How to refurbish plotter pens?

It has been almost two years since I visited this topic. But just before christmas i got around doing something about it. I interfaced it to the PDP-11/05 using an XY11 board. It seems to be very little information on the XY11 board saved. At least I didn't find anything. But the board is a quite simple dual module so I made a schematic of the circuit and then got the understanding how it should be connected to the plotter and how it should be programmed. Created a quick program for the PDP-11 and tested it. It worked just fine but then the problem was the pens. All my pens were obviously dry. Refurbish a pen seems to be impossible. The type of ink used is quite thick and I couldn't figure out how to get it into the ball point pens. Even though it was possible to clean them reasonably well using an ultrasonic cleaner there was no way I could get the ink in there. The other option is to find compatible pens. I searched google for pen refills with dimensions that would fit but couldn't find matching pens to modify and use. So I concluded that the best option is to make a new pen holder plunger which could take standard ball point refill. The Pilot BRFV-10M seemed to be very common refill and would probably work well if I had another pen holder. I asked around and found a guy with a lathe that made one for me. Unfortunately it wasn't working immediately. I hadn't thought of certain mechanical properties of the mechanism. Essentially it is two parts. The pen holder plunger itself and a small plastic part to insert into the cut off ball point refill. This latter part will reduce the exterior diameter of the pen from 4 mm to 3.2 mm so it will work with the spring in the lid. It also has a small 1 mm hole in it to let air through. Then I had a problem that the pen stayed in the up position. Most likely held by some kind of remaining magnetism that could withstand the force of the spring. A couple of M3 washers was used to reduce the contact area between the pen holder plunger and the top lid which made it work. http://i.imgur.com/PRGUa9U.jpg And in action: https://i.makeagif.com/save/QCDG_W controlled by a quick and dirty PDP-11 program : https://github.com/MattisLind/pdp11-plot Next is to draw some nice things on the plotter. Den m?n 24 apr. 2017 kl 06:59 skrev Philipp Hachtmann via cctalk < cctalk at classiccmp.org>: