Question about report

[[Bl...]]

Hello all,

 

I'm a little confused about the report with the bar all the way on the right side. If you're looking at the values, it lists them left to right as "measured value, nominal value, +tol, -tol, deviation, and +/-".

 

I've always thought that the bar on the right side under "+/-" displayed it as a measurement of low tolerance (left side of bar) and high tolerance (right side of bar) with the centerline signifying nominal. A part ran the other day and when the report came out the measured value measured under nominal value (for example, nominal is 1.50 ±0.005 and the measured value was 1.4976). The value still measured within tolerance, but the green bar was to the right of the centerline under the "+/-" display. Can someone help explain to me why that might be? I always thought that if it measured below the nominal value then it would show to the left of the centerline? I measured the actual diameter that was out with a caliper, and it measured pretty much the same as the CMM.

 

I've attached a photo below of what I'm describing

[[Jo...]]

Hello Blue,

which software and version are talking about and maybe give us a snipet of the report, that is confusing you.

Edited October 1

[[Ri...]]

Could be a simple graphical display error.

[[Bl...]]

This is the photo from the actual report. Measured value is less than nominal value

 

I would assume that the green bar should go to the left of the centerline? I may be looking at it wrong though

Edited October 1

[[No...]]

Is it really +1.50 nominal and +1.4976 actual or maybe -1.50 and -1.4976 ?

[[Jo...]]

thats why you should give us more unfiltered info ...

this is all through your lens and that doesent seem to make sense 🙂

Screenshot the whole line with nominal tolerances actual and the graphical bar.

[[Bl...]]

Yes, sorry I was looking at the wrong report. Is this ok?

[[DC...]]

Never looked that hard at the scale, usually looking at deviation. Pulled up a report and noticed the first dimension graphic appears centered around the means even though it is above the means dimensionally. Maybe scaling because of the large tolerance on the dimension? Again, never paid much attention to the graphic, I believe it is intended as a graphical aid, but you piqued my curiosity.

 

[[Bl...]]

I'm not entirely sure either. As you can see, the graphics I provided is below the nominal and it shows slightly to the right of the midline on the scale.

[[Be...]]

I am guessing here.  Is this an ID?

[[Ke...]]

The tolerance bar graphic represents the used tolerance in 2 ways depending on the type of characteristic. For features with +/- tolerance, the center is zero and the bar progresses in the direction of the used tolerance (left for negative, right for positive usually). For features with a unilateral tolerance (Roundness for example), zero is the left side and it progresses towards the tolerance at the right
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[[Bl...]]

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 It's an OD

 

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 Just to make sure I'm understanding you correctly, features with ± tolerance have the center as zero and the bar progresses in the direction of the used tolerance (left for negative, right for positive usually). As you can see in the screenshot I provided earlier it is a ± feature. 1.320 should be my center in that graphic bar, correct? The measured value all the way on the left measured 1.3176 (less than what center is), so shouldn't it have gone to the left? Please let me know if I misunderstood anything. I appreciate any and all feedback. Thank you all!

[[Be...]]

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Well i still don't know what is going on.

here are some thoughts

1) it is possible that the algorithm for drawing that graphic is just not very good.  Maybe they didn't give it as much attention as we like to think they did when the wrote it.

2) Does the nominal on the feature match the nominal on the dimension?

3) I checked a few reports and had the graphic look exactly like I would expect it to look, so thought 1 seems less likely.

4) Is there something in the tolerance setting or fit algorithm that is a little odd?

5) I don't think I have any good ideas as to why this is happening and would like to know when you find the answer.