In the video below, we go over the process of engraving our logo into Black Pearl granite using CNC tools by Vincent (formerly known as Tyrolit). We did this with our friend and partner, Dylan Mahurin, at Ultra Surfaces in Stockton, CA. We used his Park Industries TITAN CNC router to engrave, and programmed the file in AlphaCam.
We took an unorthodox approach for this project by engraving the majority of the large passes with a drainboard grooving bit, and then filling in the small inside corners with tiny passes using a PCD writing bit.
The drainboard grooving bit
The single-pass drainboard grooving bit is a sintered diamond tool, meaning multiple layers of diamonds are impregnated inside the metal matrix. That is the most common type of cutting and grinding tool used in the stone industry. This tool is specifically designed for cutting drainboards into stone.
Specification used here: 12mm diameter, 20mm length, 1/2 GAS.
The PCD writing bit
For the fine corners in the logo we used a polycrystalline diamond (PCD) 60-degree angle writing bit by Vincent. PCD is known for its exceptional hardness and wear resistance, and the very fine point is what makes it suitable for detail work. A sintered diamond grooving bit is the better choice for bulky stock removal; the PCD bit is what you reach for when the geometry gets tight.
Note on fitment: this tool has a 10mm shank, so it requires an adapter to run on a 1/2 GAS tool holder. Use adapter TYR 34008608, a 10mm to 1/2 GAS adapter with grub screw.
Why two different tools
The short version: match the tool to the geometry, not to the material. The grooving bit moves material fast and holds a consistent groove profile across long passes, which is what you want for the bulk of a logo. But it cannot reach into a tight inside corner without rounding it over. The PCD writing bit has the fine point to hold those corners crisp, and because it is only doing small passes, its lower stock-removal rate does not cost you any real time.
Running the whole job with either tool alone would have meant either soft corners or a very long cycle.
Call us anytime if you would like to discuss CNC stone tools and any creative applications you have in mind. 916.277.8877