[Cl...] Posted July 14, 2020 Share Posted July 14, 2020 Here's something related to the last post about "Scan vs single point". I'm reporting a .006 surface profile of an ellipse back to -A- & -B-. Datum -A- is the OD cylinder and -B- is the flat surface at X zero. If I scan a 2d curve and recall the points into the FFS, I get .011. If I use 4 single points and recall those into a FFS, I get .004. I just don't understand the huge difference in methods? Is the difference got something to do with the FFS itself, or just the fact that I'm covering much more surface area? Those tight (purple) corners are minus material. I can't imagine they would make that much difference? Link to comment Share on other sites More sharing options...
[Ro...] Posted July 14, 2020 Share Posted July 14, 2020 Turn your presentation to Cylinders with a small diameter so you will be able to see your high and low spots more easily.fgjhkfgdjhkfgdjhkfgd.JPG Link to comment Share on other sites More sharing options...
[Cl...] Posted July 14, 2020 Author Share Posted July 14, 2020 Ah, thank you! Link to comment Share on other sites More sharing options...
[To...] Posted July 14, 2020 Share Posted July 14, 2020 From a manufacturing perspective(if it is a milled pocket)i understand the huge difference. Those 4 four points you have taken would be the ones that should be easiest to get to fit and measure with handheld equipment like a caliper. But have you tried doing the same scan with a smaller stylus? Or doing a single points in the area which is out of tolerance? How about filtering and outlier? Link to comment Share on other sites More sharing options...
[Cl...] Posted July 14, 2020 Author Share Posted July 14, 2020 I'm using a 0.8mm stylus. Afraid to go any smaller, could shank. Can't filter a FFS. Functionally it should be fine, a tube gets welded over top of the ellipse. I still have a type 1 & a first article to do. The other problem (I'm told) is the tool path is such that he can't modify the shape enough to bring those corners in. I just don't trust a FFS. Link to comment Share on other sites More sharing options...
[Ro...] Posted July 14, 2020 Share Posted July 14, 2020 so lets see the new scan with Cylinders. Link to comment Share on other sites More sharing options...
[Cl...] Posted July 14, 2020 Author Share Posted July 14, 2020 That got bumped for a fixture. Link to comment Share on other sites More sharing options...
[Cl...] Posted July 14, 2020 Author Share Posted July 14, 2020 They are struggling with this profile at the lathe. Cylinders show the minus material condition much clearer. Link to comment Share on other sites More sharing options...
[To...] Posted July 14, 2020 Share Posted July 14, 2020 Please sign in to view this quote. This looks very much like the load or level of vibrations is not the same all around the profile. Have seen similar before. This what I find the best about CMMs. The possibility to evaluate what goes wrong by visualizing the result. Link to comment Share on other sites More sharing options...
[Cl...] Posted July 16, 2020 Author Share Posted July 16, 2020 The operator was able to adjust the tool path. Getting good parts now. Link to comment Share on other sites More sharing options...
[Ke...] Posted July 16, 2020 Share Posted July 16, 2020 Please sign in to view this quote. I love a good success story! Link to comment Share on other sites More sharing options...
[To...] Posted July 17, 2020 Share Posted July 17, 2020 Please sign in to view this quote. Is that a picture of the final profile? Link to comment Share on other sites More sharing options...
[Cl...] Posted July 17, 2020 Author Share Posted July 17, 2020 Yes, that part was actually boarder-line good. This post initially started with a question about the reliability of free form surface. Then it morphed into how to get a better graphic display to help the operator make adjustments. Link to comment Share on other sites More sharing options...
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