Revised Fully Printable Eggbot by Glasswalker - Thingiverse

Instructions

These are rough instructions since I have yet to build it myself, these will be updated once I've verified the build:

You will need:
2x NEMA17 Stepper motors
1x 9g hobby servo (Turnigy TG9e or HXT900 is what it was designed for)
All electronics for Spherebot (see link above)
2x 608ZZ "Skate Bearings"
Some M8 Threaded Rod
Several M8 Nuts
Several M4 screws and nuts
A few M4 washers
Some small round rubber "feet" (from the dollar store for putting on electronics to keep them from slipping)
A spring (8mm internal diameter, and as long as you need for your frame size)
A Sharpie (fine tip)
An egg or small ball to draw on

Printed parts:
1x Back plate
2x End plates
1x Egg cup drive
1x Egg cup idle
1x Idler knob (optional to cover sharp ends of rod if kids will use)
2x Idler Bearing Plate
1x Pen Arm Shaft Coupler
1x Pen Arm Pivot
1x Pen Arm Top

Assembly:
- Put 2 threaded rods through the back plate and tighten it down with nuts so it's in the center.
- Assemble the two end plates using threaded rods through the 2 bottom, and the rear top hole (the motor mounts face the "front" side) So that the rear plate is between the 2 back plates. The completely flat side of the rear plate should face forward (with the "bumpy side" facing the rear of the machine)
- bolt the motors onto the NEMA17 mount on one end plate (doesn't matter which) and the rear plate.
- Press fit the egg drive cup onto the end motor
- Press fit the arm shaft coupler onto the rear motor
- Use an M4 nut and short screw to lock the shaft coupler onto the rear motor (the egg cup is just friction fit)
- Fit 2 M4 nuts into the trapped nut slots on the shaft coupler, and then use line up the arm pivot and put 2 M4 screws through the slots into the trapped nuts (just loose for now you can adjust later)
- Use an M4 screw, a couple washers in the middle, and a nut to create the hinge between the arm pivot and arm top parts. Tighten only minimally to allow free swinging with no resistance (use nylock nut or locktite to keep it from falling off)
- drop an M4 nut into the arm top trapped nut hole near the end, and thread an M4 screw into it via the setscrew hole, this is for tightening onto the pen
- Install the servo in the provided bracket on the arm pivot, so that the servo horn is inline with the arm top and can push it up and down with a little rotation.
- press fit 2 608 bearings into the bearing plates (these should be tight, so you may need a little tape depending on your printed parts)
- use 4x (or even 2x) M4 screws to screw the bearing plates in place of the second end plate's NEMA17 motor mount (make sure it's centered)
- Feed a length of M8 rod through the bearings. it just sits loose
- Thread (just twist the plastic part on the hole is just a little too small so it should thread onto the rod with some moderate force) the egg cup idler onto one end of the idler rod
- Fit the spring between the idler cup and the bearing block. It should provide minimal force against the drive cup when empty, and should have enough strength to hold the egg without breaking it.
- Screw the idler knob on the other end of the idler rod.
- Fit 3 of the rubber feet into the appropriate insets on the idler and drive cup These will grip the egg
- Fit a sharpie, and wire up the electronics and you should be good to go!