Mail Archives: geda-user/2013/04/11/14:25:25
If anyone has tried to run a printer calibration in PCB and been
exceedingly confused by the so-called "Instructions", then I suspect you
are not alone. You are asked to measure one of the horizontal or
vertical lines, however, that is not exactly true. First, these are not
separate lines, they are segments of a single line on each axis. You
can only measure one of the line segments that are bounded at each end
by a grayed in semi-circle. And then, you can't measure any of these
either. Another "sucker punch" is the "large box", which you can't
measure at all if you want the calibration to work. Oddly, this is the
only box for which dimensions are given. The remaining dimensions and
how they are laid out on the sheet you have to search for elsewhere.
After studying the code, here's what I believe should be given as
instructions (based on most recent code built from source):
Run Calibrate Printer from the file menu. This will print a calibration
page. When asked for scale factors, leave the default values (1.000 on
both X and Y). Retrieve the printed page and note that in the lower
left hand corner there are 2 gray semi-circles, one facing up and one
facing right. These are the base points for all measurements. Along the
Horizontal (X) there are 3 additional semi-circles, all facing to the
left. Along the Vertical (Y) there are also three semi-circles, all
facing down. Measurements are made between the flat faces of these
semi-circles. Select a suitable pair of semi-circles on X and measure
between the faces. One of the pair MUST BE THE RIGHT FACING SEMI-CIRCLE
the other can be any one of the 3 left facing semi-circles. The nominal
values for the 3 possible pairings on X are 4 in, 15 cm and 7.5 in. Then
select a suitable pair of semi-circles on Y (remember, one of these must
be the UP facing semi-circle) and measure between these faces. Nominal
spacings on Y are 4 in, 20 cm and 10 in.
Once you have the X and Y measurements, you need to run the calibration
again. When asked for the scale factors you may either 1) calculate the
scale factor (the ratio of the segment's nominal length to the actual
measured length) on each axis (X and Y) and enter these, or 2) simply
enter your measurements and let the program calculate the scale factors
for you. In the second case, the program will select Nominal lengths
that are closest to the measurements you entered. This will only work
if the measured values are not too far off, which should almost always
be the case. If your values are way off, then you will need to calculate
the ratios yourself.
--
fictio cedit veritati
- Raw text -