Design Example: Laser Cutter Test Parts¶

The laser cutter cuts along the center of each specified line. Because the beam has a finite width, some amount of material on each side of the line is lost to the kerf. Without compensation, holes tend to be slightly oversize, and outside profiles tend to be slightly undersize.

The simplest way to compensate is to design parts not at the actual size but at a size accounting for the kerf. In practice, this often just means designing features which are tolerant to process variation, either by assuming the existence of gaps or by adding tapered features to accommodate variation. But if a tight fit is needed it can be important to draw holes at a smaller than actual size so the resulting hole is more exact.

The following parts demonstrate several approaches to calibrating the laser cutting process and fitting part dimensions for the actual cut widths.

These models can be found on the course site in the SolidWorks/laser-cutter-tests/ folder, or as a single zip file laser-cutter-tests.zip.

Hole Size Test¶

part: hole_size_test.SLDPRT
profile to laser cut: hole_size_test.DXF
drawing: hole_size_test.pdf

This part has four rows of holes corresponding to our most common fasteners. The largest is exactly on-size so the kerf will leave it loose. Each additional hole steps down by a small diameter to identify tighter fits.

Tab and Slot Size Test¶

part: tab_slot_test.SLDPRT
profile to laser cut: tab_slot_test.DXF
drawing: tab_slot_test.pdf

This part has tapered tabs at each end and a graduated set of corresponding slots. By cutting two copies, the insertion properties of each tab can be tested in each slot.

Most sample designs have settled on a 15x6 mm slot with a tab tapered at 2 degrees with a 15.2 mm tip, resulting in a light interference fit. However, this part can evaluate other options.