2019 Black Friday-Cyber Monday Sale!

In North America the last weekend in November is Black Friday/Cyber Monday when you can get some of the best deals for your holiday gift buying.

Marginally Clever Robots is no exception. This year from November 29 through December 2 we are offering $30 CAD off your purchase of a Makelangelo 5 robot. That’s free ground shipping to anywhere in North America OR a significant discount on your international order. So tell your friends and get ready for beautiful robot art action.

Makelangelo News

Bearing Tensioner Remixed!

The tensioner is a new idea to reach higher speeds by making sure the belts can never skip off the pulleys. It uses a rollerskate bearing – you’ve seen them in fidget spinners – and is 3D printed. Jason Garber remixed and improved the design, which delights me to no end.

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He said the middle pieces (2mm bend) is the his favorite. Here it is in action on Jason’s machine:


Makelangelo 5 3D printed parts updated

Change log

  • New calibrator: put it between the pen holder and the paper, insert your pen until it hits the calibrator, tighten the screw, and voila. Perfect every time, no guesswork.
  • New experimental bearing holders: holds one roller skate bearing (8x22x7mm) against the belt and the pulley on each corner of the machine to prevent skipping during high acceleration moves.
  • New downward tilting pen: A small downward tilt improves the life of the pen and the amount of ink that flows. Great for drawings over 2h.
  • Better fitting parts: the arms on your pen holder should move freely. We often had to sand and prep to make them work great. We’ve tweaked the parts to just work.

Get all the files here:

Makelangelo News

Makelangelo Belt Tensioner

Makelangelo is a wall hanging, mural drawing machine. There is a motor on the top left and top right of the wall, and belts hang down from there to the pen. Tension caused by gravity keeps the belt on the pulley.

To draw on the entire wall you need a belt long enough for the pen to reach the bottom corners, going diagonally across the drawing area. That means if the pen were to be in the middle and drop all the way to the bottom it would hit the floor.


When the machine tries to find home by touching limit switches, the pen holder hits the floor as described. Gravity stops, tension is lost, and the machine becomes confused.


This 3D printed tensioner fits a roller skate bearing (8x22x7) and holds the bearing against the belt, gently pinching it against the pulley. This prevents skipping and allows large machines to find home.

This has an added bonus of letting the machine accelerate faster without skipping.

Print two (one for each bearing) and then fit them onto the two corners and enjoy!

Download the part from Thingiverse here: