3D Printed CNC Mill Directions
Summary
This is a small, mainly printed small table router for anyone who just wants to try out
whether a CNC router or engraving machine is something for them. Ideally, you already
have some of the required parts such as stepper motors, power supplies etc. lying around.
I have wanted to build a CNC milling machine or a CNC engraving machine for a long time.
Simply out of technical curiosity, I couldn't imagine any real use other than engraving
PCBs. So I wanted it to be inexpensive, but with the best possible features.
So I came up with the idea of designing a CNC machine with as many 3D printed parts as
possible to keep costs down. All the parts fit on the print bed (220 mm x 220 mm) of my 3D
printer.
The result is a machine with the following data:
• Work volume (xyz)mm: 120 x 120 x 60
• Frame (xyz)mm: 275 x 275 x 320
• Motor: DC motor, 24V, 200W, 52mm diameter
• Spindle: 10000rpm
• Axes: 3 x NEMA17
• Controller: Arduino Uno with GRBL shield
• Firmware: GRBL 1.1
• Special features: backlash prevention, end stop, cable management
• Supported materials: Acrylic, wood, PVC, PCB and possibly soft metals
Cost if you have to buy everything: approx. 160$ - 200$
Construction
The current version is relatively rigid, I used PLA for the frame, which is a stable, hard
plastic. The thermal impact of these components is low, so PLA is well suited and also an
inexpensive material. The guide rods with a diameter of 10 mm in the X and Y axes and the
short length also contribute to stability. In addition, I have provided the corresponding files
for all those who already have 8mm guide rods lying around.
For the first version, I decided to insert the screws directly into the plastic without heatset
inserts. With the smaller threads, the screws can be screwed directly into the plastic
without first using a tap. As the screws heat up relatively strongly when they are first
3D Printed CNC Mill Directions
screwed in, I recommend waiting a moment for cooling down before finally tightening
them. The M5 threads should be pre-cut.
Features
I attached the (optional) limit switches with adapter plates. This makes it relatively easy to
set the trigger point. If limit switches other than the ones I chose are used, it is possible to
modify the adapter plates with little effort. Practice has shown that the limit switch cables
are very susceptible to interferences. I did this by using shielded audio cable for the wiring
and also galvanically isolated the signal with optocouplers in accordance with the
instructions 'Wiring Limit Switches' in the GRBL wiki.
The use of the backlash prevention nuts is also optional. If these are used, I have found
that the spring supplied is rather weak. Ideally, the spring should be replaced by a stronger
version with the same diameter.
The cable management is realized by a cable chain on the X-axis and feedthroughs for
cable ties on the side panels.
Controller
I used an Arduino Uno with GRBL shield and A4988 stepper motor drivers as the controller.
I will not provide any further information on wiring here. I assume that anyone who builds a
machine like this knows what they are doing or is able to follow the countless instructions
on the Internet.
Printed Parts
For the mechanically stressed 3D printed parts, you should ensure that the wall thickness
is sufficient, i.e. the perimeter thickness should be 1.6mm - 2mm or more. Not to be
forgotten are the horizontal layers, which should also have these dimensions. The
mechanically stressed parts include: Base-Frame, SidePanel_Left, SidePanel_Right,
RearStrut, Y-Sled, X-Sled, Z-Sled, X-Sled_BottomPlate and X-Sled_TopPlate. PLA can be
used for most parts. This results in the required rigidity for the frame construction due to
the material properties of PLA. I printed the X-, Y- and Z-sleds in PETG, as this is where
most of the vibrations occur and this material can absorb them better.
Files
All printed parts are available as STL and STEP files. The STL files are already aligned for
printing. Also published is a parts list (BOM.txt) and an assembly in STEP format with all
parts including screws, so that a good overview of the project is possible. You are also
welcome to use the STEP files for your own modifications and remixes
