I recently needed to cut some thick polyurethane foam with my Epilog Helix laser cutter.
I purchased an inexpensive 4" focal length lens to increase the working distance and depth of cut. The stock focus gauge only works with the original 2" lens, so I designed an alternative focus gauge for the 4" lens.
I designed this 4" focus gauge to mimic the original Epilog focus gauge. Two 2-56 hex nuts are pressed into the gauge so that it will stick to the existing magnets in the Epilog carriage.
There is a simple ruler printed on the gauge that helps you to put the focal plane at the center of thick materials. I have found that this works much better than focusing at the top of the material.
The author marked this model as their own original creation.