Tormach ZA6 Robot Arm Pen Holder

My friend Alec and I collaborated to create a pen holder for the ZA6 robot arm. Currently Tormach deosn't provide a default pen holder for their robot arm, and the one that I was using to test the arm was not great.

This was a fun project and the first project where I had to pay too much attention to details and perfection. The main reason we created this, is to make the robot draw precise straight lines. The robot, of course, is capable of drawing straight lines but the issue was that the previous pen holder had so much wiggle room. Also, the spring distance was too short.

For the new pen holder, we had to use a linear bearing and some steel tubing that was a perfect fit to get rid of the wiggle when drawing.
Though for the tubing, get ready to sand it down a bit to make sure it glides smoothly.
The one we got was the exact size that fits the linear bearing but it had a really thin extra layer that made it hard to glide through the bearing smoothly. It shouldn’t take longer than 5 minutes to sand it down.

Below is an image showing the dimensions you need for the tubing to work with the pen holder

At the end of the tubing, there is a hole where a 1/8’’ by 1’’ pin goes to prevent the tube from shooting out.

The pen holder has two parts the lower part (connects to the robot’s end effector) and the upper part. In the image, you will notice some insert nuts. You need ten in total. Six go into the lower part (for holding the upper part) and four go into the upper part (for holding the linear bearing).

Lower part on the left and right is the upper part

In the center that’s where the tubing goes and below that goes the spring. Between the spring and the tubing goes the plunger.

Thanks to Alec for helping me get this project done. He has some cool projects on his portfolio at https://www.alecmarshall.com/

So far I am satisfied with the results of this project but if I had to improve on it I would try to make it easy to install on the robot. Currently, it’s a bit of a journey to install or uninstall which might be terrible for some people.

All materials for this project (STL files, dimensions, links for parts, and Solidworks project files) can be found on my GitHub.

Also, this project was posted on the community Tormach forum.