# STEP geometry with inch units imports at wrong scale

**URL:** <https://prepomax.discourse.group/t/step-geometry-with-inch-units-imports-at-wrong-scale/183>\
**Category:** Bug Reports\
**Created:** [May 6, 2022, 6:08pm UTC](https://prepomax.discourse.group/t/step-geometry-with-inch-units-imports-at-wrong-scale/183 "2022-05-06T18:08:42Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![GB61](https://avatars.discourse-cdn.com/v4/letter/g/258eb7/32.png) [@GB61](https://prepomax.discourse.group/u/GB61)\
**Post date:** [May 6, 2022, 6:08pm UTC](https://prepomax.discourse.group/t/step-geometry-with-inch-units-imports-at-wrong-scale/183/1 "2022-05-06T18:08:42Z")

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After exporting a STEP model file from SolidWorks using inch units, PrePoMax imports the model with inch units but multiplies the dimensions by the conversion factor for mm (25.4).

For example:

- Geometry is created in SolidWorks and one of the dimensions is 2.0 inches.
- The geometry is exported in STEP format.
- A new file is created in PrePoMax with inch units.
- The STEP file geometry is imported into PrePoMax.
- The dimension that should be 2.0 inches is 50.8 (2.0 X 25.4) inches on the imported geometry.

After realizing what has happened, the geometry can be scaled back to the proper dimensions.

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**Author:** ![Matej](https://avatars.discourse-cdn.com/v4/letter/m/a698b9/32.png) [@Matej](https://prepomax.discourse.group/u/Matej)\
**Post date:** [May 6, 2022, 6:59pm UTC](https://prepomax.discourse.group/t/step-geometry-with-inch-units-imports-at-wrong-scale/183/2 "2022-05-06T18:59:29Z")

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I can confirm this behaviour. It seems that there are many possibilities of how to add units to a .step file. The units can be prescribed for only one dimension, one plane, one part, … That is why the geometry kernel of open-cascade, which is used for geometry processing, automatically converts all units to mm. After that automatic conversion, I would have to figure out the correct unit for each dimension in order to scale it back. Instead a scale function was added to PrePoMax to solve this problem: Geometry → Part → Transform → Scale.

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**Author:** ![Matej](https://avatars.discourse-cdn.com/v4/letter/m/a698b9/32.png) [@Matej](https://prepomax.discourse.group/u/Matej)\
**Post date:** [May 6, 2022, 7:02pm UTC](https://prepomax.discourse.group/t/step-geometry-with-inch-units-imports-at-wrong-scale/183/3 "2022-05-06T19:02:38Z")

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