CNC Tips: Engraving Glass Block

When we think of CNC routers we primarily think of cutting mainstream materials like wood or even plastic. But CNC routers have LOTS more versatility than that. In this case, we’re going to use the machine to engrave a glass block.

What does the cutting?

The work is done with a diamond drag. It’s a spring loaded stylus with a piece of diamond in the tip, available here. In addition to glass the diamond drag can be used to engrave brass, aluminum, granite and plastic. The instructions that come with it are very good, and will take you through setting up your design software and CNC router correctly for the bit. It’s very important to remember that the spindle speed of your CNC must be set to zero rpm when using the drag.

Which toolpath is used on a glass block?

In VCarve software the Quick Engrave toolpath is used with this tool. Depth of cut translates to how much down pressure the stylus puts on the surface. The harder the material, the more “depth of cut” (down pressure) you need to make a mark. Granite requires more down pressure than plastic.

CNC setup

Secure the material on your CNC and zero the X, Y and Z axes. Note that a touch plate doesn’t work with a diamond drag because you don’t have conductivity. Since the face of a glass block typically isn’t perfectly flat, I set the Z zero to a low point. Remember to set the spindle or router rpm to zero.

Engraving is a slow process, The closer your hatch lines are to each other, the longer the toolpath will take.

More on benchtop CNCs

We have a lot of info on CNC machines. If you’re new to the CNC world and want to know more about the machines, you’ll enjoy this introductory CNC router video.