The lines would always get out of sync at the same point on the wall, so I figured that my counter weights (mannequin hands) were not heavy enough, causing the belts to slip when it got to a certain point. No problem, I attached heavier hands. That made the steppers not really move at all. So, logic dictates the belts weren't slipping but struggling, so far lighter counter weights were required. Luckily I have a selection of hands. The robot is now rocking some sweet plastic hands from a partially articulated 1960s mannequin with pointy boobs.
The lines getting out of sync on smaller drawings is far less apparent as the steppers weren't having to move as much, hence why I only picked up on this as I drew bigger.
Today's drawings were A2 size, the second one taking 5 hours. Next step is to draw A1 which will double the drawing time. The poor wee motor shield will need its own fan soon, the heatsinks just aren't cutting it.
Things I have learned about getting the robot to draw problem free
- Never be organized by bringing in other things to do while it's drawing like books and thesis writings
- Never set up the camera & tripod to make a stop motion of said robot
These things guarantee robot failure.
Bring on the wall size drawings!