[Go...] Posted October 3, 2019 Share Posted October 3, 2019 Is the use of filters good? To what extent is it a good practice to make use of these options called filters? From my point of view, I think that many irregularities are being neglected in cases where they are present in the measurement, then, to what extent should the filters be applied? One of my difficulties is when making measurements or comparisons Vs the Gages that are in the production lines where the vast majority of such equipment not all that variety of filters. Link to comment Share on other sites More sharing options...
[Ja...] Posted October 3, 2019 Share Posted October 3, 2019 Yes, but only if you're scanning. To answer your question of "To what extent?" Zeiss provides a "Cookbook" that outlines various measurement and filtration strategies. I got mine while attending the Basic and Advanced Calypso classes in North Carolina, but I think it's possible to purchase one outright from Zeiss. However, it's been my experience to filter primarily on roughly finished parts. Those that have been finely-machined seem to benefit much less from it. It also depends on how tight the tolerances of the piece are. I'm sure someone more knowledgeable than myself will chime in here soon. Link to comment Share on other sites More sharing options...
[Ga...] Posted October 3, 2019 Share Posted October 3, 2019 I definitely recommend using filters all the time. It's true that you don't want to be filtering out actual deviations in your part, but you do want to filter out any mechanical deviations (ie vibrations from the CMM/other external vibrations in the room, etc). Simply turning filters on in Calypso under the default settings will help ensure that fluctuations in measurements are due to the part itself, not external sources. As Jake mentioned, if you want to go into detail on which filter/outlier settings to apply for specific parts and characteristics, the cookbook is going to be your best resource. If you don't need that much detail, though, simply turning on the default values is strongly recommended. Link to comment Share on other sites More sharing options...
[Ri...] Posted October 3, 2019 Share Posted October 3, 2019 Filters are more of a smoothing of the data - it takes out vibrations from the machine, probe, surface finish, etc. Outlier Elimination is more of what you are talking about. Link to comment Share on other sites More sharing options...
[Go...] Posted October 4, 2019 Author Share Posted October 4, 2019 I definitely see this topic very broad and it is important to have identified the cases in which they should be applied Link to comment Share on other sites More sharing options...
[Ri...] Posted October 4, 2019 Share Posted October 4, 2019 If filterings design intent is to compensate for irregular surface conditions, should one really be filtering if they are scanning near mirror finish parts for example? Probably not. The cookbook doesn't take "your" parts surface conditions into account and seems to treat every part like it has irregular surface conditions. Link to comment Share on other sites More sharing options...
[Mi...] Posted October 4, 2019 Share Posted October 4, 2019 More info than my brain can handle on a FRI... Link to comment Share on other sites More sharing options...
[Me...] Posted October 4, 2019 Share Posted October 4, 2019 Please sign in to view this quote. I was just explaining these things to a 3rd shift Zeiss Programmer/Operator at a very respectable aerospace company at their facility who had no idea about any of this. They scan all day long and have zero training. Words do not describe the pain. Link to comment Share on other sites More sharing options...
[Go...] Posted October 4, 2019 Author Share Posted October 4, 2019 Please sign in to view this quote. Will someone have an excerpt from ISO 12180-f2 regarding the type of ausar probe and the filter to apply that can be shared? Link to comment Share on other sites More sharing options...
[Ri...] Posted October 4, 2019 Share Posted October 4, 2019 Please sign in to view this quote. You probably wouldn't see too much difference if using LSQ, and if your tolerances allow for it. Link to comment Share on other sites More sharing options...
[Ro...] Posted October 7, 2019 Share Posted October 7, 2019 I was told in my Curve and Free Form classes at Zeiss Brighton Michigan that as a general rule you Always filter, always delete outlier. Then they went into the weeds with explaining what the numbers meant on the spline & gauss filters, but then told us just to click them on and accept what was given as default, they work fine. Link to comment Share on other sites More sharing options...
[Me...] Posted October 7, 2019 Share Posted October 7, 2019 Please sign in to view this quote. I would argue that if and when scanning, filters and outliers are there for very specific reasons and are extremely important, especially with tighter tolerances. "Probably won't see a difference" could mean a lot of money going one direction or the other & I would not say those exact words to a company that I'm selling a product to that does not quite understand Calypso beyond the basic level. I'm also pretty sure everyone that I've ever been trained by in the Zeiss community would not appreciate teaching that to beginners either lol. Link to comment Share on other sites More sharing options...
[Ri...] Posted October 7, 2019 Share Posted October 7, 2019 I would say that filters are more important than outliers. I understand where you are coming from, but I don't agree with just blindly throwing on filters, and outlier elimination without understanding the affects of that. Filters were designed to eliminate noise in the measurement from the measurement equipment, and to eliminate frequencies picked up due to surface roughness. Unless you are measuring form tolerances, you are not really going to see a huge impact of filters on your calculations - if using LSQ evaluations that is. Outliers were designed to eliminate sloppiness in inspection, and trying to help people not have to keep measuring parts because someone forgot to clean the part thoroughly. Outliers can be extremely dangerous if there scratches or gouges in a part (especially when measuring a roundness, or some other form tolerances). Great discussion. I'd love to continue. 🙂 Link to comment Share on other sites More sharing options...
[Me...] Posted October 7, 2019 Share Posted October 7, 2019 Please sign in to view this quote. 100% agree about Outliers, meant to say that. Sorry I can't continue the discussion bahaha Link to comment Share on other sites More sharing options...
[Gr...] Posted October 7, 2019 Share Posted October 7, 2019 Scratches, torn fibers from the cleaning cloth, and other miscellaneous crap are good reasons to leave light filters on at all times. I recently had a gnat that got smeared by the stylus. It was like the death via zamboni in Deadpool. I reran it anyway, just illustrating a point that stuff happens. Link to comment Share on other sites More sharing options...
[Cl...] Posted October 7, 2019 Share Posted October 7, 2019 I haven't read through all the reply's, so someone might have mentioned this already. If filtering a curve, get the curve length and divide by two for the wave length setting. Link to comment Share on other sites More sharing options...
[Is...] Posted October 8, 2019 Share Posted October 8, 2019 Please sign in to view this quote. Thats a bad idea, filters could hide problems or modify the actual geometry. Maybe my curves are special but normally the most convenient values that I found for wavelength are around 1/10. viewtopic.php?f=13&t=2057&start=10 Link to comment Share on other sites More sharing options...
[Cl...] Posted October 8, 2019 Share Posted October 8, 2019 Interesting. If I remember correctly, I got that from the Zeiss cookbook. Link to comment Share on other sites More sharing options...
[Is...] Posted October 8, 2019 Share Posted October 8, 2019 Please sign in to view this quote. Normally I don't take decisions based on Cookbook (I prefer to test and then agree based on the results), however even in the cookbook says that Sometimes No filter is better. Link to comment Share on other sites More sharing options...
[Cl...] Posted October 8, 2019 Share Posted October 8, 2019 I searched an older forum post and found out where that wavelength setting came from. I was fine tuning a program to pass Gage R&R, and changed a filter wavelength setting. When that feature ran, Calypso prompted me with a message that stated, "Curve length /2 = wavelength". So I naturally assumed (I know, I should never assume) that Calypso was giving me accurate info. Link to comment Share on other sites More sharing options...
[Is...] Posted October 8, 2019 Share Posted October 8, 2019 Please sign in to view this quote. I have the impression that the reason of that message is because mathematically the maximum Wavelength value that is possible to apply is around: Curve length /2 Link to comment Share on other sites More sharing options...
[Ow...] Posted October 8, 2019 Share Posted October 8, 2019 You live by the filter, you might die by the filter. If you live by single points, you’ll eventually die of what it doesn’t tell you. There are best practice guidelines and prescriptions for all kinds of shapes and finishes but, the ultimate rule is to verify everything according to its importance on fit, form and function. If I’m scanning, I’m filtering. When the scanning results are being questioned, I’ll double check with single or space points. When both methods are questioned, I make sure I have another way other than the CMM to verify. Link to comment Share on other sites More sharing options...
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