Circle Projection on Tumbler

1 min read·Updated Jul 2026
Quick
answer

Use this Excel spreadsheet to calculate the skew percentage needed to correctly project a circle onto a rotary (tumbler) surface in LightBurn.

Applies toAll machinesTopicRotary

This article provides an excel spreadsheet to be used to calculate the skew needed to adjust a circle onto a Rotary Surface.

Prior to using this sheet, make sure your steps/roller diameter are correct for the cup you are lasering onto.

Rotary Roller Diameter Calculation

How to Use

Enter the values in the blue rows:

  • Circle Diameter – Get that value from your artwork in Lightburn
  • Cup Diameter – Measure the diameter of the cup where you are engraving
  • Green Rows: FYI only
  • Orange Row: Output skew percent — enter this into LightBurn.
Excel spreadsheet showing circle projection calculator with blue input rows, green FYI rows, and orange output skew row

In LightBurn

Unlock the X and Y Axis sizing and then enter the skew value for the X axis, then rotate your art and set it up for the Rotary. In this example a 2.75" circle with the X axis skewed by 3% results in a 2.8325x2.75 oval.

LightBurn screenshot showing unlocked X and Y axis sizing with skew value applied to X axis

Still stuck?

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