Are you loved to watch the robot doing the plotting works? If you do, then you must be interested in develop a NXT Pin-Plotter III!
Before you’re getting excited with this project, you have to buy the NXT in the nearest local electronic store. Basically, the NXT is the combination of fixed base and a moving tool. On the moving tool part, there is a smaller moving tool, which it is used to move vertical on the main tool, and it’s the place, where the “pen” is mounted too!
The “pen” is an axis ending with a needle (and the needle is the only non-LEGO part of this MOC!) By the way, you also need to glue the needle in an old 1×2 brick.
The reasons why you should uses the NXT motors for this project because the NXT motor can be programmed to rotate forward or reverse at any speed (and it can reach up to 170 rpm!) and the NXT motor can be “braked” whenever you want, and this allowing you to program something like “brake after rotating for 44 degrees”.
The main issue for this project that you need to pay attention was accuracy if movements and “brakes”, incorrect direction and friction as well! [link]