Portal milling machines are cnc-machines milling small and big size pieces in 2D,2.5D and 3D. Their have a bridge like construktion and are equipped up to 6 achses. FabLab Kamp-Lintfort has a big size 'Easyworker' from 'elsign'. CNC-machines in general one has to handle carfully and watchful. In the following section I will explain some basic security advises.

Safty Instructions

Working Preparations

Designing a chair

In the shortness of time I wanted to build something easy. But I like bendable and folding elements very much. So I thought about a chair with bendable seat. I underestimated the processing power you need for bending structures. My small computer frequently crashed down.
Now, about the features: The main feature I used was setting parameters. I didn´t know exatly which tool I would use and I wanted to be free in changing the materialthickness:

sketch chair

Sketch of my chair.


A wooden fastening.


Under 'Modifiy' you will find a Sigma sign for the parameter window.


If you click on the sign a window will pop up, where you can set, modify and name the drawing lines. Here you will find all lines.


You can change 'name', 'unit', 'value'. And your drawing will adapt all linked lines.


If you draw new lines whith same sizes e.g. depending on flut diameter of a milling cutter. You don´t need to write the length you just write the name of your specification you set before in 'parameter'.


The top view of ready to cut stool.

Downloadfile Aleks' Stool

CAM Processing

For milling your object all lines need to be joined. They should not overlap. We opened my file in Rhino to prepare it for milling and for a long time we couldn´t find all overlapped and loose lines. Even if Fusion 360 shows everything is o.k., Rhino software denied. But if you want to mill in one line and only one line is loose the milling machine can´t start milling. After finding all loose ends we could prepare the file for milling and transfere the data to the milling machine via stick.

Additional preparations: As the milling computer can read the colored lines we marked all inlines green and all outlines red. Also, we wanted to check out first if the bending will work with 12mm Multiplexmaterial and if the click joint will function. We cut out a piece of bending structure and just one click joint. Both we transfered to the machine to.

cut test

coloring lines

After transfering it to the machine we located the lines by color. In Properties we created layers assigned to colors.

set properties

By this we could choose an actual layer for milling.

 cut layers

In 'Layers' we can change layer settings or copy objects to define layers.

locate by color

Afterwards we chose the process type: Offset. Because we wanted to cut out just along the lines. No engraving, no pocket process.

process type

Then we set more preferences like 'Safe-Z' or 'Start-Z' and 'FeedRate' and 'SpindelDirection'.

Feed setting

We calculated the toolpath:

calculate toolpath

It was time to set home coordinates for the milling head. By using the hand control we could set the starting points for xy quite easy.

hand control

xy home

Milling head at home

Z-achsis we set seperatly in the following way:

Feed setting

Feed setting

start icon After everything was done I had to start the milling process.

Cutting process: First inside cuts,

Feed setting

afterwards outside cuts. Inside cuts means the milling flute stays inside the line. And outside cuts means the milling flute stays all time outside the line, to preserve the material thickness.

Feed setting

In the picture above you can see the G-code (G1..., G2...,G3...) running for each process.

Milling Process

First we had to turn on the vakuum for all parts the plate is overlying. Press the green lights.

turning on vakuum

start milling

milling seat

milling beam

milled stool

First tests:

I wasn´t sure if 12mm Multiplex will bend as I wanted to bend nearly 90°.

bending test

Also, the click joint I had to try because of only 4cm cut. It worked out.

plug test

The hole seat is enormous flexible:

bend seat 1

bend seat 2

Finally, I' assembled my stool without any glue and screw. The click joint is very strong.

1Finished Stool

2Finished Stool

3Click Joint

4Finished Stool

Downloadfile for milling:

Aleks'Stool DXF-File