Sheldon Cooper LineArt

My wife started a new project at work, and as this project is a big one, it meant a new notebook! She got a very nice green moleskin, but the cover was quite plain. As we both love the Big Bang Theory I was tasked to put a likeness of Dr. Sheldon Cooper on the cover. Rigged up a sharipe in a pen holder, and off to the races!

Original picture, and gcode here.


Tie Fighter in ASCII

I saw this CNC halftones article quite some time ago and setup the the CAM drawing quite some time ago. I never really got around to routing it, as I wanted to test it in two-color plastic instead of the painted plywood the original authors used. As luck would have it, BF plastics had some white/black material on clearance last week so I picked up half a sheet. The material is only 0.1″ thick, so I used 3m spray adhesive to mount it to 1/2″ plywood. About 30 minutes or so with a 60 degree v-carve bit and it was done! I need to pick up a 45 degree bit i think, as this one did go a little deep in places, you can actually see some wood on some of the wider letters. Still looks sharp!

The .dxf and gcode can be found here.


On the machine:


Word Clock Build

This project was one of those long-running ones which took almost 7 months from when I saw the first one out there and wanted to make one, to when I actually got started.  One of the big catalysts was Joe’s blog post on his build – so hats off to him!  Joe did perf board wiring, and I wanted to create a circuit board for the task.  The reason for this was twofold: (1) I hate perf board and (2) I wanted to build the atmega circuit and bootstrap it myself.

So if you watch the video below, you will see I failed at getting my atmega to run.  Could not figure it out!  Next time I will surely include additional LED’s (pin 13 anyone?) to aid troubleshooting.  So, that said in the zip file attached you will find my eagle schematics.  If you use them, be aware the microcontroller portion requires some additional scrutiny.  Maybe its fine, and I just messed up the wiring.  Who knows.  If you want to take a peek at it and give me feedback I would appreciate it!

Other big change/addition from Joe’s build was I added a Real Time Clock (RTC).  In my case I used the ChronoDot.  It is much more accurate, and tracking time in code was MUCH easier.  Here is my code, eagle schematic, and .DXF file for the led array.



Lighting Controller :: Part 3

I got the components mounted on the main and remote boards. After much deliberation we dropped $12 per remote node to pick up some waterproof plastic ammo boxes to put the electronics in. These boxes will be out in the yard exposed to snow/rain. The boxes worked out very well, as the 3-gang outlet box fit nicely inside. Just drilled a hole in the bottom so the cords can go in/out.

Wiring up the outlets was pretty easy. Common wire was shared across them all, and the hot (black) wire was sourced from the circuit board (triac). I did not use any ground wire as the Christmas light strings don’t have ground. I also used a pretty light gauge wire as I will only be driving a single string of LED lights per outlet.


Got everything wired up at the neighbors and everything worked well. Even with 100′ cat5 runs to some of the remote boxes everything worked well. We did have some flakeyness where it would lock up occasionally after a few hours. I upgraded the wallwart power supply to an old computer supply, and at the same time fixed a solder joint for the ground wire that looked ‘cold’. Not sure which of the two upgrades fixed the issue, but all is good now.

Below is a picture of the main controller board wired up on the workbench. Will post a video of the light show in the next update!

xmas controller

One thing you may notice is the FTDI controller connected via USB. This is due to the fact the Arduino Mega changed the way they emulate usb/serial. This new chip on the arduino is not identified by the software running the lighting show (Vixen). Using an older-style FTDI board remedied that situation…

Believe christmas sign

Its rare that my wife asks me to make something for her. I think its hard for her to get over some internal negative connotation she has with ‘homemade’. This year for Christmas she did ask me to make her a sign for the front yard. My marching orders were for it to be as big as possible, and to say ‘Believe’. My CNC machine has only a 2×4′ bed, and for the first run at this I didn’t want to be patching together multiple boards. I chose to use 1/2″ plywood, as painted I think it will hold up pretty well to the elements.

First order of business was to grab an appropriate font. I usually go to No affiliation, but they have a nice selection of free fonts, and there is no hoops to jump through to get them. I chose the new font, typed up the word, and expanded it to fill my 2’x4′ work area. I then did a profile around the word, leaving a 2″ gap all around. The ‘fanciest’ part of this design was to use vectors to draw inside the letters to outline where the lights would go. My software could then space holes along those lines, and I chose to space them 1″ apart – end the end this worked out very nicely. The only other open question was how big the holes should be. Using my calipers I found out the lights were of inconsistent size. Most were around 0.21″. In the top center of the drawing you can see where I had a few holes of differing sizes that I machined initially to determine which size hole would have the best ‘friction fit’ to hold the lights in.


I painted the 2×4 sheet bright red and let it dry overnight. From there it was off to the CNC. I had big plans to use a contact paper (for lining drawers) mask for masking off the letters so they could be easily spray-painted white. This did not work well, and I would not do it again in the future. The mask isn’t super sticky, and it had a tendancy to pull up when routing. It also had a tendancy to ‘melt’ when sprayed with the spray paint I had. Regardless, my first machine operation was a profile to cut the mask with a downcut bit. This will also prevent tearout on future machine operations using an upcut bit.

So what you see here is the mask, along with repairs to mask made with blue painters tape.
believe masked

Second operation was to pocket the letters. This was just a shallow 0.2″ pocket. I then cut out the sign, spray painted the pockets (letters) and removed the mask. The led lights inserted from the rear with a friction fit, no adhesives used. Sorry I didn’t think to take more pictures of that process. Below see both day and nighttime photos of the final product.



2013 Christmas light controller :: Part 2

The controller portion of this project will be based off an Arduino Mega 2650.  Of that the intent is to use 30 of the available digital channels.  The target for 30 is arrived that for each remote board I can get 6 channels pretty easily.  That is driven by 8 wires in an rj-45, with 2 being used for power – leaving 6.  Based off how many lights we actually wanted to hang, we decided 5 groups of 6 channels should fit the bill.  Getting to the design on the Arduino shield I quickly discovered I was limited by the 4×3 inch area provided by the freeware version of Eagle PCB design.  In hindsight I should have just ponied up the credit card and purchased the hobbyist version.  I will probably end up getting that for next years’ inevitable growth.

With the working limitations I had, I needed to break the shield up into two pieces, as I could not fit everything in the 4×3 working area.  I ended up making one board for 18 channels, and another for 12.  Here is a zip with the eagle files.  I warn you in advance the .sch files are not pretty… 🙂  They are free to use for non-commercial purposes.

Overall its a pretty simple design.  Arduino pin goes high, opens the gate on an NPN transistor.  This grounds the led on board lighting it, as well as proving a ground leg for the remote board which turns on the remote LED and Optocoupler which in turn flips the triac on.  Simple daisy chain effect.

master board

Turning that into a working board was a bit trickier, as I couldn’t get it designed as a single sided board.  That mean I had to get the board aligned perfectly after milling one side and flipping it over.  After the first board which I got close but not quite (pictures below) I figured it out on the second board.  It turned out to be much easier than I was making it..

Of importance is the get the board aligned straight along the x axis.  I did this by routing a .1″ deep square the board fit in.  The square was oversized, I just wanted a straight x-axis line.  I then mounted the board against that axis with double-sided tape.  make sure there is 100% coverage on the board.. don’t leave tape gaps as board will flex down on z axis in those spots.  I then aligned the x/y corner and etched the bottom of the board, and drilled the bottom.  The gcode for these operations were created through pcbgcode which I wrote about in another article.

To get the top of the board, flip, re-tape, and align to the x axis.  Then jog the CNC to line up on a few selected holes from the previous drilling operation.  In eagle, hover your  mouse over these holes and you will see the x,y location.  Enter these in your machine, and validate a few other holes.  You should be good to go for etching on the top!

eagle xy

First attempt with trying to measure offsets for the front/back operations.  This created some offset holes, which had to be managed a bit with a dremel grinder.  Still a usable board.


Second attempt using the eagle offsets described above, which came out very nice.


Next update will show assembled boards, and hopefully a video of everything operational.

2013 Christmas light controller :: Part 1

I really don’t like hanging or taking down Christmas lights.  I generally do the bare minimum my wife requires to get through the holidays.  I HAVE always been intrigued with the computer controlled lighting displays that are synced to music.  Last year I got into a fun partnership with one of my neighbors.  He wanted to do the whole music shebang, but didn’t know how to do the hardware side of the equation.  Mmmm.. symbiotic relationship.

Last years’ system was a 12 channel deal controlled by a basic arduino.  Worked well enough, built on perfboard and stuffed into a 2-gang junction box.  Downsides were it was not engineered well at all, with the 5v logic intermixed with the 110v ac.  It also required a lot of extension cords as all 12 channels/outlets were combined at the same location (in his garage).

So, we are at it again this year.  The objectives are:

  • increase to 30 channels (arduino mega)
  • hub/spoke design.. with centralized control and 6-channel remote boards to minimize extension cord usage
  • add LEDs to show when channels are on/off for easier programming/debugging
  • safer design.. with better isolation between logic and 110v.  also include little things like fusing on board.
  • waterproof enclosures as we are approaching this as a modular multi-year initiative

So with that in mind, I first created one of the satellite boards.  I designed this in eagle, with a goal of keeping it a single-sided board for easy machining.  The initial trial board machined out well (see previous posts showing generation of gcode from eagle-cad).

First run was pretty good, and soldered up into a usable board.  I did have to hand-dremel a joined trace.  Improvements identified were:

  • Increase the amount of cnc routing around the traces to improve isolation
  • fix the 110v connector pin sizing.  I had them at .1 and they are really .2, so my screw terminal connector wont fit
  • Add a fuse which I forgot to add
  • Increase trace size where possible.  Mid-trace holes sometimes cut the whole trace, so had to bridge with solder.

Did solder up ok into a usable board though:

After a few eagle cad changes and some modifications to the cnc gcode generator you can see the a/b comparison of the boards.  With the original run on the right, and the new one of the left.  Machine time takes about 30 minutes/board.  Using a 60 degree v-carve bit… probably not the best tool for the job.  If you have recommendations on bits please let me know.