3D Printed Ballscrew Linear Actuator

Description

Welcome to our project page detailing the development of our 3D printed ballscrew actuator for use in our humanoid robots. The ballscrew system itself was designed by GearDownForWhat (great work on the design!), and modified by us for use with BLDC motors, with an added stabilization and load-mounting system.

The actuator is useful for applications where linear actuation is preferable over quasi-direct-drive (QDD) actuation. Such areas include the spine and neck of a humanoid robot. For non-bipedal robotics applications, such an actuator may be useful in stabilization platforms, or on load-lifting systems for a UGV.

The ballscrew in broken up into several modular components, with the threading of the screw being considered a "wearable" component intended to be replaced easily.

Components

2 × Carbon Fiber Rod 12mm OD, 10mm ID

1 × Printed Thread

1 × Printed Carriage Nut

50 × 4.5mm Ball Bearings Typically used in airguns

1 × Printed Carriage Supports

Project Logs

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First 'motorized' test / demo
Anthrobotics • 05/22/2020 at 03:26 • 0 comments

Here is the first test/demo of the actuator using a power drill. While we await new ESCs for driving brushless motors, this will suffice for now!
The stroke of the actuator is a bit wobbly, partly attributed to an uneven print surface. This was due to the print being performed horizontally, using support on one of the sides. The Wanhao i3 had a bit of trouble with layer separation the higher a print goes, so we will be leaving the printing of tall parts to our new delta printer.
Smooth Side
Coarse Side
Also, the nut containing the ball bearings was not completely full, which may have resulted in some added backlash. This can be fixed by filling the nut completely with BBs.
The improved motor coupler allows for secure attachment to the thread of the ballscrew, as well as easy fixation via set screw to the motor shaft. The coupler can be easily swapped based on the desired motor shaft size.
Motor Coupler
Overall, not too bad for a first prototype! We are looking forward to an improved second print, with some added features including endstop switches, and proper motorization.