Put The 3D Printer To Sleep So You Can Rest Easy

At this point you’ve probably already heard the news: cheap Chinese 3D printers sometimes catch fire. Now we can’t say we’re shocked to find out that absolute bottom of the barrel gear wasn’t designed to the highest standards (gotta cut those corners someplace), but that doesn’t change the fact that there are thousands of hackers and makers out there who are in possession of one of these suspect machines. Just tossing them to the curb is hardly the hacker way, so we’ve got to find ways to make the best of the hand dealt to us.

After sleeping with one eye (and maybe one nostril) open during some overnight prints, Hackaday.io user [TheGrim] wanted a way to make sure his Alunar Anet A6 didn’t stay powered on any longer than necessary. So he came up with a way of using the printer’s own endstop switch to detect if the print has completed, and cut the power.

The idea is simple, but of course the real trick is in the implementation. By adding a “Home” command to his ending G-Code in Cura, [TheGrim] reasoned he could use the Y endstop switch to determine if the print had completed. It was just a matter of reading the state of the switch and acting on it.

In the most basic implementation, the switch could be used to control a relay on the AC side of the power supply. But [TheGrim] doesn’t trust relays, and he wanted to pack in a couple “smart” features so he ended up using a PIC microcontroller and two 12 amp TRIACs. There’s also a couple of LEDs and toggle switches to serve as the user interface, allowing you to enable and disable the automatic shutdown and get status information about the system.

Will cutting the juice to the PSU prevent another terrible fire? It’s debatable. But it certainly can’t hurt, and if it makes [TheGrim] feel more confident about running his machine, then so be it. We’d still advise anyone with a 3D printer at home to brush up on their fire safety knowledge.

Endstops That Stay Out of the Way

In the course of building a new delta printer, [thehans] decided he needed his own endstop design that used minimal hardware. Endstops are just switches that get hit when the printer moves at the extreme of an axis, but [thehans] wanted something with a bit of refinement for his BigDelta 3D Printer build.

The result is a small unit that cradles a microswitch and needs only a single zip tie that mounts flush, resulting in a super tidy looking piece. In addition, it mounts on the delta’s v-slot rails such that the mount does not take up any of the machine’s range of motion, because the carriage can travel past it. It is a parametric design made in OpenSCAD, so feel free to modify it to accommodate other types of switches.

Continue reading “Endstops That Stay Out of the Way”

Solving Endstop Woes with a Simple Analog Filter

NoiseEndstop

You know what’s cool? Using your engineering knowledge to solve problems that you have while building something. This is exactly what [Reinis] did when his 3D printer’s endstop wasn’t working.

Many of us automatically go to a microcontroller when we run into a problem with a sensor, but often a simple analog filter will do the trick. The endstop in [Reinis’s] RepRap style 3D printer was giving off an unusual amount of noise when closed. When he hooked the endstop up to his oscilloscope, he was shocked to see how much noise there really was. In comes the low-pass filter. Unhappy with the response time of his low-pass filter, [Reinis] solved the problem using a pullup resistor. Two resistors and a capacitor was all that he needed to fix the problem. A great solution!

How have you used analog filters in your projects? Send us a tip and let us know!