Stokes' ProjBlog

Two steps forward, one (exploding) step back. October 25, 2009

In the past couple of weeks, I managed to do a little more work on the soda machine hack. With the hardware to interface 110VAC relays to 5VDC logic done, the next step is to create a means of connecting it to the TINI390 board. This has turned out to be a little more complex than I’d anticipated, specifically because I don’t have direct access to the various I/O pins (at least not through its Java VM). The TINI is set up more like a microprocessor than a microcontroller; all the I/O is done by reading from and writing to specific memory locations, divided into several pages. The board has only eight general-purpose I/O pins, but it has a twenty-bit address bus and five usable “Chip Enable” pins. All communication with the on-board peripherals (such as the flash memory and probably the Ethernet) is carried over the same data pins, so anything I attach needs some capability to decode addresses in order to avoid reading or stomping on unrelated stuff.

(more…)

Materialization: successful! October 7, 2009

After some modifications to the design and some tweaking to the print settings, pan/tilt rig version 2.0 is a success. At a marginally lower extrusion rate and temperature, the accuracy was greatly improved — this version was much less “lumpy.” This improvement turned out to be somewhat of a mixed blessing, however. The first draft ended up being slightly too small to fit the servos, so this version was scaled up by 10% prior to printing. Combined with the improved precision engendered by the print setting tweaks, the final result ended up being a bit too loose to grip the servos with friction alone. A small rubber band around each holder keeps the motor nicely in place, however.

(more…)

Blatant Fabrication October 2, 2009

I made my first tentative steps into the world of desktop manufacturing last night. Having a couple of small servo motors, I thought it would be cool to make a tiny pan/tilt rig with them. I also thought this would be a good first 3D printing project. A couple months ago, several of us at W&B got together and built a Makerbot*, a small hobbyist’s 3D printer based on the RepRap project. Like RepRap, the Makerbot fabricates objects out of extruded ABS plastic, the same stuff of which LEGO blocks are made.

The Makerbot fabricates things by laying down a thin bead of molten plastic onto a small platform. The platform moves in two dimensions beneath the extruder, creating a cross-section of the model being built. After one cross-section is complete, the extruder rises and the next cross-section begins. It is a little like creating something from cake icing — I wonder if that’s the origin of the Cupcake name.

(more…)