dr4wbac_ (tem, nikl, jakob)

TODOs

Mechanical

• maschine

  TODO zusammenbauen

• kabelführungDesign
  • brücke aufEnd die große carrier plate packenV-Kugellager
  • endstücke Kopfhalterung
  •  Motor-halterung
    •  Capstion Halterung
  •  Mittlere Halterung für kabelfüden Schlitten
  •  Kabelhalterung
  •  Stifthalterung

  IMPORTANT:

  • Capstion Line muss auf einer ebene sein
  • Check, das alles stabil ist

  TODO Bauen und testen

  •  Testprint parts und fix bugs im design
  •  Teile herstellen
    •  Kopf
    •  End V-Kugellager
    •  2x Motorhalterung
    •  Mittlerer Schlitten
    •  Kabelführung
    •  Stifthalter
  •  Zusammen bauen
    •  Kabelführung
  • motor driversHändisch bewegen + Stresstest

  Electrical

  TODO Design und Herstellung

  • marlin aufMotorsteuerung arduinoPCB packen(URUMBU?)
    •  Design
    • motoren mit steckern versehen
    • cartesian drive ausprobierenHerstellung
  • optional PCB für verbindung der Motoren und PC?

  TODO Softwareansteuerung

  • set upRAMPS urumbutesten
    •  Basis RAMPS test
    •  Marlin auf RAMPS und g-code ausführen
  •  Eigene PCB flashen
    •  URUMBU testen
    •  Klipper?

  Alternative Names

  • Drawback
  • Pencil Punk
  • HacksyDraw

  Requirements

  • size for painting a3 paper
  • capstan drive
  • h bot for movement
  • easily to assemble / disassemble
    • removable thread of the capstan drive

  Roadmap

  Syntax: 1, 2, 1.1
  - task 1 and 2 are independent from each other
  - task 1.1 can only be executed after task 1
  

  • 1 cad & assemble all parts
  • 1.1 print parts (until friday ev)
  • 2 power electronics
    • 2.1 user interface (svg to motor control code)
  • 3 toolpath planning: svg in -> toolpath out
  • 100 make video

  availability friday

  • matthias 9 bis 14.30, ab 18.00
  • niklas 15.00 bis ...
  • jakob ab 10.00

  next steps

  • friday 12.00: all single parts modeled
  • friday 15.00: all parts assembled (the other person does driver)

  References

  • https://github.com/SeanP2001/Urumbu_USB_Stepper_Motor
  • cable carriers 3d printable
  • urumbu further work
  • sampo
  • OSAP web framework for talking with usb-driven hardware modules (e.g. motors), shoving everything you would make on pcbs onto the desktop for rapid prototyping. overkill for our project.
  • capston drive
  • alternative draw bot with v guides
  • flexible-XYstage
  • Urumbu_IO
  • UrumbubotXY 2.0
  • Laid Up Gantries with Capstan Drives
  • Other Capston mechanism

  Other drawing bots

  • https://watercolorbot.com/
  • axidraw

  Mechanical Design

  • TODO insert niclas' sketches
  • cable carrier
  • CAD organization
  • keep folder structure as flat as possible
  • Have everything as .FCStd. Convert if needed.
  • one FCStd file per part/assembly
  • reason: one part can be included multiple times easily (especially if you download separate parts)

  BOM

  take 3d models from urumbot

  model in cad or find 3d models from somewher else, e.g. from here

  probabably easy to get

  • 1. v-bearing (5x)
  • 2. capstan (2x) (take from urumbot) ✅
  • 5. idler (2x) (take from urumbot) ✅
  • 7.1. extrusion vertical (1x) ✅
  • 7.2. extrusion horizontal (1x) ✅
  • 4. stepper motor (2x) ✅
  • 10. wire (1x)
  • 11. servo motor ✅

  probably model ourselfs

  • 3. mounting plate v bearing (1x)
  • 7. sledge ✅ + assemble it (2x)
  • 11. extrusion cap head (1x)
  • 12. flexture
  • 13. mounting plate servo (1x)
  • 14. mounting plate stepper motor (2x)
  • 16. pcbs

  do not model

  • 5. motor enclosure right (1x) (DEPRECATED)
  • 6. motor enclosure left (1x) (DEPRECATED)
  • 8. sledge case (1x) (DEPRECATED)

  to ask ferdi

  • what do you think of our design?
    • you somehow have to attach the two carriers. do that in 4 points. maybe print clamps for that
    • for the upper carrier, design something on your own. reason is, you need to add somehow the v wheels
  • which material do we take for attaching motors and v bearings to the end of the extrusions?
    • alimunum sheets. thickness 4 to 5mm (we have 5mm, 41mm width). they are in the top right shelf next to the carvera
  • any ideas for aufnahme of the pencil?
  • wie geht man bei pcbs vor? erst pcbs entwerfen oder nimmt man irgendein mock?
    • einfach nen quader reinklatschen
  • wie macht man das kabel fest?
    • siehe fahrrad baudenzug

  design changes

  • removing 9 to place v bearings on same level as vertical extrusion
  • to do that we have to put v bearings at the end of the extrusion caps
  • do not use motor end caps but use metal or 3d printed plastic caps. ask ferdi, maybe also acrylic

  Motor Driver

  • https://www.digikey.com/en/products/detail/texas-instruments/DRV8428PWPR/13563046
  • not in the lab. ordered
  • actually, they are in the lab
  • alternative: hbot firmware together with ramps
  • we fonud those at the 3d printer in the hackspace: https://www.allegromicro.com/~/media/Files/Datasheets/A4988-Datasheet.ashx
  • can you use different stepper drivers in one project?

  Ferdi's Tipps:

  • first, try stuff out with cartesian system, then switch to corexy
  • Den Strom der Treiber stellt ihr so ein (deepseek):

  Stepper Motor Driver Voltage (Vref) Adjustment Guide for RAMPS 1.4
  ⚠️ Safety First
  Power Off before adjusting.
  Use a multimeter (DC 0-2V range).
  Ensure proper heatsinks/fans are installed.
  🔧 How to Adjust Vref
  Locate the potentiometer on each driver.
  Connect multimeter:
  Black probe → RAMPS ground (e.g., power supply negative)
  Red probe → Potentiometer
  Adjust screw:
  Clockwise → Increase voltage
  Counter-clockwise → Decrease voltage
  📊 Recommended Vref Values
  Calculation Formulas
  Driver	Formula
  A4988	Vref = Imax × 0.7
  DRV8825	Vref = Imax × 0.5
  TMC2xxx	Configure via UART
  Common Presets (Volts)
  Motor Current	A4988	DRV8825
  1.0A	0.7V	0.5V
  1.5A	1.05V	0.75V
  2.0A	1.4V	1.0V
  🛠 Troubleshooting
  Symptom	Solution
  Skipping steps	Slightly ↑ Vref
  Overheating	↓ Vref + check cooling
  Grinding noise	Check current + wiring
  💡 Pro Tips
  Start with lower values and test.
  For TMC drivers, use software configuration.
  Label adjusted drivers with a sharpie.
  📌 Always verify motor specs in their datasheet!
  

  • Die Motor-Kabel identifiyiert Ihr, indem ihr erstmal die beiden paare identifiziert. Dazu könnt ihr zwei Kabel zusammendrehen (z.B. rot+grün) und schauen ob sich der Motor dann schwerer drehen lässt. Sobald Ihr ein paar gefunden habt, ist das andere das zweite Paar (schwarz gelb). Dann schraubt ihr zuerst Paar1 und dann Paar2 an die vier Klemmen z.B. rot, grün, schwarz, gelb. Wenn der Motor dann falsch rum dreht, invertiert Ihr ein Paar. grün, rot, schwarz, gelb. Ihr könnt aber auch einfach bis Sonntag warten wenn ich wieder da bin.

  • jakob checked:

  • find out pairs: measuring current. current is induced when turning if both are connected to one coil, current can be measured

  • pairs are:

    • blue, red
    • green, black

  Toolpaths

  • gcode to motor action
  • urumbu uses https://github.com/SeanP2001/Urumbu_USB_Stepper_Motor
  • if urumbu is used, use sampo stuff: https://gitlab.com/fab-lab-oulu/sampo