4. Outil Fab Lab sélectionné#

At the ULB Fablab, Christophe Reyntiens is a CNC (Computer Numerical Control) specialist and I was lucky enough to be able to attend one of his workshops about it. The purpose of this workshop was to get introduced on fusion 360, modeling a design and create it thanks to the CNC.

Software for the workshop#

One of the assigments was to come to the workshop with Fusion 360 installed. I could do it from the Autodesk website and thanks to the univerity, a one year subscription is given to the students assisting to the cours.
Beside that Christophe introduced us to the Hoffman manuel that gives all the details of the material that I’ll and that I used.

The first day of CNC was used to understand fusion and how to use it. I have to be completely honest, Christophe was going a bit fast and I wasn’t able to record everything he explained. I was helped by an assistant of the Fablab without who I wouldn’t have made it to the end. So I’m going to explain as best I can the stages I went through.

4.1. Stages through Fusion 360#

First of all, to maneuver your model using familiar controls select: help-> quick setup -> Solidworks. If your are a beginner on Fusion it might help you more than once. Let’s get started!

Define the axes#

One of the most important step regarding Christophe, is the the definition of the axes. The object that we design to plug in Fusion has a particular base on wich I must define the x, y and z axes. The axes are used above all to define the point(0,0,0) on our model so that we help the magine find her way. I was told that the x axe belongs to the longest side and the z axe to the shortest one. At the Fablab, the CNC has an x-axis of 1000 mm and a z-axis of 15 mm but that refers to the machine’s zero point. That means that the object that someone wants to design may not exceed 1m on the x axis.

How it’s done ? :

Select in the corner left Manufacture -> Setup in milling -> New Setup. A window will open such as this one: The red boxes are the important parameters to change: * define the orientation according to the Z axis/plane and X axis * define the z axis in the right direction with Flip Z Axis

The last red box refers to the precise point on which I define the point (0,0,0) of my design. This is set by Stock box point and Box point. I simply selected a point that I considered the best.

Define the stock#

In this part I’m setting up the stock that has the same dimensions as the pièce of wood that I selected to produce my design. You can find it in the same section as the axes. Manufacture-> New Setup -> Stock. To set the dimensions of my stock I selected mode -> fixed sized box. Mine was fairly big and I made sure I had enough height to avoid burning the floor of the machine.

Define the tools#

As seen earlier in the Hoffman’s manual, many tools are available. Depending on the shape I want and the material I choose, a particular tool will have to be selected to avoid burns, breakages, etc. This also modifies the cutting trajectory and the whole process. Everything written in the manuel about a tool must be set in Fusion for it to work properly. It’s also a key stage. The path to access the settings is as follows: Manufacture-> Manage -> Tool Laboratory. A tool needs to be added. The flat and mill option was chosen using the ‘+’ at the top left after selecting a file.

Afterwards, here is what was recommended :

Define the Face#

In order to shorten the path only along the part (which will shorten the intervention time) I selected Face-> Geometry and pressed on the lower ridge. I’ll be honest, I wasn’t paying much attention at the time, but thanks to Lucia’s Module I was able to get back on my feet.

Define the Pockets#

When I designed my piece, I added different levels. In order to define the pockets through which the milling cutter will pass (holes done in the wood), pockets need to be set. These are the step I went through:

2D pockets#

I selected 2D-> 2D Pocket-> Geometry. By pressing on one side, I select a pocket that I want to create. By pressing “ok” the Software sows me the milling cutter’s path and the amount of and how many turns it will take to create the pocket. Something that I completly forgot and and which is of great importance, is the Maximum Roughing which can be founded in 2D Pocket-> Passes-> Multiple Depths. It allows me to shorten the time of intervention because the pocket will be cutted in 3 parts if the Maximum Roughing is 3mm deep and the pocket 9mm.

Stock to leave#

In the same section than the Maximum Roughing, Stock to leave anabled me to remove excess thickness so that I don’t have any extra material.

2D Adaptive Clearing#

This section can be used to pass with the milling cutter through open pockets (see below). As there are none in my design, I don’t need it at all. .

Define the Contours#

To cut the outer edge of the piece, I use a 2D contour, selecting the bottom outline of the piece as a closed loop allowing everything to be cut off. A 3mm Maximum Roughing is also selected here in Passes.

We were advised that instead of doing the contour gradually in layers, we should do it by ramping down the piece. I selected Linking-> Ramp. "Lead-in (Entry)" and “Lead-out (Exit)” must also be unchecked.

Define the tabs#

In order to keep the piece in place while the CNC does the job, tabs must be added. I selected Geometry-> Tabs-> Tab Positionning-> Number of tabs. I decided to add 4 tabs because in my opinion it’s more than enough.

Good to knows#

inspect -> is used to determine the distance between two aretes.

Results#

I’m very happy to have learned how to handle a CNC. I like my object but it’s not the size I wanted. Never mind, I’ll make another one.

Prepare the CNC#

The CNC can be booked thanks to Fabman. An easy-to-use booking site.

Once the G-code has been programmed on Fusion (Manufacture-> Actions -> Post Process), the CNC can be launched thanks to the Kinetic NC app.

Once we have: * Opened the application * Targeted the board on the CNC * Follewed the safety rules

The CNC can be controled by using WinPC-NC USB.

To start cutting, press OK.

Safety rules#

Safety rules have been described by Christophe and must be scrupulously followed. They include in particular: * Noise-cancelling headphones must be worn * If you leave the room, the machine must be stopped. * Switching on the hoover

Improvement points#

At the first conference, I didn’t take enough notes for my documentation and to remember the stages Christophe had gone through. So I had to ask to attend a second time, which wasted a lot of time. So it’s important to take note and pay attention. A judicious choice of wood is important. Mine crumbled easily. Apart from that, I’m happy with what I’ve done and I can’t wait to use the CNC again even if I’m not very confident about using the machine.