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Free casting shrinkage calculator

Choose your alloy to make an oversized casting pattern. Compare the size along each axis, then save a scaled model for printing.

Runs in your browser. Your file is never uploaded.

Your model

Drop an STL, OBJ, or 3MF here.

Up to 250 MB. All processing stays on your device.

Files stay on your device.

Options

Used for the custom, zinc, and pewter choices.
Used for the custom choice.

Result

Choose a file or try the example.

How it works

  1. 1

    Open your model

    Drop an STL, OBJ, or 3MF, or try the drafted bracket example.

  2. 2

    Choose the allowance

    Pick a typical alloy or enter the shrink rule from your foundry.

  3. 3

    Save your pattern

    Check the before and after dimensions. Download an STL, 3MF, and report.

Patternmaker’s rule
Each dimension is multiplied by 1 + shrink/100. A 1.30% rule gives a 1.0130 scale.
Holes and pockets
Uniform scaling enlarges holes, pockets, and wall thickness along with the outer dimensions.
Confirm your process
Casting numbers are estimates. Get pour temperatures and burnout schedules from your alloy supplier or investment maker.

Questions

Does this repair a model?

No. The report checks boundary and non-manifold edges. Repair an open model in CAD before using it for production.

Are 3MF units preserved?

3MF units are read from the file. Downloads use millimeters. Set the units option for unitless STL and OBJ files.

Is my file uploaded anywhere?

No. The conversion runs in your browser with the JavaScript on this page. Your data never leaves your computer, and nothing is kept after you close the tab.

Quoting castings or patterns every week?

I build quoting tools that read a customer's CAD file, work out weight and metal cost, and price the job automatically.

Ask about automating itSee custom software work

Source code and license

You can inspect the code and the licenses here. Models are parsed and measured on your device.