Fab Academy 4

Electronics production

This week we were learning electronic production. Not so much about designing the circuits, but more about cutting them in the milling machine and soldering them. We created a LED BADGE and a USB to FTDI PCB board´s.

We Milled them in a SRM-20 milling machine, and for that, the first we had to do, was to prepare the files in the MIT MODS platform.

USB to FTDI

LED BADGE

MODS platform

Mods

Here I specify with images tha basics of the Mods configuration, but I want to highlight some important things:

It´s important to know the thickness of your material and not using the preset always because that could also damage the endmill.

The starting speed for a new endmill should be setted to 3 the first time you use it if you are milling traces. Remember also to set the speed of the milling to 0.5 if you are doing outlines.


The jog height neds to be at least 2mm above the 0 so that the endmill doesn´t breaks of scratches the material, this also for the Z home. I would recommend to have it at 5mm - 10mm. If you put it to high, it will loose a lot of time going up and down each time it moves.


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LED BADGE

Generated in Mods

We use this board as an initial soldering practice, before switching to the  USB to FTDI, which has more complicated components such as the microcontroller.

For this we had to use 10 LEDS, and we decided to use 5 red and 5 green to have variety. We also decided to use different types of resistors such as 200 OHMs, 100 OHMs, 49.9 OHMs, 10 OHMs and 1 OHMs, to see the difference generated by them.

USB to FTDI

Generated in Mods

SRM - 20 Settings

The most important thing for me in the setting of the machine, is to properly set the X, Y and Z (most of all the Z) since from that deppends also that you don´t break your endmill.

The X and Y you can set them with the Jog until you move the machine to the desired possition and set the X,Y origin. But for the Z, you have to lower it slowly (10x max) untill you arrive really close to the material. After that you should release the endmill and let it touch the material and then set the Z origin. Sometimes you have to put it a little bit lower so it properly cuts the material.

Then in the setuo, you load the files in the order to be milled. First the inner parts, then the outher ones. First the holes, then the traces.

We used 1/64 endmill for the traces and 1/32 for the outline. One tip I use to change the endmills is to cover them with the blue cover they have while changing them so if they fall they don´t break.

You can start at medium speed while checking everything is ok, and then put it to full power.

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