[Pa...] Posted March 6, 2020 Share Posted March 6, 2020 Hi All, Hoping someone can shed some light on this. I'am measuring a profile of a surface 0.250 form only/no datum reference. It is composed of 4 coplaner surfaces. I measured the 4 surfaces individually as freeform surfaces, then recalled them by feature points into a 1 freeform surface. I took that newly created freeform surface and toleranced it bilateral 2 results no datum reference. Now I'am getting a min result of -.13599 and max result of .09936. This profile is failing but Im not sure why. .13599 and .09936=.23535 which is within the .250 tolerance zone. No datum just best fit. Just looking for the form of the profile. Can you explain why it is bad? If we were to take this up on a comparator with an overlay it would pass all day I also created one freeform surface instead of 4 and recalling. It is still failing. **I also noticed and I did call this in but got no explanation--When recalling the 4 freeform into 1 freeform surface the surfaces used button doesn't populate them into the box to the left of the button--Is this normal? Thanks! Link to comment Share on other sites More sharing options...
[Jo...] Posted March 6, 2020 Share Posted March 6, 2020 Are they 4 planes ? Could you build a plane and report flatness to compare ? Link to comment Share on other sites More sharing options...
[Pa...] Posted March 6, 2020 Author Share Posted March 6, 2020 They are 4 freeform surfaces. I have tried them as planes and did the flatness and it is better with the flatness. Unfortunately, Im programming for a medical device company who wants everything per print, so reporting a flatness wouldn't be feasible. Link to comment Share on other sites More sharing options...
[Jo...] Posted March 6, 2020 Share Posted March 6, 2020 Flatness would be the difference like you calculated ? I'm not sure how it arrives at the min max without a Datum reference on a plane. With a Datum reference I could understand translation influencing that. Can you check translation in freeform to se if it would "center" results. It is showing bad because .135 violates the .125 per SIDE zone. Also did you associate freeform to surface in model ? Link to comment Share on other sites More sharing options...
[Pa...] Posted March 6, 2020 Author Share Posted March 6, 2020 When creating the freeform I have also tried a best fit with all degrees of freedom free. Still failed. Also creating it as a alignment and used it in the profile tolerancing and the numbers didn't budge....still failed. I know its showing bad because it violates the boundary but it shouldn't be violating it because like I said If you were on a compactor you would just shift the overlay and it would pass as long as all points fit in a .250 boundary. The 2 results Im getting theoretically fit that boundary. I just dont know why Calypso wants to fails it. You last question about associating freeform to surface in model. I guess Iam...im just creating it and clicking the surfaces used button. Link to comment Share on other sites More sharing options...
[Jo...] Posted March 6, 2020 Share Posted March 6, 2020 Only other thing I can think of is filtering outliers.. Turn on CAD evaluation and look at it. Link to comment Share on other sites More sharing options...
[Pa...] Posted March 6, 2020 Author Share Posted March 6, 2020 Yeh I kind of exhausted everything I could do with that. It seems like creating 4 feature planes (not freeform) then recalling those into a freeform is better. i just didn't understand why it would fail with freeform. I want to go the freeform and curve class but its not available in my area yet. Thanks for the input. Link to comment Share on other sites More sharing options...
[Da...] Posted March 6, 2020 Share Posted March 6, 2020 You will need to use the Bilateral with unequal distribution and shift it to the one side I would use a formula to calculate the Tolerance one side DanCapture.JPG Link to comment Share on other sites More sharing options...
[Jo...] Posted March 6, 2020 Share Posted March 6, 2020 Please sign in to view this quote. So Unequal with two results, Top frame is .25 and bottom frame would be formula something like ABS of max deviation in previous result ? Link to comment Share on other sites More sharing options...
[Ma...] Posted March 6, 2020 Share Posted March 6, 2020 You will need to use Free Form surfacing option. This is the only way to truly check a surface without a datum structure. Without Free Form you are forced to use a fully constrained datum structure to get a profile result. Free form will allow you to release all the degrees of freedom for a best fit. Such as what you are doing with the comparator. Mark Link to comment Share on other sites More sharing options...
[Da...] Posted March 6, 2020 Share Posted March 6, 2020 The Unequal is just a work around with out free form Link to comment Share on other sites More sharing options...
[An...] Posted March 6, 2020 Share Posted March 6, 2020 Please sign in to view this quote. Don't sum. Profile: 0.13599 * 2 = 0.27198 Link to comment Share on other sites More sharing options...
[Wi...] Posted March 6, 2020 Share Posted March 6, 2020 Max deviation x 2 Link to comment Share on other sites More sharing options...
[Jo...] Posted March 6, 2020 Share Posted March 6, 2020 Please sign in to view this quote. I think the question was , why is the deviation not equally disposed using freeform, with no datum reference? If it is comparing to cad geometry.. Link to comment Share on other sites More sharing options...
[Da...] Posted March 7, 2020 Share Posted March 7, 2020 Please sign in to view this quote. It not a sum problem it is total bilateral two results still using the cad geometry that why you need to use unequal distribution with a formula Link to comment Share on other sites More sharing options...
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