Shapeoko CNC Mill
Our CNC mill is based on the Shapeoko project with a few customizations that make our setup a little different. We bought the hardware kit, which includes the Makerslide beams, a few plates and various fasteners and brackets to fit everything together. Instead of using an Arduino and the grblShield, we're using Linux CNC (aka EMC2) to drive the CNC via a parallel port breakout board, and some pololu stepper drivers.
The electronics are enclosed in a gutted Sparcstation 5 because that's an awesome thing to do. We kept the power supply because it fits nice, has the connectors we need and supplies the power we're looking for.
- Linux install is unstable - maybe motherboard? maybe RAM? (kernel errors about kmalloc and kfree, random crashes). UPDATE: Seems more stable now, could use more testing.
- Need an accurate calculation for revolutions per inch for each axis
- There was an issue with the Y axis not moving - power cycling the driver fixed it. Maybe a hardware problem?
- The hardware is somewhat flimsy - needs things tightened, reinforced
- Z-axis pololu driver is faulty - problems with 1/16th microstepping
- Double-up the Y-axis gantry (we already have the second stepper - it needs to be wired)
- Pickup some milling bits
- Milling is messy! Need to install a vacuum system. There is a shop vac under the table, but a more permanent / stream-lined solution would be good.
- Replace the milling head with something other than a dremel (brushless DC motor?)
- Add limit switches so that homing works
- Mount the LCD on the wall (maybe a shelf?)
- Find a bigger/wider LCD
- Better table! A slotted table would let us clamp material properly. There are instructions here.
We use NEMA 17 stepper motors picked up from MixShop in Toronto.
Parallel port breakout
We are using a parallel port breakout board designed for a 5-axis CNC machine. You can find one on DealExtreme for cheap, and it comes with a parallel cable and some documentation on CD.
TODO - parallel pinout
Pololu Stepper Board
To drive the stepper motors we use the Pololu breakout boards for the A4988 stepper driver chips. We did need to turn down the current limit because the chip kept overheating. (1/5 turn counter-clockwise)
Trevyn's Pololu Breakout Board
One of our members designed a breakout board for the pololu breakout board, which adds some nice status LEDs, various connectors for control, power and stepper.
Here is some documentation on the types of materials used in the Shapeoko. As you experiment please contribute your findings to this section.
Attempted to mill a sheet of acrylic with a 1/8" routing bit. The results were bad. The acrylic partially melted and the finish was quite rough. The dremel was probably set too high (speed at 8). As discussed here using a soap/water lubrication gives a much better finish.
This soft imitation linoleum is available at Curry's art supply store for very cheap. It mills quite nicely, although it melts when the dremel is set to higher speeds. A speed setting of 2 should suffice. The material is soft enough to use a drill bit for milling. There's a big difference in finish depending on whether you use conventional vs climb milling. Climb milling gives a very rough finish with strings of material hanging off. Conventional milling gives a very nice cut.
Recently received from Shapeoko - our serial number!