Rethinking Automated Bed Leveling For 3D Printers

February 22, 2016 by Brian Benchoff 38 Comments

Automatic bed leveling is the next killer feature that will be found on all commercial filament printers. It’s a problem that has been solved a few dozen times already; there are just so many ways you can go about it. The Printrbot uses an inductive sensor to determine the position of the metal bed in relation to the nozzle. The Lulzbot Mini touches the nozzle itself to four contacts on the corner of the bed. There are even a few projects that will mechanically level the bed with the help of a system of cams and springs. It’s a difficult problem, and none of these solutions are perfect. [mjrice] has been thinking about the problem, and he hit upon a solution that is simple, elegant, and can be replicated on a 3D printer. It’s the RepRap solution to 3D printing, and it looks cool, to boot.

Instead of using the nozzle as a contact, getting an inductive sensor, or fabricating a baroque system of gears and cams, [mjrice] is doing this the old-fashioned way: a simple microswitch, the same type of switch you would find on the limit switches of any RepRap. Having a switch at the same Z position as a nozzle is an iffy idea, so [mjrice] made this switch retract into the extruder during printing, without using any motors, servos, or other electromechanical contrivances.

The key to this setup is a simple spring and a rack gear. When this rack gear is hit from the left side, it moves an arm and places the switch down on the bed. Hit the rack from the right side, and the switch folds up into the extruder. Combine this with a bit of G-code at the beginning of the print, and the switch will move down, figure out the actual height of the bed, and flip up out of the way. Beautiful, elegant, and the algorithms for bed leveling are already in most major printer firmwares.

You can check out the video of the mechanism below. It’s a great little device, and since it’s on a RepRap first, it’s not going to show up in a proprietary 3D printer next.

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Kicking The Tires Before You Buy: 3d Printers

February 22, 2016 by Gerrit Coetzee 103 Comments

So you’re looking to buy your first 3D printer, and your index finger is quivering over that 300 US Dollar printer on Amazon.com. Stop! You’re about to have a bad time. 3D printing has come a long way, but most 3D printers are designed through witchcraft, legends, and tall tales rather than any rigorous engineering process. I would say most 3D printer designs are either just plain bad, or designed by a team of Chinese engineers applying all their ingenuity to cost cutting. There are a few that are well designed, and there is a comparatively higher price tag attached.

I’ll start by going through some of the myths and legends that show up in 3D printers. After that I’ll go through some of the common, mostly gimmick, features that typically hinder your printer’s ability, rather than adding any useful function. Next I’ll go onto the things that will actually make your printer better. Finally, I’ll add some special consideration if you’re a beginner buying your first printer.

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Good Vibrations In 3D-Printed Clay

February 20, 2016 by Elliot Williams 16 Comments

An engineer with a 3D printer wants everything to be rigid and precise. Wobble induced by flex in the z-axis feedscrews, for instance, makes telltale wavy patterns in the surface that match exactly the screw pitch. Nobody likes those, right? Certainly not an engineer!

But one man’s surface irregularity is another man’s ornamentation. The details we have are sparse, but from looking at the video (also inlined below the break) it’s clear enough: [Olivier van Herpt] and [Ricky van Broekhoven] stuck a vibrating woofer underneath the print bed of their ceramic printer, and use it to intentionally ruin their smooth surface. And they do so to great artistic effect!

We’re not suggesting that you give up entirely on your calibrations, but we do appreciate a little out-of-the-box thinking from time to time. But then our internal engineer raises his head and we wonder if they’re linking the pitch of the woofer to the feed rate of the print head. Your thoughts in the comments?

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The OpenR/C Project

February 19, 2016 by Gerrit Coetzee 12 Comments

[Daniel Norée] started the OpenR/C project back in 2012 when he bought a Thing-O-Matic. In search of a project to test out his new printer, he set his sights on a remote controlled car, which as he put it,”… seemed like the perfect candidate, as it presents a lot of challenges with somewhat intricate moving parts along with the need for a certain level of precision and durability.”

After releasing his second design, the OpenR/C Truggy, he realized a community was forming around this idea, and needed a place to communicate. So, he created a Google+ group. Today, the Truggy has been downloaded over 100,000 times and the Google group has over 5,000 members. It’s a very active community of RC and 3d printing enthusiasts who are testing the limits of what a 3d printer can do.

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A 3D Printed Jet Engine Appears To Function

February 15, 2016 by Gerrit Coetzee 24 Comments

[amazingdiyprojects] has been working on a 3D printable jet engine. You may remember seeing a 3D printed jet engine grace our front page back in October. That one was beautiful didn’t function. This one flips those values around. [amazingdiyprojects] seems to make a living from selling plans for his projects, so naturally most of the details of the build are hidden from us. But from what we can see in the video clips there are some really interesting solutions here.

Some of the parts appear to be hand-formed sheet metal. Others are vitamins like bearings and an electric starter. We really liked the starter mechanism, pressing in the motor to engage with a spline, or perhaps by friction, to give the starting rotation.

What really caught our attention was casting the hot parts of the printer in refractory cement using a 3D printed mold. It reminds us of the concrete lathes from World War 1. We wonder what other things could be built using this method? Flame nozzles for a foundry? A concrete tea-kettle. It’s pretty cool.

We’re interested to see how the jet engine performs and how others will improve on the concept. Video of it in action after the break.

UPDATE: [amazingdiyprojects] posted a video of the engine being disassembled.

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Super Sizing The Printrbot Metal Simple

February 14, 2016 by Brian Benchoff 18 Comments

The Printrbot Simple Metal is a good 3D printer, with a few qualifications. More accurately, the Printrbot Simple Metal is a good first 3D printer. It’s robust, takes a beating, can produce high-quality prints, and is a great introduction to 3D printing for just $600. There are limitations to the Printbot Simple Metal, the most important is the relatively small 150mm cubed build volume.

[ken.do] wanted to print large parts, specifically scale aircraft wings and panels. While the Printrbot can’t handle these things normally, the design of the printer does lend itself to increasing the size of the build volume to 500mm long and 500mm high.

Increasing the build height on the Printrbot is as simple as adding two longer smooth rods and a single threaded rod to the Z axis. Increasing the X axis is a bit trickier: it requires a very flat sheet that doesn’t warp or bend over 500 mm, even when it’s being supported in different places. [ken.do] is engineering stiffness into a build plate here. The solution to a huge bed is a two kilogram aluminum bed supported by heavier rails and riding on a massive printed bushing block. Does it work? Sure does.

If you want to print tall objects, the current crop of 3D printers has you covered: just get a delta, and you’re limited only by the length of the extrusion used in the body. Creating big objects in all three dimensions is a marginally solved problem – just get a big printer. Big printers have drawbacks, notably the incredible power requirements for a huge heated build plate.

The ability to print long objects is a problem that’s usually not addressed with either commercial 3D printers or RepRaps. We’re glad to see someone has finally realized the limitations of the current crop of 3D printers and has come up with a way to turn a very good first printer into something that solves a problem not covered by other 3D printers.

Repairing A MakerBot Mightyboard Clone

February 13, 2016 by Will Sweatman 20 Comments

It can be argued that MakerBot, a company that makes popular 3D printers, hit its pinnacle with the introduction of the Replicator 2. It was designed well and completely open source, including the motherboard that drove the printer – known as the Mightyboard. China quickly picked up on the success of the Replicator 2 and copy/pasted several of their own versions (at a much cheaper sale price). One of these outfits is called Wanhao, and their version of the Replicator 2 is called..wait for it…the Duplicator!

Their version of the Mighyboard is identical to the original, minus a few nickle and dime components. This suggests that Wanhao made an effort to cut as much cost as possible without looking at what functionality they were removing. And anytime a company does this, you can bet the quality of the board manufacturer is at the bottom of the barrel. [Avrydev] found this out the hard way when he repaired a faulty motherboard from a broken Duplicator.

The board would not connect to the software via USB, and the startup tune pitch was off. [Arvydev] flashed new firmware via ICSP, but that did not help. He eventually clued in on the main crystal for the Atmega processor. A quick swap and presto! The printer is as good as new.