Transform 3D Printer to CNC Milling Machine

To transform the printer in a CNC milling machine first of all it is necessary to have the equipment, small hardware and various elements (visible in the picture), of which we give the full list.cnc-tools


After we completed all the parts needed for the modification. Now we can finally modify the 3D printer K8200 or the Prusa 3d printer — to transform it in a perfect CNC milling machine, to be used for the production of PCBs, or projects. In addition, we will also show you the procedures to obtain the G-Code file required for the machine to perform the contouring of the slopes and the drilling of the base: this starting from any Gerber file or from a project made with EAGLE software.


The first step is to use the K8200/Prusa to print the bracket for the mandrel/dremel whose file can be freely downloaded from the following link: The bracket, fitted out with a collar with a 20 mm hole, allows you to attach to the structure any electric-mandrel with cylindrical collar having the same diameter.

To secure other types of electric mandrels/dremel you need to change the bracket collar, creating the same kind of thread present on the power tool (by editing the skp file). To use the printer modified as CNC milling machine is necessary that the work plane is perfectly coplanar with the tool in order to obtain a uniform etching of the whole printed circuit board. For this purpose it is necessary to carry out a particularly precise adjustment as described later. For this adjustment can also be used a comparator to be mounted on the same bracket of the power tool via an adapter printable with the same printer and that, of course, will be made before you make any mechanical changes.

We recommend, therefore, to print one or both plastic pieces before proceeding with the printer changes. The electric mandrel/dremel is separately powered and requires no electrical connection to the machine. The switching on and off of the tool must be done manually via the power switch supplied.


1. Insert an M5 galvanized nut in the upper arm hollow taking advantage of the opening between the aluminum profile and the front plastic frame.


2. The next operation concerns the displacement of the extruder from the original position. The extruder is fixed to a bracket which, in turn, is attached to the horizontal printer arm using 2 M5 screws. Before moving, make a mark with a pencil on the printer arm at the centerline of the bracket that holds the extruder (to allow in the future to relocate the extruder in the correct position). Cut and remove the plastic clamps that secure the wiring to the arm.



3. Unscrew with an allen key and remove the 2 screws that fasten the bracket to the arm.


4. Also loosen the two fan screws indicated by the red arrows.


5. Move the extruder over the arm completely to the left (as shown in photo). Move to the same side also the fan.


6. In this way the nozzle of the extruder will be sufficiently separated from the work surface remaining locked to the structure. Place, in a hole of the bracket, an M5 screw (indicated by the red arrow) which will be screwed into the M5 nut previously inserted in the arm.


7. Tighten the involved screws to secure the components to the arm and reattach cables with plastic clamps. Note: it is suggested to cover with a transparent film the entire extruder to protect it from dust which is generated during the PCB milling operations. In the bracket front part a cylinder head screw M6 x 35 must be inserted (complete with 2 flat washers and self-locking nut M6) that will serve to tighten the collar to lock the electric mandrel/dremel.


8. Take the illuminator (if any) and put in the only hole available a M5 x 40 screw complete with the toothed lock washer and, on the other side, with the flat washer. Note: to illuminate the work surface is also possible to use a common lamp. Re the illuminator: this element can be powered by its own power supply capable of providing an output voltage of 15 VDC or can use the same power supply of the K8200 electronic.


9. Insert the fastening screw of the illuminator in one of the holes in the bracket as shown in the photo. Into the other hole insert the other M5 x 40 complete with toothed lock washer and two flat washers.


10. Install, under the printer arm, the bracket that will support the electric mandrel with the two cylinder head screws M5 x 40 previously inserted and bolted to the two square nuts already in the arm provided for fixing the extruder as shown in the photo below.


11. Before tightening the screws, place the bracket of the electric mandrel with the centerline moved about 1 cm to the left compared to the benchmark, reported in pencil on the arm, so that during the HOME, the position of the electric mandrel turns out external to plate, thus avoiding eventual collisions with the tool.


12. Place the power tool in the collar and, after fixing to the plastic stand, insert any bit in the mandrel and verify that, in HOME position, there is no contact between the tool and the work surface.



13. Attach to the glass / mirror a “sacrificial” plan of suitable thickness (about 1 cm) in order to drill the holes of the PCB without damaging or breaking the tool. That plan could be MDF, forex, plywood, etc. … no humps, bumps or other deformations.


Note: the thickness must be such as to keep the PCB as raised as required to perform the processing without the Z limit switch is activated.

Tip: use a Set square or a caliper body to verify the plan regularity.


The mechanical changes to K8200 end here. In order to use the K8200 as CNC milling machine you must also update the firmware of the PCB printed circuit board, so that the Z axis could assume negative values respect to the position zero. To do this, download this firmware:

 Creating G-Code

To create any project with 3D printer, by milling, it is necessary to have the G-Code files for the track pattern.

You can download the test alignment g-code here:

Alignment is highly important before you start any project.

To create g-code. It is easy to make that in easel: but you need to sign-up first before you can used it. I’ve been using this website for long now – for my g-codes.

Also, if you want to ingrave images, letters, as alternatives with easel you can go to this website: this is a perfect open source website…for editing. I made alot of picture ingrave on my cnc – using this page.

If you need to have all-in-one printer(3d printer and milling machine) you can download this open source program from here:

Procedure on how to used the program is already stated in the website where you going to download the program.

Note: Always check the alignment using (right angle tools) of the cnc machine before you start any project.