Our wide format plotter project got off to a flying start late last year (December 2013) with the main printer framework, electronics and most of the custom software completed within the first three weeks.
The next month was spent tweaking both the printer hardware and software, calibrating and getting the right ratio between speed and accuracy. The only thing then left to do was to get some kind of continuous inking system hacked up as I could not find ANY pen that would last the distance. With an effective printing area of about 1m x 1.5m, it wasn't surprising that such a magical pen could not be procured...
The next two and a half months were spent perfecting the continuous inking system! Firstly I tried every pen that I could find and buy, to no avail. Then I tried what I ended up calling a 'loaded' pen which consisted of gutting a pen and stuffing it with dense felt and loading it full of ink. It certainly was better than any commercial pen but it still didn't make the distance. I ended up pumping commercial grade ink using an ink pump into aquarium tubing and this yielded good results but keeping enough pressure on the ink line was a challenge. I printed several of our early prints using this inking system but It just ended up being to unreliable to be the set and forget system that I was after. I ended up designing a gravity fed inking system that worked perfectly in conjunction with an electronic valve that releases a precise amount of ink into a short tube directly fed into the back end of a modified pen.