All Activity

I've never understood why sometimes I get different true position results when I select a created alignment vs selecting each feature individually for the datums. Can someone please shed some light on this? I saw something pretty different today and don't know why. 505-1 and 505-2 are the specific "features" chosen, 505-3 and 505-4 created alignments.

Thank you all for posting this. I am going to try it as I have a painful problem I am trying to solve right now.

I didn't have any trainings - just what was told and shown to me in roughly 5 weeks. If you are scanning ( tensor ) then you can not change angular range - it's still force 180°. But passive should work. All i can think of is either shanking ( which would result at least in wrong probe tip diameter ), loose probe tip or it's not rigid enough for probing force. Also i am not sure if those numbers are in inch - i think they are in mm's.

The calibration procedure we are using is pretty generic. It is basically what they would teach in a beginner calypso class. I don't know if that counts as manual as I haven't learned any other way to calibrate these probes. We did switch to a 3mm probe that has more shank clearance just in case, but I don't think it is shanking. The sphericity, probe diameter, and sigma are all really good. Maybe I should reduce the angular range of the scan from 180° to 160°? I have not tried lowering the probing force and dynamics. It seems like there is the one pop-up when you create the new probe. Maybe that is the way to go. It just seems so odd that the two features are measuring off about 0.03" in the +Y direction even though the A is 90 for one and -90 for the other while they both have B=-65. The two orientations have to be calibrated with different reference sphere orientations. We have gotten the same results with a 2mm ball and a 3 mm ball over multiple calibrations. When the calibration starts we get a popup window asking about the angle. As far as I can tell we are supposed to enter the angle from the center of the reference sphere to the center of the probe if everything is right where we want it. It seeds the answer and is usually between 5°and 10° off in the X/-Z and Y/-Z directions. We have a duplex set up with two reference spheres set up roughly 15" apart on the same plate that get loaded into the machine at the same time. I would have to ask if I can post a picture as they are pretty strict here. I would have to get approval to take the picture and then have the picture reviewed before posting it. It is a big hassle.

Okay, I kind of understand this but it's going to mean re-programming my program. I think it would have been fine if datum B was just the one hole, but obviously that's not the case and I tried telling the engineer that was helping me this and he said the way I was doing it was correct. Thanks for pointing me in the right direction folks

Make sure the probe is using the correct reference sphere for its associated position or you will get some crazy numbers. This is important as you are using two different spheres.

Fixed i meant VAST XT and others where you have fixed probe rotation. With RDS you can rotate probes around head axis ( Z ) and also another angle. RDS

Maybe it's for calculation ( to be more accurate ) or for cases where more nominals would take same actual. I also don't understand when you have curve with adaptive nominal distance ( on straight path it would be less point density than on curved path ), because now you have somewhere nominals 2mm apart and then you have nominals 0.5mm apart.

Maybe I don't understand what a fixed head is. Wouldn't a fixed head mean that A=B=0 always?

Thank you Martin, this seems to be consistent with all other occurrences of this issue too. Do you know why this is the case? Is it simply a best practice for feature calculation, or is it based on some other reason?

This is the approach that I would use. three points define the plane and potentially the center of the part. I might use some side holes to control rotation about the Z axis and similarly the X? direction (the direction that the arc is open.

What i would do is make TP for all 10 holes .122 in pattern. Enable translation and rotation for bestfit together with MMC. Now you can use this "alignment" in profile datum instead of selecting single datums. Or you can create theoretical line and point ( or circle instead of a point ), set their feature's alignment as patterned and use that as your datums in profile callout. ( line for stopping rotation and circle/point for origin )

The way Ive been doing position and now profile to this point shows me my degrees of freedom in the box. This is why I thought I was doing this correctly. I followed the knowledge base example to tee. I appreciate all your help.

And to clarify something else - the SimREQ/CZ will show up anytime the Position/Profile have the exact same DRF - whether or not you turn on the SimREQ/CZ for that particular feature/group of features is entirely up to you and your drawing.

You have not shown us how you have the others setup. I'm just saying what you have defined inside of the Profile is incorrect. Datum B is not just a singular circle.

I think A and B columns are used only on RDS, but i may be wrong on this. I think on fixed heads, there is only XYZ vectors what matters.

I have run into a problem with a probe and am losing sleep over it right now. If I number the different probe angles any fool thing I want, will it mess up the calibration? Specifically, suppose I set probe 2 to A=-90, B=-65 and say probe 4 to A=90, B=-90 ... would that mess up the probes? I am kind of at my wits end for finding another issue with what is going on. They have been running like this for a while and it worked fine ... until it stopped working. Now it gives me weird results. Replacing the probe and recalibration has had no effect. FYI it is a star probe with only one leg which sticks out in the -X direction from the main shaft.

How do you do calibration? When i was doing manual calibration, then i had to touch ref. sphere in direction of probe tip - i had difficulities with A45 B60 ( i had to scan right bottom corner ). Isn't your probe shanking? Also i would considered lowering dynamics and probing force. Could you post photo of your probe setup?

I appreciate the answer, but this does not match the numbers shown in the graphic. In the first position, it looks about right. Assuming the numbers are in inches. But in position 4 the XY values should be remarkably similar but they are not. Same with position 5. Rotating the probe 90 or 180 degrees about the Z axis should give predictable results following the idea that you proposed. Based on the graphic I am guessing that this comes to me from Zeiss through you. Right now, I have two guesses I am mulling over. 1) the brand new probe that is giving great results in terms of the sigma is actually a very bad probe. But this appears to be the case with more than one new probe then. So I am disinclined to believe this is the answer. 2) The software has a built in filter that assumes very specific angles for specific probe numbers and it will just give you garbage if you program them at some other angle.

I just went through position call out for the .122 holes and the .300 holes in the exact same way. According to Zeiss support the position was correct. Does profile work differently?

I think you have this built incorrect. Datum B would be a common datum of the (10x) .122 diameter - it should not be a singular feature. Datum B is going to control the X/Y Origin and the Planar Rotation. You cannot build a common datum with Circles though. What you could do though (as long as you are in 2025+) you could create the 10x Position of the Datum B holes to Datum A - they would live inside of a SimReq. Then you can create an alignment from that Best-Fit that it builds - Resources - Utilities - GDT Best Fit - just select one of the Datum B Positions. Inside of your Profiles, you can switch over to Loose and use the GDT Best Fit alignment.

Datum B is a pattern of 10 .122 holes, which Is why I am surprised to see the 10 Counterbores in Sim Q. I was surprised to see that as well but because Datum B is a pattern I assumed that using the Sim Q was correct. Don't have freeform. I may just report these with the old GDT engine.

I am not familiar with ASME here, but shouldn't datum B a pattern of 10 holes of .122? Next - i think that profile .01|A|B is applied only on that cylindrical part of contour - rest of contour should be .02 as note 8. I don't know why using SimReq here - do you have freeform? Would be much easier to evaluate one feature, than every plane and cylinder separatelly altho same datums.

I am measuring profile of 5 separate surfaces on my part with are called out to Datums AB per the note. Datum B being the 10 .122 holes (pattern). After entering all relevant information into my surface profile box, I see that simultaneous requirement actual has the 10 counterbores in there instead of the .122 datum B holes. They are all on the same axis, but I wasn't expecting to see them there. Is this a glitch in the new GDT engine or have I got something wrong here? Would appreciate your input.

So much help!!! Thank you both!!!