How do our robots move? We will talk about actuation, bearings, and supports.
Bot of the Week
Bot of the Week in Action
Bantam Tools Desktop PCB Milling Machine (Othermill) – The carriage is actuated along the X axis, the Table is actuated along the Y. Why are the X and Y controlled the way they are? Why lead screws? Why Steppers?
Actuation, Making it Move
Steppers, timing pulleys, timing belts
For your X-carve builds you all used steppers (NEMA 23), timing pulleys (GT2), and timing belts (GT2).
Pros – You have it already. Can scale very easily. Can travel long distances.
Cons – Keeping tension, dust/debris can get in it. Belts can stretch over time.
Stepper Motor Lead Screw
Lead Screws – Acme thread. Amazon
Pros – Won’t move when unpowered. Don’t typically get jammed. Can handle high torque.
Cons – Expensive, distance is relatively short.
Rack and Pinon
Pros – Straight forward, stable. Can handle high torque.
Cons – Gears are conceptually easy, but difficult to work with in practice. Expensive. Debris can get caught in teeth.
String and Cables
Pros – Affordable. Light.
Cons – Keeping tension, only capable to carry small loads can slip. Slips off track easily.
Pros – Affordable and easy to control and power, possibly just with an Arduino.
Cons – Usually, very under powered.
Other Actuation Options
Motorized Slide Pot – Pong Game
Gantries and Support
The Makeblock kits came with rods and linear bearings. They reduce friction and add stability. If you plan on going with a different system, remember you want to eliminate as much friction as possible.
A more affordable, and less robust, option are drawer slide hardware. Can support heacy loads.
Channel Sliders – Come in various profiles, ride a specific channel system.
Tube Rollers – Gravity keeps these bearings in contact with rails or tubes.
Other Things to Think About
Shocks – For short distances in the Z axis. Perfect for keeping tension on a pen or scribe.
Counter Balance – If your machine is having trouble moving up and down, you may need to add counter balance (a weight). This is often used when machines go vertical.
We are going to build a one axis gantry out of cardboard. Based on the work of Nadya Peek and James Coleman from MIT.
Adam Savage’s Maker Tour: MIT’s Center for Bits and Atoms (Part 1)
Adam Savage’s Maker Tour: MIT’s Center for Bits and Atoms (Part 2)
Adam Savage’s Maker Tour: MIT’s Center for Bits and Atoms (Part 3)
Adam Savage’s Maker Tour: MIT’s Center for Bits and Atoms (Part 4)