[Za...] Posted August 24, 2021 Share Posted August 24, 2021 Hello all, I'm having some issues with a TP callout on this print: My diameter for -A- is almost nominal, so I should have some bonus tolerance, but I'm not getting any bonus tolerance on my results. Does anybody have any explanation or suggestions for me? I'm about 2 years into running a CMM, so I'm still quite the novice, but I appreciate any help that I can get! Thanks, Zach Link to comment https://qualityforum.zeiss.com/topic/12098-true-position-mmc-issues/ Share on other sites More sharing options...
[Ji...] Posted August 25, 2021 Share Posted August 25, 2021 Hello, I think you need check if the diameter for datum B is out of tolerance. Link to comment https://qualityforum.zeiss.com/topic/12098-true-position-mmc-issues/#findComment-60432 Share on other sites More sharing options...
[Se...] Posted August 25, 2021 Share Posted August 25, 2021 Please sign in to view this quote. It has nothing to do with datum B Your setting seems to be OK. When you set (M) at a datum, Calypso will first use your bonus to make a best fit: it will try to "slide" your hole in the best possible position. That´s why you will see no bonus on the tolerance. But your actual value will get better. Only the remaining bonus after the best fit will appear on top of the tolerance. If you want to see what´s happening in the background, you can check the Y- and Z-cooridinates of the feature "4.1 mm Dia._DatumC" and compare them with these in the TP or you can try to deactivate the MMC. In this case, the actual value of the TP should get worse. Link to comment https://qualityforum.zeiss.com/topic/12098-true-position-mmc-issues/#findComment-60434 Share on other sites More sharing options...
[To...] Posted August 25, 2021 Share Posted August 25, 2021 FYI Not sure if it applies with your application but it is my understanding that if the position passes without needing the "slide" or "datum shift", it will not use it. The "slide" or "datum shift" will only come into play when needed to help make a part pass. Link to comment https://qualityforum.zeiss.com/topic/12098-true-position-mmc-issues/#findComment-60436 Share on other sites More sharing options...
[Me...] Posted August 25, 2021 Share Posted August 25, 2021 The sooner Zeiss changes the name MMC to MMB for Datums the better. The standard that renamed it will probably be 50 years old by the time Zeiss makes the change, if ever. Link to comment https://qualityforum.zeiss.com/topic/12098-true-position-mmc-issues/#findComment-60438 Share on other sites More sharing options...
[An...] Posted August 28, 2021 Share Posted August 28, 2021 ___ Link to comment https://qualityforum.zeiss.com/topic/12098-true-position-mmc-issues/#findComment-60440 Share on other sites More sharing options...
[An...] Posted August 30, 2021 Share Posted August 30, 2021 ___ Link to comment https://qualityforum.zeiss.com/topic/12098-true-position-mmc-issues/#findComment-60442 Share on other sites More sharing options...
[Me...] Posted August 30, 2021 Share Posted August 30, 2021 Please sign in to view this quote. You're right and that's a world wide issue in the Manufacturing business. GD&T is hand in hand with our profession. Link to comment https://qualityforum.zeiss.com/topic/12098-true-position-mmc-issues/#findComment-60444 Share on other sites More sharing options...
[Za...] Posted August 30, 2021 Author Share Posted August 30, 2021 Please sign in to view this quote. That's what I guessed was happening, because I noticed that the result would change, but the MMC tolerance would still not show up. Thanks for the explanation. Link to comment https://qualityforum.zeiss.com/topic/12098-true-position-mmc-issues/#findComment-60446 Share on other sites More sharing options...
[Za...] Posted August 30, 2021 Author Share Posted August 30, 2021 Please sign in to view this quote. The callout is failing, but it is trying to add that bonus tolerance, it's just doing it in the background. My result gets worse if I take off the MMC. The thing I don't like is that Calypso won't tell me what that MMC value is like it usually does. Link to comment https://qualityforum.zeiss.com/topic/12098-true-position-mmc-issues/#findComment-60448 Share on other sites More sharing options...
[Ro...] Posted August 30, 2021 Share Posted August 30, 2021 Construct a circle from your dat A cylinder & top plane to create a Dat A Circle. I had a meeting with a very high level Zeiss programmer, in short he showed me not to use cylinders for location. If your primary datum was a circle you might get the bonus you are looking for. Link to comment https://qualityforum.zeiss.com/topic/12098-true-position-mmc-issues/#findComment-60450 Share on other sites More sharing options...
[Ma...] Posted August 31, 2021 Share Posted August 31, 2021 Does the actuals on the TP change when you change RFS to MMB on datum A? Feature MMC bonus adds to the tolerance but Datum MMB/Datum Shift deducts from the actual deviation if calypso allows it. Link to comment https://qualityforum.zeiss.com/topic/12098-true-position-mmc-issues/#findComment-60452 Share on other sites More sharing options...
[Aa...] Posted August 31, 2021 Share Posted August 31, 2021 Please sign in to view this quote. If I may ask, what is datum feature B, and what geometric tolerances are applied to it? Without knowing that, we have no way of knowing whether it violates its MMB for all potential DRFs. Also, it should be noted that MMB should never contribute "bonus tolerance" Link to comment https://qualityforum.zeiss.com/topic/12098-true-position-mmc-issues/#findComment-60454 Share on other sites More sharing options...
[Aa...] Posted August 31, 2021 Share Posted August 31, 2021 Please sign in to view this quote. Couldn't agree more. Of course, changing the name would imply that Calypso handles MMBs correctly according to the aforementioned standard. I suspect that would be a deception. Link to comment https://qualityforum.zeiss.com/topic/12098-true-position-mmc-issues/#findComment-60456 Share on other sites More sharing options...
[An...] Posted August 31, 2021 Share Posted August 31, 2021 ___ Link to comment https://qualityforum.zeiss.com/topic/12098-true-position-mmc-issues/#findComment-60458 Share on other sites More sharing options...
[An...] Posted August 31, 2021 Share Posted August 31, 2021 ___ Link to comment https://qualityforum.zeiss.com/topic/12098-true-position-mmc-issues/#findComment-60460 Share on other sites More sharing options...
[An...] Posted September 1, 2021 Share Posted September 1, 2021 ___ Link to comment https://qualityforum.zeiss.com/topic/12098-true-position-mmc-issues/#findComment-60462 Share on other sites More sharing options...
[Ma...] Posted September 1, 2021 Share Posted September 1, 2021 Please sign in to view this quote. Hi, I wonder if you are done with this thread. You can use default printout - open it, change value in TP tolerance ( just to update def.pr. ), then you will see info for TP. Above this is "Bestfit_" for TP - there you will see how much bonus you got. Remember - you can get max bonus only half of tolerance for datum A You can even use math - just compare distance and nominal distance of elements and add from datum A half of deviation from minimal and actual diameter. Then double this number ( because of TP diam. tolerance ) Link to comment https://qualityforum.zeiss.com/topic/12098-true-position-mmc-issues/#findComment-60464 Share on other sites More sharing options...
[Aa...] Posted September 1, 2021 Share Posted September 1, 2021 Please sign in to view this quote. Nice workaround, but it is inappropriate here. There should be no bonus tolerance for MMB datum feature references. Most people expect there to be, the same way there is for MMC tolerances. This is the reason for the complaint that Calypso should switch to using MMB for datums. Instead, datum shift is allowed, and there is no good easy way to add that back in after results have already been calculated. Link to comment https://qualityforum.zeiss.com/topic/12098-true-position-mmc-issues/#findComment-60466 Share on other sites More sharing options...
[Ma...] Posted September 1, 2021 Share Posted September 1, 2021 Please sign in to view this quote. I don't know if we are understanding each other, but "M" in circle for datum allows to move datum to help pass. No bonus tolerance is used in TP - so no info about it in custom or PiWeb printout - just help in bestfitting. Perhaps i should read my post carefully and add real calculation to avoid wrong text formula. Link to comment https://qualityforum.zeiss.com/topic/12098-true-position-mmc-issues/#findComment-60468 Share on other sites More sharing options...
[Er...] Posted September 2, 2021 Share Posted September 2, 2021 My bosses want to see the MMC bonus no matter what. So we have to manually enter a formula for every true position with MMC. Seems like it would be simple for Calypso to show it. Link to comment https://qualityforum.zeiss.com/topic/12098-true-position-mmc-issues/#findComment-60470 Share on other sites More sharing options...
[Ro...] Posted September 2, 2021 Share Posted September 2, 2021 As has already been stated, there is no bonus to report on a datum. MMC and MMB are 2 different things. Calypso is calling MMB on datums as MMC, which is wrong. MMC/LMC can give you BONUS on the the actual feature tolerance zone. MMB/LMB can give you MOBILITY of the datum feature. Datum mobility means you may be getting some rotation, some translation, or a combination of the 2, based on the datum condition. How are you going to report that with a formula? You'd need to report multiple factors, similar to what a best fit plot does. What formula are you using, if I may ask? Link to comment https://qualityforum.zeiss.com/topic/12098-true-position-mmc-issues/#findComment-60472 Share on other sites More sharing options...
[Za...] Posted September 2, 2021 Author Share Posted September 2, 2021 Thank you guys so much for the explanation. I was experimenting with taking the MMC off of the secondary datums and comparing the results, so I see that it was making my result closer to being in tolerance than if the MMC box wasn't clicked on, but I did not know the reasoning for it. This makes perfect sense now, so I'm on to my next issue soon 🤣 Link to comment https://qualityforum.zeiss.com/topic/12098-true-position-mmc-issues/#findComment-60474 Share on other sites More sharing options...
[An...] Posted September 3, 2021 Share Posted September 3, 2021 ___ Link to comment https://qualityforum.zeiss.com/topic/12098-true-position-mmc-issues/#findComment-60476 Share on other sites More sharing options...
[Me...] Posted September 3, 2021 Share Posted September 3, 2021 Please sign in to view this quote. Robert, like most of us that are trained under ASME Y14.5 is 100% correct. MMC is the Condition of a feature, MMB is the Boundary of a Datum Feature and there can be no additional tolerance added from MMB, only a translation and or rotational shift. If you're print is based on the ASME standard, there is no other opinion on the matter to put it nicely. See below from ASME Y14.5M-2009 Link to comment https://qualityforum.zeiss.com/topic/12098-true-position-mmc-issues/#findComment-60478 Share on other sites More sharing options...
Recommended Posts
Please sign in to comment
You will be able to leave a comment after signing in