When Does Moving To Resin 3D Printing Make Sense?

An Elegoo Mars DLP resin 3D printer, straight to my doorstep for a few hundred bucks. What a time to be alive.

Resin-based 3D printers using stereolithography (SLA) and especially digital light processing (DLP) are getting more common and much more affordable. Prosumer-level options like Formlabs and the Prusa SL1 exist, but more economical printers like the Elegoo Mars, Anycubic Photon, and more can be had for a few hundred bucks. Many printers and resin types can even be ordered directly from Amazon, right at this moment.

Resin prints can look fantastic, so when does it make sense to move to one of these cheap DLP printers? To know that, consider the following things:

  • The printing process and output of resin printers is not the same as for filament-based printers. Design considerations, pre-processing, and post-processing are very different.
  • Resin printing has a different workflow, with consumables and hidden costs beyond the price of resin refills.

Things may not be quite where fused deposition modeling (FDM) printers were just a few short years ago when we were extremely impressed with the quality of printer one could get for about $200, but it is undoubtedly far more accessible than ever before. Let’s look at how to inform a decision about whether to take the plunge. Continue reading “When Does Moving To Resin 3D Printing Make Sense?”

Why Spacecraft Of The Future Will Be Extruded

It’s been fifty years since man first landed on the Moon, but despite all the incredible advancements in technology since Armstrong made that iconic first small step, we’ve yet to reach any farther into deep space than we did during the Apollo program. The giant leap that many assumed would naturally follow the Moon landing, such as a manned flyby of Venus, never came. We’ve been stuck in low Earth orbit (LEO) ever since, with a return to deep space perpetually promised to be just a few years away.

Falcon Heavy Payload Fairing

But why? The short answer is, of course, that space travel is monstrously expensive. It’s also dangerous and complex, but those issues pale in comparison to the mind-boggling bill that would be incurred by any nation that dares to send humans more than a few hundred kilometers above the surface of the Earth. If we’re going to have any chance of getting off this rock, the cost of putting a kilogram into orbit needs to get dramatically cheaper.

Luckily, we’re finally starting to see some positive development on that front. Commercial launch providers are currently slashing the cost of putting a payload into space. In its heyday, the Space Shuttle could carry 27,500 kg (60,600 lb) to LEO, at a cost of approximately $500 million per launch. Today, SpaceX’s Falcon Heavy can put 63,800 kg (140,700 lb) into the same orbit for less than $100 million. It’s still not pocket change, but you wouldn’t be completely out of line to call it revolutionary, either.

Unfortunately there’s a catch. The rockets being produced by SpaceX and other commercial companies are relatively small. The Falcon Heavy might be able to lift more than twice the mass as the Space Shuttle, but it has considerably less internal volume. That wouldn’t be a problem if we were trying to hurl lead blocks into space, but any spacecraft designed for human occupants will by necessity be fairly large and contain a considerable amount of empty space. As an example, the largest module of the International Space Station would be too long to physically fit inside the Falcon Heavy fairing, and yet it had a mass of only 15,900 kg (35,100 lb) at liftoff.

To maximize the capabilities of volume constrained boosters, there needs to be a paradigm shift in how we approach the design and construction of crewed spacecraft. Especially ones intended for long-duration missions. As it so happens, exciting research is being conducted to do exactly that. Rather than sending an assembled spacecraft into orbit, the hope is that we can eventually just send the raw materials and print it in space.

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True Transparent Parts From A Desktop 3D Printer

We’re no strangers to seeing translucent 3D printed parts: if you print in a clear filament with thin enough walls you can sorta see through the resulting parts. It’s not perfect, but if you’re trying to make a lamp shade or decorative object, it’s good enough. You certainly couldn’t print anything practical like viewing windows or lenses, leaving “clear” 3D printing as more of a novelty than a practical process.

But after months of refining his process, [Tomer Glick] has finally put together his guide for creating transparent prints on a standard desktop FDM machine. It doesn’t even require any special filament, he says it will work on PLA, ABS, or PETG, though for the purposes of this demonstration he’s using the new Prusament ABS. The process requires some specific print settings and some post processing, but the results he’s achieved are well worth jumping though a few hoops.

According to [Tomer] the secret is in the print settings. Essentially, you want the printer to push the layers together far closer than normal, in combination with using a high hotend temperature and 100% infill. The end result (hopefully) is the plastic being laid down by the printer is completely fused with the preceding one, making a print that is more of a literal solid object than we’re used to seeing with FDM printing. In fact, you could argue these settings generate internal structures that are nearly the polar opposite of what you’d see on a normal print.

The downside with these unusual print settings is that the outside of the print is exceptionally rough and ugly (as you might expect when forcing as much plastic together as possible). To expose the clear internals, you’ll need to knock the outsides down with some fairly intense sanding. [Tomer] says he starts with 600 and works his way up to 4000, and even mentions that when you get up to the real high grits you might as well use a piece of cardboard to sand the print because that’s about how rough the sandpaper would be anyway.

[Tomer] goes on to demonstrate a printed laser lens, and even shows how you can recreate the effect of laser-engraved acrylic by intentionally putting voids inside the print in whatever shape you like. It’s a really awesome effect and honestly something we would never have believed came off a standard desktop 3D printer.

In the past we’ve seen specialized filament deliver some fairly translucent parts, but those results still weren’t as good as what [Tomer] is getting with standard filament. We’re very interested in seeing more of this process, and are excited to see what kind of applications hackers can come up with.

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3D Print Springs With Hacked GCode

If you’ve used a desktop 3D printer in the past, you’re almost certainly done battle with “strings”. These are the wispy bits of filament that harden in the air, usually as the printer’s nozzle moves quickly between points in open air. Depending on the severity and the material you’re printing with, these stringy interlopers can range from being an unsightly annoyance to triggering a heartbreaking failed print. But where most see an annoying reality of pushing melted plastic around, [Adam Kumpf] of Makefast Workshop sees inspiration.

Noticing that the nozzle of their printer left strings behind, [Adam] wondered if it would be possible to induce these mid-air printing artifacts on demand. Even better, would it be possible to tame them into producing a useful object? As it turns out it is, and now we’ve got the web-based tool to prove it.

As [Adam] explains, you can’t just load up a 3D model of a spring in your normal slicer and expect your printer to churn out a useful object. The software will, as it’s designed to do, recognize the object can’t be printed without extensive support material. Now you could in theory go ahead and print such a spring, but good luck getting the support material out.

The trick is to throw away the traditional slicer entirely, as the layer-by-layer approach simply won’t work here. By manually creating GCode using carefully tuned parameters, [Adam] found it was possible to get the printer to extrude plastic at the precise rate at which the part cooling fan would instantly solidify it. Then it was just a matter of taking that concept and applying it to a slow spiral motion. The end result are functional, albeit not very strong, helical compression springs.

But you don’t have to take their word for it. This research has lead to the creation of an online tool that allows you to plug in the variables for your desired spring (pitch, radius, revolutions, etc), as well as details about your printer such as nozzle diameter and temperature. The result is a custom GCode that (hopefully) will produce the desired spring when loaded up on your printer. We’d love to hear if any readers manage to replicate the effect on their own printers, but we should mention fiddling with your printer’s GCode directly isn’t without its risks: from skipping steps to stripped filament to head crashes.

The results remind us somewhat of the 3D lattice printer we featured a couple of years back, but even that machine didn’t use standard FDM technology. It will be interesting to see what other applications could be found for this particular technique.

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Maker Faire NY: Cocoa Press Chocolate Printer

If you haven’t figured it out by now, the hype over desktop filament printers is pretty much over. But that doesn’t mean there aren’t new avenues worth exploring that use the basic FDM printer technology. If anything, the low cost and high availability of 3D printer parts and kits makes it easier to branch off into new territory. For example, experimenting with other materials which lend themselves to being “printed” layer by layer like a thermoplastic. Materials such as cement, clay, or even chocolate.

[Evan Weinstein] brought his Cocoa Press printer to the 2018 World Maker Faire in New York, and we have to say it’s a pretty impressive piece of engineering. Hackers have been known to throw a syringe-based paste extruder onto a regular 3D printer and try their luck with squirting out an edible object from time to time, but the Cocoa Press is truly a purpose built culinary machine.

Outwardly it features the plywood case and vaguely Makerbot-looking layout that we’ve seen plenty of times before in DIY 3D printers. It even uses the same RAMPS controller running Marlin that powers your average homebrew printer. But beyond these surface similarities, the Cocoa Press has a number of purpose-built components that make it uniquely qualified to handle the challenges of building with molten chocolate.

For one, beyond the nozzle and the walls of the syringe, nothing physically comes into contact with the chocolate to be printed; keeping the mess and chance of contamination to a minimum. The leadscrew actuated plunger used in common paste extruders is removed in favor of a purely air powered system: a compressor pumps up a small reservoir tank with filtered and dried air, and the Marlin commands which would normally rotate the extruder stepper motor are intercepted and used to trigger an air valve. These bursts of pressurized air fill the empty area above the chocolate and force it out of the 0.8 mm nozzle.

In a normal 3D printer, the “melt zone” is tiny, which allows for the heater itself to be relatively small. But that won’t work here; the entire chocolate load has to be liquefied. It’s a bit like having to keep a whole roll of PLA melted during the entire print. Accordingly, the heater on the Cocoa Press is huge, and [Evan] even has a couple spare heaters loaded up with chocolate syringes next to the printer so he can keep them warm until they’re ready to get loaded up.

Of course, getting your working material hot in a 3D printer is only half the battle, you also need to rapidly cool it back down if you want it to hold its shape as new layers are placed on top of it. A normal 3D printer can generally get away with a little fan hanging next to the nozzle, but [Evan] found the chocolate needed a bit of a chill to really solidify.

So he came up with a cooling system that makes use of water-cooled Peltier units. The cold side of the Peltier array is inside a box through which air is forced, which makes its way through an insulated hose up to the extruder, where a centrifugal fan and 3D printed manifold direct it towards the just-printed chocolate. He reports this system works well under normal circumstances, but unusually high ambient temperatures can overwhelm the cooler.

While “the man” prevented show goers from actually eating any of the machine’s creations (to give out food in New York, you must first register with the city), they certainly looked fantastic, and we’re interested in seeing where the project goes from here.

Hybrid 3D-Printer Creates Complete Circuits, Case And All

The cool kids these days all seem to think we’re on the verge of an AI apocalypse, at least judging by all the virtual ink expended on various theories. But our putative AI overlords will have a hard time taking over the world without being able to build robotic legions to impose their will. That’s why this advance in 3D printing that can incorporate electronic circuits may be a little terrifying, at least to some.

The basic idea that [Florens Wasserfall] and colleagues at the University of Hamburg have come up with is a 3D-printer with a few special modifications. One is a separate extruder than squirts a conductive silver-polymer ink, the other is a simple vacuum tip on the printer extruder for pick and place operations. The bed of the printer also has a tray for storing SMD parts and cameras for the pick-and-place to locate parts and orient them before placing them into the uncured conductive ink traces.

The key to making the hardware work together though is a toolchain that allows circuits to be integrated into the print. It starts with a schematic in Eagle, which joins with the CAD model of the part to be printed in a modified version of Slic3r, the open-source slicing package. Locations for SMD components are defined, traces are routed, and the hybrid printer builds the whole assembly at once. The video below shows it in action, and we’ve got to say it’s pretty slick.

Sure, it’s all academic for now, with simple blinky light circuits and the like. But team this up with something like these PCB motors, and you’ve got the makings of a robotic nightmare. Or not.

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3D Printering: Print Smoothing Tests With UV Resin

Smoothing the layer lines out of filament-based 3D prints is a common desire, and there are various methods for doing it. Besides good old sanding, another method is to apply a liquid coating of some kind that fills in irregularities and creates a smooth surface. There’s even a product specifically for this purpose: XTC-3D by Smooth-on. However, I happened to have access to the syrup-thick UV resin from an SLA printer and it occurred to me to see whether I could smooth a 3D print by brushing the resin on, then curing it. I didn’t see any reason it shouldn’t work, and it might even bring its own advantages. Filament printers and resin-based printers don’t normally have anything to do with one another, but since I had access to both I decided to cross the streams a little.

The UV-curable resin I tested is Clear Standard resin from a Formlabs printer. Other UV resins should work similarly from what I understand, but I haven’t tested them.

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