[Jo...] Posted October 27, 2025 Share Posted October 27, 2025 Hey all, I am looking for some input on general 2d curve evaluation settings. I know this may be generic, but I figured I would put out a post. For some background. I have came across a few instances in my company where the same feature in different programs are being filtered differently. the examples below show a 2d curve evaluated with spline with 50 upr and a second instance where it is evaluated with Gauss with Lc 2.6. Appreciate the help! Link to comment https://qualityforum.zeiss.com/topic/24879-rules-of-thumb-for-2d-curve-evaluations/ Share on other sites More sharing options...
[Jo...] Posted October 27, 2025 Author Share Posted October 27, 2025 Posted in General for more traffic. Link to comment https://qualityforum.zeiss.com/topic/24879-rules-of-thumb-for-2d-curve-evaluations/#findComment-140927 Share on other sites More sharing options...
[Kl...] Posted October 29, 2025 Share Posted October 29, 2025 Hey, short handout (pptx) Gaussian versus Spline for curves Aditional customized PiWeb Report (pdf), simulated program. Hope it helps Gauss versus Spline.pptx 30.pdf 3 Link to comment https://qualityforum.zeiss.com/topic/24879-rules-of-thumb-for-2d-curve-evaluations/#findComment-141049 Share on other sites More sharing options...
[To...] Posted October 29, 2025 Share Posted October 29, 2025 Please sign in to view this username. There is a lot to look over on these. Thank you. Did you use step width for determining the Lc in the powerpoint? Link to comment https://qualityforum.zeiss.com/topic/24879-rules-of-thumb-for-2d-curve-evaluations/#findComment-141067 Share on other sites More sharing options...
[Kl...] Posted October 29, 2025 Share Posted October 29, 2025 Hey Tom problematic is always inside radius. 1st What's the best stylus radius 2nd probe center path defines step distance, minimum 18 points at 90° arc 3rd Determine the break even Lc for spline filter and compare it to Gaussian I found no background inside the standardisation and the used parameters for Spline-Math is also a mystery The result must be plausible. It is best, if I have similar results, e.g. CMM versus form tester. 1 Link to comment https://qualityforum.zeiss.com/topic/24879-rules-of-thumb-for-2d-curve-evaluations/#findComment-141083 Share on other sites More sharing options...
[Jo...] Posted October 29, 2025 Author Share Posted October 29, 2025 Thank you Please sign in to view this username. ! That is very helpful. Based on the best practice note. For my example, I am measuring a spiral 2d curve. Since the slope tightens towards the center, I should be using Gaussian. Am I interpreting that correctly? Link to comment https://qualityforum.zeiss.com/topic/24879-rules-of-thumb-for-2d-curve-evaluations/#findComment-141085 Share on other sites More sharing options...
[Kl...] Posted October 29, 2025 Share Posted October 29, 2025 (edited) Hey Joseph the gradient growes up for inner to outer, means not constant. I prefer Gaussian, because it only can get problems at start and end. An adequate overlap (cutoff) solves this. Additional compare the result Gaussian & Spline with same Lc to get a feeling for the behaviour. In order to make more precise statements, I need to know the exact geometry Please look at inspection Klaus Spiral.zip Edited October 29, 2025 1 Link to comment https://qualityforum.zeiss.com/topic/24879-rules-of-thumb-for-2d-curve-evaluations/#findComment-141089 Share on other sites More sharing options...
[Jo...] Posted October 30, 2025 Author Share Posted October 30, 2025 Thanks Klause, So my print calls for the below Lambda filtering settings in regards to profilometer measurements. Should I be using 0.8mm for my filtering method when it comes to CMM filtering? Link to comment https://qualityforum.zeiss.com/topic/24879-rules-of-thumb-for-2d-curve-evaluations/#findComment-141177 Share on other sites More sharing options...
[Kl...] Posted October 30, 2025 Share Posted October 30, 2025 Hey Joseph The typical specification of a roughness Evaluation length 4,000 mm Lc = 0.800 mm Ls = 0.0025 mm Samples = 5 Standard CutOff = 1 Measuring length = 4,800 mm There are no specification evaluate the total profile of the spiral Use the spec above, and the number of samplings = MeasuredLenght/Lc Link to comment https://qualityforum.zeiss.com/topic/24879-rules-of-thumb-for-2d-curve-evaluations/#findComment-141185 Share on other sites More sharing options...
[Jo...] Posted November 6, 2025 Author Share Posted November 6, 2025 Thanks for the reply Klaus! so what should the CMM Filtering? You mention Measured length/Lc, so I need to understand the spiral length as if it was flattened out? Link to comment https://qualityforum.zeiss.com/topic/24879-rules-of-thumb-for-2d-curve-evaluations/#findComment-141579 Share on other sites More sharing options...
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