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EQ7: Printed Block Size Not Accurate Vertically

Why is the size of my printed block off in one direction?

Printing accuracy, on any inkjet printer, is almost always better in the horizontal direction (direction that the print head moves when the paper is stopped), than it is in the vertical direction in which the paper moves. The reason for this is that paper feeding motors are not as accurate as print-head positioning. So if the block you printed at 6″W x 6″H comes out 6″W but not exactly 6″H, it most likely is caused by your printer’s paper feed. Each printer also has a margin of error range in the paper feeding direction. Each printer has an internal self-test page that, when you know the secret formula, you can measure the paper feeding error to see if it is within spec.

Test your printer’s feeding

  • print a 12×12 square
  • measure the error in the vertical direction
  • divide by 12 to get approximate error per inch
  • calculate what length you wanted to print
  • add (subtract) the error per inch to the length desired
  • do a test print to verify
  • adjust error measurement
  • this would then give you a pretty good vertical error rate for that particular printer’s paper feed. This error per inch should be usable for other printouts needing a more accurate vertical size. You should only need to do this once in the printer’s lifetime.
  • use the Custom Paper Size setting in the printer driver to set the page length accounting for error measurement

Each model of printer will likely be different in terms of paper moving accuracy. Inkjet printers can be very accurate at moving paper, but for example in many of the inexpensive inkjet printers, the parts used to build the printer may not have been selected to move paper with high accuracy. This may or may not be the same case for LaserJet printers. Since each model printer uses different components the only way to determine the printing dimension accuracy is to test it out by printing a graphic with known dimensions and then measuring it.