[Ün...] Posted March 31, 2021 Share Posted March 31, 2021 Hello , There is a new measurement request from our customer. I am asked to check axial runout according to A-B-C references. But calypso also does not allow me to select cylinders in two references for runout control. Whatever I create for the A-B reference is appropriate What would your suggestion be? Ekran Alıntısı.PNG Link to comment Share on other sites More sharing options...
[Me...] Posted March 31, 2021 Share Posted March 31, 2021 Go into your A-B stepped cylinder in the runout characteristic & constrain it to Datum C. I believe that would be acceptable per the print. Link to comment Share on other sites More sharing options...
[Ri...] Posted March 31, 2021 Share Posted March 31, 2021 Please sign in to view this quote. I wouldn't do that. A-B is the primary, so it is controlling the vectors. C serves no function here other than a stop, it has no rotational degree of freedom control. Link to comment Share on other sites More sharing options...
[Ri...] Posted March 31, 2021 Share Posted March 31, 2021 The reason for the difference between the two is that in the first, the Circle cannot control the spatial rotation, so it is only controlling the translational directions, since the Circle cannot control the vector, it is then using the Plane to control the vector. In this case you are essentially measuring Parallelism between two Planes. Link to comment Share on other sites More sharing options...
[Da...] Posted March 31, 2021 Share Posted March 31, 2021 Datum C can’t constrain A-B, because a secondary datum can’t constrain the degrees of freedom that are already constrained by the primary datum. Datum C doesn’t do anything for this call-out at all. The second solution with the step cylinder looks correct to me. Link to comment Share on other sites More sharing options...
[Ke...] Posted March 31, 2021 Share Posted March 31, 2021 Next conversation topic: Axial vs Radial Runout 😃 Link to comment Share on other sites More sharing options...
[SH...] Posted March 31, 2021 Share Posted March 31, 2021 I think perpedicular distance between stepped cylinder AB and plane c will be the better option. Link to comment Share on other sites More sharing options...
[Te...] Posted March 31, 2021 Share Posted March 31, 2021 I would just create a 3d Line from A and B (using recall) for A-B and the runout would be the 3d line (A-B) and C per the print. The surface needs to be parallel to C and perpendicular to A-B If you are using a version of Calypso older than 2020 where you cannot use 2 datum features for runout, construct a perpendicular using the the 3d Line (A-B) and the Plane C and report the runout to the perpendicular. Link to comment Share on other sites More sharing options...
[Da...] Posted March 31, 2021 Share Posted March 31, 2021 Please sign in to view this quote. I don't understand what you mean by "the 3d line (A-B) and C". How are you going to get those datums together? According to the standards, a common datum A-B doesn't work by using a line constructed of center points. And the datum for a runout is always an axis, nothing more. You could use an auxiliary datum made of a plane and a line perpendicular to that plane (resulting in a new line perpendicular to the plane, having its origin in the intersection), but in this case an auxiliary datum is not needed, because A-B is a fully qualified datum for a runout on its own. Please sign in to view this quote. The datum describes the orientation of the tolerance zone. Is the tolerance zone parallel to C or is it perpendicular to A-B? It can't be both. Please sign in to view this quote. Again, anything you construct can only be perpendicular or parallel to either A-B OR C, never both. I agree, that in the versions before Calypso offered the possibility to construct a stepped cylinder, I would have approached this problem via a 3d-line as well, but I've run some tests on this and I've seen the significant differences of both methods, and found the step cylinder results being much more plausible than the 3d-line method. Personally, if possible, I would contact the engineer, make him or her aware of this mistake, ask what they really desired, make my suggestion, have the drawing changed and go on with my life. I have seen too many bad call-outs, and more often than not the engineer was not aware that their callout was not making sense. Link to comment Share on other sites More sharing options...
[Jo...] Posted March 31, 2021 Share Posted March 31, 2021 since my opinion is free, here it goes. The engineer could have wanted the runout of each surface to A-B. The engineer could have wanted the runout of each surface to each other (C) The engineer could have wanted the functional width of two surfaces (symmetry plane) as combined to A-B The engineer may get the worst case of all all the above methods because IDK what he needs. I don't know the function of the part. Link to comment Share on other sites More sharing options...
[An...] Posted March 31, 2021 Share Posted March 31, 2021 Please sign in to view this quote. See attached.Contribution_31_03_2021_1.pdf Link to comment Share on other sites More sharing options...
[Ri...] Posted March 31, 2021 Share Posted March 31, 2021 Please sign in to view this quote. I'm going to need a lot more explanation there. The axis is defined by A-B. I don't see how the form error of Datum C would have any impact on the result. If C is impacting results, you are no longer measuring Runout, but instead a form of Profile where you are also controlling the nominal distance of C to your feature . Link to comment Share on other sites More sharing options...
[Da...] Posted March 31, 2021 Share Posted March 31, 2021 Please sign in to view this quote. A datum system both in ASME and in ISO standards is build upon a datum simulator (although in ISO it isn't called that, but the concept is the same), which is totally independent from form errors. Of course, anyone can choose not to follow a standard, so feel free to do whatever you want, but the standards are meant to represent functional reality. Link to comment Share on other sites More sharing options...
[Te...] Posted March 31, 2021 Share Posted March 31, 2021 The 3d Line created from A and B would be the axis of both Cylinder A and Cylinder B (A-B), an axis created from datum A and datum B. I agree that the Datum C in the callout is kind of useless I don't understand why it is there because A-B seem it would be very stable. You would think that if Datum C was that import it would be a runout to A-B and a tighter Parallel callout to C If A and B are not very large datum C can help stabilize the data by forcing the A-B line perpendicular to C Link to comment Share on other sites More sharing options...
[An...] Posted April 1, 2021 Share Posted April 1, 2021 Please sign in to view this quote. Beyond the standards designs also represent functional reality. It's up to the designer to declare this per drawing. Creating so-called inhouse standards is a valid instrument to do so. See attached.Contribution_01_04_2021_1.pdf Link to comment Share on other sites More sharing options...
[Da...] Posted April 1, 2021 Share Posted April 1, 2021 Please sign in to view this quote. You’re absolutely right, it is your own decision to override any standard by your very own solution, but you need to declare it on your drawing. Still, you presented your solution as part of a general answer to the OPs‘ problem. I might have missed that we‘re discussing in-house variations of widely accepted standards. Besides both ASME and ISO provide means to modify the datum system to your liking, but using an additional datum and then make people guess is not one of them. The recent standards are toolboxes providing so much more functionality than older editions to cover almost every aspect a designer can think about, but using those tools shouldn’t take a master in „interpreting“ what the designers‘ intentions were. And this is such a case. This call-out is an oversight at best, but it raises some doubts of the engineers constructing abilities. Doesn’t help anyone understanding the designers‘ intentions when you suddenly need to outsource your part a thousand kilometers away, either. Link to comment Share on other sites More sharing options...
[An...] Posted April 1, 2021 Share Posted April 1, 2021 Please sign in to view this quote. Totally agreed! There has to be a very good communication between supplier customer and poor CALYPSO user. Link to comment Share on other sites More sharing options...
[An...] Posted April 2, 2021 Share Posted April 2, 2021 Deleted. Link to comment Share on other sites More sharing options...
[An...] Posted April 6, 2021 Share Posted April 6, 2021 Please sign in to view this quote. See attached.Contribution_06_04_2021_1.pdf Link to comment Share on other sites More sharing options...
[Da...] Posted April 6, 2021 Share Posted April 6, 2021 Isn't a DATUM a single point or axis from which to measure ? By putting the two imperfect cylinder in Vee blocks aren't you getting a SINGLE axis derived from the averages of both cylinders imperfections ? So, why would you have a VARIABLE C Datum as shown ? Link to comment Share on other sites More sharing options...
[SH...] Posted April 6, 2021 Share Posted April 6, 2021 Please sign in to view this quote. Which version , you are using. I have only one datum for runout. Runout is asked for midplane or just one side??. Link to comment Share on other sites More sharing options...
[Ri...] Posted April 6, 2021 Share Posted April 6, 2021 Please sign in to view this quote. Andreas, I appreciate the work that you put into this. Having said that, there is absolutely still no functional impact on the runout with Datum C. The indicator has allowable movement. The point of the runout measurement (axially) is to ensure that the surface is perpendicular to Datum A-B. If you were to force it to Datum C, you would now be ensuring that the surface is parallel to Datum C. I have seen these types of runout callouts in multiple instances in the automotive world, and they are wrong. Checking on a bench center, or a set of Vs as shown will net you the same result with or without Datum C. Datum precedence means something in all GD&T tolerance schemes. If it doesn't, the engineer needs to explain that. Link to comment Share on other sites More sharing options...
[An...] Posted April 6, 2021 Share Posted April 6, 2021 I see. A 21 pages pdf is a little bit challenging. It's much more easier to follow the paragraphs of the ASME. There isn't any reality beyond the standard,right? So,how did you americans reach the moon and the mars? Think about it! Link to comment Share on other sites More sharing options...
[Ch...] Posted April 6, 2021 Share Posted April 6, 2021 Please sign in to view this quote. \ Link to comment Share on other sites More sharing options...
[Ke...] Posted April 6, 2021 Share Posted April 6, 2021 Please sign in to view this quote. The presentation was pretty clear, and I thought it was very interesting... I think mental the hurdle that some are experiencing is: "why would I want to check the "run out" using this method?" Based on my metrology experience, I cannot conceive of a scenario where this method would be needed, however that does not mean that I don't see the intrinsic value in it. With that being said, this method does look more like a Profile check, that utilizes two C datums (Min & Max points on the C datum surface)? Link to comment Share on other sites More sharing options...
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