Step Cylinder

[[Mi...]]

Hi All,

I've never used a step cylinder before. Would this be a acceptable way of measure the 3 coaxial diameters?

Screenshot 2021-08-10 095130.png

[[SH...]]

Yes, but I never see this call-out, weird.

[[Mi...]]

Please sign in to view this quote.

This would be a first for me too. Had to pull out the Y14.5-2009 to get an understanding.

[[Da...]]

It might be something you’ll see more often in the future, because since ASME Y14.5-2018, the coaxiality/concentricity symbol (and the symmetry symbol for that matter) has been removed from the standard.

In order to evaluate coaxiality, you have to use the position tolerance now. The former ASME way of evaluating the concentricity has been removed in favor of a method similar to the ISO method (only difference in ASME is that you have to use an outer tangential element for evaluation if the feature is RMB), which is also a positional tolerance.

The step cylinder is the right way to create a common datum at MMB to check the coaxiality/position of each diameter to.

[[Mi...]]

Please sign in to view this quote.

Thanks for the reply Daniel!!

[[Da...]]

On second thought, the only problem I see here is that one call-out specifies the minor diameter, the next the pitch diameter (which you can check best with a thread plug) –both can only be the thread–, but the third call-out only specifies „3 coaxial diameters“. But it doesn’t say which (I suspect the designer means the diameters that are not the thread).