|Re: HP7470A Plotter calibration with an HP-IL interface|
Message #2 Posted by Garth Wilson on 23 June 2011, 4:58 p.m.,
in response to message #1 by Richard L. Taylor
Are you missing the manual? I have the manual here for the 7475 which is almost the same thing but for bigger paper, with HPIB which should work the same way, and I don't find anything about calibration. If it were an analog machine, there would be trimmers inside for that; but it's not. It's all stepper-motor controlled, with gears and a toothed belt, so it cannot come out of calibration. We used one continuously for months at my last place of work around 1990, and I wondered about the rough wheels that control the paper movement wearing down, but I guess their carbide surface was so hard that it wasn't a problem. Otherwise, I suppose you could plot something, measure it, and crank calibration constants into your software to multiply the X and Y values by.
What we were using it for was plotting PC boards (2x or 4x actual size) on very tough, stable-based material, before the days of being able to just send your files to a board house via the internet, and the boards always came out perfect and screw holes and connectors lined up perfectly with what they were supposed to mate with. There was no discernable error. Ever.