Diamond Drag Engraving with my CNC Router

Includes affiliate links that help offset our expenses at no cost to you.

This shows how I use my CNC Router with a diamond drag engraving bit to engrave anodized aluminum. I’m making a credit-card-sized map ruler, which I designed for Fortune Bay Expedition Team, as a trinket that we can leave in geocaches when we’re out practicing our navigation skills.

Engraving Feed and Speed

I tried a few different feed depths, which is the distance the Z axis plunges the bit “below” the surface to compress its spring-loaded tip. A depth of 0.5mm gave good results, because it didn’t apply too much pressure and was far enough that it wasn’t significantly affected by variations in the surface height. So I zeroed out the Z axis when the diamond just touched the surface, and then set the depth of cut in VCarve to 0.5mm.

After trying a range of travel speeds, I settled on 1500 mm/min as the fastest speed that gave good-looking results. This has a lot to do with the rigidity of my machine, or lack thereof, as faster speeds gave lines that had more wiggles in them. I think the diamond bit itself could give good results with a faster speed on a more rigid machine.

Vacuum Fixture Details

The vacuum fixture is made from MDF, and I sprayed it with two coats of polyurethane to seal the pores. Probably any type of clear finish would work fine, polyurethane or acrylic for example. It’s not going to seal the material perfectly but it does result in MUCH less air leakage versus unsealed MDF.

It took some trial and error to get a good fit with the 3mm diameter rubber seal, and in the end I cut the groove 2.85mm wide. That gave enough snugness to hold the rubber in place, but not so much that it was hard to put in. The side-to-side compression of the rubber squishes it up a little, so the groove is a full 3mm deep but the rubber gets squeezed above the surface in order to make a seal against the card.

Stuff That I Used

Here are links to the diamond drag bit that I used, plus the parts for the vacuum fixture and the 0.8mm thick business card blanks.

CNC Diamond Engraving Bit 90-degree
The above link takes you to this item on eBay, where the manufacturer sells it for a little less than on their own website at engravingbit.com.
RDZ Engraver for CNC Machine
This is a similar alternative that’s somewhat less expensive on Amazon. I haven’t used this one but I would expect very similar performance.
Foam Rubber Seal Weather Strip 3mm Diameter
(This is the size that I used)

Foam Rubber Seal Weather Strip 4mm Diameter
(I also got some of the 4mm size to use for larger parts in the future)
Air Tank Valve 1/8″ MNPT
(Remove the valve core to use as a vacuum fitting)
Metal Business Cards Anodized Aluminum Plaque Plate 86X54X0.8mm (Blue, Blank,10PCS)
Metal Business Cards Anodized Aluminum Plaque Plate 86X54X0.8mm (Black, Blank,10PCS)
Metal Business Cards Anodized Aluminum Plaque Plate 86X54X0.8mm (Green, Blank,10PCS)

VCarve Pro Project File

If you have Vectric VCarve Pro and want to make something similar, you may download my project file below. It was created with VCarve Pro 11.5 and may or may not work in earlier versions of the software.

CNC Epoxy Inlay Backgammon and Cribbage Board

Includes affiliate links that help offset our expenses at no cost to you.

I’m using my CNC router to make a travel-sized backgammon and cribbage board, inlaid with epoxy and colored mica powder.

Part 1 – Milling Stock, Cutting Pockets

In this first installment I introduce the project, mill the wood to size, and set up the CNC router to cut the inlay pockets on the backgammon board.

Part 2 – Backgammon Inlay

In the second installment I mix the mica and epoxy, and pour the inlays.

Part 3 – Special Details

In the third installment I add gold edges to the points on the backgammon board, and make the inlay and holes on the cribbage board side.

Part 4 – Finishing It Up

In the fourth and final installment I dye the wooden playing pieces and build the finished boxes with splined miter joints.

Resources

Here are links to some of the tools, materials and software that I’m using in this project:

AutoDesk Fusion 360 for personal use
Blender software
Next Wave CNC Shark Router
Carbide 2-flute Down-cut end-mills
Mica Powder for Epoxy Resin
West System Epoxy
Wooden checker pieces
Wooden cribbage pegs
Keda Aniline Dye 5 Color Kit

CNC Feeds & Speeds

UsageBitRPMDepth of
cut
Plunge
mm/min
Cut
mm/min
Comments
Roughing0.1250″ (3.18mm)
2-flute downcut
250003/32″ (2.38mm)500800
Finish0.0313″ (0.80mm)
2-flute downcut
250003/32″ (2.38mm)200250
Drill0.1250″ (3.18mm)
4-flute upcut
250000.25″ (6.35mm)
200n/aPeg holes
Engrave0.1250″ (3.18mm)
30-degree point
25000Variable400400V-carved text

Wood Dye Info

I dyed the playing pieces using a Keda Aniline Dye 5 Color Kit, and I mixed it following the manufacturer’s instructions but with a higher ratio of dye to water to get more concentrated colors. Here are the amounts of dye I mixed with 3 ounces of warm water:

Red: 1/8 teaspoon
Blue: 1/4 teaspoon
Green: 1/8 teaspoon yellow + 1/4 teaspoon blue
Purple: 1/8 teaspoon red + 1/4 teaspoon blue

Next time I use the blue dye, I’ll mix it with hot (not just warm) water in hopes of getting it to dissolve better.

How to Use a CNC Router for Shell Inlay

Here’s how I designed a shell inlay for a guitar headstock using Fusion 360, and cut the inlay using my CNC router.

Part 1 – Design in Fusion 360

Part 2 – Cutting Shell Material

Resources

Here are links to some of the tools, materials and software that I’m using in this project:

AutoDesk Fusion 360 for personal use
Next Wave CNC Shark Router
Carbide 2-flute Down-cut end-mills
1/32″ Carbide shell cutter
Phenolic backer board

CNC Feeds & Speeds

UsageBitRPMDepth of
cut
Plunge
mm/min
Cut
mm/min
Comments
Wood pocket0.0313″ (0.80mm)
2-flute downcut
250000.5mm roughing
0.2mm finish
200250
Shell0.0313″ (0.80mm)
shell cutter
250000.3mm125250