Makelangelo News Robot Arm

Friday Facts

This week I worked on the Sixi 3 arm quite a lot.

Coding

Monday, I made a new tool to talk to my robots. Arduino Serial monitor is all well and good but I needed more features and some color coding.

Sixi 3

Tuesday I tackled a problem with the base of the robot. When I designed the first version it seemed fine! Then I tried to drive it while in a Zoom meeting for the Vancouver Robotics Club and discovered that at the right spot the base and the J1 actuator collide.

Whoops. So I designed and 3D printed a new base…

…which didn’t work! The screws to attach the base to the board could not be accessed after the base was on the J0 gearbox. No tool clearance is bad! Taking the whole robot off the board just to fix J0 is bad! So that went in the recycling and I tried again.

That worked much better!

The screws that go on an angle through the top and bottom halves of the base need a nut. The nut can’t turn. I could make a really tight slot that the nut barely fits into… but then how do i get the nut out later? My solution is these nut holding tools. They fit snugly, prevent the nut from turning, and give me a convenient handle to grab with pliers when I need to pull them out. A gift to my future self!

Makelangelo 5

As you know from the previous post, there’s a new firmware coming that is faster, smoother, and much more friendly to all they DIY people out there. Much of this week has been talking with people on Discord, showing them how to set up their custom versions. In short,

  • Install the apps mentioned in https://mcr.dozuki.com/Guide/How+to+upload+Makelangelo-firmware+from+Windows+(2021+)/33?lang=en
  • Get the firmware currently at https://github.com/i-make-robots/Marlin-polargraph
  • read Marlin/Configuration.h and change where needed for your board, your drivers, your LCD.
  • For size changes and more advanced stuff, come talk with us!

I’ve also filmed raw footage about how to use 3M hooks to put a Makelangelo on a flat wall. Some people don’t like the suction cups or they don’t have a big window. No problem! Subscribe to my Youtube channel and watch for the announcement.

News Robot Arm

Sixi robot ROS package

Sixi robot now has a URDF description and can be found on the ROS wiki.

ROS (Robot Operating System) was first developed by Willow Garage, a Boston robotics company. Though Willow Garage no longer exists, the ROS has been so successful that it has outlived its creator.

Since ROS is such a popular tool, I hired sachinkumar1235 on Fiverr who built the URDF package. It includes decimated STL files created by Andre.

You can now find Sixi robot on the ROS wiki, or grab the package directly from the Sixi robot github project.

Robot Arm

A Sixi Robot cycloid gearbox eccentric cam shaft

An eccentric cam shaft is at the heart of our cycloid gearbox. Any force acting on the gearbox is focused at this point. So it makes sense that a good gearbox has a super strong cam shaft. This design is made to connect on a motor with a 1/4in diameter shaft, which happens to be the same as the NEMA23 motor in the elbow of the Sixi Robot.

Want to practice your CAD skills? Try making a 3D model of this part, yourself. Tag us on social media if you do!

Here it is inside the gearbox.