Since we have a stack of 1/2" Glacier White Corian around here, we started out by pocketing the back of a piece we had laying around that was already cut to size. We left a wall around the outside with at least .200" thickness. This gives us more strength to use Toe clamps for holding the Corian in place so it stays flat on our router table when making aggressive cuts into it. We prefer Toe or Side type clamps so there is nothing sticking above the material that could hit the dust shoe or tool bit. When having the wall the full .500" Corian thickness around the outside, it makes a border/frame around the Lithophane when back-lit.
We used MS Paint to create a black filled image and then brought it into the PicEngrave Pro 5 editor for resizing to a 7.00" width & 2.975" height. We are using a 1/4" carbide end mill for the pocket, so it will cut 7.250" X 3.225" in size. That is the size of the Lithophane engraving that was cut into the other side.
The Pixel Resolution in PicEngrave Pro 5 was set for a .025 step over for both resizing and generating the gcode file. We then set the Max 3rd Axis Depth to -.360" so there will be .140" thickness remaining to cut the Lithophane into the other side. The pocket was cut at a 80IPM feedrate in one pass and it took 13:20 total time.
We first resized the original image in the editor for a .010" Pixel Resolution and then used the Crop feature in the main menu to get the engraving to fit in the pocket size space. The Lithophane option was selected to reverse the depths of cut based on the shades in the original image. We then set the Litho’s Max 3rd Axis Max Depth to -.100" and Min at 0.000". That left .04" for the light to come though in the lightest shaded areas. The Vertical 2X engraving angle was selected with the same .010" Pixel Resolution, so the step over was .005" and step ahead .010" in the gcode file.
After flipping the Corian over and re-clamping, we cut it in one pass using a 1/32" Ball End Mill with a 150IPM set feedrate and a 30% Feed Rate Change (variable feedrate) to slow the feedrate down to reduce chip load in the deeper depths of cut. Total cutting time was 52:21 with our 45,000 RPM Precise Super 65 spindle. As you can see in the video, the dust shoe we made is out of a Mr. Gasket SBC thermostat housing. 