Reporting true position, getting strange numbers

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andycmm
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Reporting true position, getting strange numbers

Post by andycmm » Wed Dec 27, 2017 2:28 pm

Not sure where to put this.

I am trying to report true position of 2 simple holes. I have attached my program screen shot and a screen shot of the issue.

The way we make programs here is so that the operator never has to take a manual hit.

When I program this is how we are supposed to make that happen:

1. we setup the part
2 take manual measurements of the datum features.
3. create an origin.
4. translate from a known reference point on our R and R fixture grid (The A1 position hole) and then sync the cad to our origin.

After that we redefine those manual measurements with DCC. Level, align, set origin and then sync the cad.

The issue that I am having is that everything appears to sync up to the CAD all throughout the program until I go to report a true position after the program is done running. The program is then out of sync with the CAD and it affects the way the true position is reported.

In my screen grab you can see that my datum' ref. frame and my cad ref frame are out of sync with each other in this picture the CAD ref frame is off by .004 in X and .001 in Y which would account for my .0141 result. I know the true position is actually about .003-.005. I have measured it 3 different ways. Optical Comparator, height gauge, and a vision system.

Does anyone have an idea of how the CAD got out of sync at the end? Or any idea how to fix it?
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medupriest
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Re: Reporting true position, getting strange numbers

Post by medupriest » Thu Dec 28, 2017 10:43 am

If the CAD is out of sync when the program is done running, please zip and attache the program so we can look at it here. In the screenshot, you are in teach mode and the CAD will only sync if you double-click on your sync CAD step and select "OK".

We do not automatically sync your CAD when you go from run mode to teach mode because if you had moved your part reference frame, then you would not want that to happen. Sync the CAD before programming the reporting steps.

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Ryan Christopher
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Re: Reporting true position, getting strange numbers

Post by Ryan Christopher » Thu Dec 28, 2017 1:40 pm

Every blue moon CMM Manager looses a sync and you will need to delete a sync cad command and re-insert to wake it up again.

In this case it doesn't matter really because the sync status won't effect the reporting of position reports as the nominals are locked in at the time those items are programmed.

Do you program while on-line and running the program as you go? If so, you should go to PREFERENCES > GENERAL > SIMULATE AND VERIFY > and turn off "UPDATE ACTUAL FEATURE" to make sure the nominal and actual values are the same while you are writing the program.

Just curious: why are you reporting the circles as points?...are you creating your points by projecting the circles onto the XY plane?
Ryan Tackes
Applications Manager, VMS Inc.
http://www.vantagemeasure.com/

andycmm
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Re: Reporting true position, getting strange numbers

Post by andycmm » Wed Jan 17, 2018 1:43 pm

Ryan Christopher wrote:Every blue moon CMM Manager looses a sync and you will need to delete a sync cad command and re-insert to wake it up again.

In this case it doesn't matter really because the sync status won't effect the reporting of position reports as the nominals are locked in at the time those items are programmed.

Do you program while on-line and running the program as you go? If so, you should go to PREFERENCES > GENERAL > SIMULATE AND VERIFY > and turn off "UPDATE ACTUAL FEATURE" to make sure the nominal and actual values are the same while you are writing the program.

Just curious: why are you reporting the circles as points?...are you creating your points by projecting the circles onto the XY plane?
Hi Ryan,

Thanks for the response.

when you say: "In this case it doesn't matter really because the sync status won't effect the reporting of position reports as the nominal are locked in at the time those items are programmed."

Are you saying that this is actually reporting properly and that it does not matter if the CAD ref. frame and datum ref .frame are off from each other? It looks like when the CAD ref. frame is off from the Datum ref frame, the report is showing a triangle with an origin at the datum ref frame, but the cad is moved from the position it should be at.

I program on-line and verify every step, I am a beginner. The points were for troubleshooting. I normally just report the circles since they are point reducible features.

"We do not automatically sync your CAD when you go from run mode to teach mode because if you had moved your part reference frame, then you would not want that to happen. Sync the CAD before programming the reporting steps."

So to understand better: it's perfectly normal for the CAD ref frame and the Datum ref frame to be off from each other after you run a program and then switch to teach mode? If this is the case I have been chasing my tail for no reason.

What I don't get is: When i measure with a height Gage my numbers are right on.

Should I be using point projected onto a plane for an origin? I usually do a point at the intersection of two datums and the project that point onto the leveling plane. Is that a bad method? Is it possible this is why my CAD is getting out of sync?

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Ryan Christopher
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Re: Reporting true position, getting strange numbers

Post by Ryan Christopher » Tue Jan 30, 2018 1:56 pm

Hi Andy,

The short answer is that the CAD and Part Coordinate systems don't have to be sync'd all the time. For beginners it may be best though to act as though they should be. Then later, once you've mastered the 4 sync's start doing things in a more 'free wheeling' kind of way.

Specifically in this program there may be a few things going on here.

Firstly the cad coordinate system may not be where you think it is. You could leave teach mode, click 'sync part reference frame' to make the c/s's coincident then use pick and define to see if your nominal surfaces are at nominal.

Second, I'm wondering about the nominal of 8.624 for X. Is that right? Seems like an odd nominal value to me. It could be that "Update Actual Feature" got you. In which case you would want to "select all" in the program database and then "reset actuals" to make the actuals = to the noms. Then you would need to select the report items and "update report" with the updated nominal values.

If you want you can pm me and send me this file (if possible).
Ryan Tackes
Applications Manager, VMS Inc.
http://www.vantagemeasure.com/

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