This tutorial will guide you through the milling process of single sided PCBs

You can use the example files from our download site, or use our EAGLE CAM-Job to create the Gerberfiles for your own project.

Example project: LED Backlight

Open the MINImill Software

Connect your qBot MINImill and press the Unlock button. Your MINImill will start homing.

Open the PCB Tab

Open the PCB Tab of the software, by clicking onto the “PCB” Symbol in the bottom toolbar. On the right side you can open the gerber files for top, bottom, drill and outline.

If you want to use the Gerber- files used in this Tutorial, you can download them at the first step.

You should generate the Gerber-files according to this list, or just download the preconfigured CAM-Job (EAGLE-only at the moment)

Top: Top-layer traces, Vias, top-SMD-pads, Through hole-pads
Bottom: Bottom-layer-traces, Vias, bottom-SMD-pads, Through hole-pads
Drill (Excellon): Drills, Holes, Pads, Vias
Outline: Dimension, Milling

The outline must have a width >0mm, and must to be one closed shape. Milling-features inside the outline are ignored, only the outermost one is being milled.

Open your gerber files

Click on the files and open them accordingly (For the Top Layout – open the Top Layout Gerber file, for the Drill Layout- open the Drill Gerber file, for the Outline Layout – open the Outline Gerber file).

Note: If you are milling single sided PCBs, don’t open a bottom file.

The progress-bars indicate the success of your conversion process.

Grey: no file loaded
Yellow: Conversion active
Green: Conversion successful
Red: Error

Note: If you drew your single-sided board in the bottom-layer, just load the bottom file into the top layer and leave the bottom empty

Place your file on the PCB

Click on the part and drag it until it is within the PCB (use the left mouse button to drag, the mouse wheel to zoom and the right mouse button to turn your work table), and where you want it to be milled – be careful that the whole part is within the cooper-colored PCB, and that you leave enough space near the screws and the border.

Mount the PCB milling bracket

Mount the PCB-bracket, remove the protective film of the PCB and place the PCB on the provided space.

Insert the Engraving Bit

Press the play button to start the milling process – a text box will open which asks you to insert the correct tool.

Insert the engraving bit into the collet, so that it protrudes around 20mm from the collet. Use the 13mm and 17mm wrenches that are provided with your MINImill to tighten the collet nut. Be careful not to overtighten the nut!

Remove the protective sleeve after you have inserted the engraving bit into the collet. This way the bit will not be damaged if you accidentally drop it.

After inserting the engraving bit – confirm the tool change message.

The engraving process

After pressing confirm – press PLAY to start the engraving process.

After you press PLAY MINImill will start to measure the toollength, and probe the surface of the PCB.

The heightmap generated during this step is used to make a virtual image of the PCB in your MINImill, which is then used to recalculate the GCode and make everything perfectly flat. Do not touch the PCB after the probing is done or the height could change, and lead to not perfectly milled PCBs!

After the measuring procedure is done, MINImill will start the milling cycle automatically.

Change to the drilling bit

The MINImill software will pop up a window, asking you to change the engraving bit to the right drill. The procedure is the same as for inserting the Engraving bit. Again, pay attention how firmly you tighten the collet nut.

You’ll notice when you go to take tools out that there is a tight/loose/tight/loose again torque response as you unscrew the nut, as the collet “sticks” a bit to the tool. The tool is still fairly tightly held until you pass that second sticking spot. Once you get past that, the tool will fall right out, so be ready to catch it!

Confirm the tool change message to get to the next step.

The drilling process

Confirm the tool change message and press PLAY to start the drilling process.

MINImill will measure the length of the tool, and automatically drill all holes. If a drill with a different size is needed you will be asked to change the drill to the new one.

Note: The size is displayed in inch or mm, depending on the settings of your CAD-program.

Change the drill bit to the outline bit

You will be asked to change the drill bit to the outline bit (2mm endmill, suited for hard plastics).

The procedure is the same as described above, after pressing confirm and play, MINImill will measure the toollength, and automatically start the milling process.

The outline milling process

After pressing confirm and PLAY MINImill will start with the outline milling process.

You do not need to take any actions here. MINImill will do several passes, until the part is finally cut out, and ready to be used.

Use a vacuum cleaner to clean away the dust, and be careful not to suck in your part. If the edges of the part and the traces are a bit rough you can use wet sandpaper (1200 grit and above) to sand them down. For this, lay down the sandpaper on a flat surface, wet it with some water, put the PCB on the sandpaper with the traces down and use circling motions to sand the edges down. You don’t need a lot of pressure for this, and you should also not do this for to long, as not to sand away the trace. Be careful not to overdo it.

The finished part

When you are happy with the finished part you can use some industrial alcohol to clean away any oxide (this is not necessary if you used PCBs with a protective film).

We would be happy to receive pictures of your finished parts for our instagram site!

Happy milling!