Forskningsavdelningen have been working on a new vectorization algorithm specifically designed for tracing PCB layouts, keeping CNC routing restrictions in mind to produce G-code that executes with minimal dwelling-requirements. This is a preview of stage-1 (vectorization) output of a sample input containing a large variety of potentially problematic designs:

Bitmap PCB to G-code conversion, stage 1
(Click to enlarge)

The algorithm is complete, and now begins the work of writing stage-2 (tool-size correction) and stage-3 (g-code generation). The finished solution will allow autonomous conversion of any PCB bitmap image to G-code for tracing, drilling and outline milling. Output options will be one program per operation and drill-size, or a single program with tool-change operations.

CNC remote controlOn Thursday 5/5 and Tuesday 10/5 STG held a basic CNC milling workshop using the Roland MDX-40A at Fabriken. We went through the basics on how to set up and calibrate the machine, attach a workpiece and specifying geometry, generating toolpaths of a couple different types (holes, surfacing, from 3d-models) and performing the actual milling.

This will be followed by a PCB-engraving workshop on Sunday 22/5, and also advanced workshops (dates not set, will be posted on the list) including some basic CAD and two-sided milling with supports and using guide-pins.

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For the Hackathon event last weekend, we wanted to build a robot and decided to go for a kiwi-drive.

The kiwi-drive is a three wheel drive configurations that use special wheels to achieve omnidirectional movement.

The robot was designed in Corel Draw (that’s what the laser cutter prefers) during the two weeks leading up to Hackathon and parts were purchased so that everything would be ready when the build started. We also moved the design from Corel Draw, via AutoCAD for cleanup, to SketchUp for a virtual test assembly and rendering to make sure everything would fit together.

The design was named KiwiRay, from kiwi-drive and stingray as the original design kind of looked like a stingray from above. Those design elements were later removed, but the motherboard mounting plate was shaped as a stingray instead.

The idea behind the platform was to create a design that uses only standard, easily available parts, so that anyone can reproduce it. The exception is the wheels from vexrobotics, but they can be replaced by any wheels of the same type. Other than that it uses an Arduino Uno, NEMA 23 motors, M5, M4 and M3 nuts and bolts and the chassis is cut from any 4mm material – plastic/plexiglass, wood or even metal. It can also easily be redisigned to support a wide variety of ball bearings and motors and has enough space to fit virtually any choice of motors, stepper drivers and even gear boxes if necessary

The Arduino provides a simple serial interface and does all of the required drive calculations. It also provides an add-on interface that can be accessed using the same serial link and allows up to over a hundred expansions to easily be added to the system. The first two addons will be a battery voltage monitor and an emoticon display.

The actual build went smoothly, all parts fit together nicely although some nuts turned out to be quite hard to get attached, prolonging the build time significantly. We didn’t get as far as we’d like, but the entire platform was assembled during the weekend and can now be controlled over a usb-connection that will be hooked up to the on-board computer once that is finished.

See our wiki page for the details.

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