DrZib Projects

CNC Miller Lite

After spending hundreds of dollars on prototype material, tools and hardware, I decided to document the final pieces I used for my CNC machine so that it will save everyone else the time, money, and hassle.

Stages and frame: Modular CNC - $220 + $10 S&H- He took a looong time to ship the kit to me (over a month) so I was very displeased but the kit is amazing and simple to assemble.
Axis Couplers: - ~$30 - This kit also requires 3 LoveJoy couplers to attach the axis to the motors - get them from the same guy - Modular CNC which sells them for the same price as my local machine shop.
Stepper Motors and Driver: Xylotex 3-Axis Kit - $410 + $25 S&H - The motors are a bit pricey compared to the free ones you could get out of a printer, but the torque and quality is well worth the price. Also, the driver could be made DIY if you want to save a couple hundred bucks (Google L298 L297 CNC), but it wasn't worth the hassle for me.
Spindle: Wolfgang Engineering TB-350 - $260 - This spindle is near perfect. There is virtually no runout and it is very easy to mount to the Z-axis, thanks to the mounting kit. The motor belts broke after only a few hours of milling so you'll want to get a couple of O-ring gaskets from a hardware store (50 cents) that fit. If the $260 price is too much here is another option: CNC On a Budget for $90 but can't say how well it works.
Software: TurboCNC - $60 - TurboCNC is meant for DOS so you can run it on a very old machine with a printer port (mine is a 266MHz laptop). The software can be used for free but they ask for a $60 registration. If you want a Windows machine, look at Mach3. For Linux, use EMC2.

For circuit schematics, EAGLE is the best choice since there is a free version and using the free PCB-GCODE script you can export your design to TurboCNC, Mach2/3, or EMC2 G-Code.
Bits: Drill Bit City - ~$20 - Drill Bit City sells a good PCB milling starter set that includes all the bit sizes you'll need. The actual trace bit is pretty thick so you can't do any small circuits with it. For that, I suggest searching eBay for a 20deg 0.2mm engraving bit. I ordered a few and will try them out when I get them. Update
Other: The stepper motors and spindle get very hot. So you'll want heatsinks/fans mounted on them. I ordered three Rosewell RCX-Z200 92mm coolers from Newegg for the motors. Mounting a fan on the spindle may be a little tricky.

You may also want to get a small dust buster to clean up all the debris.

The only other thing I did was cut the cord for the spindle motor and wired in an ON-OFF relay circuit connected into my parallel port. (Schematics) This lets the software turn on and off the spindle automatically.

The results of the first board

Update: I got some thinner drill bits on eBay (0.2mm 15deg engraving bits) - something like five for $12 shipped. I was worried they might snap but they seem to be very sturdy. They do a much better job with the tracing than the "tracing bit" sold at Drill Bit City as shown in the comparison pictures below:

I just wanted to test out the bit in the second picture so the holes aren't drilled all the way through.

LED Display

Now that I got my CNC machine working and the traces can be narrow, thanks to the smaller engraving bit, I decided to start work on my LED Display. I have been planning this for a long time so I've come up with many features:

Can be changed remotely with pre-programmed messages
Can be sent, wirelessly, new messages to display
Displays all standard keyboard characters
Displays all characters as 5(+1) pixels wide by 7 pixels tall
Has pre-programmed fade-in/out effects
Can be powered from a car accessory outlet (so I can send messages to asshole tail-gaters and bad drivers.)
(Eventually) Displays 2 lines by 16 characters
Possibly update over the internet, but will need a net-capable computer nearby

An example message would be something like a realtor sign, displayed inside the window of a house for sale:

Concerns:

Even updating only one column at a time, the MCU must have 6x16 pins for controlling the active column, PLUS 15 pins for the individual row per column. That means 111 output pins just to control the LEDs. - Because I have not found a MUX with more than 32 output ports, I will probably combine multiple MUXes or 40 pin MCUs
MCU may not be able to output enough power to turn on up to 15 LEDs at a time - if this is the case, a transistor will be used for each row.
Updating 96 columns consecutively, the duty cycle may not be enough for adequate brightness - shift registers may be used.
The board is going to be fairly large, too big for my CNC machine to mill - I'll probably end up doing it in pieces then connecting them all together.

There are more concerns, but this will keep me occupied for now. Here is a list of parts that I plan on using:

RF Receiver
RF Transmitter
Several PIC16F777 - They provide something like 36 I/O pins, so 3 of them will take care of the column MUXing and one will take care of the row output and RF signal.
Many 220ohm 8-resistor networks - I'll test it out with regular resistors first, 220ohms may be too large considering the current will only be applied for 1 out of every 96 ticks.
Bright LEDs - I got some of these to test out. They seem to be pretty bright, but I may need SM LEDs to get the display resolution I want.
5V-3A voltage regulator - just in case I bump up to ultra bright, eye-melting LEDs
Various resistors and NPN transistors.

Here are all the characters I plan to display and how they will look.

CNC Miller V2

I found that for big projects, the stages on my CNC Miller Lite are not large enough - especially for my LED Sign project. So I am building a new CNC Miller. The x/y stage travel distance will be ~2.5ft (figure the Y stage is half that because physics can be a big pain sometimes) which should be good for cutting wood stuff too. I haven't put much time into it so far, but here's the image I took after getting some of the pieces cut.

I decided to make the frame out of poly cutting boards because they're easy to get, easy to cut, and very sturdy. I ordered three unfinished 0.75x24x30 inch cutting boards (but I'll probably have to order one more) from FreckleFace.com for $200 shipped, traced out the pieces I would need (Apologies, I do not have the dimensions/pictures of the traced boards but you can use the Google Sketchup model to measure the pieces needed.) and cut them with a table saw.

There are two features I'm planning on implementing that will be VERY useful:

1) An attached webcam zoomed/centered on the spindle drill bit - for easily aligning the spindle
2) A nozzle mount for a *very* small wet/dry vac - I'll probably put it on the same relay as the spindle on/off so that anytime the spindle is spinning, the vacuum will be sucking up the debris

I plan to work on it quite a bit in a couple weeks so I'll have some pictures to post at that time.

Car Sign

Since the whole LED Display is put on hold until I make the CNC Miller V2, I decided to just buy an LED sign and make an interface for it. I found an LED Marquee Sign from Office Depot and found out the protocol it used to display the messages, then wrote a quick PIC program to let me display pre-programmed messages (up to 12 messages) with the press of a button. My goal is to mount it in my car so I can flash messages to people behind me like "YOU SUCK AT DRIVING!" Here's a video of the interface before I milled the board:

Components:

PIC16F88 - The brains
MAX232N - The sign requires higher voltage levels for the serial communication than TTL can provide
Numeric Keypad 0-9, #, and *
Castle BEC regulator - Step the 12V car battery down to 9V (to power the sign)
LM7805 voltage regulator - Car 12V battery stepped down to TTL for the PIC and MAXIM chip
DB9 serial port or cable
10k resistors for pull-up/down and some capacitors for the MAXIM chip
A few feet of wire
DB9 serial port or cable
LED Marquee Sign from Home Depot

Software: SourceBoost, PIC Source Code, PIC Support Source Code, PIC Support Header File

I just milled the board so here's what it looks like, (I used pull-down instead of pull-up because there's no power constraints here, and it makes more sense in my head):

And of course I learned from looking at the final result that I should probably recalibrate/realign my CNC Miller Lite.

I haven't yet soldered on all the components so here's the board with the pieces in place.

My hope is to bring it all into the shop tomorrow and get it all put together and installed in my car, at which time I'll post pictures.

Tetris Under Three

CNC Miller Lite

Noise Maker

LED Display

CNC Miller V2

Car Sign