Dorkbot SF, the San Francisco chapter of Dorkbot, is having its next meeting tomorrow, July 31. And, we will be bringing along the WaterColorBot for show and tell between the main acts. So if you’re in the area, this would be a great opportunity to come and see the WaterColorBot up close and personal.
Dorkbot is a loosely organized sporadic meeting of people generally interested in “Doing Strange Things with Electricity.” The event will be at Otherlab starting at 7:30 pm. You may know Otherlab from their wonderful Othermill recently launched on Kickstarter. Anyone can attend and admission is free, although there is a suggested donation.
The Mug Marker
Don McRae recently stopped by our shop last week to show off his homebrew CNC project, the “Mug Marker” — a wonderful little cardboard robot that can draw on mugs.
Much like the Mug Plotter on Instructables, it uses the same EBB controller board and stepper motors as the Eggbot, but with linear motion for the pen instead of rotation. However, unlike that version, Don has incorporated the same winch-drive mechanism that we use on the WaterColorBot to provide motion for the linear axis– meaning that it can go fast or slow, with very good accuracy.
Don laser cut the large white winch on the back of the machine from acrylic. It controls a string that pulls the pen carriage back and forth as it rides on a pair of rods:
The pen holder itself slides into some additional bearings, and has a small protrusion on the back that rests on the servo horn, allowing it to be lifted up or lowered down. Like the Eggbot’s pen-lift mechanism, this mechanism only (actively) lifts the pen, which means that it can ride over uneven surfaces, or plot on mugs with variable diameter.
Underneath the pen carriage, the opening of the mug fits onto a three-jaw coupler on the motor shaft, and the base of the mug is held against a rubber faced spring loaded plunger.