Milling PCBs and Circuit Board Evolution

I've been dabbling in electronics for years. Most of the time this involves starting on a breadboard and then transferring your finished circuit onto stripboard.

More often than not I'm trying to squeeze far too much stuff into a tiny space, for example in my Zippo Burglar Alarm.
Which means that the resulting boards are an awful mess of wires and massive solder lumps.

For this post I'm going to use my Hellboy Corpse Locator light board as an example, because it's been through a fair few revisions.
It's a fairly simple piece, I needed a board to fit under the dial of my corpse locator prop, and make the dome light up red. A simple task electronically, but mechanically it's difficult to get everything to fit.

I started by using a tank cutter to cut disks out of stripboard.

I was surprised by how well this worked, it made it easier, not having to shape each board by hand, but each one still took about 10 minutes.

I wanted to use surface mount LEDs, they were on the copper side, meaning everything else was on the reverse side. Which left me trying to find a way to create a second battery contact on the reverse side of the board.

The most reliable solution I could come up with was stitching a grid with copper wire.

Again, at the time, I was proud of my little inovation, conductive paint had too much resistance, glueing foil to the board had been problematic, this wasn't perfect (some wide copper tape would have been good) but working with materials at hand it did the job.

Once everything else was attached, the board looked like this. 

After making about 10 of these I managed to get them quite neat. But it was very labour intensive, each one probably took over 3 hours of quite fiddly work. 

And due to the nature of cutting out the boards, each one was slightly different, in where the LEDs went and where the wires were routed.

Many months later, the dawn of my CNC machine, and obviously one of the first things I wanted to have a go at was milling PCBs. I drew up the design in Vectorworks (EagleCAD* is the proper tool) and bought some copper clad board and was very easily able to cut out a simple PCB.

Milled PCBs are different to proper manufactured PCBs, you start with a solid layer of copper and simply mill away 'isolation paths' to create your tracks.

The one on the left is my very first attempt, I just used a cheap V bit that I had and the result was some very rough looking paths, but an entirely functional board.
My second attempt (using a 0.8mm ball nose) was much neater, but after my PCB milling bits arrived from China I was able to cut really neat boards. These are 0.2mm isolation paths, so potentially I can mill some really complex boards with lots of tiny surface mount parts.

Designing for CNC always affects your design. For example I wanted to take advantage of the fact that the copper layer could act as my other battery contact (no more stitching) so that meant the board was flipped and everything was soldered on the back. 

This also meant I had to switch to normal 3mm LEDs and mount them upside down (poking through the board) I originally use smt LEDs to keep the board thin, but the limiting factor is always the battery thickness so this works out fine, and the 3mm leds are brighter.

The boards look really cool now, very neat and I can do cool stuff like engrave labels and my logo. But the main thing that makes these far better than their predecessors is the time they take to produce. Each one probably takes about 20 minutes of milling, because it requires several tool changes. But then only about 10 minutes of soldering and it's finished.

Also each one is identical, which means I can add matching screw holes to my plastic corpse locator parts. rather than the tedious task of lining up and drilling each individual part to match it's specific board.



* Eagle is a program which allows you to draw up circuit diagrams, as well as layout circuit board designs for sending off to have fabricated. With the proper add on you can also create Gcode to send to a CNC machine. It sounds like a fantastic tool, but when I had a go there was a lot to learn and, for such a simple circuit, with mostly through hole components it was just slowing me down.

CNC Mill Build - Enclosure

After finally getting the mill running it became obvious that I was nowhere near done.

Firstly, in their current position the electronics didn't give the machine enough room to move freely, so they would have to be relocated.

Also my current method of using drawing pins to hold down material wasn't going to be a permanent solution.


The first problem is easily fixable, I collected a bunch of connectors, then got out my calipers, cracked open Vectorworks* and began designing an enclosure. 
I cut all the pieces out of 3mm MDF and when assembled they looked like this.

From the front all you see is the name and power switch.

One side features a cut out for a fan.

The back has all the connections, A/C power in, parallel signals from the computer and five molex connectors, one for each motor and one for the limit switches.


I designed the box to be low profile so it would fit in the sliding drawer under my desk.

Here it's nice and out of the way but easily accessible if I need to fiddle with it.

Under the hood, you can see the power supply takes up most of the space. Main power is routed through the illuminated switch at the front. The 24V supply then gives power to the motors, it also drives a tiny 5V regulator for the logic power supply and the motor is supplied by a slightly larger 12V regulator (you can see it glued to wall on the right)

I found some little fuse holders and intend to put a small fuse in after the switch. There's also room at the back for adding more connections, for things like spindle control and an emergency stop button.



Being the first real thing I've made with my machine this taught me a lot. Firstly my machine is pretty damn accurate. 
The pieces just fit, I was expecting to have to sand things, but they actually fit great and I measured the pieces to be well within 0.2mm of what I intended, that's nowhere near what some CNC machines can achieve but with MDF it's more accuracy than I'll ever need.

Another thing to note is, always measure your material. I should have remembered this from when I designed stuff for laser cutting, but my 3mm MDF turned out to be 3.2mm, so my box joints aren't quite flush.

A lot of time designing this was spent on the engraving. The majority of fonts these days are solid blocks, you can turn them into outlines with a vector program, but the best results are achieved from single line fonts. You can see that the axis labels I engraved on the back of the box are a bit chunky, I didn't like that so I spent a while manually creating single line letters for my title font.

This was tedious but I'm happy with how the final thing came out.

The M⁶ for short

I'd like to make the lettering black so it pops more, but I can't think of a good way to do this, hand painting would be tricky, and detract from the nice clean finish.

The easiest solution is to mill all the way through a material and place black behind it.

I also installed a hold down table. Essentially this just involved sinking a bunch of t-nuts into the back of my board in a grid. I now have a grid of points where I can bolt things down to the table.

Above you can see me marking out holes, and a couple of nuts ready to insert.
The grid is now finished, I'll snap a proper picture next time I'm using it.

I've actually found that for most materials  double sided tape is a better solution, most of the time the clamping bolts just get in the way.


I've been happy with this set up for the past few weeks, I've had a go at milling a phone dock, pcbs, and at the moment I'm milling maps out of cork. :D

One thing I haven't really tried is milling plastic, I've got some chunks of acrylic on the way so that's next on my to do list.


*Vectorworks is my CAD program of choice, mainly because it's what I used during my architecture degree. However it seems that I'm in the minority using this program. Most people use AutoCad or SketchUp, or for simple 2D work, Inkscape.
Supposedly AutoCad was designed by engineers and Vectorworks by architects.
I've got a copy of Illustrator, but most of the time I get frustrated with the alien pen tool, give up and switch back to Vectorworks. 

CNC Mill Build - It Works!

Very quick update, I did finally sort out my electronics problem and was able to mill my first piece.

Behold the power of my machine:

When I shot this video my setup looked like this.

Already I'm not happy with it, the electronics are too close and don't allow the wires enough room so I can't use the full length of the Y axis, also they really need to be covered. 

I'm currently holding work down using push pins, not a great solution.
Already working on changing all that. But for now it works !



See my next stage of improvements here.

CNC Mill Build - eLectronics

The last post saw me putting the finishing touches to my machine build, by adding the belts. Unfortunately that's the easy part over, now I'm tackling electronics.


There are two stages to controlling a CNC machine. The first is a controller which will take a Gcode file* and turn it into step and direction pulses that tell each motor when to turn.
The second is a motor driver which takes these low voltage data signals and sends high power signals to actually drive the motor.

For the driver (the second part) I'm using pololu a4988 drivers along with a stepper shield. After finally sourcing all the parts this is what they look like.

The driver is quite small, you can see one of them in the top left. The rest is just capacitors, to even out power, and connectors, to attach all the motors.

This board is a 'sheild' which is intended to be used with an arduino. You can use an arduino as your controller, but I wanted to use a PC because it gives me more control and a  nice graphical interface.

Which means I had to build a separate board to make it so the signals to and from this shield could be sent via a parallel cable.

This is what I put together. Again not much going on here, the parallel cable is broken out and the signals sent to the right sockets (so they match up when the shield is plugged in on top).

There is also a 5v regulator to supply the logic voltage and all the connections are optically isolated. This means that the CNC motors and the computer aren't physically connected, this means any noise caused by the motors won't affect the computer.

Bart Dring, of Buildlog.net designed this board which does exactly what I want. But he doesn't sell them anymore. So what I did was buy the arduino version (also designed by Bart, but now made by Reactive Substance) and adding in the missing components so that it was functionally the same. It probably would have been easier to just build the whole thing myself from Bart's schematic. But the black boards help with heat dissipation  as well as matching the drivers I bought, and looking badass.
Edit: of course now that the M6 is finished, I could design a new PCB with everything on and mill it on my machine, how ever I'm unlikely to ever get round to this.

Now the shield carrying the stepper drivers, just plugs in on top. Each one of those drivers (now with large blue heat sinks on) controls one of the motors, each motor has 4 wires.

The large silver box off to the left is the 24V power supply, this is the power that is used to drive the motors, the 5V logic is supplied by a small regulator I put on the lower board.


That's most of the hardware set up, the other end is an old PC running Ubuntu, I'm using LinuxCNC to control my machine, it's a very powerful tool (probably overkill for this little thing) but nice all the same.

What came next was lots or testing tinkering and , to be honest, swearing as I tried to figure out why it wouldn't work.

(figured it out eventually WooHoo!)




*Gcode is the end result of designing on a computer, it's composed of simple lines of text that instruct the machine where to go using an absolute positioning system. E.g. g0 x10 y10 would tell the machine to move to that co-ordinate (g0 is just max speed) so kind of like playing Battleships.

CNC Mill Build - Belting Along

The Z Axis I finished up last time now gets fitted to the front of the X carriage.

The Makerslide is slide between the V wheels attached to the front of the X carriage, and the black delrin nut is bolted in place.


The final task is to attach the pulleys and belts.

The red aluminium blocks are belt tensioners. By turning the bolt you can easy tune how tight your belts are.

That completes the physical build, or at least I've run out of kit parts.

The next thing to do will be to hook up some electronics and see if I can get it moving.

CNC Mill Build - Zzzzz

I am slightly regretting this procedural format I've locked myself into now, but I'd better finish it . 

In the previous post I bolted together the X and Y carriages to form the main framework of the machine. Now I'm tackling the Z axis.

The Z axis is different in that it is screw, rather than belt, driven.

The flexible coupler and flanged bearing are attached to a length of M8 threaded rod. The aluminium tape is wrapped round the rod to ensure a tight fit.

The threaded rod is coupled to the final motor and the bearing is sandwiched between the two Z plates.

The black brick is a delrin nut, it is threaded onto the screw and the final length of Makerslide is bolted on.

These are the spindle mounts, once the machine is finished they will hold the Dremel.

That finishes up the Z axis. Now all I have to do is mount it to the machine, 
and add the belts,
and sort the electronics...

CNC Mill Build - Squaring Up

Starting with the two Y motor plates I'm going to build the gantry for the X carriage I built last time.

These are the two X lengths of Makerslide as well as the belt anchors and a belt and pulley.  (I'm going to wait until the end to mount the belts.

The X carriage is now mounted between the two Y plates, completing the Y carriage.

Two more (longer) lengths of Makerslide and the two endplates.

I now have the basis of the machine assembled :D

The mechanics of this bolt together nice and easily, I'm less certain about the electronics :s

Next up is making the Z axis.

CNC Mill Build - X Carriage

This is continuing fromt he last post where I was assembling one of the Y plates.

This time I'm going to put together the X carriage.

X Plate (all plates are identical)

Motor, smooth idlers and fixings.

This starts off similarly to the Y plates, except that here the motor is mounted flush against the plate.

The two X plates get bolted together to create a nice solid box, here you can see what's going on inside (that shot was a lot harder to take than it looks, because nothing is fixed)

The last X plate finishes off the carriage, but in this step the V wheels for the Z axis are also added.

Next I'm going to bolt the motor carriages together to form the basis of the machine. : )

Once it's all squared up you get a much better idea of how the machine is going to work.

CNC Mill Build - Just Like Lego

Last gime I gave a bit more info on how I got interested in CNC and where this kit came from. Now I'm actually putting it all together.



Everything in this kit was so beautifully packaged and labelled it reminded me of cracking open a fresh Lego kit. The sheer delight of all the tiny bags of sorted pieces brought back many a childhood memory.

Anyway all this organisation prompted me to tackle the build in a very measured and precise way, not at all how I usually work.

So for each step, I laid out all the parts and took a picture. 

The first step is bolting one of the Y motors to a motor plate.

Bolt on 2 smooth idler wheels. These just guide the timing belt in the right direction.

Bolt on 4 V-wheels. These are what will actually grip the Makersilde rail. 

Those two small parts in the bottom left are eccentric spacers, they're slightly offset so that you can adjust how tightly the wheels grip the rail. It's this kind of simple problem solving, that makes this design so good.

That's one of the Y drive plates finished (the other is simply a mirror image).

Next time I'll be assembling the X carriage.

CNC Mill Build - Intro

Ever since I found out about computer controlled production, I've wanted one of the machines for myself. 

Start up projects like the MakerBot (my first love) have made it much easier for anyone to get into digital production. But The $1000 price tag was still far too much for me seeing as I was still a student.

Image credit: BrePettis.com

During my time at uni I had access to a laser cutter, which was great, but limited to 2D production, and I used the Shapeways service to get a few 3D models printed. But found the price tag prohibitive and the 2 weeks of waiting between design and product was painful, and ruined one of the fundamental principles of digital production*.

But in my third year of uni I got it into my head that I was going to build a CNC mill. 
I did a lot of research and made a bill of materials. My aim was to build the whole thing for under £200. Long story short, I got the mechanics working (sort of) then ran out of steam.
The beast is currently disassembled in a box and may be worth it's own (rather depressing) post, it just wasn't going to be accurate enough for me.


Jump to October 2012 and for the first time in a long time I have a job and then stumble upon project Shapeoko. An open source kit that aimed to get you up and running for $300.

And just when I started looking at how I would get all the parts in the U.K I found the eShapeoko! Someone in Europe was selling kits, so almost immediately I ordered one.


Because the project was new they were still having problems sourcing all the parts but finally in mid January this rather small, but tantalisingly heavy package arrived at the door.

eShapeoko #23

Individually labelled parts bags. Almost more exciting than the actual machine.

Here's everything that came with the kit. Lots of lasercut steel, several lengths of Makerslide (more on that later) and various other bits of hardware.


I wanted to paint my kit to protect it, but mostly so it would look cool. I had a lot of black spray paint, and only a bit of red (left over from my Red Dwarf phone). I think that dyeing all the nylon spacers may have been a step too far, but I guess I was just over excited.

I may never get it running, but it's damn well going to look sexy!

The only other bit of prep is tapping the ends of the Makerslide. 

Makerslide is a new bit of hardware that was originally a kick-starter project by Bart Dring. It's similar to a standard aluminium extrusion, used in many designs that need to be strong light and inflexible. The key difference is that Makerslide has a set of V rails on it, which allows it to be used as the primary linear motion system as well as the main structural support which makes it ideal for small (or quite large) machines that need linear motion.



Well the colour scheme's all done, now I suppose I actually have to put it together. 

In my next post I begin assembling the kit.



* I think the direct link between designing on a computer and then very quickly being able to hold it in your hand, assess it and make changes is one of the best things about this technology.
However I still think Shapeways is a great service and I've always been really happy with their parts. It's still probably the best way to for newcomers to experience digital production without having to spend hundreds on getting set up. As well as the fact that the machines they use are far better than any home setup and give the option of printing in all sorts of cool materials.