"The datum features must have nominal and measured primitives"

Started by dawangprod1, September 27, 2013, 07:14:07 AM

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dawangprod1

When probing without a CAD model, I keep getting this error when trying to do GD&T. Do I have to construct all of the nominal primitives numerically before I try to measure the part? That would be very time consuming. Is there a work around for this? The previous guy, the one I am replacing, used to just plug the data into an equation and input the data into a spreadsheet. That seems ridiculous to me. Is it not possible to have this info on my polyworks report? What am I missing? Is V12 designed to be used with cad files in order to make use of all the basic features? I'm growing more confused by the day. Any input is greatly appreciated.
Thanks in advance!

jrayself

IMInspect is designed around CAD based inspections. Basic GD&T functionality will work without having nominal primitives, e.g., flatness, cylindricity, concentricity etc. Other GD&T calculations that require a datum reference frame all require nominal values for the calculation.
Jason R. Self
Dimensional Engineering, Inc.

jrayself

Perhaps a more detailed description of a situation would help me to offer suggestions to improve your workflow.
Jason R. Self
Dimensional Engineering, Inc.

dawangprod1

Sorry, I just reread my post and noticed I never mentioned the fact that the true position is what I'm having issue with. Would it work if I create nominal datum planes numerically before I start probing? <--- I wrote this last week. I did just that and constructed all the associated features numerically that have true position and it worked. With some practice, I should get pretty quick at doing this when I need to. Most likely, I will have the CAD files to use when checking our parts, I was just wanting the ability to grab something off the floor and check it without having to request files from engineering while I am learning this software. The box says, "Powered by SmartGD&T". Perhaps they should rename it. j/k

Parts are mostly burnouts of various thicknesses with machined hole patterns. Some of them have quite a bit of true positions called out to various features. And there are a few versions of each one with slight differences.

I'm in an environment that is more like the wild west, "this is the way we've always done it" mentality. Quality is more dictated by the customers rejections than the prints they're made to. Checking parts at the machines by the operators is substandard at best. I'm used to working with a CMM that I could quickly build good repeatable programs for any part that was brought before me. I don't think I will be able to operate like that with this software. Unless of course, there is something that I am ovelooking. I really need to have confidence with my inspections before I can approach production management with in house rejections.

Reading back over this it's like I'm rambling. Please excuse this. I am just overwhelmed, I guess, and not very good at putting my thoughts into words. Thanks for your time!

Admin

You will need nominal primitives to calculate true position, however there is an easier way to create them. Once you've measured all your features, you can create duplicates of those measured features, then swap them to nominals. Then you can edit each new "nominal" numerically to give it the proper values. After that, you can match then back up to your measured values.

After you've done one part like that, you basically have a CMM program you can "run" for the next part.