Reforming 3D Prints With Salt And Heat

September 23, 2020 by Al Williams 83 Comments

The biggest problem with fused deposition 3D prints is that while the layers should stick together, they aren’t the same as a solid piece of plastic you would get from, say, injection molding. You can anneal plastic using moderate heat, but it is likely to cause the part to deform or change size. [Free Spirit 1] has a solution for this. Using a powdered salt, the part is packed on the inside and out and put in an oven. The results in the video below look really impressive.

In addition to making the part look solid and — we assume — adding strength, the resulting prints are also water- and gas-tight which was the purpose of the effort. That alone would make the technique worthwhile.

The only thing we noticed is that the part has to have access to hold the salt. Anything not supported would be subject to deformation. However, the ground-up salt is so fine that it should be relatively easy to fill in most parts and, of course, print with 100% infill to avoid hollow internal areas.

[Free spirit 1] used a coffee grinder to get the salt powder, but apparently you can buy “flour salt.” We wondered if other powders might work well, too. Apparently, sand didn’t work out, perhaps because the salt dissolves out in water, so whatever you use, it should probably dissolve in something that won’t attack your plastic.

Annealing isn’t a new idea, and we’d love to see some objective tests on this new method.

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Figuro Draws 3D In Browser

September 17, 2020 by Al Williams 11 Comments

We would have never guessed there would be so many browser-based CAD packages. While TinkerCAD is great for simple things, there are also packages such as OnShape that rival commercial CAD programs. A site calle Figuro claims to occupy the space between TinkerCAD and Blender. We aren’t so sure, but it is an interesting entry into the field. Apparently, Figuro has been around for some time, but has recently had a major face lift. The new interface looks good, but it has invalidated a number of video tutorials on their YouTube channel.

One of the things we like about TinkerCAD is it is highly discoverable. That is, you can fire it up, play with it a bit, and probably do quite a few things. Maybe it is just us, but Figuro didn’t give us the same experience. It is easy enough to draw simple shapes. But trying to multiselect was unreliable. Panning and rotating the view was very sensitive too, so we found we were occasionally lost in the work view with no easy way to reset the view. Even something as simple as subtracting one shape from another was painful.

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Roll Your Own Heelys

September 17, 2020 by Kristina Panos 17 Comments

Remember Heelys, the shoes with wheels in the heels? Just lift up your toes, and away you go. We were at least ten or fifteen years older than the target demographic, but got a pair anyway just to please our inner child and have some fun. Young kids would wear them everywhere and zip around inside stores to the annoyance of everyone but other young kids. We imagine some shopkeepers got to the point where they could spot the things as they walked in the door and nipped the skating party in the bud.

[DevNerd] has conceived of the ultimate plan: if you make your own Heelys, no one necessarily has to know unless you start rolling around. [DevNerd] started by cutting some large, 20mm-deep holes in the bottoms of a pair of Air Jordans and printed a sturdy wheel and a box frame for support.

Each wheel has a bearing on both ends that spin on a threaded rod. We’re not sure why [DevNerd] went with threaded rod, because it seems like that would prematurely wear out the frame box.

Don’t want to cut up your shoes, but want some sweet roller kicks for the daily commute down the hall? You could always make them out of pallet wood.

PLA-F Blends PLA And ABS

September 12, 2020 by Al Williams 31 Comments

In the early days of 3D printing, most people used ABS plastic. It is durable and sticks well to simple surfaces. However, it smells and emits fumes that may be dangerous. It also tends to warp as it cools which causes problems when printing. PLA smells nicer and since it is made from corn is supposed to be less noxious. However, PLA isn’t as temperature resistant and while it will stick better to beds without heat, it also requires more airflow to set the plastic as it prints. [Kerry Stevenson] recently reviewed PLA-F which is a blend of the two plastics. Is it the best of both worlds? Or the worst?

[Kerry] did several tests with interesting results. He did a temperature test tower and found the material printed well between 190 and 240 °C. He did note some stringing problems, though.

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Filament Dust Filter Helps Keep Your Print Quality High

September 6, 2020 by Lewin Day 19 Comments

If we’re honest, our workshop isn’t as clean as it probably should be, and likely many makers out there will say the same. This can have knock-on effects, such as iron filings clogging motors, or in this case, dust affecting the quality of 3D prints. Aiming to tackle this, [3Demon] built a fun Spongebob-themed dust filter for their 3D printer.

The filter works in a simple way. The Spongebob shell is 3D printed in two halves, with a hinge joining both parts. Inside each half, a section of sponge is stuck inside. The two halves are then closed with a snap fit, with the filament passing through a hole in Spongebob’s head and out through the (square) pants. With the sponge packed in nice and tight, dust is wiped from the filament as it feeds through bob to the printer.

While it’s important to install carefully to avoid filament feed issues, it’s an easy way to automatically clean filament during the printing process. You may be surprised just how dirty your filament gets after sitting on the shelf for a few months. Getting rid of such contamination decreases the likelihood of annoying problems like delaminations and jams. Avid printers may also want to consider making their own filament, too. Happy printing!

Impossibilities And 3D Printing

August 29, 2020 by Elliot Williams 43 Comments

This week our own [Donald Papp] wrote a thought-provoking piece on buying and selling 3D-printer models. His basic point: if you don’t know what you’re getting until you’ve purchased it, and there’s no refund policy, how can you tell if your money is being well spent? It’s a serious problem for these nascent markets, because when customers aren’t satisfied they won’t come back.

It got me thinking about my own experience, albeit with all of the free 3D models out there. They are a supremely mixed bag, and even though you’re not paying for the model, you’re paying in printing time, filament, and effort. It pays to be choosy, and all of [Donald]’s suggestions hold in the “free” market as well.

Only download models that have been printed at least once, have decent documentation about things like layer height, filament type, and support, and to the best of your abilities, be critical about the ability to fabricate the part at all. Fused-deposition printers can only print on top of previous layers, and have a distinct grain, so you need to watch out for overhangs and print orientation. With resin printers, you need to be careful about trapped volumes of uncured resin. You want to be sure that the modeler at least took these considerations into account.

But when your parts have strength requirements, fits, and tolerances, it gets even worse. There’s almost no way a designer can know if you’re overextruding on your first layers or not. Different slicers handle corners differently, making inner surfaces shrink to varying degrees. How can the designer work around your particular situation?

My personal answer is open-source. Whenever possible, I prefer models in OpenSCAD. If you download an STL with ten M8 bolt holes, you could widen them all in a modeling program, but if you’ve got the source code, it’s as easy as changing a single variable. Using the source plays to the customizability of 3D printing, which is perhaps its strongest suit, in my mind. Nobody knows exactly how thick your desk is but you, after all. Making a headphone hook that’s customizable is key.

So even if the markets for 3D prints can solve the reliability problems, through customer reviews or requirements of extensive documentation, they’ll never be able to solve the one-size-fits-nobody issue. Open source fixes this easily. Sell me the source, not the STL!

E3D Teaches Additive 3D-Printers How To Subtract

August 18, 2020 by Sonya Vasquez 29 Comments

We might’ve thought that extrusion based 3D printers have hit their peak in performance capabilities. With the remaining process variables being tricky to model and control, there’s only so much we can expect on dimensional accuracy from extruded plastic processes. But what if we mixed machines, adding a second machining process to give the resulting part a machined quality finish? That’s exactly what the folks at E3D have been cooking up over the last few years: a toolchanging workflow that mixes milling and 3D printing into the same process to produce buttery smooth part finishes with tighter dimensional accuracy over merely 3D printing alone.

Dubbed ASMBL (Additive/Subtractive Machining By Layer), the process is actually the merging of two complimentary processes combined into one workflow to produce a single part. Here, vanilla 3D printing does the work of producing the part’s overall shape. But at the end of every layer, an endmill enters the workspace and trims down the imperfections of the perimeter with a light finishing pass while local suction pulls away the debris. This concept of mixing og coarse and fine manufacturing processes to produce parts quickly is a re-imagining of a tried-and-true industrial process called near-net-shape manufacturing. However, unlike the industrial process, which happens across separate machines on a large manufacturing facility, E3D’s ASMBL takes place in a single machine that can change tools automatically. The result is that you can kick off a process and then wander back a few hours (and a few hundred tool changes) later to a finished part with machined tolerances.

What are the benefits of such an odd complimentary concoction, you might ask? Well, for one, truly sharp outer corners, something that’s been evading 3D printer enthusiasts for years, are now possible. Layer lines on vertical surfaces all but disappear, and the dimensional tolerances of holes increases as the accuracy of the process is more tightly controlled (or cleaned up!) yielding parts that are more dimensionally accurate… in theory.

But there are certainly more avenues to explore with this mixed process setup, and that’s where you come in. ASMBL is still early in development, but E3D has taken generous steps to let you build on top of their work by posting their Fusion 360 CAM plugin, the bill-of-materials and model files for their milling tool, and even the STEP files for their toolchanging motion system online. Pushing for a future where 3d printers produce the finer details might just be a matter of participating.

It’s exciting to see the community of 3D printer designers continue to rethink the capabilities of its own infrastructure when folks start pushing the bounds beyond pushing plastic. From homebrew headchanging solutions that open opportunity by lowering the price point, to optical calibration software that makes machines smarter, to breakaway Sharpie-assisted support material, there’s no shortage of new ideas to play with in an ecosystem of mixed tools and processes.

Have a look at ASMBL at 2:29 in their preview after the break.

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