Why does sketch geometry move with added dimensions?

[pimm]

I am a little new to fully constraining sketches. What I am finding is that I get a small amount of movement of my geometry by just adding a dimension.

I'd like my geometry to stay put because I'm copying over top of an imported model that I need to duplicate features.

My 1st guess is that the dimension redistributes exactly to the decimal places that are the system default. Depending on how lines, arcs and curves connect with each other there would be more or less actual variation. Am I correct with my assumption?

I would prefer that the geometry just stay put. Is there a way of ensuring this?

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[Patriot_1776]

Sketch geometry moving while in MODELING mode, or drawing mode?

[dellens]

This would be in the modeling application.

I referenced curves from a customer IGES in the sketch.

From this I projected the reference curves to build my own curves.

I then removed the references, which set up Creo's own dimensioning and constraint scheme.

When I started placing my own dimensions I observed a small placement variation with every dimension.

[James62]

hi Dennis and Paul,

Your observation is right. Once you remove the refs from your sketch the newly created dimensions get rounded and so the sketcher entities move slightly.

Try to make an offset of a line in your sketch by 0.001. This will give you an error no matter how fine your accuracy setting is.

In case with imported models it's better if you find a way how to avoid sketcher or only use sketcher features in cases where you can keep edge refs.