Hacker News new | ask | show | jobs
by chantepierre 1061 days ago
A printer will usually leave a dot pattern to reproduce shapes, with a resolution fine enough that everything will be sharply defined.

The blackness of a laser printer is a bit less qualitative than ink, because it's shinier from a large variety of viewing angles.

Here if you zoom it a bit, you can see a very slight wobble in the pen tracks because it catches a bit of the paper's grain, and depositing ink, the paper "drinks" the ink which fattens the lines a tiny bit.

This is more noticeable on the drawings with a lot of pen lifts/drops, where both the lift and the drop leave a dot a bit larger than the line between them.

The one with gradients made with lines closer and closer is especially eye-catching to me because all of those imperfections adding to produce this "worn-out" look in the darkest parts of the gradients.

Some paths overlap a bit and if you look very closely there are more than one nuance of black because of this - in some other places, the lift/drop are close enough that a bit of ink seems to travel by capillarity between the lift and the drop, resulting in two touching lines that were separated in the program..

The ones having a lot of circles show other imperfections, with a bit of ovalization in the circles, and the paths generated to fill the circles with black missing a few parts..

What I like a lot is that the result shows all of those little details that accumulate and produce this imperfect look, without needing to simulate it in Photoshop or another software if you were to print it with a regular printer.

2 comments

> Here if you zoom it a bit, you can see a very slight wobble in the pen tracks because it catches a bit of the paper's grain, and depositing ink, the paper "drinks" the ink which fattens the lines a tiny bit.

I think you're misattributing things. Plotters use stepper motors and so have a minimum distance they can move along each axis. Due to this, they don't produce perfect lines at an angle and do introduce similar artifacts to what you'd see on a screen.

IME older plotters use DC motors and optical encoders rather than steppers, and do seem to produce perfect lines at angles. They can't do curves perfectly, as even when you specify an arc or bezier curve, the plotter breaks it down into small straight segments.
the step resolution is such (80 steps/mm) on the axidraw v3 that this isn't really an issue. From their product page:

* Native XY resolution: 2032 steps per inch (80 steps per mm).

* Reproducibility (XY): Typically better than 0.005 inches (0.1 mm) at low speeds.

You must be right, there also must be mechanical steps or wobble at play here. I was hesitant because my 3D printer (lower-end than an Axidraw) seems capable of smoother angled/curved lines than what we can see here. On the other hand plotters I've seen (a long time ago) seemed to not eliminate all vibration in the pen.. but I did not see a mid to high end recent plotter running.
FDM 3D printers squish molten plastic onto the previous layer, and that probably helps balance out the limited "resolution" of stepper motors. Also I'm guessing the inertia makes the extruder movement a bit more continuous, after all it's enough to cause artifacts like ghosting when printing at higher speeds.
That's disappointing. I had assumed these devices were analogue and able to draw true curves. This makes me not so excited about them.
No true draftsman
An analog one could be built with 3 phase motors, but that's another project.
It's also not that uncommon for people to build intentionally bad plotters (I've done it), because the results when you stick a picture through the process have their own charm.
Similar to a 'prepared piano'. By making your instrument unique you introduce interesting variation and improvisation.