dr4wbac_k (tem, nikl, jakob)

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

Other drawing bots

• https://watercolorbot.com/
• axidraw

Mechanical Design

• TODO insert niclas' sketches
• cable carrier

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) ✅
• 3. idler (2x) (take from urumbot) ✅
• 7.1) extrusion vertical (1x) ✅
• 7.2) extrusion horizontal (1x) ✅
• 9. 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)

todo (jakob)

• capstan drive urumbot durchlesen

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?

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