Angle Callout on a Section Cut

[[Da...]]

I am working on a drawing that is a cylindrical part and there is an angle callout on an edge to the axis. I'm assuming since the part is cylindrical, that the drawing does not mean literally at this one spot the angle needs to be Xdeg. Would you measure this in 4 (or more) places, 4 because one measurement in each quadrant, and then create a result step and average them? Or what is the proper way to measure per the standard?

[[Am...]]

Im having a hard time visualizing what you're describing. Is it like a chamfer at the edge? Can you draw something similiar if you don't want to share a pic of the dimension.

[[De...]]

According to the standard, a defined angle should meet the call out at any place it is measured.

So what this means for measuring it on the CMM is that taking the total of all the places it is measured, both the highest and lowest result on the feature must be within tolerance.

Just like if it were being checked on using a plate inspection method, a determination must be made based on the tolerance and function of the angle as to how far to go checking the angle. If an angle is called out +/- 5 degrees and +/- 0.030" then a check in one place is likely fine unless you can visibly see a lot of error in the angle.

If this is a functional angle that is intended to mate with another part like a taper, it would clearly require a much more stringent check.

Unfortunately how in depth your check needs to be is up to you as it is not something covered in the spec. The goal is to make a stringent enough check to be relatively certain within some margin of error that the feature is in tolerance. A lot of this determination depends on the stability of the process used to manufacture the part and the amount of time allowed for the inspection. If time is no object you could check it in enough places to assure it is correct no matter what. If the process has been proven to be very stable, and the tolerance is not too tight, a check in one place might also do the same.

[[Da...]]

Ok, thanks Derek. I initially measured in 4 quadrants and reported all 4 findings, so it seems as if I measured per the standard. I got some kickback saying its only called out once, so should only be reporting once. I'll go back to the standard and pass along the information. Thanks again.

[[Da...]]

By any chance, do you know where in the standard it states "... a defined angle should meet the call out at any place it is measured."?

[[Ro...]]

If the part is machined around the centerline on a lathe then i personally would consider 1 place good enough.
If the angle is cut using a fixed angle cutter (say a chamfer tool) then i would consider 1 place good enough.
if you're using a lolipop cutter and doing a lot of 3d machining then i would check it in several places

[[Da...]]

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The parts are molded plastic.

[[De...]]

The following section covers if this were an angled surface on the edge of a square part, I can't find anything that specifies that the same rule applies specifically in the case you are asking about, however it seems unrealistic to expect that an angle would be defined in only one location on the end of a diameter unless there was more to it than you have stated.

It has always been my understanding that any dimension needs to be in tolerance over the entire applicable surface unless otherwise specified. If there was something defining the orientation, and showing that the dimension changes except in that one location that would make sense.

Regarding the idea of it being 'one dimension on the print', this is great for a print where everything has perfect form, on real parts most features have some form error which results in a low and a high result. If they wan't only one result, you could always just report the worst deviation you find.

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