# Not really parametric?

**URL:** <https://discourse.shapr3d.com/t/not-really-parametric/32748>\
**Category:** Modeling Questions\
**Created:** [July 7, 2024, 1:34am UTC](https://discourse.shapr3d.com/t/not-really-parametric/32748 "2024-07-07T01:34:26Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![rogerh](https://avatars.discourse-cdn.com/v4/letter/r/7ba0ec/32.png) [@rogerh](https://discourse.shapr3d.com/u/rogerh)\
**Post date:** [July 7, 2024, 1:34am UTC](https://discourse.shapr3d.com/t/not-really-parametric/32748/1 "2024-07-07T01:34:26Z")

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The way Shapr3D handles certain parametric relations runs counter to my expectations. Let’s say I extrude Face A to Face B (Extrusion Extent = To Object) which happens to be 1" away. Everything looks good. However, let’s say I change my model such that Face B is now 2" away. Shapr3D maintains the original extension of 1" instead of increasing the extension to 2". It does not appear to be truly parametric.

In another example, I imported a model and used the Translate command to position the imported model to my model by aligning edge midpoints. Everything looks good. However, when I modify some of the overall dimensions, these items are no longer aligned by their edge midpoints.

In this case, Shapr3D appears to convert the initial midpoint to a point in X, Y, Z instead of maintaining the edge midpoint relationship. When other dimensions change, it continues using the X, Y, Z position instead of updating things based on the new edge midpoint. Again, this is unexpected for parametric modeling.

Hopefully, I’m either missing something or this is a bug.

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**Author:** ![Istvan](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/istvan/32/23668_2.png) [@Istvan](https://discourse.shapr3d.com/u/Istvan)\
**Post date:** [July 7, 2024, 4:19am UTC](https://discourse.shapr3d.com/t/not-really-parametric/32748/2 "2024-07-07T04:19:57Z")

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> [@rogerh](#):
>
> However, let’s say I change my model such that Face B is now 2" away. Shapr3D maintains the original extension of 1" instead of increasing the extension to 2". It does not appear to be truly parametric.

If you change the original body in the feature tree, the model will update. If you add a new operation, it won’t.

> [@rogerh](#):
>
> In another example, I imported a model and used the Translate command to position the imported model to my model by aligning edge midpoints.

The move/translate/align command’s snap points don’t create parametric relationship. This is the scope of assemblies, which is coming later.

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**Author:** ![jcclow](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.shapr3d.com/jcclow/32/23888_2.png) [@jcclow](https://discourse.shapr3d.com/u/jcclow)\
**Post date:** [July 9, 2024, 12:15pm UTC](https://discourse.shapr3d.com/t/not-really-parametric/32748/3 "2024-07-09T12:15:54Z")

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Ah ha…I ran into this issue last Friday and thought it was weird also. Thanks for the work-around.