[SH...] Posted March 9, 2021 Share Posted March 9, 2021 I really can't visualise the perpendicularity graph, does it tells the area where perpendicularity is high, it is a perpendicularity of a plane with respect to a cylinder. I have attached the graph of the flatness and perpendicularity of the planeScreenshot_2021-03-09-18-58-01-04.png Link to comment Share on other sites More sharing options...
[Ri...] Posted March 9, 2021 Share Posted March 9, 2021 Perpendicularity of a Plane to a Cylinder is the same as Axial Runout. CAD Presentation is a better tool of showing the high and low spots. Link to comment Share on other sites More sharing options...
[Ja...] Posted March 10, 2021 Share Posted March 10, 2021 It looks like the error magnification on the perpendicularity is 100. If you change it to 1000 so it is the same as the flatness, then you should see the same as the flatness but including the angle between the feature and the datum. But the angle in the perpendicularity might push it off the page. Link to comment Share on other sites More sharing options...
[Ch...] Posted March 10, 2021 Share Posted March 10, 2021 In a Piweb report like shown, both the minimum (always 0) and maximum points, shown with the red circles, are influencing the perpendicularity result. That is, if the low points were higher, your result would be better, and likewise if the high points were lower. Piweb plot is a good presentation of this because the blue circle is the collection of measured points, and the grid-base is a representation of the nominal orientation of the plane. So you can clearly see that the blue collection of measured points lies in a plane that is "tilted" (relative to nominal). Link to comment Share on other sites More sharing options...
[To...] Posted March 10, 2021 Share Posted March 10, 2021 Why does the flatness plot show LSQ Feature? Also, shouldn't the perpendicularity be Minimum Feature instead of LSQ? Or does it not matter? In my simulation, I get the same result either way. I guess Max Point and Min Point are the same in this case. Link to comment Share on other sites More sharing options...
[SH...] Posted March 10, 2021 Author Share Posted March 10, 2021 Please sign in to view this quote. My people sometimes check flatness maunally, if i use least squares CMM reading and manual reading same, it is hard to explain them about minimum feature evaluation. Link to comment Share on other sites More sharing options...
[Ch...] Posted March 10, 2021 Share Posted March 10, 2021 Please sign in to view this quote. Both flatness and perpendicularity will produce better results with Minimum Feature. It is therefore recommended. Link to comment Share on other sites More sharing options...
[To...] Posted March 10, 2021 Share Posted March 10, 2021 Please sign in to view this quote. Hey Patrick, I understand know flatness SHOULD be Min Feature but I was asking why Shabu was using LSQ. For perpendicularity, Calypso defaults to LSQ and I usually don't second guess the defaults in Calypso so it was a surprise to see it on Shabu's plot. Link to comment Share on other sites More sharing options...
[To...] Posted March 10, 2021 Share Posted March 10, 2021 Funny, Perpendicularity, Parallelism and Angularity all default to LSQ. If all we are doing is checking to see if all of the feature's data points are within a tolerance zone, does the evaluation really matter. Link to comment Share on other sites More sharing options...
[Ch...] Posted March 10, 2021 Share Posted March 10, 2021 Please sign in to view this quote. Exactly! In a hard-gauging world it doesn't matter at all! However, in Calypso, you will get different results, so some input from the programmer is required to ensure you get the real result (most accurate answer given the measurement data). Link to comment Share on other sites More sharing options...
[Ke...] Posted March 10, 2021 Share Posted March 10, 2021 Please sign in to view this quote. Nope 🙂 , and for precisely the reasoned that you mentioned. Form, however, (if you look at a plot using MIn Feature) evenly distributes the Min point & Max point. Whereas, if you change the evaluation method to LSQ, the MIn & Max points are no longer evenly distributed, and you get a *larger* out of round result. So, it looks like, even though LSQ is not the "correct" method to use, it is "safer" to use, if your main concern is to ensure that questionable parts (bordeline "passing") do not make it to the customer. Link to comment Share on other sites More sharing options...
[Ke...] Posted March 10, 2021 Share Posted March 10, 2021 Please sign in to view this quote. You may want to reconsider this aproach... If using LSQ gives a larger Flatness result, you may be failing/reworking/scrapping parts that could pass if you were using the Min Feature evaluation $$$ Link to comment Share on other sites More sharing options...
[Me...] Posted March 10, 2021 Share Posted March 10, 2021 Please sign in to view this quote. Yes, Calypso is still performing the "Minimum Feature" fit for the evaluation. Nothing to worry about unless you do not like seeing LSQ show up on the plot. Link to comment Share on other sites More sharing options...
[To...] Posted March 10, 2021 Share Posted March 10, 2021 Please sign in to view this quote. In my testing, I saw no difference in the results but I don't know how much I can rely on dispersion data. However, I found a part with some data and found no difference in the results. Mind you, the results shown are in metric. I know the 2 algorithms affect how the derived feature is calculated, which like you mentioned, changes the values of the min and max point. Is it possible for the 2 evaluations to find different min and max points? Doesn't appear to in my testing. I honestly don't care about the derived feature because it's all about the points.Screenshot 2021-03-10 162045.jpg Link to comment Share on other sites More sharing options...
[Ke...] Posted March 10, 2021 Share Posted March 10, 2021 Please sign in to view this quote. No, I don't think you will see a difference in perpendicularity of parallelism (anything that is relative to a datum = location) Only when looking at pure form ( roundness, flatness, cylindricity, etc.) Link to comment Share on other sites More sharing options...
[Ch...] Posted March 10, 2021 Share Posted March 10, 2021 You most certainly will see a difference sometimes. My guess as to why you don't see the same difference is that outlier elimination does a fantastic job of making Min Zone very similar to LSQ. In the example above, outlier elimination has been turned off. The reason there is a difference at all is that in these orientation controls, there are still some degrees of freedom that Calypso has to deal with, and the evaluation method is involved in how Calypso locks down those degrees of freedom. Link to comment Share on other sites More sharing options...
[Ke...] Posted March 10, 2021 Share Posted March 10, 2021 Please sign in to view this quote. Interesting... are you changing the evaluation method of your Primary Datum, too; or just the Feature being evaluated to it? Link to comment Share on other sites More sharing options...
[Ch...] Posted March 10, 2021 Share Posted March 10, 2021 This is the result of changing only the evaluation method of the considered plane (with some admittedly dreadful data that helps exaggerate the deviation). The datum was "measured" without dispersion, and the datum evaluation method was left at Outer Tangential in both cases. Link to comment Share on other sites More sharing options...
[To...] Posted March 10, 2021 Share Posted March 10, 2021 Please sign in to view this quote. Just the feature. The primary datum is set to outer tangential element in both results. Link to comment Share on other sites More sharing options...
[To...] Posted March 10, 2021 Share Posted March 10, 2021 Please sign in to view this quote. Interesting. Would it be possible for you to zip up your program file and email it to me? I'd really like to see what is different between your test and mine. I will send you my email via private message. Link to comment Share on other sites More sharing options...
[Me...] Posted March 11, 2021 Share Posted March 11, 2021 Please sign in to view this quote. What version of Calypso are you using? Link to comment Share on other sites More sharing options...
[SH...] Posted March 11, 2021 Author Share Posted March 11, 2021 Please sign in to view this quote. Usually I try to showcase maximum deviation, we are doing assembly only ,part is given by supplier. I will verify all the evaluation before confirming NC. Link to comment Share on other sites More sharing options...
[Ch...] Posted March 11, 2021 Share Posted March 11, 2021 Please sign in to view this quote. The screenshots were taken from Calypso 2020, but I was able to produce the results in 2019 as well. Link to comment Share on other sites More sharing options...
[Me...] Posted March 11, 2021 Share Posted March 11, 2021 Interesting... I'm currently on 2018 and the fitting method has no impact on the result. The same can be said when forcing all of the form / orientation characteristics to evaluate perpendicularity. Link to comment Share on other sites More sharing options...
[Ke...] Posted March 11, 2021 Share Posted March 11, 2021 Please sign in to view this quote. More interesting.... I'm running 2017 on an Accura - which does *not* vary when changing the fitting method. But 2018 on is on the Contura - which *does* vary when changing the fitting method. Link to comment Share on other sites More sharing options...
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