GD&T Concentricity (Don't Use It)

[@crazyingenieur3277]

1. There is no standard called out in the video. So I have no choice but to assume that it is either ASME Y14.5M-1994 or Y14.5-2009 because the committee removed concentricity and symmetry in Y14.5-2018. 2. All the dimensions technically do not meet the standard. For instance, ⌀36.00 ± .4 should be ⌀36.00 ± .40 for imperial dimensions or ⌀36 ± 0.4 for metric ones (yeah, details matter). 3. All concentricity callouts in the video are missing the "⌀" symbol in the feature control frame because the concentricity tolerance zone is a cylinder. 4. The flywheel part shown (timestamp 2:50) does not have a surface of revolution. So that one concentricity callout does not apply to other areas of the part. So you would need 3 concentricity callouts for each partial cylindrical area with a CONTINOUS FEATURE callout/flag. And that still does not cover the planar features of the part. In my humble opinion, a training company that claims to teach people GD&T should not make these mistakes. My advice for all viewers, please do your homework before buying subscriptions. You should check the credentials of the instructors, etc. Unfortunately, anyone can "teach" on KZbin these days. There is no checking authority. So be careful. Always question. It is very easy to learn new things wrong. Do yourself a favor and buy the standard. It is a good investment and a good starting point.

[@jamescarter9147]

Thanks for the video, a suggestion of which different control to use would be helpful.

[@RDTengineered]

total runout. runout. position.

[@lakshmipathi8340]

I have one doubt, for concentricity inspection there is alignment required

[@deadhead7930]

Dont use concentricity? Your statement is ridiculous. Your misleading beginners on a very important subject. A subject that can termine if someone lives or dies - coming from aerospace industry, its the most important aspect - safety. A lot of blueprints in aviation use concentricty. Then again - anyone can create a YT channel and "teach" things.

[@crazyingenieur3277]

@@mscscambodia It is a mistake that they removed concentricity ( and symmetry). You will see they will add them back. The concentricity solves a design intent that no other geometric control can. Imagine a cylindrical portion of a shaft that spins relatively fast, so the weight distribution and balancing is important. This portion does not mate with any other features in the assembly. So you would have a relatively large size tolerance and a tight concentricity tolerance. The form is not important either as long as the feature is concentric. You cannot have this with any other geometric control! - total runout: you would have a large error for a tapered, barralled, waited feature. - runout: you would have a large error for an elliptical cross-section, but that would be concentric. - profile (with or without the dynamic modifier): this would force the size tolerance and/or the form to be tight, which you don't care, because all you want is large size tolerance and tight concentricity!