3D Printering: When An STL File Is Not Quite Right

May 16, 2018 by Donald Papp 49 Comments

STL files are everywhere. When there’s something to 3D print, it’s probably going to be an STL. Which, as long as the model is good just as it is, is no trouble at all. But sooner or later there will be a model that isn’t quite right in some way and suddenly project progress hits a snag.

When models interface with other physical things, those other components may not always be exactly as the designer expected. Being mindful about such potential inconsistencies during the design phase can help prevent problems, but it’s not always avoidable. The reason it’s a problem is because an STL file represents a solid model as a finished unit; it is not really intended to be rolled back into CAD programs for additional design changes.

STL files can be edited, but just like re-modeling a component from scratch, it can be a tricky process for those who don’t live and breathe this stuff. I’ll describe a few common issues related to STLs that can hold up getting that new project together, along with ways to deal with them. Thanks to 3D printing becoming much more commonplace, basic tools are within reach of even the least CAD-aware among us.

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3D Printing Air Quality Study

May 13, 2018 by Al Williams 18 Comments

You’ll often hear about some study in the media and then — on examination — find it doesn’t really apply to your situation. Sure, substance X causes cancer in rats, but they ate 8 pounds of it a day for a decade. That’s why we were glad to see [Chuck] post a series of videos about 3D printing air quality based on his practical experience. You can see the summary video, below.

[Chuck] is quick to point out that he isn’t a doctor or even a chemist. He also admits the $100 meter from IGERESS he is using isn’t necessarily high-quality test gear. Still, the data is a good guideline and he did get repeatable results.

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Fail Of The Week: 3D Printed Worm Gear Drive Project Unveils Invisible Flaw

May 11, 2018 by Roger Cheng 27 Comments

All of us would love to bring our projects to life while spending less money doing so. Sometimes our bargain hunting pays off, sometimes not. Many of us would just shrug at a failure and move on, but that is not [Mark Rehorst]’s style. He tried to build a Z-axis drive for his 3D printer around an inexpensive worm gear from AliExpress. This project was doomed by a gear flaw invisible to the human eye, but he documented the experience so we could all follow along.

We’ve featured [Mark]’s projects for his ever-evolving printer before, because we love reading his well-documented upgrade adventures. He’s not shy about exploring ideas that run against 3D printer conventions, from using belts to drive the Z-axis to moving print cooling fan off the print head (with followup). And lucky for us, he’s not shy about document his failures alongside the successes.

He walks us through the project, starting from initial motivation, moving on to parts selection, and describes how he designed his gearbox parts to work around weaknesses inherent to 3D printing. After the gearbox was installed, the resulting print came out flawed. Each of the regularly spaced print bulge can be directly correlated to a single turn of the worm gear making it the prime suspect. Then, to verify this observation more rigorously, Z-axis movement was measured with an indicator and plotted against desired movement. If the problem was caused by a piece of debris or surface damage, that would create a sharp bump in the plot. The sinusoidal plot tells us the problem is more fundamental than that.

This particular worm gear provided enough lifting power to move the print bed by multiplying motor torque, but it also multiplied flaws rendering it unsuitable for precisely positioning a 3D printer’s Z-axis. [Mark] plans to revisit the idea when he could find a source for better worm gears, and when he does we’ll certainly have the chance to read what happens.

How To Build Anything Out Of Aluminum Extrusion And 3D Printed Brackets

May 8, 2018 by Roger Cheng 42 Comments

The real power of 3D printing is in infinite customization of parts. This becomes especially powerful when you combine 3D printing with existing materials. I have been developing a few simple tricks to make generic fasteners and printed connectors a perfect match for aluminum extrusion, via a novel twist or two on top of techniques you may already know.

Work long enough with 3D printers, and our ideas inevitably grow beyond our print volume. Depending on the nature of the project, it may be possible to divide into pieces then glue them together. But usually a larger project also places higher structural demands ill-suited to plastic.

Those of us lucky enough to have nice workshops can turn to woodworking, welding, or metal machining for larger projects. Whether you have that option or not, aluminum extrusion beams provide the structure we need to go bigger and to do it quickly. And as an added bonus, 3D printing can make using aluminum extrusion easier and cheaper.

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3D Printed Bicycle Tire Not Full Of Hot Air

May 7, 2018 by Al Williams 30 Comments

To show off its new TPU filament called PRO FLEX, BigRep GmbH posted a video showing a 3D printed bike tire that uses a flexible plastic structure instead of air. The video shows them driving the bike around Berlin.

According to the company, the filament will allow the creation of a large number of industrial objects not readily built with other types of plastic. Their release claims the material has high temperature resistance, low temperature impact resistance, and is highly durable. Applications include gear knobs, door handles, skateboard wheels, and other flexible parts that need to be durable.

The material has a Shore 98 A rating. By way of comparison, a shoe heel is typically about 80 on the same scale and an automobile tire is usually around 70 or so. The hard rubber wheels you find on shopping carts are about the same hardness rating as PRO FLEX.

Obviously, a bicycle tire is going to take a big printer. BigRep is the company that makes the BigRep One which has a large build volume. Even with a wide diameter tip, though, be prepared to wait. One of their case studies is entitled, “Large Architectural Model 3D Printed in Only 11 Days.” Large, in this case, is a 1:50 scale model of a villa. Not tiny, but still.

We’ve looked at other large printers in the past including 3DMonstr, and the Gigimaker. Of course, the latest trend is printers with a practically infinite build volume.

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3D Printing Electronics Direct To Body

April 29, 2018 by Al Williams 11 Comments

Some argue that the original Star Trek series predicted the flip phone. Later installments of the franchise used little badges. But Babylon 5 had people talking into a link that stuck mysteriously to the back of their hand. This might turn out to be true if researchers at the University of Minnesota have their way. They’ve modified a common 3D printer to print electronic circuits directly to the skin, including the back of the hand, as you can see in the video below. There’s also a preview of an academic paper available, but you’ll have to pay for access to that, for now, unless you can find it on the gray market.

In addition, the techniques also allowed printing biologically compatible material directly on the skin wound of a mouse. The base printer was inexpensive, an Anycubic Delta Rostock that sells for about $300.

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2018’s Hottest Accessory Is A 3D Printed Air Raid Siren

April 27, 2018 by Lewin Day 11 Comments

Some say the spectre of global nuclear annihilation is closer than ever before. What better time to head to the workshop to prepare for the coming apocalypse? [MrExpert] is here with the build you need – an air raid siren you can print at home.

It’s a simple build, which makes it fun and accessible for just about anyone with a 3D printer. Rotational power is provided by a brushless outrunner motor hooked up to an ESC, controlled with a servo tester. The rotor and frame for the parts are 3D printed, and held together with a handful of standard fasteners.

Initial testing proves that yes, it does work and generates a rather earsplitting tone. The second revision improves upon this somewhat. However, the key to getting that authentic sound is in the sweep of the tone. By replacing the servo tester with an Arduino or other micro that can generate smoothly sweeping pulses to ramp the rotational speed up and down, you’ll get much closer to that genuine the-sky-is-falling timbre.

It’s certainly not rocket science, and would make a great project to whip up with the kids on a rainy weekend. While you’re at it you can share the wisdom behind the duck and cover technique, but maybe save the geopolitical rants for when they’re a bit older. We’ve seen air raid siren builds before, too – like this sturdy wooden unit.