Getting It Right By Getting It Wrong: RepRap And The Evolution Of 3D Printing

March 2, 2016 by Elliot Williams 68 Comments

The beginning of the DIY 3D printing movement was a heady time. There was a vision of a post-scarcity world in which everything could and would be made at home, for free. Printers printing other printers would ensure the exponential growth that would put a 3D printer in every home. As it says on the front page: “RepRap is humanity’s first general-purpose self-replicating manufacturing machine.” Well, kinda.

RepRapOneDarwin-darwin — Original Darwin. Photo: Adrian Bowyer, founder of RepRap.

Just to set the record straight, I love the RepRap project. My hackerspace put our funds together to build one of the first few Darwins in the US: Zach “Hoeken” came down and delivered the cut-acrylic pieces in person. I have, sitting on my desk, a Prusa Mendel with 3D parts printed by Joseph Prusa himself, and I spent a fantastic weekend with him and Kliment Yanev (author of Pronterface) putting it together. Most everyone I’ve met in the RepRap community has been awesome, giving, and talented. The overarching goal of RepRap — getting 3D printers in as many peoples’ hands as possible — is worthy.

But one foundational RepRap idea(l) is wrong, and unfortunately it’s in the name: replication. The original plan was that RepRap printers would print other printers and soon everyone on Earth would have one. In reality, an infinitesimal percentage of RepRap owners print other printers, and the cost of a mass-produced, commercial RepRap spinoff is much less than it would cost me to print you one and source the parts. Because of economies of scale, replicating 3D printers one at a time is just wasteful. Five years ago, this was a controversial stance in the community.

On the other hand, the openness of the RepRap community has fostered great advances in the state of the DIY 3D printing art. Printers haven’t reproduced like wildfire, but ideas and designs have. It’s time to look back on the ideal of literal replication and realize that the replication of designs, building methods, and the software that drives the RepRap project is its great success. It’s the Open Hardware, smarty! A corollary of this shift in thought is to use whatever materials are at hand that make experimentation with new designs as easy as possible, including embracing cheap mass-produced machines as a first step. The number of RepRaps may never grow exponentially, but the quality and number of RepRap designs can.

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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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Hackaday Links: January 24, 2016

January 24, 2016 by Brian Benchoff 14 Comments

The RepRap wiki was spammed this week. Everything is fine now, but I feel I should call attention to the fact that the RepRap wiki needs some people to contribute, organize, and maintain everything. The wikis for obscure anime shows are better than the RepRap wiki, so if you’re looking to contribute to an important open source project, there ‘ya go.

The 200cc, 5.5HP, 4-stroke OHV Honda GX200 engine is found in a whole lot of tools, and is a fantastic power plant to build a go-kart around. It also costs about $350. There are clones of this engine available direct from China for about $100. Here’s how you add a turbo to one of these clone engines.

Freescale makes some pretty cool sensors and [Juan Ignacio Cerrudo] figured they needed breakout boards. He has some boards for a low-power three-axis accelerometer, an accelerometer and magnetometer, and a pressure sensor.

The Tektronix TDS744A is an older but still extremely capable 500MHz, 2Gsps, 4-channel scope. You can upgrade it to the 1GHz TDS784A by desoldering a few resistors. Very cool if you’re looking for a cheap-ish 1GHz scope.

[TheBackyardScientist] hung out with some cub scouts a few weekends ago and launched a high altitude balloon over Florida. The payload included a game camera, APRS tracker, GoPro, and a few other bits and bobs. The balloon reached 106,000 feet and landed only a few miles from Cape Canaveral.

Big RC planes – UAVs especially – are a pain to launch. Flying wings above a certain size are just dangerous to launch by hand, and landing gear is heavy and for the most part unnecessary. What’s the next best solution? A trebuchet, of course. It mounts on a car and is able to give a UAV a little bit of altitude and some speed. A pretty good idea that could be easily implemented with some load-bearing PVC pipe.

Everybody likes the Game of Life, so here’s one built with a 6502. It’s built around a Western Design Center 65c816 board we’ve seen before, nine MAX7219 LED controllers mapped to the VIA, and nine 8×8 LED matrix displays. Here’s a video of it in action.

About a month ago, a search of AliExpress turned up Apple’s A8 CPU. I bought one. Here’s what I got. It’s a stupidly small pitch BGA, and I don’t have a datasheet. What am I going to do with it? Make a non-functioning board with a few ports, resistors, no traces, and the A8 chip planted square in the middle.

The Effects Of Color On Material Properties Of 3D Printed Components

December 28, 2015 by Brian Benchoff 16 Comments

The strength of object printed on filament-based 3D printers varies by the plastic used, the G-code used by the printer, the percent infill, and even the temperature the plastic was extruded at. Everything, it seems, has an effect on the strength of 3D printed parts, but does the color of filament have an effect on the stress and strain a plastic part it can withstand? [Joshua M. Pearce] set out to answer that question in one of his most recent papers.

The methods section of the paper is about what you would expect for someone investigating the strength of parts printed on a RepRap. A Lulzbot TAZ 4 was used, along with natural, white, black, silver, and blue 3mm PLA filament. All parts were printed at 190°C with a 60°C heated bed.

The printed parts demonstrated yet again that a RepRap can produce parts that are at least equal in material strength to those produced by a proprietary 3D printer. But what about a difference in the strength among different colors? While there wasn’t a significant variation in the Young’s modulus of parts printed in different colors, there was a significant variation of the crystallization of differently colored printed parts, with white PLA producing the largest percent crystallinity, followed by blue, grey, black, and finally natural PLA. This crystallinity of a printed part can affect the tensile properties of a printed part, but [Pearce] found the extrusion temperature also has a large effect on the percentage of crystallinity.

3D Printing Has Evolved Two Filament Standards

September 29, 2015 by Brian Benchoff 56 Comments

We’re far beyond the heyday of the RepRap project, and the Hackaday tip line isn’t seeing multiple Kickstarters for 3D printers every week. In a way, this is a bit of a loss. The rapid evolution of the low-cost 3D printer seen in the first half of this decade will never be matched, and from now on we’ll only see incremental improvements instead of the revolutionary steps taken by the first Prusa, the first Printrbot, and even the Makerbot Replicator.

This doesn’t mean everything is standardized. There’s still enough room for arguing over deltas versus Cartesians, beds moving on the Y axis versus moving along the Z, and a host of other details that make the current crop of printers so diverse. One of these small arguments is especially interesting: the diameter of the filament. Today, you can get any type of plastic you want, in any color, in two sizes: 1.75 and 3mm. If you think about it, it’s bizarre. Why on Earth would filament manufacturers, hot end fabricators, and even printer manufacturers decide to support two different varieties of the same consumable? The answer is a mix of a historical choice, engineering tradeoffs, and an absolutely arbitrary consequence of what 3D printers actually do.

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The Most Self-Replicating RepRap Yet

September 12, 2015 by Brian Benchoff 46 Comments

The goal of the RepRap project was always a machine that could replicate itself. The project began with the RepRap Darwin, a machine with a frame made nearly entirely of threaded rods, and progressed to the Mendel, with a slightly higher proportion of printed parts. Around 2011, the goal of self-replication fell by the wayside after some money was thrown around. The goal now, it seems, is to create the 3D printer with the best profit margins. That doesn’t mean there still isn’t a small contingent of RepRappers out there trying to improve the status quo and create a printer that can truly self-replicate. [Revar] is one of those tinkerers, and he has just released the RepRap Snappy, a snap-together 3D printer built nearly entirely out of 3D printed parts.

Other 3D printers designed around the idea of self-replication, like the RepRap Morgan and the Simpson family of printers, use strange kinematics. The reason for this is that Cartesian bots can’t print up to the limits of their frame, yet self-replication requires all parts be replicated at the same scale.

[Revar] is setting a new tack in the problem of printer self-replication and is joining parts together with snap fit connectors. The entire frame of the Snappy printer is built out of small parts that interlock to form larger units.

Another of the tricks up [Revar]’s scheme is reducing the number of ‘vitamins’ or parts that cannot be 3D printed. This includes belts, motors, screws, and electronics. You can’t really print machine screws yet, but [Revar] did manage to eliminate some belts and bearings. He’s using a rack and pinion system, all made with printed parts. It’s a technique that hasn’t been seen before, but it does seem to work rather well.

[Revar] has made all the files for the printed parts available in his repository. If you have enough filament, these files are enough to print 73% of the RepRap Snappy.

Thanks [Matt] for sending this one in. Video below.

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