[Ni...] Posted April 20, 2021 Share Posted April 20, 2021 Good Morning Everyone, I wanted to get everyone's opinion on the Form Datum ISO 5459. Do you keep it on or off? When should it be on and when should it be off? When we took the training with Zeiss and even when I was on the phone with them for support, we were told that should be turned on as a rule of thumb. Zeiss recommends it to be on. One of the senior programmers at the company I'm at told us we should keep it off though. His reason was this: "We don’t use ISO5459 here in SV because most of the time there is not a way for us to validate outages* because there is no way to constrain the part according to this standard with the tools that we have. Same goes for the OT on datums if there is any debris or erroneous scanning it is translated into the base alignment throwing out the rest of the part." *By outage they mean out of spec. What are your thoughts. Thank you, Link to comment Share on other sites More sharing options...
[Ri...] Posted April 20, 2021 Share Posted April 20, 2021 I've always wondered why you wouldn't want to use the ISO 5459 setting. If you were placing the part on a granite table with stop, it would most likely get constrained natively per ISO5459. In addition, when functionally testing parts, the OTE is how it would get tested according to. Measuring using OTE is a choice that your company and your customer need to agree on. There are pros and cons to using it. Link to comment Share on other sites More sharing options...
[Ni...] Posted April 20, 2021 Author Share Posted April 20, 2021 Please sign in to view this quote. Can you explain why you think it should be on? That is the one thing I am having a hard time trying to fully understand so I to talk to the other programmers about turning it on. The OTE I agree with keeping it off so that isn't much of an issue. Link to comment Share on other sites More sharing options...
[Er...] Posted April 20, 2021 Share Posted April 20, 2021 It might be helpful to steady section 4 of the ASME Y14.5 GD&T spec. Just because you don't have a way to verify doesn't necessarily mean you shouldn't check it to the spec. Link to comment Share on other sites More sharing options...
[Ri...] Posted April 20, 2021 Share Posted April 20, 2021 Mark Boucher has a little bit of a writeup of this. http://cmmquarterly.mbccmm.com/index.ph ... form-datum It is for attempting to replicate functional testing. As far as I am aware, it does not impact repeatability the same way using OTE does. Link to comment Share on other sites More sharing options...
[Ch...] Posted April 20, 2021 Share Posted April 20, 2021 In my opinion, your senior programmer is probably more right than wrong. If what he says is correct, then turning it off "meets the needs of the business" more than turning it on. For example, if it has been established that turning it on yields incorrect results due to dirty parts( as he claims) then it is entirely acceptable under ASME B89.7 to measure that parts in a way that is not according to Y14.5. Remember guys, Y14.5 is a design standard and not a measurement standard. Link to comment Share on other sites More sharing options...
[Ri...] Posted April 20, 2021 Share Posted April 20, 2021 Please sign in to view this quote. No, no, no. OTE on everything. Cylinders only. Planes only. Who cares about repeatability. I'm just checking a box. Link to comment Share on other sites More sharing options...
[Ch...] Posted April 20, 2021 Share Posted April 20, 2021 I personally use OTE on everything but I could imagine shops where this is not doable. It's legit Link to comment Share on other sites More sharing options...
[Ri...] Posted April 20, 2021 Share Posted April 20, 2021 Please sign in to view this quote. Just depends on the situation. People want the world, but don't want to pay for it. Link to comment Share on other sites More sharing options...
[Ch...] Posted April 20, 2021 Share Posted April 20, 2021 Please sign in to view this quote. It 100% depends on the situation. That is the entire point of ASME B89.7 Measurement Uncertainty. P.S. ya know I'm just picking you Richard. I like to give my Y14.5 hawks crap. Link to comment Share on other sites More sharing options...
[Jo...] Posted April 20, 2021 Share Posted April 20, 2021 IMO ASME 14.5 was supposed to establish the Functional aspect of part dimensions. Therefore a plane would function as OTE The secondary and tertiary Datum would translate until it touched. Holes(cylinders) would function as max inscribed pin diameter I work with castings so this is unpopular when a caliper check doesn't agree with CMM report. It still represents the functional condition of the part but as deviations of form increase, so does the discrepancy. Build two alignments with both methods to quantify the differences. Link to comment Share on other sites More sharing options...
[Er...] Posted April 20, 2021 Share Posted April 20, 2021 Please sign in to view this quote. Chad, Do we not inspect parts to the design intent as per the drawing? Therefore doesn't apply to both design and inspection? I do agree with you, bottom line is getting the customer what they are asking. Link to comment Share on other sites More sharing options...
[Ri...] Posted April 20, 2021 Share Posted April 20, 2021 Please sign in to view this quote. I find it more rare to have a customer who even knows what ASME Y14.5 is. Link to comment Share on other sites More sharing options...
[Da...] Posted April 21, 2021 Share Posted April 21, 2021 Another point would be, what is the customer's software doing about 5459 by default, if it's other than Calypso? If I'm not mistaken, PC-DMIS has it ON by default. What about others? Link to comment Share on other sites More sharing options...
[Er...] Posted April 21, 2021 Share Posted April 21, 2021 This setting don't affect the base alignment, or any other coordinate systems for that matter... Link to comment Share on other sites More sharing options...
[Ri...] Posted April 21, 2021 Share Posted April 21, 2021 Please sign in to view this quote. Correct - you would have to hit the button manually inside of the alignment. Link to comment Share on other sites More sharing options...
[Aa...] Posted April 21, 2021 Share Posted April 21, 2021 Please sign in to view this quote. Sounds very reasonable to me. Please sign in to view this quote. If it has been established that you get incorrect results due to dirty parts, clean them. We saw night and day difference in our results when we started ultrasonic cleaning our parts before running them on the CMM. Link to comment Share on other sites More sharing options...
[Ch...] Posted April 22, 2021 Share Posted April 22, 2021 Please sign in to view this quote. Again, the existence of the standard is proof that these situations exist. If you believe that these situations will never occur then you must also believe that ASME wrote and entire standard for no reason. Link to comment Share on other sites More sharing options...
[Aa...] Posted April 22, 2021 Share Posted April 22, 2021 Please sign in to view this quote. I wouldn't say "for no reason". There are likely situations where two different parties get different results because they have some differences in how they measure or evaluate the measurement data. E.g., whether they clean the parts, how accurate their machine is, whether they adhere to ISO 5459, whether or not they use OTE for evaluation, etc., etc., etc. Link to comment Share on other sites More sharing options...
[Aa...] Posted April 22, 2021 Share Posted April 22, 2021 Anyone notice that if you quote someone on the forum, your response gets shoved into the quote box. This seems to be a bug in their bbcode interpreter. Thank you, Microsoft! Link to comment Share on other sites More sharing options...
[Ri...] Posted April 22, 2021 Share Posted April 22, 2021 Please sign in to view this quote. It probably has to do with the browser you are using. Link to comment Share on other sites More sharing options...
[Ch...] Posted April 22, 2021 Share Posted April 22, 2021 Please sign in to view this quote. Weird, I feel like I did the exact same thing as this morning but now it is functioning properly. Link to comment Share on other sites More sharing options...
[Ri...] Posted April 22, 2021 Share Posted April 22, 2021 Aliens. Link to comment Share on other sites More sharing options...
[Te...] Posted April 23, 2021 Share Posted April 23, 2021 Please remember that Form Datum setting only applies for position and profile when you break the alignment out to the individual datum features. If you leave it to the alignment of the feature it is not being applied. Does not fix itself for already written programs if you turn it on. Have to go back in and re-enter the Datum Features for all GD&T characteristics to get it to update. I would always use it and it is almost always a different result, sometimes better, sometimes worse. From my understanding always correct for ASME and ISO. Link to comment Share on other sites More sharing options...
[Aa...] Posted April 26, 2021 Share Posted April 26, 2021 Please sign in to view this quote. Good point! Link to comment Share on other sites More sharing options...
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