[Za...] Posted November 25, 2020 Share Posted November 25, 2020 what is the best way to measure perp. of the PG13.5 hole to the Face? This is a painted cast face. Better to do a recorded centerline or with reference lengths? Production can never get them in. They are saying cmm is wrong and just signing off. What would be the best way to measure this?perp.pdf Link to comment Share on other sites More sharing options...
[Jo...] Posted November 25, 2020 Share Posted November 25, 2020 The first thing I would do.. Turn on cad evaluation and see where it is out. That is a short feature compared to Datum feature. If that is .003" error it should be easy to find. The other habits are filter your features and it has been suggested to recall the plane into a theoretical so it takes out form error. Link to comment Share on other sites More sharing options...
[Me...] Posted November 25, 2020 Share Posted November 25, 2020 Please sign in to view this quote. What does one gain from doing this since the direction vector is the same? Link to comment Share on other sites More sharing options...
[Jo...] Posted November 25, 2020 Share Posted November 25, 2020 Please sign in to view this quote. I don't know, this is similar conversation.. Re: Establish a plain from highest points Post by Phillip Keller » Tue Jun 30, 2020 11:41 am If intent of the drawing requirement is for the tangent plane fall within the specified tolerance zones, then as other have stated, you would evaluate the plane as an outer tangential element. However, the plane cannot be directly entered into a position or parallelism characteristic. The reason for this is that each characteristic will automatically include the form error in the result. For evaluation, you will need to recall the measured outer tangential plane into a new feature via “Recall One Feature”. This will allow each characteristic to only evaluate the location / orientation of the associated feature. Link to comment Share on other sites More sharing options...
[Ri...] Posted November 25, 2020 Share Posted November 25, 2020 This is an ASME requirement. Link to comment Share on other sites More sharing options...
[Jo...] Posted November 25, 2020 Share Posted November 25, 2020 Please sign in to view this quote. Thanks Richard. I know we've been over this before but could find it. Maybe you could link it or expound on that. I didn't know if perpendicularity was similar. Link to comment Share on other sites More sharing options...
[Me...] Posted November 26, 2020 Share Posted November 26, 2020 Please sign in to view this quote. John, That post was in reference to a situation where the OP wanted to evaluate the tangent plane of the considered feature. In this example, the plane is being used as the datum reference and a cylinder (feature of size) is the considered feature. Please sign in to view this quote. Richard, When an orientation control has been applied to a feature of size, ASME requires that the axis of the unrelated actual mating envelope be within the specified tolerance zone. This is the default behavior in Calypso (assuming the appropriate fitting algorithms have been applied). In this case, there is no reason to create an additional feature ("Recall One Feature”) just to remove form error when the software is ignoring it anyway. [ Link to comment Share on other sites More sharing options...
[Za...] Posted November 30, 2020 Author Share Posted November 30, 2020 The casting has draft on that face which is why I think they are never able to get perpendicularity in tolerance on any of the parts in this family. I want to make sure I am not doing anything wrong on my end when measuring the part. I have been using OT on both the cylinder and the plane. Just so I understand per ASME, the cylinder should be OT and I should use recall one feature on the plane to remove the form error? Link to comment Share on other sites More sharing options...
[Ri...] Posted November 30, 2020 Share Posted November 30, 2020 Please sign in to view this quote. I'm glad someone else said this. Lol. I had never heard of this requirement until I was reviewing the cookbook. I had tried it out a few times, and it had no affect on the results. I assume it would only affect the results if you were using say the LSQ evaluation instead of the OTE/ITE? Link to comment Share on other sites More sharing options...
[Da...] Posted November 30, 2020 Share Posted November 30, 2020 How is production inspecting the perpendicularity that they say the cmm is wrong? Link to comment Share on other sites More sharing options...
[Za...] Posted November 30, 2020 Author Share Posted November 30, 2020 Please sign in to view this quote. With a dial indicator Link to comment Share on other sites More sharing options...
[Jo...] Posted November 30, 2020 Share Posted November 30, 2020 Please sign in to view this quote. Sorry I muddied the water regarding the recall issue. So back to your print. So we can get a better idea of the magnitude, Is the print in inches ? what is the diameter of the hole, and the thickness of the wall ? It would also be nice to know the form of that hole, I'm guessing it is machined. Unless you are using a projected zone, I guess you could indicate up the cylinder wall in various places with the part lying Datum side on granite, and get an idea of error. CMM would be vector, and feature length . It wouldn't be a bad idea to verify those nominals are good. Link to comment Share on other sites More sharing options...
[Wo...] Posted November 30, 2020 Share Posted November 30, 2020 PG is a thread or a hole? Maybe there is something off in your strategy? What happens if you evaluate the Datum wall as LSQ (Just for investigation) Link to comment Share on other sites More sharing options...
[Za...] Posted December 1, 2020 Author Share Posted December 1, 2020 It is a threaded hole on this part. But even when it is a machined hole we get the same issue. Once I get another one in in the next few days I will be able to share more results/testing these ideas. I really appreciate everyone's feedback! Link to comment Share on other sites More sharing options...
[Da...] Posted December 2, 2020 Share Posted December 2, 2020 Production says its wrong because they don't agree with the results. If the CMM says pass, then it is a good measure. Link to comment Share on other sites More sharing options...
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