This is a simple pen drawing bot. It is like a T-Bot (AxiDraw), but I moved the motors to the middle. This has the advantage of making the machine a little smaller and way cooler, in my opinion. See the video.

I made mine really small, so it can fit in my backpack, but it is easily scaled up by using longer rods and a longer belt. With that said, the X axis rods will start to get springy above 200mm long.

The firmware is a special version of Grbl. The only change is the spindle PWM is used to raise and lower the pen. It also has the CoreXY features of Grbl enabled.

You can use just about any CNC controller that can run 2 steppers and a servo, but I made a custom controller that sits in the center and makes the wiring super clean. A limited qty are for sale on Tindie.

See my blog post blog post on this for further details. Follow me on Twitter for announcement.