[Lu...] Posted January 14 Share Posted January 14 Hello, I decided to measure a few ring gages with our Accura II, and I am seeing a result of .0002avg over nominal with most of our probes (including the master probe). I am measuring as a single hit circle, scanned circle, and a single hit cylinder. I am reporting as an average, inner and outer tangential, and 2-point diameter. Our 3MMX75MM probe generated the worst result (pushing .0004avg over nominal). The best result I found was measuring a 4" ring gage with the master probe. The average diameter for that was .00008 above nominal, but the inner and outer tangential had a .0002 spread. I am using Class X and class XX calibrated ring gages. Any thoughts or suggestions? Is this normal? our Accura was just calibrated by Zeiss a month ago. Thanks Link to comment Share on other sites More sharing options...
[DW...] Posted January 14 Share Posted January 14 Please sign in to view this quote. Go to your reference sphere management.. Does the highlighted value in your software match the value of your reference sphere certificate? Link to comment Share on other sites More sharing options...
[Lu...] Posted January 14 Author Share Posted January 14 Sorry, I can't find certs...I found a cert for one of our 3 spheres but it is pretty outdated cert and it is for our smallest sphere (8mm sphere for calibrating 1mm probes). The radius is off by 0.00044196mm and the roundness is off by 0.058 microns. Perhaps our other calibration spheres are off even more. I guess I have no way of knowing if this is what is causing the issue without sending the spheres out for calibration? Link to comment Share on other sites More sharing options...
[Lu...] Posted January 14 Author Share Posted January 14 I do have serial numbers on the spheres...maybe Zeiss can look up the certs for me? Link to comment Share on other sites More sharing options...
[DW...] Posted January 15 Share Posted January 15 (edited) Please sign in to view this quote. Yes, without the certificates you have a big unknown value in your sphere radius. The number supplied by the Zeiss certificate would be input by you as the operator when setting up your spheres to allow the software to do its calculations. It might be worth calling the Zeiss 800 number or reaching out to Please sign in to view this username. . The other option would be to have it calibrated by a reputable lab that you trust. Keep in mind, the theory of the value being off in your sphere management is just a beginning point when troubleshooting your initial comments. Edited January 15 Link to comment Share on other sites More sharing options...
[Lu...] Posted January 17 Author Share Posted January 17 Thank you. Turns out, the issue was mainly caused by using double-sided tape. The ring gage was moving. We may still have a small issue (<.0001) related to the calibration sphere - I am going to try to find those certs. Link to comment Share on other sites More sharing options...
[Je...] Posted January 18 Share Posted January 18 Please sign in to view this quote. Lukas, great job on figuring out the root cause of the problem. That's a vital skill in metrology. I know I've run into similar situations before of discovering that the main contributor to measurement error was fixturing or the movement of the workpiece. We've all been there. Link to comment Share on other sites More sharing options...
[Mi...] Posted January 20 Share Posted January 20 This is a great argument for good fixturing and Looped Base Alignments, especially if you have PCM so you can make the program stop if the Alignment value never resolves down to your limit. Convincing a programmer to do it when they are convinced they don't need to is hard, but the results are undeniable. Link to comment Share on other sites More sharing options...
[DW...] Posted January 21 Share Posted January 21 Please sign in to view this quote. Check out Rayco's website. Sounds like you need a threaded hole base plate, stands, and hold downs. Link to comment Share on other sites More sharing options...
[Da...] Posted January 22 Share Posted January 22 Double-sided tape? Are you using the paper-backed type? Yeah, I'd say your numbers are better than I would've expected. FWIW, Scotch does make a double-sided tape that has a thin plastic backing, which induces much less error. At my workplace, we use a non-backing PSA tape in manufacturing, 3M#9485. This stuff has NO backing, and you have to cut the protective wax-paper to size, stick the adhesive side down, then prise the wax-paper strip off the adhesive with an Ex-acto knife; if you touch it, it will stick to your fingers! Use this stuff sparingly, because it holds like super-glue! Removing it is best by rolling the adhesive off with your fingertips (on either the part or the plate), because if you use alcohol to remove it you will make a mess of both! Link to comment Share on other sites More sharing options...
[Je...] Posted January 22 Share Posted January 22 Use a mechanical hold down, not an adhesive. Adhesives are shown to ADD to flex rather than prevent it vs direct plate>base contact. If you cant secure the base of the ref stand or ring to the plate using a mechanical hold down (bolt/clamp) then leaving it on the plate and adding "hot glue" to the edges is best but only if absolutely necessary. Do not place anything between the granite and gage artifact. If your measurements arent giving you the results you expect, ALWAYS run a GRR to isolate where the problem is before you communicate doubt in the equipment. Yes a GRR takes time but its usually significantly less than the random troubleshooting that ensues instead and eats up production time, and more importantly, production dept confidence in the quality dept reporting. Link to comment Share on other sites More sharing options...
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