First attempt at a “raster-like” CNC photo engraving
This weekend I made my first attempt at a "raster-like" photo-engraving into wood using my home-built CNC mill. My previous photo-engravings with the CNC used the "vector" method of using software to define the "edges" of color zones in the image and only engraving these edges into the wood, sort of like a black and white line drawing. For the "raster-like" method, every inch of the image gets "cut" into the wood by the CNC’s cutter using lawn-mower-like back-and-forth passes. The darker the color of each photo pixel, the deeper the cut’s plunge. Therefore, if you are using a "V" style bit in the CNC, the deeper the cut also translates into a slightly "wider" cut as more of the "V" enters the wood with depth. This method results in a more photo-like result with much more detail than the vector method, but it is also harder to do and slower.
For this first attempt, I used a 9"x14" piece of mahogany ply mounted to the CNC’s table, and a carbide Dremel 1/4" V-bit. I generated the g-code of the image of the "Big Ben" clock tower, using the trial version of the Vectric PhotoEngrave software that I download from their website. The software was intuitive, and produced a g-code file that easily imported into TurboCNC on my CNC’s PC with no errors.
The CNC ran for almost 3 hours, and engraved the photo very well, but most of the detail of the image was not visible because I apparently used a "V"-bit that did not have enough width at the top…i.e., the changes in depth did not cause enough changes in width of cut to be easily visible.
Therefore, I will buy a bit with either a 60-degree or a 90-degree point and try again….
So, my first attempt at raster-engraving met with mixed results…time to try again.