[To...] Posted October 25, 2019 Share Posted October 25, 2019 If you were measuring a 6.5 ±0.0015 mm diameter, would you trust just the probe qualification, or would you use a gage correction? Prismo Ultra. Link to comment https://qualityforum.zeiss.com/topic/17332-measuring-tight-diameters/ Share on other sites More sharing options...
[Da...] Posted October 25, 2019 Share Posted October 25, 2019 I would trust the probe. If you're going to use a gage, make sure you use the Actual calibration numbers for size. Remember the calibration house uses a 2 point diameter, so .... it may be slightly different. Temp probes would help too. Link to comment https://qualityforum.zeiss.com/topic/17332-measuring-tight-diameters/#findComment-97102 Share on other sites More sharing options...
[Ch...] Posted October 25, 2019 Share Posted October 25, 2019 I have a diameter about that size with a +- .002mm and I trust the qualification. Link to comment https://qualityforum.zeiss.com/topic/17332-measuring-tight-diameters/#findComment-97104 Share on other sites More sharing options...
[Me...] Posted October 25, 2019 Share Posted October 25, 2019 I would absolutely use gage correction using a ring that's as close to 6.5 as possible. Link to comment https://qualityforum.zeiss.com/topic/17332-measuring-tight-diameters/#findComment-97106 Share on other sites More sharing options...
[Ri...] Posted October 26, 2019 Share Posted October 26, 2019 Trust the qualification. Go slow, high number of points, probably even suggest using a 15UPR filter. It's a CMM, not a comparative gage. Link to comment https://qualityforum.zeiss.com/topic/17332-measuring-tight-diameters/#findComment-97108 Share on other sites More sharing options...
[Me...] Posted October 28, 2019 Share Posted October 28, 2019 So if this isn't a good example of when to use Gage Correction then what is? Link to comment https://qualityforum.zeiss.com/topic/17332-measuring-tight-diameters/#findComment-97110 Share on other sites More sharing options...
[Ch...] Posted October 28, 2019 Share Posted October 28, 2019 I agree that this is exactly the type of situation that gage correction was designed for; However, in this situation I don't think you're gaining anything, especially considering the equipment used, with using gage correction over normal qualification. Link to comment https://qualityforum.zeiss.com/topic/17332-measuring-tight-diameters/#findComment-97112 Share on other sites More sharing options...
[Me...] Posted October 28, 2019 Share Posted October 28, 2019 Just curious Tom, what is the accuracy of that Prismo? Link to comment https://qualityforum.zeiss.com/topic/17332-measuring-tight-diameters/#findComment-97114 Share on other sites More sharing options...
[Ke...] Posted October 28, 2019 Share Posted October 28, 2019 I usually start with measuring the master that I'm considering using for the correction. If the results are "close enough" to the stated calibration value, then I would probably not use the correction. Link to comment https://qualityforum.zeiss.com/topic/17332-measuring-tight-diameters/#findComment-97116 Share on other sites More sharing options...
[To...] Posted October 28, 2019 Author Share Posted October 28, 2019 Please sign in to view this quote. 0.5um + L/500 Link to comment https://qualityforum.zeiss.com/topic/17332-measuring-tight-diameters/#findComment-97118 Share on other sites More sharing options...
[To...] Posted October 28, 2019 Author Share Posted October 28, 2019 Please sign in to view this quote. I don't think I can rely on the ring gage because it is class x and has 0.001um mfg tolerance. I'm already seeing a 0.3 deviation from the stated size. I didn't know the mfg tolerance when I posted the original question. Link to comment https://qualityforum.zeiss.com/topic/17332-measuring-tight-diameters/#findComment-97120 Share on other sites More sharing options...
[Ke...] Posted October 28, 2019 Share Posted October 28, 2019 Please sign in to view this quote. The class of the gage does not matter, if you have the actuals from the ring's calibration report; then, then only outlier would be the stated uncertainty of the calibration ... if it was only certified as "pass/fail", then you are correct. Link to comment https://qualityforum.zeiss.com/topic/17332-measuring-tight-diameters/#findComment-97122 Share on other sites More sharing options...
[Ke...] Posted October 28, 2019 Share Posted October 28, 2019 Follow-up: ...Of course, the roundness of the ring could also be a factor, that you can verify. Link to comment https://qualityforum.zeiss.com/topic/17332-measuring-tight-diameters/#findComment-97124 Share on other sites More sharing options...
[Da...] Posted October 29, 2019 Share Posted October 29, 2019 Look at your calibration charts for the machine, you'll see that the machine is MORE than capable of checking to that tolerance. The remaining variables are , work holding , Temperature , Filtering, Outlier elimination, Dirt, and gaging pressure. Make sure they're all good and it should be a piece of cake! Link to comment https://qualityforum.zeiss.com/topic/17332-measuring-tight-diameters/#findComment-97126 Share on other sites More sharing options...
[Me...] Posted October 29, 2019 Share Posted October 29, 2019 So Tom gave us the accuracy of his Prismo which is 5um/.0000196in... Am I correct in saying the repeat-ability is the standard factor by 10? I use a Contura 2014 RDS XXT, and I try to keep my calibration at under .0002mm and when I first started this job we had some parts that were + / - .00005in...From what I've been able to gather from our Zeiss Tech is that the *repeat-ability* is somewhere around .00008in, which tells me our machine is not accurate in millionths. Sorry to go on a tangent topic here but I was just wondering what everyone else thinks on this. Link to comment https://qualityforum.zeiss.com/topic/17332-measuring-tight-diameters/#findComment-97128 Share on other sites More sharing options...
[Ma...] Posted October 30, 2019 Share Posted October 30, 2019 🤣 🙄 I have a similar measuring task + a form of 0.01mm I do before the start of a comparison with the probe used on the reference sphere and then have the difference as a formula in the result. Link to comment https://qualityforum.zeiss.com/topic/17332-measuring-tight-diameters/#findComment-97130 Share on other sites More sharing options...
[To...] Posted October 30, 2019 Author Share Posted October 30, 2019 Please sign in to view this quote. Sorry, how does 0.5um + L/500 equate to 5um /.0000196? What do you mean by "repeatability is the standard factor by 10"? You hear statements like "accurate to within .xxxx and repeatable to within .xxxx when dealing with CNC machine tools but I'm not aware of this practice as it pertains to CMM's. I've always believed my Contura machines were not good to the millionths either. Link to comment https://qualityforum.zeiss.com/topic/17332-measuring-tight-diameters/#findComment-97132 Share on other sites More sharing options...
[Ri...] Posted October 30, 2019 Share Posted October 30, 2019 The golden rule is to use no more than 10% of your tolerance with your gage's accuracy. Link to comment https://qualityforum.zeiss.com/topic/17332-measuring-tight-diameters/#findComment-97134 Share on other sites More sharing options...
[To...] Posted October 30, 2019 Author Share Posted October 30, 2019 Please sign in to view this quote. I was wondering if that was what he was referring to. However, when you get into tolerances where 10 to 1 can't be attained, I've read somewhere that a 5 to 1 was industry accepted. Link to comment https://qualityforum.zeiss.com/topic/17332-measuring-tight-diameters/#findComment-97136 Share on other sites More sharing options...
[Me...] Posted October 31, 2019 Share Posted October 31, 2019 My calculation for 5um might not be correct lol. What I do know is my MasterProbe calibrates to .0002mm or better and I go by the factor of 10 or 10% of the tolerance because that's how I was trained. I also asked my Zeiss trainers about this and it was confirmed as well by them. They told me my *repeat-ability* or *accuracy* is .00008in. The .00008in is a factor of 10 from the under or around .0002mm MasterProbe calibration. Link to comment https://qualityforum.zeiss.com/topic/17332-measuring-tight-diameters/#findComment-97138 Share on other sites More sharing options...
[Da...] Posted November 5, 2019 Share Posted November 5, 2019 So Tom, how did this work out ??? Link to comment https://qualityforum.zeiss.com/topic/17332-measuring-tight-diameters/#findComment-97140 Share on other sites More sharing options...
[To...] Posted November 5, 2019 Author Share Posted November 5, 2019 Since I don't have certification on the gage, I am going to trust the CMM. Early on, we were getting good results but have since run into manufacturing issues that are distorting the part and are trying to work through these hurdles. Link to comment https://qualityforum.zeiss.com/topic/17332-measuring-tight-diameters/#findComment-97142 Share on other sites More sharing options...
[Da...] Posted November 5, 2019 Share Posted November 5, 2019 Do you feel pretty confident in your readings ? Have you checked the same part a few times ? How is the repeat?? Link to comment https://qualityforum.zeiss.com/topic/17332-measuring-tight-diameters/#findComment-97144 Share on other sites More sharing options...
[To...] Posted November 5, 2019 Author Share Posted November 5, 2019 only showing 4 places, I got a range of .0001. So that could be anywhere from .00005 to .000140 Link to comment https://qualityforum.zeiss.com/topic/17332-measuring-tight-diameters/#findComment-97146 Share on other sites More sharing options...
[Da...] Posted November 6, 2019 Share Posted November 6, 2019 Awe...punch it up to 6 places, lets see what it can do ! 😃 Link to comment https://qualityforum.zeiss.com/topic/17332-measuring-tight-diameters/#findComment-97148 Share on other sites More sharing options...
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