Introduction

Next year is the 100th anniversary of William Shockley (1910 –1989) the inventor of the Transistor ( a milestone of the third millennium), and the father of Silicon Valley and finally it's the 580th anniversary of Johannes Gutenberg who introduced mechanical movable type to the world a milestone of the second millennium. In the framework of global paradigm shifts this week is exeptional. We will learn different tecniques of making Printed circuit board (PCB), mounting electronic components and finally programming them. The evolution of mounting schemes used for electronic components is very interesting:
1.Point-to-point construction (tag boards or turret boards)
2.Through-hole technology (THT)
3.Surface-mount technology (SMT)
I liked Honghao Deng's example, he made a version of FabTinyISP AVR ISP programmer/board using vinyl cutter and copper foil tape. He gives a tip that transferring copper foil from it's original backfilm to transfer tape's backfilm dramaticaly increases the quality of the cuts. So I wanted to try this.

FabTinyISP

I recommend to read this paper Demystifying the FabISP before making the ISP In System Programmer, where you can learn in detail the purpose of each component on the board. Here are some points that I belive are essential:
1.Pull-Up & Pull-Down Resistors
2.Decoupling Capacitors
3.Diodes

Making of PCB

We will mill the Printed circuit board and solder the componets. The milling machine that we'll use is Roland-monoFab SRM-20 you can find it's manual here. We teamed up with Miqael to explore our machine and to mill the recommended linetest pattern and it's cutout. We used 1/64in(0.4mm) endmill for milling the PCB traces and 1/32in endmill to cut out the PCB from the base material in our case FR-1.

Setting up the Machine

It's always a good idea to follow the manual.
1.Make sure the machine is clean of cutting waste.
2.Turn the Power On
3.Open the VPanel (This is a dedicated software for controlling the machine)
4.Confirm the Command Set (in our case we'll be using NC code-Numerical control) This is the "language" that we'll be using to communicate with the machine and send the cutting commands.

5.Check the total Spindle motor rotation time (image below). It is recommended to change spindle motor after 500hours in our case it was about 27hours so we are ok to go.

6.Attach the cutting tool (image below). It's a good idea to mill the surface of the material and make the cutout from the base material after. In our case we will use 1/64in(0.4mm) endmill for milling the PCB traces and 1/32in endmill to cut out the PCB from the base material in our case FR-1. I made some macro photos of the endmills. They are magnified 200 times.

7.Attach the material to the table (image below).

My advice on this is to take out the table (unscrew 4 screws at sides) and clamp the board for 5min to increase adhision, be careful not to tighten too much this can bend the table. Put something between clamp jaws and the table to keep the board and the table safe from scratches.

8.Set the origin point. Select [Machine Coordinate System] in our case will use G54 and G55 that's the first 2 of 6 Work Coordinate Systems. Drive the bit to desired location with [X/Y] buttons shown above, and hit [X/Y] set origin point button in the right side of the Vpanel interface shown in the picture below. Drive down the bit just a little bit above the material using the [Z] buttons shown in the picture above. Unscrew the tiny bolt that holds the milling tool in place, support the tool with your finger so it drops and touches the copper surface. Fasten the bolt, but not too hard. Once done hit the [Z] set origin point button in the right side of the Vpanel interface shown in the picture below.

Getting the cut files and generating the toolpaths.

At this point an image should appear under the selection we just did and a detailed settings on the right side. (image below). In "output" section you can set the
1."cut speed" (Cutting speed) is the speed difference between the cutting tool and the surface of the workpiece while the tool is operating on it. The units are mm/s (milimeters per second).
2."plunge speed" is the speed at which the router bit is driven down into the material when starting a cut and will vary depending on the bit used and the material being processed. The units are mm/s (milimeters per second)
3."jog speed" is the speed at which the bit is driven when it's not in contact with the material (when the bit is not cutting). The units are mm/s (milimeters per second).
4."jog height" is the height at which the router bit is driven up when it's trying to move from one working area to another. The units are mm (milimeters).
5."spindle speed" is the speed at which the spindle is turning the bit. The units are RPM (Revolutions per minute).
6."cut depth" is the depth which the bit will remove from the material material. The units are mm (milimeters).
7."number of offsets" I couldn't get a precise definition for this setting, but what it actually does it adds toolpaths near the main toolpath while adding a space between them so the bigger the number the more times the tool will travel near the same place and eventually remove the copper near the traces. It's default value is 4 but I tried with 5 it took slightly more time but let less extra copper near the traces that had to be removed manually after. I would recommend to put 6 in order get less extra copper near the traces.

The default values work completly fine so hit "Calculate" from the right side of the interface and you'll get a toolpath like in the image above. Now save it. Now do the same thing for FabtinyISP cutout but instead of "traces 1/64" select "cutout 1/32" in the process tab of Fabmodules.org, now save it. The default Work Coordinate System of Fabmodules G-code is G54, but changing it is easier than you think. Just open the .nc file (G-code) with a text editor any will work. And find the G54 somewhere in the starting part of the code.

Cutting process

Open the V-panel make sure the 1/64 endmill is on the tool and is zeroed. Push the "cut" button from the interface hit "Delete all" to remove previous NC codes, now select the NC file you generated for the traces it's name should be "fts_mini_traces.nc" Change the speed value to 10 at the start of the cutting in order to have more time to react if something goes wrong. If everything is ok increase the speed to 100.

Soldering components

FabISP needs the following components

• 1x ATtiny45
• 2x 1k resistors
• 2x 499om resistors
• 2x 49om resistors
• 2x 3.3v zener diodes
• 2x LED
• 1x 100nF capacitor
• 1x 2x3 pin header

Programming the board

For programming the FabISP you will need

• An Ubuntu computer with 2 USB ports
• AVR programmer (in my case it was avrisp2)
• "avrdude" and "avr-gcc" installed (Need to install? go HERE)