I’m trying to cut out some printed designs, and it’s pointing out that my laser is WAY off of where it thinks it is.
What I’m after:
Print on a sheet of 8.5 x 11 label paper.
Stick the label down to 1/8" plywood.
Get the plywood positioned so that the laser should be able to trace all the lines on the print, cutting them out.
But the laser is going ~3-4% farther than it thinks it’s going: It starts out cutting the top-left pieces out and tracing the outlines. By the time it’s on the bottom right corner of the page, it’s about a full centimeter off. It’s missing the trace lines completely.
One of the cut-out pieces at the bottom right of the page. Note how the arc at the bottom right corner isn’t lining up with the trace-line up-left of it, and the four cut-outs at the bottom-left don’t line up with their trace lines, either.
I’ve pulled out a ruler and confirmed: The ink print is accurate: It wasn’t scaled down. It’s the laser that’s overshooting.
Anyone familiar with this issue?
Know a way to correct for this, either in hardware or software?
The original drawing was created in Affinity Designer 2.
Like you suggested, I just an hour ago made a drawing for the purposes of measuring more precisely, and indeed, the print IS off. It doesn’t account for the full error, but on measuring more closely, it looks like that’s where almost half the error is coming from. Changing the “scale” of the print a smidge percentile corrects it.
That still leaves some error to correct in the laser, though. I could brute force it the same way: Scale the cut-drawing down until it matches the print, that I’m scaling up, until they both agree with each other and the ruler. That’s one option.
Consumer grade inkjet printers are notoriously bad at accuracy, both in absolute and relative terms. Laser printers are worse than inkjets, because the fuser heater cooks the paper and produces irregular distortions:
The laser cutter may have a small scale error on each axis, although it should come out very very very close to the right answer with the step distance calculated correctly:
I eventually gave up printing those scales and plotted them on a CNC gantry machine, which led to the discovery of a leadscrew pitch error:
How they cut the leadscrew that far off-spec remains a mystery.
Basically, unless you measure and calibrate everything, you’ll find nothing matches anything else.