hexagon logo
Register Sign in
  • Replies 14 replies
  • Subscribers 223 subscribers
  • Views 268 views
  • Users 0 members are here
Options
Related

"Cannot find Nominals"

nooners4
Hi,

I am having an issue when running a programme on PCDMIS 2014 SP4. A "cannot find nominals" text box is popping up when running certain programmes.

What I would really appreciate is, what exactly is causing this to pop up and are there any consequences for ignoring the message.

For Example if I click yes and update previous scans or if I say ignore and don't update scans, will this have an effect on the results?

I am not the one who writes the programmes (Guys in the US do this O am from Ireland!) and our programmers don't seem to know how to resolve the issue nor do they know what are the consequences for selecting yes or no on the text box.

A fix for this and some insight into how and why it comes up would be seriously appreciated!
Thanks,

Cian
  • Hi,

    I am having an issue when running a programme on PCDMIS 2014 SP4. A "cannot find nominals" text box is popping up when running certain programmes.

    What I would really appreciate is, what exactly is causing this to pop up and are there any consequences for ignoring the message.

    For Example if I click yes and update previous scans or if I say ignore and don't update scans, will this have an effect on the results?

    I am not the one who writes the programmes (Guys in the US do this O am from Ireland!) and our programmers don't seem to know how to resolve the issue nor do they know what are the consequences for selecting yes or no on the text box.

    A fix for this and some insight into how and why it comes up would be seriously appreciated!
    Thanks,

    Cian

    Cian,
    Tell the programmers to edit their scans and increase their FINDNOMS Tolerance values.
    PC-DMIS performs the scan, recording raw data that's "ball center", then looks for nominals on the specified CAD surfaces - and finally offsets the actuals by the calibrated stylus radius and delivers the results.
    What can happen is if the FINDNOMS Tolerance value is too small, like equal or less than the stylus radius - then it cannot look far enough to find the CAD at all!

    Good luck and let us know how it works out.

    And tell your boss to send you to training so you can become proficient at programming and not have to rely on those dodgy Americans.
  • Hi Josh,

    Thanks for the info. I appreciate it and I will pass on the message to our dodgy American counter parts Slight smile

    My main query on it now is. In the mean time, can we continue to run our programmes and ignore the "Cannot find Nominals" text boxes.

    If we select no for both of the text boxes, will it affect the outcome of the programme and/or the results?

    Again, any help is appreciated!

    Thanks,

    Cian
  • My main query on it now is. In the mean time, can we continue to run our programmes and ignore the "Cannot find Nominals" text boxes.

    If we select no for both of the text boxes, will it affect the outcome of the programme and/or the results?

    It will affect the results of the scans that are having the problem. Basically what happens is when you click no is that all the points taken in the scan that pcdmis cannot find nominal data for get 'deleted' and are not reported in the results. Meaning that the points taken which are furthest from nominal will not get reported and you may think your parts are better than they actually are.
  • Ok thanks for the info,

    Two questions if that's ok!
    1. Will changing the find nominals tolerance affect the programme results?
    2. Until the programmes are updated should we click "No" or "Yes" when the text box pops up. Which of these answers will ensure we do not compromise part quality?

    Or, should we put the SKU on hold until the problem is rectified?

    Thanks again,

    Cian
  • You have the option to select a new FINDNOMS tolerance and then an option to define if this new tolerance will apply just to that particular run or will become a permanent change to the program. You need to increase the tolerance until you stop getting the error. If you select "For This Program" and then save the program when you are done with the run it should become a permanent update to the program. Whether you want to do that or not, and whether you are authorized to do that or not, is for you to determine.

    What is sure is that you can not continue to run as-is. You must either modify the program yourself by responding appropriately to the dialogs or wait for your counterparts to modify it for you.

    The FINDNOMS tolerance is a radial value from ball center so it must be equal to the radius of your stylus ruby plus the maximum deviation from nominal that you anticipate that you could have on each particular surface. The trick is that if you set it too large it could start finding nominals on the wrong surface.

    The reason you are having trouble could be as simple as you are using a larger diameter ruby than the original programmer expected or it could be that your parts are deviating from nominal more than the original programmer expected. It could also be that the original programmer didn't pay any attention to it at all and just set the tolerance way too low.

    There are also other, more subtle issues that can cause this. For example, if the original programmer selected a group of CAD surfaces for the scan but missed a very small surface somewhere in the middle of the group you could get this error due to the software's inability to find a nominal value for the few points that fall on the surface that was skipped.

    And to your first question: Yes, changing the tolerance will affect the results because it will cause more or fewer points to be included in the scan results. The points that get included/excluded first as the tolerance changes are the points that are furthest from nominal so this will very directly drive the value of any profile of line or profile of surface evaluation.
  • If you up the find nominal tols you should be okay; where you have to be careful however is that by upping the tol, the scan isn't picking up a nearby surface and using those for nominals instead of the correct surface (can be an issue on thin parts)
  • You have the option to select a new FINDNOMS tolerance and then an option to define if this new tolerance will apply just to that particular run or will become a permanent change to the program. You need to increase the tolerance until you stop getting the error. If you select "For This Program" and then save the program when you are done with the run it should become a permanent update to the program. Whether you want to do that or not, and whether you are authorized to do that or not, is for you to determine.

    What is sure is that you can not continue to run as-is. You must either modify the program yourself by responding appropriately to the dialogs or wait for your counterparts to modify it for you.

    The FINDNOMS tolerance is a radial value from ball center so it must be equal to the radius of your stylus ruby plus the maximum deviation from nominal that you anticipate that you could have on each particular surface. The trick is that if you set it too large it could start finding nominals on the wrong surface.

    The reason you are having trouble could be as simple as you are using a larger diameter ruby than the original programmer expected or it could be that your parts are deviating from nominal more than the original programmer expected. It could also be that the original programmer didn't pay any attention to it at all and just set the tolerance way too low.

    There are also other, more subtle issues that can cause this. For example, if the original programmer selected a group of CAD surfaces for the scan but missed a very small surface somewhere in the middle of the group you could get this error due to the software's inability to find a nominal value for the few points that fall on the surface that was skipped.

    And to your first question: Yes, changing the tolerance will affect the results because it will cause more or fewer points to be included in the scan results. The points that get included/excluded first as the tolerance changes are the points that are furthest from nominal so this will very directly drive the value of any profile of line or profile of surface evaluation.

    Thanks for the input,

    How do you respond appropriately to the dialogue boxes?

    Thanks,

    Cian
  • You do what I said in the first paragraph. If it still isn't clear to you after the responses in this thread you should consider holding off until you can get some assistance from someone with more experience.
  • You do what I said in the first paragraph. If it still isn't clear to you after the responses in this thread you should consider holding off until you can get some assistance from someone with more experience.

    My problem is, is that the programmers are saying that hitting No and No on the Dialogue boxes will not result in any issue or compromisation to the Part being measured. From what is being said above this is not the case. So unfortunately, it is this forum that is helping me understand what is going on with the issue.
  • You do what I said in the first paragraph. If it still isn't clear to you after the responses in this thread you should consider holding off until you can get some assistance from someone with more experience.

    Hi DeSalo, Apologies on the misnderstanding I mis-interpreted what you said in your first paragraph and know what you were referring to now! Thakns for you help on the matter.

    Cian
© 2024 Hexagon AB and/or its subsidiaries. Privacy Policy | Cloud Services Agreement