanderloop1686]

DATUMS of SIZE will shift with an axis of size. The Video is Great! Thanks for the Tip & God Bless Don Day. T J (Tom) Vanderloop, Author, Technology-Instructor & Manufacturing Consultant

[@adityang5327]

@1:50- The boss is not fitting (when datum B is co-axial to gage) only because it is out of spec (location/perp. more than .3 @ mmc). Now it passes due to datum shift (datum feature is @lmc) so datum shift has been added as a bonus (otherwise part should have been rejected). Am I missing something?

[@danezu791]

I am confused about this statement too. If the right boss is perfectly centered with the gage and the left boss in not matching the sleeve the part should be rejected. The distance between the bosses has to be within 60+-0.15. You have allow a deviation (bonus) so that a smaller distance will pass the inspection. But when supplier is reporting the dimension between the holes it will be 60+-0.15+datum shift. In other words if the supplier is reporting the distance as 59.85-0.3=59.55 the part will be IN SPEC.

[@adityang5327]

Dan Botez I think you are right. Datum shift will be a kind of bonus.

[@danezu791]

aditya ng The only way you can keep the orientation control of 0.3 is to change the nominal basic dimension 60 to whatever the datum shift is. It this case you move the datum feature simulator holes closer, to 60-0.3=59.7. In this way you will have the same orientation tolerance at 0.3 and you will be able to shift the part until you find the holes and part can pass the inspection. But is that what he implies here? In this presentation is presented backwards. If the part is not fitting the 60 mm displaced holes than you have to shift it. But something has to change, e ither the tolerance or the nominal? Agree?

[@adityang5327]

Dan Botez Changing nominal won't help, it will just shift the whole issue center to the new nominal. But changing the tolerance will do or introduce new "multiple" FCF with required perpendicularity. One can also limit the bonus applicable (by specifying max position tol)..

[@danezu791]

aditya ng Thanks Aditya. Makes sense that the inspection will not overwrite the perpendicularity requirement. To make sure it is better to use a refinement control. Bottom line: never use Maximum boundary unless you really have to when the supplier requires gaging inspection. For CMM inspection it is a nightmare because it is not so easy to measure datum shift.

[@thevegg3275]

Virtual condition is always the worst case condition regardless of hole or pin size. How can that be? An infiniately large hole should have a larger VC than a 1" hole. Please explain. Thx

[@SuperSWguy]

Vegg, you will never have a "infinitely large" hole because according to ASME Y14.5-2009, every dimension must have a tolerance, which sets the size limits. See Fundamental Rules section 1.4 (a). If you have a 1" diameter hole with a +/-.01 size tolerance on it, & a position tolerance of diameter .01 at MMC, your virtual condition will be diameter .98: (1.00 - .01) - .01 = .98 VC

[@jamsmechanicaladvantagellc4906]

Thanks Don, another great tip and explanation. Maybe the "experts" that think otherwise should produce their own video series, have their books published or perhaps start multiple successful companies? Just saying.

[@jaspergunnar1439]

i know it's pretty randomly asking but do anybody know of a good website to watch newly released series online ?

[@jasemisael646]

@Jasper Gunnar Flixportal :)

[@jaspergunnar1439]

@Jase Misael Thank you, I signed up and it seems like a nice service =) I really appreciate it!

[@jasemisael646]

@Jasper Gunnar you are welcome :)

[@arreacts3142]

I am a regular viewer of your videos, I am also a GDTP senior level certified. Just few thing i observed you missed that the Datum A should be the other surface of dimension 10 and Datum B should be the next pin next to datum C

[@manojv2840]

If two faces are parallel then can we say that they have flatness

[@yadavparas4729]

what is bonus point and hw it's calculate?

[@lokchandsantoshkumar7555]

In this video the feature is shifting then why we called it as datum shift why not as datum feature shift...

[@SuperSWguy]

You are correct in the fact that the official term for it is "datum feature shift" (See ASME Y14.5-2009 section 4.11.9). However, most people just shorten it to "datum shift" because it's easier to say. They both mean the same thing.

[@muthuk5060]

Have seen many videos , but not satisfied,,,,, but this video ,,,, it's simply the best,,,, thanks for clearing my doubt.... I'm subscribing u r channel,,in hope of getting more videos like this....

[@longbeachjjh]

I hope I'm not the only one who laughed at that bumper sticker joke. Thanks for another great vid Mr Day!

[@pankajpatil8411]

Can we give maxium material condition in datum reference frame after tolerance value when feature of size is tapper?

[@SuperSWguy]

Yes. You can use the method described in ASME Y14.5-2009, fig. 7-27. Except that you would have two different size callouts at each end of the hole, creating a conical tolerance zone. However, a better method would be to use profile of a surface similar to fig. 8-17 "Specifying Profile of a Conical Feature", or use fig. 8-18 if you want to relate to datums.

[@Bhatkal1991]

Awesome demonstration.thank u

[@danalex2991]

that's a great insight Thank you!

[@akshayjagadale90]

Thank you

[@memphisliu8497]

very gooooooooooooooooooooooooood!

[@outerthoughts30]

So MMC doesn't exist? So why is it all over my prints?

[@Smellslikegelfling]

MMC & MMB are two different things... They use the same symbol, but MMB was added to ASME in 2009.

[@kingallsup4]

you need to stop making videos you have no clue what you are doing.. I would fire you.. it is a bonus period..

[@SuperSWguy]

This video was produced by Don Day, who up until his death in 2015 was a member of the ASME Y14 standards committee, which includes ASME Y14.5-2009 "Dimensioning and Tolerancing".

[@Smellslikegelfling]

You probably make shitty parts all day because you can't read GD&T... but you can't hire anyone knowledgeable to call you out on your mistakes.

[@pawelborowski6653]

This video only proves that entire GD&T system is full of crap and needs further developments!