Reference PCB Business Card on a CNC

I’ve found myself in the situation a few times where I was trying to explain that PCBs can be routed using a low cost CNC, like the 3040 CNC I purchased on Ebay a while back.  Since I have routed dozens of PCBs this sounds obvious to me, however it is not very obvious to some of the engineers I have explained it to, it seems as if they can’t visualize what can be accomplished.  In those moments I wish I had an example PCB to show them.  Not to mention  a few times I was stuck without a quick way to measure small lengths, or I wanted to know the SMD footprint used for a resistor to see if I had one, or when I needed to compare the pin spacing of a cable to see if it is 0.1″.  A few days ago I found a post about TinkerRule, a reference PCB that could be used to solve pretty much all the engineering scenarios I just mentioned. I really liked what they did and it inspired me to see if I could make a reference PCB on my CNC in the form factor of a business card to fit in a wallet, that way not only would I have a useful tool, but I would have a demo of the capabilities of my CNC PCB router too!

It turns out that my small 3040 CNC is quite capable of making a 2.125 x 3.25″ PCB business card with a number of useful features, including an inch ruler, centimeter ruler, some reference traces, reference vias, reference holes, and  0.1″ grid.  The board also has 150 mil letters so it is easy to read.  Plus, since the single sided copper board I used is only about 50 mils thick, it’s only 50% thicker than a credit card, so it isn’t a noticeable addition to my wallet. This was the first pass and there are 2 missed sections, this was due to my setting of the router bit a little too shallow…things to fix on Rev 2.

I have uploaded the Eagle PCB and GCode so anyone can download it and try and make their own: biz_pcb.brd & biz_pcb.ngc

I already have identified some things I want to change on Rev 2, any ideas or suggestions?