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CNC machine a wooden inlay as company sign

A custom wooden inlay, to be used as sign for a grief counselor

A wood inlay is made by inserting wood of a certain color into a wooden base of a different color. Displaying a custom wooden inlay sign is a great way to advertise your business in a rustic and personal way. This project is about the company sign for my partner's grief counseling practice:
Ouwehand rouw- en verliesbegeleiding in Utrecht, NL (website in Dutch).

The image above shows the design in Inkscape: a 2D vector drawing (this means that the drawing was made using vector curves). Such vector file (SVG, DXF or AI) can be loaded as CAD data in a DeskProto vector project. DeskProto only reads the vector curves, not the color information. The logo has been designed by Finn van Sluis.



This screen video shows these same design curves in DeskProto. As you can see I have added a few curves: an offset curve round the design curves, a rectangle round the block, and 4 single points to be used to drill mounting holes in the sign. Total size of the sign is 300 x 140 mm.

For an inlay two parts need to be machined: a base and a plug. For more details see the Tutorial video about inlays. The screen video above shows the toolpaths for the base - for this part only the design curves have been used. Settings were a conical cutter (V-bit) with a 30 degree angle (included angle 60 degr) and machining depth limited to 4 mm. This limitation is needed as otherwise the V-groove for the large key icon would become much deeper. The characters as drawn by the toolpaths seem much thinner than in the design: this is because the path is for the tip of the cutter, at 4 mm depth. On the surface the groove will be exactly as wide as in the design.


Both parts have been CNC machined on our old in-house CNC machine: an Isel CPM-4030 (no longer in production), here you see the base being machined. I don't know what type of wood this is, it comes from an old table-top. The video shows some of the V-Carving toolpaths of the second layer: I have set a roughing layer height of 2 mm, so to reach the machining depth of -4 two layers were needed.

After these V-Carving paths a Cleanup operation has been applied. In this operation a flat end-mill has been used to clean up the bottom of the large key icon area, as the V-bit (with a sharp tip) cannot machine a flat horizontal surface. Creating such cleanup operation is one of the options that are offered on tab page V-Carving of the Vector operation parameters.



This image shows the DeskProto screen for the plug. The most noticeable change will be that you now see a mirror image: for the plug the design needs to be mirrored. Next important change is that one extra curve has been selected, all around the design. As a result now the area between the design curves and this extra curve will be V-Carved and cleared, leaving the design raised above a horizontal surface. A third difference is that for the plug we could use a smaller block of material.

First the V-Carving operation, with the offset curve around the design as extra curve. The same cutter was used as for the base, and also the same Maximum depth of -4 mm. To make the plug fit into the base (as explained in the Tutorial video) we have set the Curve depth for this operation on -3 mm.

Next the Cleanup operation, with a curve all around the block as extra curve, and a flat cutter. This operation removes all rest material round the design, at the same depth of -4 mm. The (animated) image shows the curves and the toolpaths for both operations in turn.



For the plug we have used a piece of American Tulip wood. The V-Carving toolpath took a lot of time, using an offset curve closer to the design curves will improve that. The video shows some corner sharpening movements: at each sharp inner corner in the design the V-cutter moves along a sloped path to the top of the material block in order to create that sharp corner.

This is a relatively soft wood, so the cleanup operation could immediately machine at full depth, with a large stepover.



The use of V-Carving toolpaths makes the assembly a simple process: after applying a generous amount of wood glue on both parts they can simply be combined: the V-Carving makes this a self-centering process. Tightly press both parts together and leave them overnight for a secure connection.



The next day I have removed the remainder of the plug. As this sign was too large to fit in our small band saw I have done so with the CNC machine: simple toolpaths for a flat surface. In order not to damage any small details the final layer, as shown in the video above, was very thin.
Final operation on the CNC machine was drilling the four mounting holes, done in a Vector operation (tab drilling), with a drill as cutter.

The next step was sanding the sign, to make its surface completely flat and smooth. Finally two layers of transparent varnish have been applied, to protect the sign (to be used outside), and to deepen the color of the dark wood.



This is the result: a nice wooden company sign, mounted next to the front door. Note the brass screws, in style with the wooden sign. The NFG (Nederlandse Federatie Gezondheidszorg) is an independent organization that monitors the quality of the care provided by the affiliated professionals.

I am quite happy with the result (and so is my partner).
Nevertheless improvement is possible. The light color wood (American Tulip) was too soft: some of the small characters were damaged as a small sections broke off while machining. Using a harder wood type would be better. An alternative solution could be to use a larger size: the font below the key icon is quite fragile due to its small size. Using a darker wood color for the base can also be a way to improve readability, however, these colors are in fact very nice for a door sign.