Building With Acrylic: Kerf Compensation

After learning my 3D printer’s inability to hold dimensional tolerance, I went back to practicing building with acrylic. Laser cutter kerf may be annoying but it is at least consistent. Now that I know my choice is between a consistent kerf or an inconsistent extrusion width, I choose to deal with consistency.

A bit of Google confirms laser cutter kerf compensation is a fairly common problem people have sought to deal with. What’s less common are actual practicable solutions for designing 3D structures intended to be built up from laser-cut pieces of acrylic. While 2D work on a laser cutter is common, construction for 3D structures appears to be less so.

A laser cutter workflow usually ends in a series of vector graphics commands. Common formats are DXF, DWG, SVG, and PDF. All are good for describing lines, but they only describe where to cut. They don’t contain information on which side of the line is the desired output. So while it is possible for an automated script to offset all lines, it doesn’t know which direction is “inside” vs “outside” in order to perform the proper offset for kerf compensation calculation.

The CAD software (Fusion 360) knows this information, so I thought it’s an obvious place for such mechanism to exist. Google knew of people who have devised some very clever workarounds to make it happen, but not an actual feature in the CAD software itself. Before I started using other people’s workarounds, I thought I’d try to do it manually first, adding to the kerf amount to the dimensions of individual components to CAD.

The result was very encouraging, the laser cut pieces came out at the desired dimensions and pieces fit together with their edges well aligned. This validated my manual process but added mystery. What I did was tedious for a human, simple for a computer, but for some reason the software doesn’t do it. Perhaps I will find out why as I continue learning about laser-cut acrylic construction.

Successful kerf

 

 

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