Thoughts on Improving the Makelangelo Pen Holder

I’ve removed nearly all the contentious parts from the Makelangelo and now I’d like your help to finish a new pen holder. Here are some of the challenges I’m facing.

I’ve been working behind the scenes on an update to the Makelangelo. I’ve removed all the glue, solder, and zip ties from the motor mounts and the control box. Each piece assembles in under ten minutes. Great right? Well… the pen holder has always been a challenge, and now it’s got me stumped.

There are many factors that fight each other with the pen holder. It has to hold at least one pen 8-20mm in diameter; lift the pen off a wall or a board; be accurate; be easy to assemble; be easy to disassemble; be fast; and look good, in that order.

The picture above is the current pen holder. The wide wood surface keeps the pen from wobbling. The metal electrical connector holds the pen tilting down so the ink keeps flowing. The black servo on the bottom lifts the whole pen holder away from the paper, taking the pen with it.

…but this pen holder needs to be glued together in a few places. The mass of the pen holder swings below the screws, limiting the top speed. That servo can lift maybe 3mm so there’s not a lot of room for error. It also means the servo has to stay really close to the wall, which affects the weight balance.

Here is a recent prototype I’m playing with. Two teardrop halves slide inside each other so the line from the motor down the belt is always straight through the pen. It’s easy to put together and take apart, swings less at the top of the drawing area (more accurate/faster), and it has clearly visible part numbers. What it doesn’t have is a way to lift the pen. I can put the servo almost anywhere, but none of them seem to work!

Final thoughts

On a meta level, I notice that every design I publish goes through at least four failures before a success. I’ve started working that cost into my estimates. I also notice that I spend a lot of time just thinking about a problem. There’s nothing wrong with thinking, some people even do it for fun. What’s really tricky is recognizing when I have become confused. Like… when I don’t know if something will work, I’ll try to imagine new solutions and then I have more options that ALSO might not work. It would be faster to just try one and see what happens.

If you have some thoughts, please comment below or in the R&D forums.

I published this earlier today as a Page instead of a Post. Whoops.