MTVplot (whiteboard robot) remix - LPWAN option

thingiverse

# Remixed MTvplot with Optional LPWAN Couldn't find several parts from the original, so remixed it to fit, mainly replacing bearings in the original with a printed barrel attached to the servo holder. In my version, I connected it to a CatM1 network via serial output (TX/RX to RX/TX) then simulating serial communication between the 2 boards with commands coming from a server instead of a USB connection. *More to come on that.* ## Parts - 5m roller blind cord, 4.5 sphere /12mm gap or 4.5 sphere /6mm gap - 2x Stepper Motor - NEMA-17 200 steps/rev, 12V 350mA - 1x Arduino Uno - 1x Motor Drive Shield L293D For Arduino, used Adafruit v2 motor shield - 8x set screws M4 (10mm), only had 15mm screws - Some M2/M3/M4 screws to secure the motor holders, servo and gears - 10 meters of 4 wire electrical cable, this is to extend the cables from the motors and servo to the Arduino. - Whiteboard marker, used Expo dry erase markers - 12v power supply with at least 2 amps, this will depend what stepper motors are being used. The NEMA 17 motors have a very low amp requirement so for my build I used a 12v 1amp supply going straight to the Uno stack. Most of the below I printed at 0.2 layer height with 20% infill using rafts for just about everything (depending on printer specs). ## Instructions #### Soldering This is easier before you start assembling everything, depending what shield you use will depend if that needs soldering. With the Adafruit v2 motorshield, I used M4 screws to secure it to the Arduino Uno. Mounting the Stepper motors I used 3m sticky hook backings (which had more than enough load) but could just as easily be screwed into the board. #### Stepper Gears Screw onto the end of the stepper motor, this needs to sit as close to the board/glass as possible to make sure the gondola sits close to the board. I used 4.5mm spheres at a distance of 6mm mid-sphere (this one prints a bit easier in 2 parts). #### Blind Cord Weights For this, I repurposed one of my favourite prints Capsules. The idea for these is to counter weigh the gondola by clipping the capsule around the blind cord so that it feeds through the middle of the capsule, fit the cord itself (between the spheres) between the teeth of the capsule half then line the other side up with the gaps in the print. Inside the capsule I loaded some spare screws to weigh it down but just about anything can be used providing it adds enough counter weight and is easy to clip everything together. ## Software Tried a few different sketches and apps but by far the best is Polargraph by Sandy Noble, namely [https://github.com/euphy/polargraph_server_a1](https://github.com/euphy/polargraph_server_a1). In my version I connected the plotter to a CatM1 LPWAN network via the Arduino MKR NB1500 by linking serial outputs between that and the Arduino Uno + Adafruit v2 motorshield stack. Then streaming gcode from a server (more on that to come) but works fine with direct USB or SDCard output too. ## Todo Eraser on the back of the servo arm