Cup Bot

Alt text

Client Objective: Design a robot that draws designs on cups.

Motivation

Environmentally friendly packages
custom printed hot cups
minimum of 25000
inventory challenges
uv inkjet
Inspiration: egg-bot

Prototyping Phase

Design Sketches

Robotics

https://www.instructables.com/Mug-O-Matic-a-Modular-Tiny-CNC-Drawing-Robot/ Arduino CNC drawing robot - eggbot Drawing with robots DIY Pen Plotter with Automatic Tool Changer | Arduino based CNC Drawing Machine

Cup dispenser

Inspiration https://www.dispensingcomponents.com/cup-dispensers.html Automatic Paper Cup Dispenser. push pull 12 volt solenoid valve Paper cup dispenser - thang AUTOMATIC CUP HOLDER made of PVC pipe how to make

Reciprocating Linear Motor

Activates the cup dispenser. Reciprocal motion enables repeatable dispense action. https://www.youtube.com/watch?v=QAcdDiX4zQE

Motorized turret line (Area of development)

How do index each cup turret? Rail system that accomodates multiple cup types

Parts

linear guide rail x2
rail carriages x2 per turret
motors to moving turrets
indexing system?

Cup catch/funnel (Area of development)

Breaks the fall of the cup coming out of the dispenser. Can optionally present the cup to the consumer mechanically

Pen lifter mechanism

The primary component of the robot. Changes levels in the z and horizontal axis to efficiently move a singular pen that draws any conceivable design on a cup of any size. The horizontal motion is driven by a rack and pinion design. The main design concern is securing the open end of the stepper motor axle to mitigate axle deflection so that the pinion properly grips the rack. This problem was not solved but may not be a huge issue practically. Additional motor mounting orientations and horizontal movement driving methods were deliberated upon and tested, but ultimately I falled back on the rack and pinion due to its simple and elegant design. The z axis is driven by a stepper motor attached to a lead screw. This takes inspiration from 3d printer gantries that function in a similar way. While most 3d printers run with 2 lead screws to drive the z axis (to evenly drive the upwards motion on both ends with the 3d printer nozzle in the middle to still accomadate its horizontal motion), I adopted the design to run with only 1 stepper motor. Requires limit switches to calibrate the motion and limit the linear motion of both axes.

Inspiration
Compliant pen lifter
https://us.openbuilds.com/scribe-pen-lifter/

Horizontal pen movement actuation ideas

https://www.reddit.com/r/robotics/comments/z91sn8/looking_for_a_high_speed_linear_actuator/
PCB Linear Actuator
- fast, but not load bearing/backdriveable
Xeryon Piezo mini linear actuators
- fast, but not cost effective
[IRIS][https://irisdynamics.com/products/orca-series] archimedes screw too slow, not responsive?

Pen

The primary design challenge with the pen was to have it spring loaded to maintain consistent contact pressure and take out some of the guess work of positioning the pen at the perfect location.

Making your own plotter pens for the CE-150
https://www.servomagazine.com/magazine/article/make-a-spring-loaded-pen-holder-for-your-cnc-router-for-5

Linear guide

rail with linear bearings
- spring implementation much easier
rail with roller bearings
- more compact

How to drive pen motion?

Rack and pinion
- too slow
stepper with pulleys
- complex

Parts
Pen lifter

rack and pinion
NEMA-17 Stepper
springs Pen z-axis
GT3 Timing belt
GT Pulley

Turntable

Rotates the cup Driven by a stepper motor attached to the turntable via timing belt.

Inspiration
https://www.audiomatica.com/wp/?page_id=3024
https://www.instructables.com/Automated-Turntable-With-Steppermotor/
https://learn.adafruit.com/stepper-motor-turntable

Design challenges