[Me...] Posted December 27, 2018 Share Posted December 27, 2018 when using the true position characteristic what is the difference between the buttons next to the RFS and MMC LMC, "Tolerates the feature as recorded center line" and "tolerates the feature with reference lengths"? Link to comment Share on other sites More sharing options...
[Aa...] Posted December 28, 2018 Share Posted December 28, 2018 That's all about Projected Tolerance. The first option is with Projected Tolerance turned off. That means the position characteristic is measuring the diametrical position of each of the ends of the cylinder. (The ends are determined by the nominal position and length of the cylinder feature.) If you change the nominal length of the feature, it affects the result. The other option is with Projected Tolerance turned on. That means the axis of the evaluated cylinder is being projected to a distance (or between two distances) that you enter. The concept of Projected Tolerance is in both ASME Y14.5 and ISO 1101. What distances you should enter for the projected tolerance in Calypso is, in my experience, very confusing. Note: that was all pulling from deep recesses of my memory, so take it with a grain of salt. (Since it's coming from me, maybe take the whole shaker...) Link to comment Share on other sites More sharing options...
[Me...] Posted December 28, 2018 Author Share Posted December 28, 2018 hey thanks for the reply. alright if i have not changed anything about the feature size in calypso then i should have it turned off. and if i do say change the depth of the hole (even the diameter?) i should turn it on, then from my understanding it should use the info that i have imported to calculate the ends of the hole? also what if the probe that i am using cannot reach the bottom, .230" deep hole using a .5mm styli which can only go so about .075" down inside. Should i change the depth of the hole to match what the styli can reach and then turn on the option? Link to comment Share on other sites More sharing options...
[Br...] Posted December 28, 2018 Share Posted December 28, 2018 "Tolerates the feature as recorded center line" will look at the derived median line of a cylinder and compare that to the tolerance zone, whereas "tolerates the feature with reference lengths" will evaluate an axis. If you don't do anything "tolerates the feature with reference lengths", will just look at the length of the feature. If you double click it, you can project it out to a specific distance. Link to comment Share on other sites More sharing options...
[Aa...] Posted December 28, 2018 Share Posted December 28, 2018 Not to argue, Brett, but I don't believe Calypso will evaluate a derived median line of a cylinder, no matter what settings you select in the position characteristic. But then, it sounds like the OP is actually looking at a feature of a newer version of Calypso than I've ever dealt with. Link to comment Share on other sites More sharing options...
[Me...] Posted December 28, 2018 Author Share Posted December 28, 2018 Please sign in to view this quote. if you cant tell im new at using calypso and also new at the Quality Control department, (been a cnc programmer and operator for 10 yrs) all of are parts we do are for "function fit" and it sounds like i should just have it turned off to achieve the "function fit" am i wrong? Link to comment Share on other sites More sharing options...
[Me...] Posted December 28, 2018 Author Share Posted December 28, 2018 Please sign in to view this quote. im using 2017 about to upgrade to 2018. Link to comment Share on other sites More sharing options...
[Br...] Posted December 28, 2018 Share Posted December 28, 2018 Please sign in to view this quote. Read page 5-40 and 5-41 of the Calypso manual. That sounds to me like a derived median line. But for position you don't want this selected anyway. What you want is the axis of the cylinder created by the actual mating envelope. So don't worry about those buttons unless you have a projected tolerance zone. Set the fitting algorithm for Outer Tangential and input your tolerance. Link to comment Share on other sites More sharing options...
[Me...] Posted December 28, 2018 Author Share Posted December 28, 2018 in layman's terms i should then have the "tolerates the feature as recorded center line" button pressed? and just input my tolerances as required. Link to comment Share on other sites More sharing options...
[Br...] Posted December 28, 2018 Share Posted December 28, 2018 Please sign in to view this quote. No you do not want that pressed. Not for Position. You want the circle "P" button pressed. This should automatically be the default, and if you don't have a projected tolerance zone, you don't have to do anything, as it will evaluate the length of the feature by default. Link to comment Share on other sites More sharing options...
[Aa...] Posted January 2, 2019 Share Posted January 2, 2019 Please sign in to view this quote. 🤣 My manual's so old, the pages aren't even numbered by chapter like that. And chapter 5 is Printout Design and Backup. Yes, that sounds like a Derived Median Line. I forget, does anyone know whether the OP is dealing with ISO or ASME? Because if it's ISO, then position isn't all about controlling the mating envelope. It's either about controlling the derived feature or controlling the integral feature, depending on how it's drawn. Interestingly enough, integral feature is not even close to the same as controlling the axis endpoints, which used to be Calypso's only option for evaluation of position characteristics. It's actually much more similar to a dynamic profile tolerance (a concept working its way into the ASME standard, which is like an unequally disposed profile tolerance where the second number in the FCF is allowed to "float" to optimize results). Link to comment Share on other sites More sharing options...
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