Pen plotters are like the inkjet printer of the 1980s. Instead of printing in ink, they use anywhere from one to eight different coloured pens to draw vectorised graphics. I first discovered them when I found an old HP 7440a plotter and rigged it to use a ballpoint pen I cut in two. I soon discovered there is awesome potential in these oldschool business printers. I have tried several pen plotters before settling on keeping a Roland DXY-1150 flatbed plotter. After months of searching I finally found one, incomplete (missing a power supply) - more on that later.
I have owned three pen plotters. Each plotter has a built-in demo programme to produce a sample document.
This was printed on the HP 7440a plotter. Notice the pen is marking smooth lines though the colour is washed out. The pen is dried out and plotter pens are no longer made except for a small stockpile available in Germany. I asked around and couldn't find a business that would consider supplying them to me in the USA so I turned out a few sharpie marker adapters on my lathe. These don't work on HP plotters because of the limited clearance above the pen carriage. This is one of the reasons I switched from an HP 7440a to an HP 7550a and finally a Roland DXY-1150.
My current plotter is a Roland DXY-1150. As I mentioned, I bought it from a surplus source without a power supply. This plotter is a bit weird, requiring 9.7 and 31VDC on separate rails with common ground supplied by an external power supply. Of course this power supply is not standard and I had to design one.
Roland Power Supply: February 2015
Since little documentation exists detailing the internal function of the plotter, I designed a power supply which features dual linear tunable power regulators with large bypass capacitors for high PSRR. I used a compact power entry module for input from the wall and a DIN connector to output to the Roland plotter. The wooden enclosure is my first self-designed wooden enclosure. I have 3D printed enclosures for past projects; due to the size of this power supply I decided to build one out of wood. You'll see in some of my more recent projects I have learned a lot since this one.
Kicad natively supports direct exporting of PCB layouts to hpgl plotter code. This is a copper trace layer. More to come in this area when I perfect the pen adapter.
Reproduction of handwritten computerised notes. This one's a bit more abstract. I take notes on a convertible laptop with a Wacom digitiser using Xournal. I wrote a program to convert Xournal xoj files to hpgl code. Using this program, I converted my handwritten notes and used the pen plotter to write them on paper. Interestingly enough it looks remarkably handwritten, though a bit sloppy since I selected an excerpt from my class notes.
If you have a pen plotter and are struggling to get it to work on a modern computer, I recommend the guide written by Alfred Klomp here. These instructions worked for me on various plotters including the Roland DXY-1150. I still haven't figured out how to feed directions to the HP plotters as simply catting a file to the serial port sends data too fast and fills up the limited internal memory in my base model 7550a. I believe there was a graphics storage memory upgrade available in its day - tracking one down these days has dim prospects.
My code for the Roland plotter and converting files to hpgl language is a work in progress. If I have something interesting to share I'll add it to this page. If you have any questions I may be able to answer, feel free to contact me.