A member on Time-Nuts asked how to use an old HP plotter under XP

There seems to be a wealth of knowledge here about keeping older HP
hardware running. Would anyone in this group have experience using a
7475A plotter under XP or Linux to plot test data or drawings. I'd
like to get mine running again.

Here is what Neon John had to say:

No problem. I use an E-size HP engineering plotter to make neon patterns and to plot schematics. I have it working quite well under XP.

These old plotters are HPGL or HPGL-1 - same thing. They are NOT compatible with HPGL-2. An additional complication that arises with some software packages is that there are two common implementations of HPGL. The HP standard one has the origin at the corner of the paper and all movement instructions are positive integers. The other one has the origin in the center of the page and movement instructions involve positive and negative integers. They are not compatible. If you get a plot but it's only about a quarter of the drawing then the driver is outputting a center-zero file to a corner-zero plotter.

Microsoft dropped HPGL support, what little there was, from XP. No problem. Sign vinyl cutters almost all use HPGL and are still in production. Unfortunately many use center-page-origin HPGL. Fortunately Roland does not. Therefore Roland drivers will work with HP plotters.

Unfortunately, Roland apparently has taken down their windows plotter drivers. Fortunately I haven't You can get the drivers from my site here:

http://www.neon-john.com/Neon/Misc/misc_home.htm

Bottom of the page. ( a google click or two would be appreciated You'll have to experiment a bit to find out which Roland plotter most closely approximates your plotter.

This is a universal solution that will let just about any program send vector images to the plotter via windows printing. Just for kicks sometime, print a text file from ?WordPad and watch what happens. The plotter carefully draws each and every letter.

If, for some reason, this doesn't work, there is another method that I use with ?CorelDraw and any other package that can export the drawing in HPGL format.

Simply choose “export”, select “HPGL” and select a place to store the file. Then use Hyperterm or any other terminal package capable of sending out an ASCII file and copy the HPGL file to the COM port that the plotter is connected to. This will be generic HPGL and won't have any plotter setup info in it. OTOH, usually none is needed.

My HP plotter and/or Hyperterm (can't remember which is the culprit) does NOT use Xon/Xoff handshaking. Therefore hardware handshaking MUST be enabled and wired in the interface. Additionally, several pins must be jumpered together to make things work. When you get that far, drop me a note and I'll go dig out my adapter and give you the wiring. This handshaking requirement applies to the XP drivers too.

A few notes about using a pen plotter with Windows and Corel in particular. Set ALL lines to “hairline”. Use the ^A key to “select all” and then set the line width to “hairline”. The reason is that Corel and/or the driver is so dumb that instead of making a wide line by making several long strokes with the pen offset a little each time, it scribbles it in like a first grader coloring. That is, if the line is to be 24 points wide, the pin is driven to scribble back and forth on 24 point strokes. It draws effectively about an inch a minute like that, if it doesn't wear a hole in the paper.

Set your actual line widths by using various width pens. Set, say, a 4 point wide line to pen 1, an 8 point line to pen 2, etc.

Also, convert all the colors to black. For some reason the translation from color to pen number doesn't work too well. If you need the output to be in color then move each color in the drawing to a different layer and then assign the appropriate pen to each layer.

Sometimes text comes out looking better if you “convert to curves” before plotting.

Rots o Ruck finding pens. They're available but hard to find and very expensive. I'm fortunate to have acquired several Rapidograph drafting pen to HP pen adapters so that I can use india ink to draw with. India ink on mylar is still THE kick-ass way to make PCB masks if you don't have a photo-plotter handy. I bought out the entire remaining stock so there are no more anywhere in the country according to the factory.

When I don't feel like messing with liquid ink, I use felt tip pens. I've hacked up an HP pen to accept a shortened ordinary writing felt tip. I've also tried roller ball and gel pens. Both work but the plotting speed has to be kept down to 1“ per second.

BTW, I found this painful-to-retrieve programming manual for your plotter while googling around.

http://www.luberth.com/help/HP_7475_Graphics_Plotter_interfacing_and_programming_manual/

BTW2, Several years ago I experimented with photo-plotting by making up a pen adapter that held an optical fiber instead of a pen. I tapped the pen up/down solenoid to turn the light source on and off. Plotting in a dark room directly to film worked fairly well. Now that green laser modules are available so cheaply, I'm going to revisit the concept, only this time with the module mounted directly in a pen body.

So as not to waste so much film on my fixed-width plotter, I'd set up an E-size page in Corel. I draw a box in the center of the page the size of the film. to be used. I plot this to a carrier sheet of mylar in the plotter using a pencil mounted in a pen body. This lets me erase the lines later and reuse the mylar.

In Corel, I then turn on the layer with the PCB artwork, tape the film to the square on the paper and plot only the artwork layer. Works great. I use this same technique when plotting to mylar so as not to waste a large sheet on small artwork.

Adhering the film to the mylar with 3M spray adhesive greatly improves the dimensional accuracy.

John De Armond