[Th...] Posted February 1, 2019 Share Posted February 1, 2019 Every day seems to dredge up a new question for me lately. Today I started work on a measurement plan for a part that has some slots in it. Most newer drawings in our inventory have used profiles to control these, but this particular one uses true position with the boundary condition applied, and I realized that I have no idea how to handle these. I spent some time looking at the relevant sections in Y14.5-2009, but I'm struggling to understand it, and I'm on a bit of a time crunch with this program, so once again I turn to the forum for assistance. How do I correctly report these positional callouts? I apologize for the awful hand-drawn example in advance. This sticky note doesn't agree with the pen I'm using, and my writing is pretty bad. Link to comment Share on other sites More sharing options...
[Me...] Posted February 1, 2019 Share Posted February 1, 2019 Report it twice, once in each axis, with a planar tolerance zone, not diametrical. You should be able to use a slot feature. Link to comment Share on other sites More sharing options...
[Th...] Posted February 1, 2019 Author Share Posted February 1, 2019 Oh, all I have to do is switch the position from diametrical XY to only X (or Y) and create another position characteristic for the other axis? For some reason I thought it was going to be more complicated than that. Link to comment Share on other sites More sharing options...
[Ri...] Posted February 1, 2019 Share Posted February 1, 2019 Man... wouldn't a Profile measurement be so much simpler in this case? I can't believe I just said that either... I hate Profile. lol Link to comment Share on other sites More sharing options...
[Th...] Posted February 1, 2019 Author Share Posted February 1, 2019 It would, but it's not on this particular drawing so my hands are tied. Link to comment Share on other sites More sharing options...
[Br...] Posted February 2, 2019 Share Posted February 2, 2019 Theres no boundary without MMC. Those feature control frames shouldn't say boundary under them if they don't have the MMC symbol. Just treat it as a normal slot at RFS and forget the boundary. You can actually create a slot at the virtual condition size, turn it into a curve, and report the profile to infinity in one direction. That would simulate the boundary. Link to comment Share on other sites More sharing options...
[Ca...] Posted April 9, 2019 Share Posted April 9, 2019 My turn. I've had a few boundary location callouts before, and I've received general instruction (from the customer)* on how to check them with Calypso, but I'd like to just bounce it off some of you. My part has an INSIDE slot with a boundary location of .005", and a profile callout of .002" I've been told to check the boundary with a profile characteristic, set to Outward to Infinity, with a tolerance of half the location plus half the profile. Put simply, I'm checking a Boundary location with an Outward to Infinity profile, with a tolerance of .0035". Does what I've said make sense, and is it "right"? I have serious concerns, as sometimes features read a straight 0.000000, which I seriously doubt. I don't have FFS, and I don't have Curve. I'm running Calypso version 6.6.12. Thoughts? Link to comment Share on other sites More sharing options...
[Br...] Posted April 9, 2019 Share Posted April 9, 2019 Please sign in to view this quote. Assuming the characteristic is a .002" Profile to no datum references, attached above the position FCF with a single leader line directed to the slot, then that's a good way to do it. You still need to report that .002" Profile separately though because that is what is controlling the size. Doing this without curve will be difficult. You should be able to measure cylinders and planes in order to report profile of a surface. Link to comment Share on other sites More sharing options...
[Me...] Posted April 10, 2019 Share Posted April 10, 2019 Please sign in to view this quote. You'll need to use "Inwards into Infinity". This will report the largest deviation that adds material to the surface which is what you need in order to verify that the virtual condition has not been violated. Please sign in to view this quote. If the profile result is 0.000, then all of the surface deviations are "minus material" and the boundary verified. Link to comment Share on other sites More sharing options...
[Br...] Posted April 10, 2019 Share Posted April 10, 2019 Please sign in to view this quote. Good catch. I always get confused about which way the tolerance zone is going between inward and outward to infinity. I always have to turn the graphical evaluations on so I can physically see the tolerance zone. Maybe I should think of it as Inwards to Infinity=The tolerance zone extends Into the material to infinity Link to comment Share on other sites More sharing options...
[Da...] Posted April 10, 2019 Share Posted April 10, 2019 Guys sorry if I'm blind, but, is this about hole or boss?slot.PNG Link to comment Share on other sites More sharing options...
[Aa...] Posted April 10, 2019 Share Posted April 10, 2019 Please sign in to view this quote. Spot on. Y14.5.1M-1994 goes one step further. It only allows for position tolerancing to be applied to "elongated holes" on an MMC basis, and then it's only in Surface Interpretation. (Section 5.6) What I find interesting is that this section explicitly avoids defining how to calculate an actual result. It basically just says the surface can't violate the virtual boundary. Link to comment Share on other sites More sharing options...
[Me...] Posted April 11, 2019 Share Posted April 11, 2019 Please sign in to view this quote. One could make the case that the 1994 revision also allows for LMC to be applied to noncylindrical features. 6.5.5.1 “Profile tolerancing may be combined with positional tolerancing where it is necessary to control the boundary of a noncylindrical feature”. 5.2(b) "Where specified on an MMC or LMC basis, a boundary, defined as the virtual condition, located at the true (theoretically exact) position, that may not be violated by the surface or surfaces of the considered feature.” Thoughts? Link to comment Share on other sites More sharing options...
[An...] Posted April 11, 2019 Share Posted April 11, 2019 Please sign in to view this quote. Apologizing the unprecise scetch regarding the maximum deviation. Just my two cents.Contribution_11_04_2019.pdf Link to comment Share on other sites More sharing options...
[Aa...] Posted April 11, 2019 Share Posted April 11, 2019 Please sign in to view this quote. That's Y14.5M, not Y14.5.1M. They don't contradict, but they're setting up two different approaches. 5.6 of Y14.5.1 is setting up an "elongated hole" as a feature of two sizes, which can be toleranced with size limits and position tolerances, in very much the same way as cylindrical holes. The combined controls situation in 6.5.5.5 of Y14.5 is about any generic irregular surface, which are controlled by a profile instead of size limits. I personally prefer the combined controls approach from the main standard, but mostly from an awareness perspective. Even though the interpretation in Y14.5.1 is a kind of profile tolerance, but just having size limits and a position FCF on the print doesn't necessarily make the reader think of a profile, so I think it is more prone to misinterpretation or misapplication. Link to comment Share on other sites More sharing options...
[Me...] Posted April 12, 2019 Share Posted April 12, 2019 Now that I got my head checked, I think we’re on the same page. My concern is that while Section 5.6 (Y14.5.1M-1994) describes the tolerance zone for an elongated hole tolerance at MMC, it does not explicitly prohibit the use of LMC. In my opinion, the statement “such tolerancing is always considered bidirectional in nature” would point to reader to Section 5.5. The main difference that I see is that the inner boundary defined in Section 5.6 is fully constrained, whereas Section 5.5 allows the inner boundary to be positioned along a defined plane of motion. In either case, the outer boundary is not allowed to move. What am I missing? Link to comment 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