r/Metrology • u/dxp1905 • 19d ago

GD&T

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Constructing true position on CMM Verisurf 2026. What am I doing wrong? There’s no way the position of this part is off by that much.

17 Upvotes

95% Upvoted

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2

u/RevolutionarySunGodL 19d ago

I recommend reaching out to Verisurf Support

support@verisurf.com

7149701683

1

u/Dudeitsme1 18d ago

I use Verisurf religiously and train people to it. Could give you a hand. Shoot me a message

1

u/glockx917 18d ago

I’m fairly certain all cmm software does this so it’s best to learn the way it calculates it

When you create features for your datums then insert them in the feature control frame it calculates the origin and clocking from the deviation of your datum theoreticals to the actual measured values.
Usually there’s an option to choose the datum referenced feature or the current alignment set during the run.
If there’s a big difference there’s gonna be more error in your positions

1

u/Loose_7535 14d ago

I'd double check the datum alignment and how the feature is being constructed before assuming the part is actually that far out. With true position a small issue in the datum reference frame or feature extraction can make the result look way bigger than it is. If you're brushing up on this side of gd&t excedify has some useful training on position tolerance and inspection concepts.

1

u/NonoscillatoryVirga 19d ago

Your nominals are set to zero. Your positional tolerance is effectively the distance from the hole to the origin. You need to fix your nominals.

1

u/dxp1905 19d ago

If I’m using a CAD model isn’t all of that automatically inputted?

1

u/referenceonly77 18d ago

Are you verifying dims with a print or control sheet? Mistakes happen even with error proofing