Circular Scale

thingiverse

This is a straightforward round threaded indicator marked 0 through 9. I used it when testing the consistency of a TTP223 capacitive switch's repeat performance. It splits the thread pitch of 1/32 inches into ten, so the linear movement is 1/320 inches (virtually 0.08mm) for every step. The thread is 8-32 because that was the longest available screw at hand, and PLA caused it to be very tight; scaling it up a few percent might be better. I simply sized the thread with a tap after printing. Whether you insert it into the screw clockwise or counterclockwise, it will count up or down as you turn it. My filament was white, making the markings difficult to see, so I painted over them with a permanent marker and then rubbed them off with isopropyl alcohol to enhance visibility. I printed the indicator upright, which helped minimize the impact of bed spreading on the marking's clarity.