Jun 8, 2015 | By Alec

Our problems are over! One of the biggest challenges facing 3D printing enthusiasts of all shapes, sizes and 3D printers has finally been solved: removing finished prints from your printbed. Nothing is more nightmarish than laboring over your designs for hours and patiently waiting for your printer to finish, only to have your creations ruined by a sticky printbed. Fortunately, the guys from Matterhackers have developed a 3D printable design that provides all of us with a fun and easy solution to this problem: the Automatic Print Ejector.

How can you describe the Automatic Print Ejector? It’s probably best to check out the clip above before reading on. For the Automatic Print Ejector is a fabulous tool that has been taken straight out of a cartoon and applied in a workshop. Essentially consisting of a boxing glove at the end of a scissor mechanism, it automatically punches your designs off the printbed. Perfect for anyone making 20 prints of the same objects while leaving for the weekend, and for everyone who wants to have a bit of fun.

As you have already seen, it works very well and could become a key tool in any maker’s arsenal. ‘The purpose of this device is to remove finished objects from the printer in the most amusing Rube Goldbergish way possible. The original plan was to have a boot swing down and kick the part off the bed, but we decided that a boxing glove would be more hilarious. It is inspired by similar things from old cartoons,’ Tyler Anderson explains. Fortunately, he has also written up a very useful tutorial for easily assembling one of these Automatic Print Ejectors at home.

As he explains, they’ve made the Automatic Print Ejector with some parts they had laying around, but for us it’s a simple matter of downloading all the 3D printable files here. Every part was printed in PLA at a layer thickness of 0.2 mm, 2 Perimeters and 30% infill. ‘In order to actuate the scissor mechanism, I added a gear to the end of one of the linkages. I also found an old stepper motor to drive it. I could have used a hobby servo, but the stepper is what we had and its got more torque anyways. It also conveniently had a small gear already on the shaft,’ Tyler explains. Specifically, they used an old Polulu stepper driver and a Brainwave they had laying around, though these can easily be replaced with similar parts.

Now assembly can be a little bit complicated if you haven’t tackled complex builds before, though Tyler’s tutorial will help you along greatly. Also be sure to keep an eye on the dimensions of your 3D printer, as you might have to alter a few parts. The guys from Matterhackers victimized an OpenBeam Kossel Pro 3D printer for this project, and in their experience it only just worked without damaging the extruder. ‘The 24 cm beam is just barely long enough. The print head narrowly misses the glove while doing the auto-calibration routine and bumps into it a little bit when printing all the way out to the edges,’ Tyler said. However, a potentially hilarious trial and error process will quickly reveal the necessary dimensions.

After assembly and wiring, the programming itself is fairly simple. Tyler has made all the necessary code available on GitHub here. ‘The programming is also not complicated The firmware is based on the OpenBeam branch of Marlin firmware. The changes should not be hard to patch into any other branch of Marlin, though,’ he adds.

And that is, essentially, all there is to it. While it looks great on the video, it also shouldn’t be hard and fast enough to completely break your prints. ‘300 steps/s seems to be the ideal speed. It is quick and forceful, but not so fast that it overloads the stepper motor. Sometimes it skips steps while punching but this is fine because it resets its position when it retracts,’ Tyler explains. So what are you waiting for? Every maker needs an Automatic Print Ejector!


Posted in 3D Printer Accessories



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