[Ja...] Posted August 25, 2021 Share Posted August 25, 2021 Do these two FCF have the same meaning where the concerned feature is a cylinder and datum feature(datum -A-) is a plane? 1) [ perpendicularity | Ø .001 MMC | A ] 2) [ location | Ø .001 MMC | A ] Link to comment Share on other sites More sharing options...
[Da...] Posted August 25, 2021 Share Posted August 25, 2021 Please sign in to view this quote. Identical, test it in Calypso. You should get the same numbers. Link to comment Share on other sites More sharing options...
[Ja...] Posted August 25, 2021 Author Share Posted August 25, 2021 I wanted to ask this because I was doing software update validation from 2016 to 2021 and 2016 version showed me different results for these 2 FCF's while 2021 showed it to be the same. In 2016, location characteristic result was twice the perpendicularity characteristic result. Link to comment Share on other sites More sharing options...
[SH...] Posted August 26, 2021 Share Posted August 26, 2021 Please sign in to view this quote. Should be your mistake. Link to comment Share on other sites More sharing options...
[Ja...] Posted August 26, 2021 Author Share Posted August 26, 2021 Please sign in to view this quote. How? I did not change anything in the program between evaluations and so the results should be same unless the software update made changes to how it calculates the characteristic. see attached. Anyways, I also think that both FCFs should yield the same results. Link to comment Share on other sites More sharing options...
[Ma...] Posted August 26, 2021 Share Posted August 26, 2021 Well as you see - it has changed X value - so something with evaluation has changed. Maybe related to base. Perpendicularity takes difference of start and end of line or cylinder. True position compare between start and end of element and base dimension. Maybe projection error can occure? I would measure it again to verify repeatability. Link to comment Share on other sites More sharing options...
[Ja...] Posted August 26, 2021 Author Share Posted August 26, 2021 Please sign in to view this quote. I have measured a new part on calypso 2016 and did subsequent evaluation for it on calypso 2021 by just loading measured points and same thing. 2016 showed location twice that of perpendicularity result while 2021 showed them to be same. Link to comment Share on other sites More sharing options...
[Ma...] Posted August 26, 2021 Share Posted August 26, 2021 Well here is calc formula https://www.gdandtbasics.com/true-position/True-Position-Formula[1].jpg Link to comment Share on other sites More sharing options...
[Ma...] Posted August 26, 2021 Share Posted August 26, 2021 The confusion here seems to be between "location" and "True Position" In this case, deviations for location and perpendicularity are exactly the same and True Position deviation is 2x location or perpendicularity. Link to comment Share on other sites More sharing options...
[Ke...] Posted August 26, 2021 Share Posted August 26, 2021 Please sign in to view this quote. You are 100% correct. Link to comment Share on other sites More sharing options...
[An...] Posted August 26, 2021 Share Posted August 26, 2021 See attached.Contribution_26_08_2021_1.pdf Link to comment Share on other sites More sharing options...
[Ma...] Posted August 26, 2021 Share Posted August 26, 2021 Please sign in to view this quote. I don't think that Calypso consider midpoint - I think it takes worst deviation of start or end of axis. Link to comment Share on other sites More sharing options...
[To...] Posted August 26, 2021 Share Posted August 26, 2021 Please sign in to view this quote. One way to find out. Turn on Axis End Points??? Link to comment Share on other sites More sharing options...
[An...] Posted August 27, 2021 Share Posted August 27, 2021 Please sign in to view this quote. See attached.Contribution_27_08_2021_1.pdf Link to comment Share on other sites More sharing options...
[Ja...] Posted August 27, 2021 Author Share Posted August 27, 2021 Please sign in to view this quote. What do you mean by that Tom? And what is your answer to my original question if both these FCF's should yield the same results? Link to comment Share on other sites More sharing options...
[Ja...] Posted August 27, 2021 Author Share Posted August 27, 2021 Please sign in to view this quote. Hi Andreas, what do you mean by "New datum A according to Calypso-operator"? In your latest post, are you trying to point out difference between how old Calypso and new Calypso calculated the FCF? And what is your answer to my original question that both those FCF's should yield the same results? Link to comment Share on other sites More sharing options...
[To...] Posted August 27, 2021 Share Posted August 27, 2021 Please sign in to view this quote. On Andreas' sketch, Martin was questioning where the X was calculated from since Andreas appeared to be referencing the mid-point. Something I've often wondered myself. In the characteristics settings editor, there is an option to turn on axis end points which reports the X & Y values at the each end of the cylinder axis. I thought end points may show something that makes sense to the calculation. However, I'm not sure where the X is coming from since you're only referencing Datum A. Original question: I believe the results of position to A and perpendicularity to A should be the same. Andreas may be correct on how the axes are evaluated between the two but I'm not sure how significant the difference may be. To me, it is odd that you're seeing double the deviation based on Calypso versions. Link to comment Share on other sites More sharing options...
[Ja...] Posted August 27, 2021 Author Share Posted August 27, 2021 Yes, I also had the understanding that the result/meaning for both FCF's should be same. Now I get what Andreas wanted to say. Thanks Tom! And I checked axis endpoints on a new part with both versions of Calypso and they matched with Andreas' sketch. 2016 version had base point at (0,0) and top point at (-.0002,0) and was doubling that radial distance to give position deviation of .0004 while perpendicularity also had point (-.0002,0), the result is not doubled to give deviation of .0002. Therefore 2016 version was calculating it differently and is obviously wrong how it did that but luckily it did not pass a bad part as good. So no problem there. Now 2021 version had base point at (.0001,0) and top point at (-.0001,0) adjusting itself to center it between the end points and doubling that radial distance to give .0002 deviation result , same as perpendicularity (but perpendicularity point (-.0002,0) remained the same). So the newer version is correct. Thank you guys for all your help with this. Link to comment Share on other sites More sharing options...
[Ma...] Posted August 30, 2021 Share Posted August 30, 2021 Please sign in to view this quote. Well i did that now. And it is as i said. Calypso don't take midpoint in TP. As Andreas draw all depends on where is base and element. You can use shifted tolerance to simulate longer element. I actualy answered to author here Please sign in to view this quote. Link to comment Share on other sites More sharing options...
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