Parallelism Applied with Profile Tolerance

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Profile locates a surface while parallelism refines the orientation of a feature. This video shows the differences in these tow symbols and how they may be used together to offer the most manufacturing tolerance and still maintain function. A practical example is used to illustrate the concepts. Inspection data helps show the measurement differences. The concepts are per ASME Y14.5 but also applies the same in ISO-GPS.
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#profile tolerance #datum #datum feature #position tolerance #asme #asme Y14.5 #Y14.5
#GD&T #geometric tolerance #Y14.5-2018 #flatness #perpendicularity

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11 сен 2024

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Комментарии : 24

@Zach-ed4nx 17 дней назад

Good talk. Good.

@dance5875 Год назад

Thank you so much

@dance5875 Год назад

Epic lecturers

@sem7207 Год назад

Thanks for the great video. Could you clarify the following? In the measurement plan, for requirement no. 3 (perpendicularity, zeo at MMC), the inspection method is "height gage and angle plate, not measured if size above .800." How would this work for inspection of perpendicularity? and why not measured if size is above .800?

@GeoTolPro Год назад

The MMC modifier allows bonus tolerance as the feature departs from MMC. If the hole is produced at .800, it is allowed .015 position tolerance. This is a huge tolerance and easy to pass. Perpendicularity is a little difficult and time-consuming to measure (with a height gage). Lets save time and money and make it a pass thru inspection (because we're confident in the lathe manufacturing process).

@sem7207 Год назад

@@GeoTolPro thanks a lot for the clarification. It makes sense. So if the hole diameter is smaller than .800 I understand that a measurement of perpendicularity is still required, could you tell how it is performed with a height gage? I imagine it is no easy task because it would be needed to evaluate the axis deviation? A surface method fixture that includes the simulator for datum A and a virtual condition pin gage for perpendicularity (diametet of .785) would probably be easier to implement but would only allow a pass/fail test. Right?

@GeoTolPro Год назад

First, you must align the part to datum A (probably with an angle plate). You must now find the center of the hole in two places (call it front and back). The height gage touches top and bottom of the hole at the front and top and bottom at the back. This displacement represents the deviation of the axis in the Y direction. Rotate the part 90 degrees and repeat for the X direction. Now you have the deviation of the axis in both X and Y. Use the Pythagorean theorem to get the hypotenuse and perpendicularity value. Hard to explain in a comment. Look at my video on parallelism for the hole. It shows more detail on this inspection data for an orientation tolerance: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-qtp_VqpnPZg.html

@sem7207 Год назад

@@GeoTolProThank you for the thorough explanation, the other video was very helpful too! Your content is awesome.

@adrianm6351 Год назад

Well explained, just wondering if positional tolerance could be used to control the 1.460 height? That mean we'd have parallelism to control shape and position to control location.

@GeoTolPro Год назад

In ASME Y14.5, position tolerance only controls the location of features of size (holes, slots, pins, etc.). While profile controls the location of surfaces. In ISO-GPS standards, however, position may be used to control the location of planar surfaces (ISO 1101: 2017)

@TAH1712 5 месяцев назад

I don't get why 0.002 is considered a 'nice flatness' tolerance over about a 1 inch diameter. I'd expect 0.0002 easily and 0.0001 inch with a little care on a new machine ... and I would think that if 0.002 was accepted , that inaccurate flatness pressing on a bearing would be bad.

@GeoTolPro 3 месяца назад

Good comment. Of course it all depends on function but I agree that a tighter flatness than .002 may be needed and would be easy to manufacture to. Fourth decimal tolerance values are hard to do teaching and explanations with.

@nikhilfci 2 года назад

By providing one common profile symbol for both segments we can eliminate the parallelism symbol right?

@GeoTolPro Год назад

That is correct. However, for a planar surface at zero degrees, I prefer the simplicity of parallelism.

@nikhilfci Год назад

@@GeoTolPro Thanks

@solonglife8130 11 месяцев назад

How about we put the composite profile .012 on top row with Datum A, while .002 on bottom row without datum? It is to control the form (i know it is not parallel) but it achieve the similar result.

@GeoTolPro 11 месяцев назад

The lower frame in your example would only control flatness (no datum, to itself). Composite profile with A in both the lower and upper would be the same as the drawing in the video. However, profile and parallelism is easier to understand (keep it simple). Use composite profile if its a complex surface or multiple surfaces.

@YuvarajMr 2 года назад

Composite profile tolerance will work? hope the 2nd segment will have same functionality of controlling orientation?

@GeoTolPro Год назад

That is correct. I prefer the simplicity of parallelism in this case.

@fernandorodriguezespinoza4649 Год назад

How would you understand the parallelism of the surface if we also relate it to the shaft axis like 0.002 | [A] | [B]?

@GeoTolPro Год назад

There would be no difference. Datum A constrains all the rotations necessary to determine the parallelism of the top surface.

@adithyaasrinivaas1445 Год назад

Can you please explain , why are we not adding Flatness value to basic ? even flatness also contributes to the variation right?

@trentwood1449 Год назад

Flatness is there called out on Datum A.

@GeoTolPro Год назад

Flatness is applied to a feature (surface) not to a basic. The datum feature A must be flat. The top surface must be located (profile) to datum A and also with a tighter parallelism. Both profile and parallelism control flatness on the top surface.