Scaling factor for laser printers?


#1

Greetings, all.
I seem to be having an issue with the laser printer not printing to scale for home etching.

What I have tried is:
Plotting the circuit board as both PDF and SVG formats.
When loading either format into Inkscape, both plot formats are the exact same. I have a grid setup in Inscape to verify they are true and correct.

However, when printed to the laser printer, the prints are always smaller… Example: A 2.5mm pitch for pin headers, etc. is simply not correct… Always too small on the printout, as with everything else on the board.

Is there a “rule-of-thumb” scaling factor to use when printing ? A printer setting ? Just trial-and-error ?

Printer is Canon Image Class MF232w.
Any advice appreciated.


#2

Have you turned off the “fit to page” function in your printing?


#3

Print directly from KiCad using the “Print board” icon on the Main Icon Menu (one icon left of the Plot icon) and select “Accurate scale 1”.


#4

Make sure that your paper settings are correct US letter vs A4.
Laser printers always do print slightly off, a fraud prevention measure


#5

I’ve not seen original scans printed other then 100% accurate on extremely expensive machines that a certain defence contractor had in their print room.

My home office Cannon scanner/printer won’t let me scan a US dollar bill (might have been a Sliver Certificate)( I was not trying to attempt to print my own paper currency).


#6

The print dialog of kicad has scaling options for x and y direction. (Home printers are not meant for highly accurate printouts.)

Print something with a known size. There are mreasurement scales or calibration scales (name depends on library version.) that can be used for that purpose.

Measure the resulting printout in both directions and calculate a calibration factor for them. Enter them in the print dialog. I advice for another test print after the calibration.


#7

Thank everyone for their reply and help on this. I will try to address every response here at the same time:

Seth_h:
Didn’t try to mess with printer settings… Was doing dry runs… Wanted to avoid having a bunch of printer settings to have to remember.

Sprig (print board, accurate scale):
Appears that printing directly from KiCad fails, at least on mine here.

Sprig and davidsrsb:
Interesting thing on the fraud prevention… Never thought about that.

Rene:
Yes, it ended up being a trial-and-error thing, with 4 print-outs to get “what appears” to be able to work. Not completely sure until a blank board is etched and drilled, but matching components to the print-out looks like it will work.

For everyone else:
I had to “bump-up” the scaling by 1.05% for this particular printer. Your scaling for your particular printer may vary.

Thanks again to everyone that replied !!
Greg