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?
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).
@@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?
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: th-cam.com/video/qtp_VqpnPZg/w-d-xo.html
Thanks for these great videos. They are really useful. I have a question on this one if you dont mind. On these cylindrical parts(spacer) where they may be interference fits would the interference or maybe transition fit dictate that the axis of the spacer becomes datum A then the lower end is controlled with a tight perpendicular tol, that becomes datum B, then the opposite end would be controlled as you've shown back to A and B? or are these spacers clearance and that's why the end is datum A. Does it depend on what sort of fit the hole/shaft relationship is ? Hope you understand what I'm trying to say. Thanks.
Yes, in your scenario, the fit on the diameter is so tight that the axis dominates the rotational alignment of the part. I agree the axis would be a better datum A and face as secondary datum feature B. On my part shown, the fit is so sloppy that the face sets the initial "attitude" and is a better primary.
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.
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)
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.
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.
When you have a profile tolerance refined by parallelism, and you have surface imperfections (chatter marks, non cleanup) in the surface, are those imperfections allowed to be filtered out of the parallelism? In other words, I have a surface that passes profile but when the chatter is captured in the parallelism with laser inspection, the parallelism fails.
This is a controversial topic. Per ASME Y14.5-2018, sec 4.1 fundamental rules (s): "UOS, elements of a surface include surface texture and flaws. All elements of a surface shall be within the applicable specified tolerance zone boundaries." This rule has caused issues in the metrology world. Y14.5.1-1994 section 2.1.1 says "a certain amount of smoothing is necessary...". The best I can say is a new standard will be released on this topic soon, Y14.49 supplemental dimensioning and tolerancing specification, to better address filtering and the functional requirements.
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.
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.
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.
Good talk. Good.
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?
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).
@@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?
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: th-cam.com/video/qtp_VqpnPZg/w-d-xo.html
@@GeoTolProThank you for the thorough explanation, the other video was very helpful too! Your content is awesome.
Thanks for these great videos. They are really useful. I have a question on this one if you dont mind. On these cylindrical parts(spacer) where they may be interference fits would the interference or maybe transition fit dictate that the axis of the spacer becomes datum A then the lower end is controlled with a tight perpendicular tol, that becomes datum B, then the opposite end would be controlled as you've shown back to A and B? or are these spacers clearance and that's why the end is datum A. Does it depend on what sort of fit the hole/shaft relationship is ? Hope you understand what I'm trying to say. Thanks.
Yes, in your scenario, the fit on the diameter is so tight that the axis dominates the rotational alignment of the part. I agree the axis would be a better datum A and face as secondary datum feature B. On my part shown, the fit is so sloppy that the face sets the initial "attitude" and is a better primary.
@@GeoTolProperfect, thanks for the reply.
Epic lecturers
Thank you so much
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.
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)
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.
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.
When you have a profile tolerance refined by parallelism, and you have surface imperfections (chatter marks, non cleanup) in the surface, are those imperfections allowed to be filtered out of the parallelism? In other words, I have a surface that passes profile but when the chatter is captured in the parallelism with laser inspection, the parallelism fails.
This is a controversial topic. Per ASME Y14.5-2018, sec 4.1 fundamental rules (s): "UOS, elements of a surface include surface texture and flaws. All elements of a surface shall be within the applicable specified tolerance zone boundaries." This rule has caused issues in the metrology world. Y14.5.1-1994 section 2.1.1 says "a certain amount of smoothing is necessary...". The best I can say is a new standard will be released on this topic soon, Y14.49 supplemental dimensioning and tolerancing specification, to better address filtering and the functional requirements.
Thank you for taking the time to reply!
By providing one common profile symbol for both segments we can eliminate the parallelism symbol right?
That is correct. However, for a planar surface at zero degrees, I prefer the simplicity of parallelism.
@@GeoTolPro Thanks
Can you please explain , why are we not adding Flatness value to basic ? even flatness also contributes to the variation right?
Flatness is there called out on Datum A.
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.
Composite profile tolerance will work? hope the 2nd segment will have same functionality of controlling orientation?
That is correct. I prefer the simplicity of parallelism in this case.
How would you understand the parallelism of the surface if we also relate it to the shaft axis like 0.002 | [A] | [B]?
There would be no difference. Datum A constrains all the rotations necessary to determine the parallelism of the top surface.
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.
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.
Hi engineer - Do you have Telagram channel? How can I contact you?