In order to gain enough control over the writing apparatus, we had to slow the motors down to a step (at least 20 ms).  Faster than this made it difficult for the user to control the apparatus, and also did not give enough time for the solenoid to lift the pen as required. 


While the pen apparatus is able to write over a large area of the page, its plot accuracy is maintained only within a small area.  Outside of this, there is not enough tension between the strings and spring to robustly control the apparatus.  For writing and drawing specifically, there is a small region over which the system can print correctly.  This usually equals around 7 characters.  Within this region however, the system incredibly well with neat and legible letters.  Each of the letters fit into a 1cmx1cm box, and are spaced 0.1 cm apart.


The key safety features involve keeping the pen apparatus under control.  Everything has been super-glued or nailed to ensure nothing will fly off.  The slow speed of the motors also ensured this.  One safety feature we had hoped to add, but were unable to due to lack of time, was a power-saving feature which would activate when the motors were idle.  Our current design keeps the motors on when they are idle, which not only wastes power, but also quickly heats up the motors.  The power-saving feature would turn the motors on and off intermittently during idle time in order to save power and work as a safety precaution for overheating. 


The Non-Orthogonal Plotter is usable by almost anyone who can physically press buttons and read menus in English.  It is simple to use and does not require any technical expertise.  In the future, we would make it more user-friendly by making the menus easier to use for children and develop features for people who cannot push buttons because of a physical handicap.