How to fix 9 common Polargraph drawing problems
Here is a picture I’ve correctly drawn on a polargraph machine. Here are nine examples of common mistakes that can happen on any polargraph drawing robot – including the Makelangelo – and how to fix them. They are all a result of miscalibration. These should only need fixing once, so take the time to do it right: Slow is smooth, smooth is fast.
Size
The pulleys are not turning enough, which makes the picture too small.
Same again, but turning too much. In the Makelangelo software this can be fixed in Settings > Adjust pulley size. Center the pen holder and use the manual control “X+100”. This should draw a line 10cm to the right. Measure the line you actually get, A.
new pulley size = current pulley size * 10/A
should fix it. This is the same calculation you have to do on a 3D printer to correct movement and extrusion.
Flip & Twist
The motors are moving backwards. In the Makelangelo software this can be fixed in Settings > Jog Motors by clicking the “invert” checkboxes.
One of the two motors is inverted. In the Settings > Jog Motors the “out” button should make the pen holder move away from the motor. The “in” button should move the pen holder towards the motor.
The left motor is on the right side of the board, and vice versa. You can either physically swap the motors or you can swap the wires on the control board.
Yes! It is possible to get a picture upside down and backwards.
Bowing
Bowing is a sign that your board measurements do not match the actual measurements.
Pinching
Your pen home position is too high on the board. Move it down a bit and try again.
Your pen home position is too low on the board. Move it up and try again.
Final thought
The manual control buttons are a huge help here. When everything is correct the top, bottom, left, right buttons will drive the pen holder right up to the edge of the paper. pressing top, right, bottom, left, top, go home should trace the edge of the paper in nice straight lines.
Still having challenges? Discuss it in our forums.
