[Mo...] Posted October 30, 2018 Share Posted October 30, 2018 Hello All, This is my first time posting here. I have a shaft with a flange and a plate welded to the flange. There are 3 holes in a bolt circle drilled through both the plate and the flange. (6 holes total, 3 in a bolt circle drilled through the flange and the plate) Shaft is datum -A-G- Flange face is datum -B- (perpendicular to -A-G-) I'm attaching two pictures of the two callouts we have for the hole positions on the flange/plate. Edited to add one more picture to show more of the part. Please help me understand the difference and how to measure them.op.220.jpg Link to comment Share on other sites More sharing options...
[To...] Posted October 30, 2018 Share Posted October 30, 2018 I've attached something to help get you started. It's not your actual application. I'm sure others will contribute.BF Bore Pattern Example.pdf Link to comment Share on other sites More sharing options...
[Mo...] Posted October 30, 2018 Author Share Posted October 30, 2018 What I'm not sure about is what daturms to use. A-G is the center of the part. -B- is the face. No rotational alignment. So I would do a cylindrical alignment on -G-A- and only use -B- as a datum. 1. What's the difference between -G-A- & -B- and the second line of -G-A- without -B-. What is -B-'s purpose? 2. Do I check off the rotation and/or translation boxes? 3. What's the difference if it is a composite tolerance vs. the two separate callout? Link to comment Share on other sites More sharing options...
[An...] Posted October 30, 2018 Share Posted October 30, 2018 -B- is the axial run-out to the cylinder! Alignment -A- and -G- as cylinder, Area -B- as plane A diameter of 26.479 as secondary alignment, then make a Bore Pattern Example! Link to comment Share on other sites More sharing options...
[Mo...] Posted October 30, 2018 Author Share Posted October 30, 2018 Please sign in to view this quote. Is that not the third callout of perpendicularity of the bores to -B-? Link to comment Share on other sites More sharing options...
[An...] Posted October 30, 2018 Share Posted October 30, 2018 The holes must have a perpendicularity of .075 to the plane surface -B-! Link to comment Share on other sites More sharing options...
[Mo...] Posted October 30, 2018 Author Share Posted October 30, 2018 Please sign in to view this quote. Yes, I understand this part. I measure the 2 coaxial holes and print perpendicularity to -B- I didn't understand what you meant by: Please sign in to view this quote. What's the difference between measuring the TP of the holes to -G-A- & -B- and the TP to -G-A- and omitting -B- plane? Link to comment Share on other sites More sharing options...
[An...] Posted October 30, 2018 Share Posted October 30, 2018 Plane -B- is a reference plane, and is related to cylinders -A- and -G-. The Bore pattern may only deviate from the position within the specified tolerance zone! Why the -B- is missing at the value 0.1 I cannot say! Link to comment Share on other sites More sharing options...
[De...] Posted October 30, 2018 Share Posted October 30, 2018 On the composite true position: First Line: 0.2 A-G | B Interpreted as regular true position callout, A-G controls rotation in two axes and location in two axes, B controls location in one additional axis, the final rotation is unconstrained. All three holes must meet this tolerance and simultaneous requirement applies, bore pattern allows the three coaxial holes to be treated as one feature with regards to best fitting rotation around A-G as there is no specific rotational datum called out. Second Line: 0.1 A-G With composite true position, additional lines refine orientation only. In this case, the second line refines the orientation tolerance of the holes to A-G which requires the holes must be aligned to A-G (and to themselves) within 0.1, so the pattern can still rotate around A-G but may also now be allowed to be translated all three axes because only orientation with respect to A-G is called out with this line. Multiple Single segment true position. First Line: First line is interpreted identically to composite true position. Second Line: 0.1 A-G With multiple single segment true position, subsequent lines still control location AND orientation, so this line requires that all three holes in the pattern meet a 0.1 true position with respect to A-G, the pattern may still be best fitted around A-G, however location translations may not be made with respect to A-G, the pattern may be allowed to float in relation to B since it is not called out, however this should not have any effect on the result since A-G controls two axes of rotation. The main takeaway here is that with composite true position subsequent lines refine orientation only, with multiple single segment true position subsequent lines continue to control location as well as orientation. In both cases all features within the pattern must meet the tolerance to the pattern itself. Link to comment Share on other sites More sharing options...
[Mo...] Posted October 30, 2018 Author Share Posted October 30, 2018 Thank you so much!!! Derek, Just to verify. 1. Composite tolerance top section I would use -G-A- as primary datum -B- secondary, leave both rotate and translate boxes blank. 2. Composite tolerance bottom section -G-A- as primary, leave rest empty, check both rotate and translate boxes. 3. Multiple segment top section same as composite top section. 4. Multiple segment bottom -G-A- as primary, leave rest blank, check rotate box but not translate. I'm confused about the top section being allowed to rotate or not. Link to comment Share on other sites More sharing options...
[Jo...] Posted October 30, 2018 Share Posted October 30, 2018 Please sign in to view this quote. I would add that the lower segment also controls the feature to feature location, not just orientation. So the spacing between features cannot exceed the value of the bottom tier of a composite FCF. Link to comment Share on other sites More sharing options...
[De...] Posted October 30, 2018 Share Posted October 30, 2018 Please sign in to view this quote. Perhaps I didn't explain it well but that is what this line was meant to convey. Link to comment Share on other sites More sharing options...
[An...] Posted October 30, 2018 Share Posted October 30, 2018 Please sign in to view this quote. Not generally! Datum ABC Datum AB Refining the orientation and the size of the pattern Pic 8-20 Datum ABC Datum A Refining the size of the pattern Pic 8-21 Link to comment Share on other sites More sharing options...
[An...] Posted October 30, 2018 Share Posted October 30, 2018 Please sign in to view this quote. A very good question! Link to comment Share on other sites More sharing options...
[To...] Posted October 30, 2018 Share Posted October 30, 2018 I agree. What does B do that A-G doesn't already do? Link to comment Share on other sites More sharing options...
[De...] Posted October 30, 2018 Share Posted October 30, 2018 I guess I should have formatted that part where I said "in both cases the pattern must be good to itself" in bold type. Link to comment Share on other sites More sharing options...
[An...] Posted October 31, 2018 Share Posted October 31, 2018 The actual center of the hole must lie in a circle with d=X mm, the center of which corresponds to the theoretically exact location of the hole. Link to comment Share on other sites More sharing options...
[An...] Posted October 31, 2018 Share Posted October 31, 2018 Please sign in to view this quote. Honestly,I don't understand this explanation. Attached is a comparison.Composite_vs_Multiple_1.pdf Link to comment Share on other sites More sharing options...
[Aa...] Posted October 31, 2018 Share Posted October 31, 2018 Andreas B., I'm not sure how that "comparison" is supposed to be helpful. The first line is definitely wrong. The FRTZF of the composite tolerance only controls the orientation of the pattern of holes to A-G and the position of each hole within the pattern. Technically, the holes don't have to be located within .1 to A-G; the whole pattern could be shifted more than that. (This would not be true with multiple single segment.) In The B in the PLTZF of the composite position tolerance (A-G|B) has no bearing on the tolerance. However, the PLTZF is a simultaneous requirement with any other FCFs to the same datum reference frame. If there were another feature or pattern with a position or profile FCF to A-G|B, and the B would actually make a difference to that feature/pattern (if, for example, the holes were radial or angled outward), then including B both places would be a way to make the two FCFs simultaneous requirement. (Given that they used the pattern in question as a datum to control other holes, though, I doubt that was the reason for including B...) Link to comment Share on other sites More sharing options...
[De...] Posted October 31, 2018 Share Posted October 31, 2018 I could type for a month and not be able to explain Composite True position better than the following series of videos.. they not only explain what the blueprint call out's mean, but also why they should be used. Once an understanding of the reasoning behind composite true position is understood it becomes much easier to interpret the call outs. https://www.youtube.com/watch?v=gHuXKGitgMY https://www.youtube.com/watch?v=WJhdbZWwnbo https://www.youtube.com/watch?v=IbkL8x4gGaI Link to comment Share on other sites More sharing options...
[An...] Posted November 1, 2018 Share Posted November 1, 2018 Please sign in to view this quote. A.G. is definitely right! It took long time to understand this. To whom it may concern ... see attached!Composite_vs_Multiple_2.pdf Link to comment Share on other sites More sharing options...
[Mo...] Posted November 1, 2018 Author Share Posted November 1, 2018 I think I'm getting more and more confused here. Most of the samples I see (including the ASME Y14.5 examples) have a plane that is perpendicular to the holes as primary datum. My drawing has 2 diameters -G-A- that is parallel to the holes as primary datum. So when you have lets say a composite tolerance and bottom callout still has -G-A- in the feature control frame, would it not mean that the holes can not move freely from -G-A-? Meaning it is allowed to rotate, but not translate? Which is the same as the top part of the composite tolerance as there is no rotational alignment to anything on the print. Or are they allowed to be off the center line of -G-A- and rotate, but has to be parallel to the -G-A- center line? Link to comment Share on other sites More sharing options...
[De...] Posted November 1, 2018 Share Posted November 1, 2018 The first line defines the location of each hole as a 0.2 diameter zone which is located as defined by the basic values given for the holes in relation to the axis A-G and located along that axis at the location defined by Plane B. The axes of the holes must each fall with their respective 0.2 diameter zone. The second line is concerning the alignment of the pattern to the axis of A-G. Essentially it is saying once you remove location of the pattern from consideration, the axis of the holes must fall into a 0.1 Zone that is perfectly aligned to the axis A-G. The holes must also fall within a zone that is 0.1 with respect to one another. This is essentially just saying that the end goal is to refine the orientation of the pattern and keep it aligned to the axis A-G while allowing slightly more runout of the pattern to A-G - the call out allows the pattern to run out to A-G up to 0.2 but the pattern axis must remain parallel to A-G within 0.1 Link to comment Share on other sites More sharing options...
[An...] Posted November 2, 2018 Share Posted November 2, 2018 CALYPSO procedure: First tier Spatial alignment of axis A-G X zero and Y zero is axis A-G Rotatory fit of 3 cylinders True Position tolerance: 0.2 Second tier Spatial alignment of axis A-G 'X zero and Y zero is axis A-G Translatory and rotatory fit of 3 cylinders True Position tolerance: 0.1 Datum B not regarded! Link to comment Share on other sites More sharing options...
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