How to properly report Cloud to CAD.

andycmm
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How to properly report Cloud to CAD.

Post by andycmm » Fri Jun 29, 2018 11:02 am

Hi All,

We use a cloud to CAD for many of our parts. We are going to surface files based on step files provided by our customers, they rarely even dimension the blueprints anymore.

At our company all the CMM programmers we have ever had have used the Profile Tol. block in the Cloud to CAD reporting window. What we noticed was that no matter what we changed that to the spike always ended at ±.010 in the graphical report. After a half hour of messing around in that window and trying different things we have come to the conclusion that the correct way to report cloud to CAD deviation is to check 3D only (Uncheck X, Y, Z). Then set the surface profile tolerance from the print (eg .040 would be in -.02 + .02) in the fields to the right .

Is this the correct method?

What we don't understand is 3D was not checked so how was it influencing the graphical report?

Also, what is the profile tolerance block actually used for? The help file included in the program does not explain what each option does.

All of our programs past and present are using Profile Tol. for Cloud to CAD reporting and we did not understand the data we were seeing so maybe this explains all the problems we have been having.

Thanks, Andy

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CrashN8
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Re: How to properly report Cloud to CAD.

Post by CrashN8 » Wed Nov 28, 2018 11:55 am

The 3D tolerance when checked will (of course) display a list of 3D deviations for all individual points in the Cloud. Even when unchecked the tolerance specified in 3D field will be used to determine tolerance band for graphical report. Thus, you will typically set Profile and 3D to the same value even if you only check the Profile options. This way any corresponding graphical report will exhibit same tolerance band as the Profile report output.

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Re: How to properly report Cloud to CAD.

Post by Jean lin » Sun May 19, 2019 3:14 am

Hello,
I want to ask about Cloud to CAD reporting when i output Cloud to CAD deviation results, why nominal values are different from the program that I choose from CAD? the nominal values will change every report that i output why it won't be the same as the program that i choose from CAD? I think it should be the same. Am i rihgt ?

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CrashN8
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Re: How to properly report Cloud to CAD.

Post by CrashN8 » Mon May 20, 2019 9:19 am

No actually the nominal value is not a discreet XYZ point but actually a 3D CAD surface... SO this means the nominal XYZ point changes from one program execution to the next due to small position deviations attributed to CMM motion. Think instead of a manual CMM... How would the user ever take points in the same exact position from one program to the next? They cannot, so instead this Cloud to CAD report operation is comparing Measured Point Cloud to Nominal CAD Surface. The same concept applies to your motorized (DCC) CMM only on a much smaller scale, the motorized CMM only moves the probe to the approximate position for each measured point.

In the end, this is desired behavior... You would not want to introduce artificial error into your measurements to to position capability of your CMM, right? The measured point from CMM is VERY accurate, it's just the fact that motor system cannot always move the probe to the exact position.

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Re: How to properly report Cloud to CAD.

Post by Jean lin » Thu May 23, 2019 11:47 am

Thank you for your reply!
So if the nominal values that i output from each Cloud to CAD report are different from I choose from CAD, due to my alignment is not well? And the nominal values will change in every measurement due to the alignment is different every time,right?

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Re: How to properly report Cloud to CAD.

Post by CrashN8 » Thu May 23, 2019 12:02 pm

Nothing to do with Alignment... Everything to do with fact that CMM can NEVER measure the same points twice in the exact same spot. Nominal Value for each point comparison is adjusted according to nearest location of NOMINAL CAD to ACTUAL point. Every time the program runs, the CMM measures the point(s) in slightly different location, and then nominal value shown on report is adjusted accordingly.

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Re: How to properly report Cloud to CAD.

Post by Jean lin » Sat Jun 08, 2019 12:15 pm

Thank you for your reply!
I got confused about "Every time the program runs, the CMM measures the point(s) in slightly different location, and then nominal value shown on report is adjusted accordingly." How much deviation of nominal is reasonable between drawing and cloud to CAD report ? I have one example, please refer to attachment

Thanks in advance!
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Re: How to properly report Cloud to CAD.

Post by jaudelo1 » Fri Aug 16, 2019 3:21 pm

My company is getting into more and more parts that have limited dimension drawings, and are relying on an all-over surface profile tolerance. I'm still a bit confused as how to properly do/report a proper Cloud to CAD. One of the questions I had was: when I do a manual alignment, the CAD model snaps to the alignment. If I then do a DCC alignment, do I need to re-sync the CAD in order to get good numbers on my Cloud to CAD report, or is the original "snap" sync good enough?

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medupriest
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Re: How to properly report Cloud to CAD.

Post by medupriest » Fri Aug 16, 2019 5:10 pm

Yes. You do need to re-sync with most types of alignments when it is your second. We automatically sync the CAD with your first determinate reference frame, but it is up to you to do it on subsequent alignments.

If you wanted to change your part coordinate system to something that isn't your CAD reference frame, the behavior would be undesirable.

When you are doing Cloud-to-CAD reporting, it is important that the CAD is synced.

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Re: How to properly report Cloud to CAD.

Post by jaudelo1 » Thu Aug 22, 2019 12:50 pm

Whenever possible, I try to make my alignments on my part datums. Depending on part geometry and datum location, sometimes I will make my CAD ref frame on features that are more easily measured manually, for my initial alignment. This got me thinking, my whole CAD sync will be based off these less important features, and I can't sync my CAD after measuring/aligning to my datum features, the coordinate system would be off. Is this bad practice to have my CAD ref frame on unimportant features?

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