[To...] Posted January 16, 2020 Share Posted January 16, 2020 I am interpreting this drawing to say that they want straightness of the axis of the OD of this part. In a Straightness characteristic, you can select a Cylinder, 2d Line, 3d Line, Cone and Step Cylinder. From the ASME Y14.5 standard, it shows this should be done from the derived median line. Does this mean I should be developing a 3d Line from circles? No problem, right? However, when it comes to the Straightness Reference characteristic, Calypso only allows a 2d line. This part is only .31" long so, I'm guessing I could "loosely" translate the .001" / 1.0" straightness reference to a regular straightness using .00031" / .31" and call it a day. Ironically, it also calls this with MMC and I have .006" tolerance on the diameter so I don't think meeting the original call-out would be in question. Link to comment Share on other sites More sharing options...
[Cl...] Posted January 16, 2020 Share Posted January 16, 2020 Depending on how its being manufactured and the fact it's only .31" long, I'd be surprised to see much straightness deviation at all. Got a Talyrond? Link to comment Share on other sites More sharing options...
[An...] Posted January 17, 2020 Share Posted January 17, 2020 Please sign in to view this quote. Straightness Reference always requires a huge amount of points - therefore 2D line. Derived Median Point line yields a little amount of points. Straightness and MMC: see attached.Contribution_17_01_2020.pdf Link to comment Share on other sites More sharing options...
[To...] Posted January 17, 2020 Author Share Posted January 17, 2020 Please sign in to view this quote. So, are you saying Calypso can't measure straightness reference according the ASME standard? Link to comment Share on other sites More sharing options...
[An...] Posted January 17, 2020 Share Posted January 17, 2020 Please sign in to view this quote. My status of information is: NO! (If we talk about derived median point line and 3D line) Link to comment Share on other sites More sharing options...
[To...] Posted January 17, 2020 Author Share Posted January 17, 2020 Please sign in to view this quote. We've been talking about a derived median line since my original post. Link to comment Share on other sites More sharing options...
[An...] Posted January 20, 2020 Share Posted January 20, 2020 Please sign in to view this quote. How many circles do you want to probe with the CMM in order to get a REFERENCED STRAIGHTNESS of a cylinder axis? See attached.Contribution_20_01_2020_a.pdf Link to comment Share on other sites More sharing options...
[An...] Posted January 20, 2020 Share Posted January 20, 2020 Please sign in to view this quote. Weird answer in my opinion. CALYPSO can't evaluate according ASME since the CMM's are not able to scan 5000 circles on the cylinder's surface in let me say: 5 seconds. Link to comment Share on other sites More sharing options...
[To...] Posted January 20, 2020 Author Share Posted January 20, 2020 Please sign in to view this quote. In your reply, you say "NO!" but later, you say it can't be done quickly. Whether it takes 5 seconds or 5 hours is not the issue. Sounds like it is possible, though probably not practical, but just not in Calypso due to not accepting a 3D line. When the customer learns that it might take 5 hours to inspect, maybe they will consider revising their drawing. 🤣 I was looking for alternate solutions, which this forum often provides but it appears there are none in Calypso. I am curious what the ISO standard is on this topic. Link to comment Share on other sites More sharing options...
[Gr...] Posted January 20, 2020 Share Posted January 20, 2020 Based on what we do here at our facility, straightness is seldom called out. What I have done, when having to provide this characteristic, is measure the cylinder using a helix in strategy. The last time we had to provide straightness on a cylinder Ø1.875 with a length of .800. The strategy was set up 9 rotations, Step Width 0.010 yielded 5302 points and this defaulted to a speed of .7874. After this was measured we went into form and location grabbed straightness and under features we were allowed to use the cylinder among other features. After selecting the measured cylinder, I noticed the Tol. direction changes to polar, but modifiers are available. As I have stated, this is how we have done it the past 10 years, and have not run into any issues from the customers, even when they do an inspection of one of our samplings. Hopefully I am not opening up a can of worms over this topic Greg Link to comment Share on other sites More sharing options...
[Da...] Posted January 20, 2020 Share Posted January 20, 2020 Doesn't the diameter sign make this Straightness of the Axis ? So circles and 3d line. Link to comment Share on other sites More sharing options...
[Gr...] Posted January 20, 2020 Share Posted January 20, 2020 The selections allowed in the straightness characteristics are 2d Line, 3d Line, Cylinder, Cone and Step Cylinder. When the features of size are used, Cylinder, Cone and Step Cylinder, one is allowed MMC, LMC, and RFS. The result, admittedly, is axial but use of the modifiers can dictate a good or bad result which leads me to believe size, along with the axis is a result. Link to comment Share on other sites More sharing options...
[To...] Posted January 20, 2020 Author Share Posted January 20, 2020 Please sign in to view this quote. I was inquiring into the lower half of the straightness, which in Calypso is called Straightness Reference, which only allows a 2D line. Link to comment Share on other sites More sharing options...
[Gr...] Posted January 20, 2020 Share Posted January 20, 2020 Now I get what you are looking for. The .31 length will, as Clarke pointed out, not show much if any deviation. Link to comment Share on other sites More sharing options...
[To...] Posted January 20, 2020 Author Share Posted January 20, 2020 Please sign in to view this quote. Key words "show the deviation". I don't think the inspection report will look good if I put "not much if any deviation" as the result. 🤣 Link to comment Share on other sites More sharing options...
[Da...] Posted January 20, 2020 Share Posted January 20, 2020 Even the illustration you posted say the tolerance zone is diametrical even on the shorter evaluation lengths . So, I'm going with CALYPSO is wrong. You can't have a 2d line for an axis. Link to comment Share on other sites More sharing options...
[To...] Posted January 20, 2020 Author Share Posted January 20, 2020 Please sign in to view this quote. The illustration is ASME. Calypso is ISO. Maybe ISO has a different interpretation. Link to comment Share on other sites More sharing options...
[An...] Posted January 21, 2020 Share Posted January 21, 2020 Please sign in to view this quote. "The axis has to lie within the Tolerance-Cylinder". An example of dimensioning see attached.Contribution_21_01_2020.pdf Link to comment Share on other sites More sharing options...
[Me...] Posted January 21, 2020 Share Posted January 21, 2020 Please sign in to view this quote. Straightness per Unit Length of the DML can be approximated within Calypso. Simply create a number of short cylinders that span the unit length value stated in the FCF. Evaluate each cylinder with the straightness characteristic and report the worst case. In your example, the lower segment is overriding the upper control because as you stated, the part is only .310” in length. Link to comment Share on other sites More sharing options...
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