Draw Bot
Contents |
Concept
Initially, the plan was to duplicate the Der Kritzler; however, one of the design goals was affordability. Der Kritzler's toothed belts and pulleys add significant cost, but seem to deliver little advantage over a spooled line design.
Also, a goal is to co-locate the motors with the embedded controller and pen on the chassis. The thought is that the system will be simpler and cleaner.
Prototype plans call for an Arduino Uno and breadboard, with the final device as a custom PCB w/ ATMega328 or maybe ATTiny? Anyway, the PCB might be part of the chassis?
Also, we'd like to change the design so the DrawBot reads it's commands from an SD card instead of a command station.
Bill of Materials
- Chassis/pen holder
- custom part, will need to build in house
- 2x Spools for steppers
- 2 x suction cups (mount points for belts)
- 2 x stepper drivers
- H Bridge power control TI 1320
- 2 x stepper motors
- 1 x servo (for controlling pen?)
- 1 x Arduino
- Suspension Cable
- Eyelets (these are mounted to the chassis and provide both a pivot point for the cable and insurance the cable goes onto the pulley)
Deprecated
- 2 x stepper motors
- go w/ 5mm shaft
- need 40ish oz/in?
- 2 x toothed belt pulleys
- go w/ 5mm shaft
- 20 ft toothed belt
Spools
Right now, the spools are mounted on the stepper spindles. A possible change: a small gear on the spindles that meshes with teeth on the spool. Gear reduction.
Motor Control
http://arduino.cc/en/Reference/StepperBipolarCircuit
http://www.arduino.cc/en/Tutorial/MotorKnob
H-Bridge Resources
http://en.wikipedia.org/wiki/H_bridge
http://www.ti.com/lit/ds/symlink/sn754410.pdf
The steppers we have are R,G,Y,B for pins 1,2,3,4 respectively.
Links
- Der Kritzler
- Project3, Drawbot Uses monofillament
- Hector -- the inspiration for DK
- Gates Mectrol -- possible source for the Polyurethane (PU) timing belts (aka linear motion belt)
