3DP Differential Swerve Module

Summary

This is a small (95x120mm) diffy swerve drive that I designed last weekend for a project with a friend. It has been printed and mechanically all seems to work, but we haven't gotten to control electronics yet.

Although this model was entirely designed from scratch, it was definitely inspired by Wild Willy's design here: https://www.printables.com/model/300105-differential-swerve-drive.

Features:

• AS5600 Magnetic Encoder for Direction
• 25D Motors
• 50mm Wheel Radius
• Theoretical Twist speed: 140 rpm
• Theoretical Drive Speed: 1.3m/s

Assembly Notes:

• In order to reduce resistance in the main pivot, you should really only install 2 of the 5 lower bearings.
• The plug for the wheel axle was designed to make the assembly spin smoother, but it turns out that it isn't actually necessary.
• All of the bolt holes are designed to be clearance fits or self-tapping so there is no need for threaded inserts or nuts.
• There is a bit of a mix of metric and imperial hardware due to what resources I had on hand, but in general it tends towards metric.
• As it is the motors are oversized, so you could likely get lower gear reduction motors to speed the entire module up without running into torque limitations.

Parts

With good sourcing, all of this can be had for ~$120 excluding shipping and filament costs.

Hardware List:

• 1/4in rod (aluminum, brass, nylon are all fine) for axle
• 4x R168ZZ bearings
• 8x V623ZZ bearings
• 7-10x 695ZZ bearings
• 8x M3x16 socket cap bolts
• 1x M3x4mm grub screw (optional)
• 5x M4x20mm socket cap screws
• 4-10 M4x8mm socket cap screws
• 4-10 M4x8mm countersunk screws
• 2x M4x35mm socket cap screw
• 2x M3x12mm socket cap screw
• 4x M3x5mm socket cap screws
• 4x M3x6mm countersunk screws
• 2x 1/4-20x1/4in flat grub screw

Electronics:

• 1x AS5600 breakout and magnet
• 2x 25D motor with 20.4:1 planetary gearbox and encoder (much cheaper if sourced from somewhere other than pololu)

Printing

Almost everything can be printed without supports. The parts that do need supports are as follows:

• Encoder Mount - for bolt holes
• Wheel Body - for bearing hole
• Main Plate - for outer ledge and gear tooth clearance

For printing the Bearing Holders, you will have to enable thin walls, as they are quite small.

Cheers!