Recently I bought some 1.5mm thick Walnut sheet as I wanted to try it out with my CNC router and see how good the results would be. Walnut is quite a dark wood with a nice dense grain, so it seemed like an excellent opportunity to take my CNC intergallactic by making a small inlayed Darth Vader from Star Wars. Hopefully George Lucas will approve if he happens by, so below is my completed Darth Vader head (at around 10% water content, in case you’d like to know).
I was quite pleased with the results, the details being routed to 0.75 mm deep in two passes, and the edge being cut in three passes, using the 1.2mm diameter end-cutting bit shown above (which gave finished grooves almost 2 mm wide). As the image at the top of this page shows, the Walnut sheet cut quite well and cleanly with the spindle at 1000 rpm and a feed rate of 50 mm/min to minimise potential breakage of the bit. The above photo is then after I’d given it some sanding with a fine grit paper, which took little work. Even sanding out the recesses with folded over sandpaper was quite easy, with a little patience. So overall I’m looking forward to some more small projects using this lovely wood.
CNC routers are wonderful machines for cutting and shaping wood and other materials but sometimes there’s no choice but to use a router without computer control. For example, when trimming the edges of wood to size, or for using the router as a finisher with sanding drums. When that kind of work is needed I don’t want another machine: rather I want to use my CNC router for occasional manual feeding. To do that a fence is very useful, as it allows pieces of feedstock to be pushed past the tool/sander in a straight line. Not only can that help ensure edges are kept parallel, but it also allows creation of small mouldings with edge-shaping bits.
This 3D printing project is my attempt at creating a very simple fence system for my cheap Chinese CNC. The fence part simply slides into the groove along the top of the CNC bed, after light sanding to get a good fit that doesn’t wobble. However, for manual feeding we don’t want the fence to be able to move along the bed groove, so a part is included for a simple stop that can be used to prevent that happening. The stop connects to the side of the bed using a winged hold-down nut as shown in the photo below. You can download the 3D printing files by clicking here, including the OpenSCAD file for any adjustments you’d like to make.
Hopefully you won’t mind if I finish with a word of caution. But, using a CNC router for manual feeding of materials brings risks you may not be experienced with. Probably two of the main ones are the dangers of having hands near your tool/cutter (which can be avoided using a proper push/feed stick) and extra dangers of pieces of tools and feedstock breaking and flying away (which can be largely avoided by feeding slowly and wearing sensible clothes and eye protection).
Another rookie error is to feed material with the rotation of the tool, which means it could unexpectedly get pulled through and shoot out like a javelin (I did that on a router table years ago and it’s amazing how fast the expelled material can be). Not only is that dangerous: it can even ruin your work. You may also want to wear ear protection as the sound level will be higher working close to the motor and tool. Basically, please be very careful and don’t take chances using the 3D models provided here 🙂
Many cheap CNC routers are based on 20mm square extruded aluminium frames, with slots and a hole running along them to attach fixtures. Often the four pieces of the frame at the bottom lie directly on the underlying surface, with no supports at the corners. That can be a problem as routing can cause a fair bit of vibration that can be transmitted straight into your work surface. If left unchecked, that can lead to annoying noise as the work surface and adjoined walls and floors vibrate with it. So, I designed this simple foot that can be slotted into the end of a 20mm extrusion that lifts it off the surface below, and which you can also use to add a small rubber or felt pad, further reducing noise and vibration. To get the STL files for 3D printing just click here.
Mahogany is a wonderful wood with fine, beautiful looking, grain. It’s ideal for any CNC routing project where you want to give your work a professional, and high-quality, look. So I thought it a good idea to write a short article about my experience of working with it on my cheap Chinese 1610 CNC machine. I decided I’d use a small (c. 50mm or 2″ long) fish design because it includes some shallow work for inlay, as well as a full-depth cut around the outside. The sheet was cut from a 1.5mm thick sustainably sourced plank and, according to my meter, had a water content around 9%. Below is a photo of the wood on the CNC during cutting.
As this was a small piece I chose to use a 1mm end-milling bit, so that the shallow details would look tidy. Bits/tools of that size are easily broken through overly deep or fast cutting. For that reason I cut in two passes for the shallow details and three for the outside cut-through, which equates to between 0.5mm and 0.6mm depth per pass. Also, I kept the feed rate down at 50 mm/min which, although a little slow to watch, usually keeps my small diameter bits in one piece. The spindle speed was the maximum of 1000 rpm which, together with the low feed rate, provides a nice clean cut in my experience.
As you can see in the photo below, after just a light sanding, including using a folded piece of sandpaper to run along the shallow grooves, the fish looked quite nice. The only issue I’ve found, if it can be called an ‘issue’, is that the cutting tolerance around the bit is a little more than I’d like: with a 1mm diameter bit I ended up with 1.5mm wide grooves. That’s a 50% overcut which, given the simplicity of the spindle system, and the amount of vibration, is probably technically not bad for a small tool, although it does cause some difficulties cutting thin grooves for things like hammered wire inlaying. Overall though, my experience is that Mahogany can give inspiring and impressive results.