[Li...] Posted March 21 Share Posted March 21 We are working on a new project and our engineering design dept has required a 3 decimal angle on a port orifice. It is a basic dimension that I'd rotate my alignment to. 6.533° from Datum A around "Z" axis. We are concerned that Calypso and the CMM-Contura XXT-RDS-CAA will have trouble measuring accurately. Not to mention will the CNC machine that will machine this housing be able to hold that consistently. The port will be dimensioned with a basic "Y" distance rotated at 6.533° on the face of the port. Inside the port the ID will have a diameter tolerance, and we are hoping for at least a .010" true position from ABC at a 6.533°(Z axis) and 20.9°(Y axis) SELY01P20225032113410.pdf I'd like to hear some ideas. Does anyone feel this check would be difficult for the CMM? I'm of the mindset that this is a non-issue. This what CMM's are for! Lincoln SELY01P20225032113410.pdf Link to comment Share on other sites More sharing options...
[To...] Posted March 21 Share Posted March 21 (edited) The accuracy of the angle is not relevant. The angle could be 8 decimal places out. You have a .010 cylindrical tolerance zone that the feature's axis must fall within. The BASIC dimensions define where the cylindrical zone lies. You don't report the angle. Edited March 21 Link to comment Share on other sites More sharing options...
[Li...] Posted March 21 Author Share Posted March 21 Yes, thanks Tom. We are just wanting some more opinions on the dimensions. Our team is leery on the 3 decimals. I believe we are early enough in the process that dwg changes can be made to coincide to what we normally see on drawings. Link to comment Share on other sites More sharing options...
[Ja...] Posted March 21 Share Posted March 21 As Tom said, accuracy of the angle reported is not important. And, as far as I have seen depth of port orifices are not big enough for getting a good repeatability to 3 decimals on that angle measurement. I am sure you know this of RDS-CAA probes :for more accuracy and repeatability, qualify the probe at the angle you will use to measure that orifice instead of relying on all CAA qualification. Link to comment Share on other sites More sharing options...
[Da...] Posted March 24 Share Posted March 24 Seriously, just what is the angular tolerance? If you are using a positional tolerance of 0.010, why would they be asking you to do an angular tolerance that is essentially ±0.01°? I could see maybe ±0.1° if you are doing VERY precision machining, but I doubt even F1/Rolex/NASA/ESA do machining to ±0.001°... Link to comment Share on other sites More sharing options...
[Li...] Posted March 24 Author Share Posted March 24 The 6.533° won't have a tolerance, (unless Eng. decides to) as this will just be a rotation of the alignment of A, B, C, in addition to another rotation around "Y" of 20.9° These are BASIC dimensions We would just report the distance of the port face (2.472") while rotated 6.533° [Z axis] and 20.9° [Y axis] Diameter and location of the ID of the port. Will Calypso be able to accurately(theoretically) rotate to these basics [6.533° and 20.9°] to measure this port feature repeatably. Link to comment Share on other sites More sharing options...
[Da...] Posted March 24 Share Posted March 24 According to the HELP button, the RDS has a step width of 2.5°. This applies to both A and B. You would end up with either a 5° or 7.5° angle in your rotation. Link to comment Share on other sites More sharing options...
[To...] Posted March 24 Share Posted March 24 Please sign in to view this quote. 7.5 is closer to required 6.533 angle but if there is enough clearance, you could use either. Link to comment Share on other sites More sharing options...
[Li...] Posted March 24 Author Share Posted March 24 Yeah, getting into the port will be a challenge. I don't know if I'll be able to scan the entire port/bore. I'll get as much as I can without running off the ball and rubbing stem. I won't have to be that deep into the port so if I stay at the edge, I might be ok to scan the whole diameter. Our main concern is the alignment and rotation that is so angular specific of 6.533° Link to comment Share on other sites More sharing options...
[Ja...] Posted March 24 Share Posted March 24 (edited) I don't think you should have much of a problem, as others have said the trick will be setting up a stylus system at that basic angle and approaching it correctly. Since we have a VAST XXT and don't have a fancy RDS head we made a stylus system that has a single probe on an adjustable knuckle for a specific part that has an angled bore inside a tube, so I feel if we can do it without an RDS you shouldn't have much issue. Here's what ours looks like and you can find that knuckle joint on the Zeiss metrology shop as "Rotating knuckle joint, M2 626112-5000-004". Edited March 24 Link to comment Share on other sites More sharing options...
[De...] Posted March 25 Share Posted March 25 Please sign in to view this quote. Lincoln Angles are different ways of expressing distances. If you want to learn how accurate your device is when measuring an angle, you should first investigate the performance of your device at certain reference distances. hese reference distances should also be related to the dimensions of the geometries that will calculate the angle you want to measure. This example may only be useful if you are using only CMM, otherwise there are laser interferometers designed only for measuring angles ( called autocollimator) Comparing these lasers and CMM at certain angles would be the most accurate result. Devrim Link to comment Share on other sites More sharing options...
[To...] Posted March 25 Share Posted March 25 (edited) Please sign in to view this quote. Let's say your hole was at 7.5°, what size stylus (D, L, ML, S) would you be using (or part number)? What is the length of your cylinder? Are there any other clearance issues above the hole? Edited March 25 Link to comment Share on other sites More sharing options...
[Da...] Posted March 26 Share Posted March 26 Please sign in to view this quote. Oh, you are just rotating the ALIGNMENT? In that case, you don't really need to show the angle to extra decimals; those "extra decimals" will be entered into the rotation and I don't think the number VIEWED makes a difference. But, if I'm wrong, somebody, please correct me. At least that's the way it was on PC-DMIS... Please sign in to view this quote. You haven't mentioned the clearances for this feature you are measuring, but it looks like you will have at least a 1° difference in angles between the feature axis and the probe shaft. This will require (depending on the depth measures) a minimizing of the shaft diameter and a maximizing of the sphere diameter, to avoid "shanking". I've had to 'trig-out' programs like these before... Link to comment Share on other sites More sharing options...
[Li...] Posted March 26 Author Share Posted March 26 I may make a new stylus system for this feature. I haven't decided yet. That would lead me to getting a new rack and holders. We will likely have nylon printed part before we have anything poured into aluminum(Casting). Having the nylon part will help in prove-out since there are other features that will be a challenge to reach as well. Not to mention how I am going to fixture this part. It may need two fixtures. I wish I could share more visuals, but the CAD and drawing are ITAR. Hence my crude hand drawn attachment. Link to comment Share on other sites More sharing options...
[Ro...] Posted April 10 Share Posted April 10 I am trying to create a +Z stylus on a Duramax CMM w/ XXT head. I do this all the time with Contura VAST XT, but the Duramax unit is telling me it needs "28 degrees" and to use a different Ref sphere. The probe extends 65mm and weighs 12.5 grams. Curious if anyone has tried this before? Thanks so much Link to comment Share on other sites More sharing options...
[To...] Posted April 10 Share Posted April 10 Please sign in to view this quote. Did you mean to say +Z stylus, i.e. pointing straight up? Link to comment Share on other sites More sharing options...
[Ro...] Posted April 10 Share Posted April 10 Yes, The stylus is pointing up. Thank you. Link to comment Share on other sites More sharing options...
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