Hackaday Prize Entry: Linear Stepper Motors

Today, your average desktop 3D printer is a mess of belts, leadscrews, and pulleys. For his Hackaday Prize entry, [DeepSOIC] is eliminating them entirely. How’s he doing this? With a linear stepper motor.

Search Google for ‘linear stepper motor’ and you’ll find a bunch of NEMA-bodied motors with leadscrews down the middle. This is not a linear stepper motor. This is a stepper motor with a leadscrew down the middle. The motor [DeepSOIC] has in mind is more like a mashup of a rack gear and a maglev train. The ‘linear’ part of this motor is a track of magnets perpendicular to the axis of the motor, with alternating polarities. The ‘motor’ part of this motor is a carriage with two field windings. It’s an unrolled stepper motor, basically, and could run a 3D printer much faster without as much slop and backlash.

Right now [DeepSOIC] is in the experimental phase, and he had a plan to print the axis of his linear stepper in ferromagnetic filament. This did not work well. The steel found in electric motors has a magnetic permeability of about 4000, while the magnetic permeability of his brand of ferromagnetic filament is about 2. Even if the idea of printing part of a motor was a complete failure, it was a great success at characterizing the properties of a magnetic 3D printing filament. That makes it a great entry for the Hackaday Prize, and a perfect example of what we’re looking for in the Citizen Science portion of the Prize.

3D Printering: Makerbot’s Class Action Suit Dismissed

This time last year, Stratasys, parent company of Makerbot, was implicated in a class action suit. Investors claimed Stratasys violated securities laws, and overstated both the performance of the 5th generation of Makerbot printers and the performance of the company itself. Court docs received by Adafruit have revealed this case has been dismissed with prejudice. Makerbot won this one.

The case presented by Stratasys investors relied on two obvious facts. First, the price of Stratasys shares fell far beyond expectations. Second, the extruder for the 5th generation of Makerbot printers – the ‘Smart Extruder’ – was terrible. No one can reasonably dispute these claims; shares of SYSS fell from $120 in September of 2014 to $30 in September of 2015. With many returns to handle, Makerbot quickly redesigned the Smart Extruder.

Both of these indisputable facts are in stark contrast to statements made by Stratasys and Makerbot at the time. In a press release for the 4th quarter 2013 financial results, Stratasys’ expected sales to grow at least 25% over 2013 and stated it was experiencing “strong sales” of its desktop 3D printer. Concerning the Smart Extruder, Makerbot stated this new feature of the 5th generation Makerbots would make them easy to use, and “define the new standard for quality and reliability.”

The facts of this case are not in dispute – Stratasys did not see the growth they expected in late 2013. The Smart Extruder certainly did not make printers more reliable. These facts, however, are not sufficient to violate securities law.  In a wonderful legal turn of phrase, the judge deciding this case called the statements about the quality of the 5th generation Makerbots consisted of, “non-actionable puffery,” and a ‘statement so vague and such obvious hyperbole than no reasonable investor would rely on them.’

Statements made by Stratasys on their financial performance were also found not to be sufficient to violate securities laws. Stratasys did make several statements about negative performance in late 2014 and 2015, and positive statements made earlier did not have an intent to deceive investors.

This is good news for Makerbot. The claims brought by investors in this case had little merit. The case cannot be appealed, and Stratasys is no longer facing a class action suit. Does this news actually matter? Not really; Makerbot is a dead man walking, and 2016 sales will be at levels not seen since 2010 or 2011.

The consumer 3D printing industry is booming, despite the Makerbot bellwether though.

Modding The Monoprice MP Mini Printer

Two weeks after my review of the MP Select Mini 3D printer, Monoprice’s own website has said this printer has been out of stock, in stock, and out of stock again several times. This almost unimaginably cheap 3D printer is proving to be exceptionally popular, and is in my opinion, a game-changing machine for the entire world of 3D printing.

With the popularity of this cheap printer that’s more than halfway decent, there are bound to be improvements. Those of us who have any experience with 3D printers aren’t going to be satisfied with a machine with any shortcomings, especially if it means we can print enhancements and mods for our printers.

Below are the best mods currently available for this exceptional printer. Obvious problems with the printer are corrected, and it’s made a little more robust. There are mods to add a glass build plate, and a few people are even messing around with the firmware on this machine. Consider this volume one of the MP Mini hacks; with a cheap printer that’s actually good, there are bound to be more improvements.

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Build A 3D Printer Workhorse, Not An Amazing Disappointment Machine

3D printers have become incredibly cheap, you can get a fully workable unit for $200 – even without throwing your money down a crowdfunded abyss. Looking at the folks who still buy kits or even build their own 3D printer from scratch, investing far more than those $200 and so many hours of work into a machine you can buy for cheap, the question “Why the heck would you do that?” may justifiably arise.

The answer is simple: DIY 3D printers done right are rugged workhorses. They work every single time, they never break, and even if: they are an inexhaustible source of spare parts for themselves. They have exactly the quality and functionality you build them to have. No clutter and nothing’s missing. However, the term DIY 3D printer, in its current commonly accepted use, actually means: the first and the last 3D printer someone ever built, which often ends in the amazing disappointment machine.

This post is dedicated to unlocking the full potential in all of these builds, and to turning almost any combination of threaded rods and plywood into a workshop-grade piece of equipment.

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R/C Hot Rod Built Completely From Scratch

[ossum]’s R/C hot rod shows what’s possible when a talented hacker takes full advantage of all the modern resources available to them. The results are stunning.

[ossum] had a stack of Amazon and Shapeways credits lying around after winning a few competitions. He had this dream of building an R/C car for a while, and decided now was the time. After ordering all the needed parts from Amazon, he made an extremely nice model of the car in Fusion 360. The CAD model is a great learning resource. If you want to learn how to use reference photos, parts, and more to build a detailed and useful CAD model we recommend downloading it as a Fusion archive and scrubbing through the timeline to see how he did it.

Some of the parts were sent off for laser cutting. Others were 3D printed. The rest he made himself. Thanks to his model, they all went together well. You can see his R/C rod racing in the video after the break.

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Improving 3D Printed Gears With… Hot Water

Being able to print out custom gears is one area where 3D printing can really shine, and [Karl Lew] has been busy doing exactly that with pinion gears printed in PLA and mounted to stepper motor shafts, but there are tradeoffs. Pinion gears need to grip a motor shaft tightly – normally done with a screw through the gear and onto the motor shaft. But a motor and its shaft can get quite warm when doing a lot of work, and a tight screw on a hot motor’s shaft will transmit that heat into the PLA, which can then deform.

[Karl Lew] managed to improve things in an unusual way: using a hot water bath to anneal the gear while it is attached to the stepper shaft. Annealing PLA has the effect of increasing the crystallinity of the material, which – according to an article going into some detail about the process of annealing PLA – increases stiffness, strength, and heat deflection. The annealing process also shrinks the part slightly, which happens to result in a very tight joint made between the gear and the slotted stepper shaft if the gear is annealed while connected to the motor.

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A Hydra Of A 3D Printer

3D printers are great for producing one thing, but if you need multiple copies, the workflow quickly starts to go downhill. The solution? Build a 3D printer with multiple print heads, capable of printing four objects in the same amount of time it takes to print one.

This build is an experiment for [allted]’ Mostly Printed CNC / MultiTool. It’s a CNC machine that uses printed parts and 3/4″ electrical conduit for the frame and rails.  That last bit is the interesting part: electrical conduit is cheap, easy to acquire, available everywhere, and can be cut with a hacksaw. As far as desktop CNC machines go, it doesn’t get simpler or cheaper than this, and a few of these builds are milling wood with the same quality of a machine based on linear rails. It won the grand prize in the recent Boca Bearings contest, and is a great basis for a cheap and serviceable 2.5 or 3D CNC.

[allted] already has this cheap CNC mill cutting aluminum and engraving wood with a laser, showing off the capabilities of a remarkably cheap but highly expandable CNC machine. It’s a fantastic build, and we can’t wait to see more of these machines pop up in garages and workspaces.

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