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8. Computer controlled machining

This week I want to show you my experience with the CNC machine, it configuration and the work I have realized.

Welcome to our FabLab Controlled Machine

Now I am going to explain our FabLab CNC,

- Alarsis FRH 250
- Cutting Area - 245x125 cm
- Z Max High - 12 cm
- Resolution - 0,005 mm
- Speed - 20 m/min
- Milling Head - 6000-24000 rpm
- fixing method - suction

You can find other information here:

First steps

We always start changing the mills with the machine off! it is important to our secure.

It´s important to choose the better mill for each type of cutting too. In this case we will use 4 - 6 mm mills because the are enough to cut a MDF panel.

Now you have to prepare the machine, to change the mills in case you have to replace it. We recommend to put something soft below not to break the mills in case of falling.

Our machine as I have said has a suction system that fix two panels

- Wooden martyr panel
- The wooden you are going to use

Here you can see it:

Now its the turn to say to the machine where is the XY origin. In this model we have 2 options: One with the control panel putting the mill in the corner of the wood panel; Second we use the laser reference. This is the option I have used. Just go with the laser cross to the corner and fix it with the button laser origin

Finally you have to calibrate Z axis with the calibration test. Just put it below the mill and with the control panel just press z0 calibration and DO NOT FORGET TO CONNECT IT TO THE MACHINE!! The mill will down slowly until contact with the metal piece.

Model to cut

For this assignment I want to create a machine that will help me in my final project. It consist on one PP Yarn Winder but around a yoga ball. The objective is create a yarn ball with a polypropylene filament or a similar plastic, warming it, and stopping when the fibers will melt. Then I want to know if it is structural enough.

So before milling in the machine I decided to replicate it in a little test model cutting in Laser cut machine. And I can see that everything is correct so we can continue.

You can download the files here:

Ready to mill

Our machine uses Vcarve Pro software to mill in 2D. you can find it here:

Star opening the program and the first thing you will to configure are the measures of your wooden board: In our case 2x 600 x 1200 x 19 mm MDF / 23,6 x 47,2 x 0,74 in

Now we generate the configuration of the vector that will be the path of the mill.

  • Deep of cutting - in this case 20 mm because the board is 19 mm
  • Selection of mill - universal 6mm because we want to be accurate but fast as the same time
  • Number of paths in deep - I have decide 3 paths NO 2 AS YOU CAN SEE IN THE PICTURE
  • Direction of paths - You always have to generate first inner cuts

Now you have to select the tool and its properties.

Here you can see the parameters of milling i have used:

  • 4mm universal mill
  • 3mm of depth each path
  • 1400 r.p.m.
  • 2000mm/min Feed rate
  • 750mm/min speed when down

Continue with more options.

  • It is highly recommended add tabs. This is useful when you are cutting the outside paths and you want you piece good fixed. If you don´t fixed your pieces they could be very dangerous for your machine and for the security

  • For the mill effort is recommended too add a soft cutting ramp
  • Finally Calculate the path

This program has a 3D simulation with the parameters you choose. Here we can see the vector, the paths, even the tabs of each piece.

If you make zoom you can see the simulation by layer of the depth of each path when the mill pass throw.

I have to say that our machine new and its perfectly calibrated maybe in the future we will need to do a press-fit to know the best approximation to the fixing measures but now I didn´t need to do anything and my pieces fix very well and without slack

Process and results


Always use a glasses and ear protectors

Here are the cuts of the boards and little details I have found interesting to let you know it.

After milling It´s necesary to remove al the dust of the wooden board to keep the FabLab clean, check all pieces are OK and it will be easy to find taps and cut them.

If you pay attention you can see the famous tabs to fix pieces.

Finally I have jointed all pieces designing with dogBones as you can see here.

This is the result and here I could checked if there was any important structural problems. I know it is not finished but this machine is for the last assignments so I have time to complete it later.

But I discovered one error in the design!! I didn´t realized that I forgot to make the dogBones joints in those pieces!! There is no problem because it is not an important structural piece.

Thank you for read and I hope you have found this interesting and useful.

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