These 3D Printed Supports Can Take Hard Use, Thanks to Resin Filling

Liquid two-part resins that cure into a solid are normally used for casting, and [Cuddleburrito] also found them useful to add strength and rigidity to 3D printed pillar supports. In this case, the supports are a frame for some arcade-style buttons, which must stand up to a lot of forceful mashing. Casting the part entirely out of a tough resin would require a mold, and it turns out that filling a 3D print with resin gets comparable benefits while making it easy to embed fastener hardware, if done right.

Cap design shows how the nut will be encased and the cap anchored even if the pillar is slightly underfilled with resin. The screw can be backed out after the resin cures.

Filling the inside of an object with some kind of epoxy or resin to reinforce it isn’t a new idea, but [Cuddleburrito] learned how a few small design considerations can lead to less messy and more successful results. The first is that resin can be poured with screws in place without any worry of trapping the screws in the resin, if done correctly. As long as only the threads of the screw are in the resin, they can be backed out after the resin has cured. Embedding nuts into the resin to act as fasteners becomes a much easier task when one can simply pour resin with both nut and screw in place, and remove the screw afterwards. A thin layer of a lubricant on the threads to act as a release may help, but [Cuddleburrito] didn’t seem to need any.

The second thing learned was that, for a pillar that needs a cap and embedded nut on both ends, it can be tricky to fill the object’s void with the perfect amount of required resin before capping it off. On [Cuddleburrito]’s first attempt, he underfilled and there wasn’t enough resin to capture the nut on the top lid of the pillar he was making. The way around this was to offset the nut on a riser, and design in either a witness hole or an overflow relief. A small drain hole or a safe area for runoff allows for filling things right up without an uncontrolled mess in the case of overfilling.

Something worth keeping in mind when experimenting in this area is that in general the faster a resin cures, the more it heats up in the process. It may be tempting to use something like 5 minute epoxy in a pinch, but the heat released from any nontrivial amount of it risks deforming a thin-walled 3D print in the process. For cases where resin would be overkill and the fasteners are small, don’t forget we covered the best ways to add fasteners directly to 3D printed parts.

Epoxy Fix For A Combusted PCB

When the Magic Smoke is released, chances are pretty good that you’ve got some component-level diagnosis to do. It’s usually not that hard to find the faulty part, charred and crusty as it likely appears. In that case, some snips, a new non-crusty part, and a little solder are usually enough to get you back in business.

But what if the smoke came not from a component but from the PCB itself? [Happymacer] chanced upon this sorry situation in a power supply for an electric gate opener. Basking in the Australian sunshine for a few years, the opener started acting fussy at first, then not acting at all. Inspection of its innards revealed that some unlucky ants had shorted across line and neutral on the power supply board, which burned not only the traces but the FR4 of the board as well. Rather than replace the entire board, [Happymacer] carefully removed the carbonized (and therefore conductive) fiberglass and resin, leaving a gaping hole in the board. He fastened a patch for the hole from some epoxy glue; Araldite is the brand he used, but any two-part epoxy, like JB Weld, should work. One side of the hole was covered with tape and the epoxy was smeared into the hole, and after a week of curing and a little cleanup, it was ready for duty. The components were placed into freshly drilled holes, missing traces were replaced with wire, and it seems to be working fine.

This seems like a great tip to keep in mind for when catastrophe strikes your boards. There are more extreme ways to do it, of course, but perhaps none so flexible. After all, epoxy is versatile stuff.

Prusa Introduces A Resin Printer at Maker Faire NY

For one reason or another, the World Maker Faire in New York has become the preeminent place to launch 3D printers. MakerBot did it with the Thing-O-Matic way back when, and over the years we’ve seen some interesting new advances come out of Queens during one special weekend in September.

Today Prusa Research announced their latest creation. It’s the resin printer you’ve all been waiting for. The Prusa SL1 is aiming to become the Prusa Mk 3 of the resin printer world: it’s a solid printer, it’s relatively cheap (kit price starts at $1299/€1299), and it produces prints that are at least as good as resin printers that cost three times as much.

The tech inside the SL1 is about what you’d expect if you’ve been following resin printers for a while. The resin is activated by a bank of LEDs shining through a photomask, in this case a 5.5 inch, 1440p display. Everything is printed on a removable bed that can be transferred over to a separate ‘curing chamber’ after the print is done. It’s more or less what you would expect, but there are some fascinating refinements to the design that make this a resin printer worthy of carrying the Prusa name.

Common problems with a masked SLA printer that uses LEDs and an LCD are the interface between the LCD and the resin, and the temperature of the display itself. Resin is not kind to LCD displays, and to remedy this problem, Prusa has included an FEP film on the bottom of the removable tank. This is a user-replaceable part (technically a consumable, at least to the same extent as a PEI build plate on a filament printer), and Prusa will be selling those as spare parts on their store. The LCD is also cooled; one of the major drawbacks of shining several watts of UV through an LCD is the lifetime of the display. Cooling the display helps, and should greatly increase the lifetime of the printer. All of this is wrapped up in an exceptionally heavy metal case with the lovely hinged UV-opaque orange plastic lid.

Of course, saying you’ve built a resin printer is one thing, but how do the prints look? Exceptional. The Prusa booth at Maker Faire was loaded up with sample prints from the machine, and they’re of the same high quality you would expect from the Form 3D printers that have been the go-to in the resin printer world. The Prusa SLA also works with big-O Open resins, meaning you’re not tied to a single resin vendor.

This is just the announcement of the Prusa resin printer, but they are taking preorders. The price for the kit — no word on how complex of a kit it is — is $1300, while the assembled printer is $1600, with the first units shipping in January.

Incredible Atari 800XL Case Restoration

If you’ve been hanging around Hackaday for a while, you know that a large portion of the stuff we publish goes above and beyond what most people would consider a reasonable level of time and effort. One could argue that’s sort of the point: the easy way out is rarely the most exciting and interesting route you can take. We, and by extension our readers, are drawn to the projects that someone has really put their heart and soul into. If the person who created the thing wasn’t passionate about it, why should we be?

That being said, on occasion, even we are left in awe about the lengths some people will go to. A perfect example of this is the absolutely insane amount of time and effort [Drygol] has put into restoring an Atari 800XL that looked like it was run over by a truck. Through trial, error, and a bunch of polyester resin, he’s recreated whole sections of the Atari’s case that were missing.

To start the process, [Drygol] used metal rods to bridge the areas where the plastic was completely gone. By heating the rods with a torch and pushing them into the Atari’s case, he was able to create a firm base to work from. Additional rods were then soldered to these and bent, recreating the shape of the original case. With the “skeleton” of the repair in palce, the next step was filling it in.

[Drygol] borrowed an intact Atari 800XL case from a friend, and used that to create a mold of the missing sections from his own case. Most of his rear panel was missing, so it took some experimentation to create such a large mold. In the end he used silicone and a custom built tray that the case could sit in vertically, but he does mention that he never quite solved the problem of degassing the silicone. The mold still worked, but bubbles caused imperfections which needed to be filled in manually during the finishing process.

Using his silicone mold and the same tray, he was then able to pour polyester resin over the wire frame. This got him most of the way to rebuilding the case, but there was still plenty of filler and sanding required before the surface finish started to look half-way decent. When he got towards the very end of the finishing process, he used a mold he created of the case surface texture to roughen up the smooth areas left over from the filling process. Add a bit of custom spray paint, and the end result looks absolutely phenomenal considering the condition it was in originally.

We were already impressed by the work he put in during the first stages of the restoration, but this case repair is really on a whole new level. Between this and the incredible instructional videos [Eric Strebel] has been putting out, we’re really gaining a whole new respect for the power of polyester.

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Mechanisms: Abrasives

In our “Mechanisms” series, we’ve featured the fascinating bits and pieces that go into making our mechanical world work. From simple machines such as screws and levers, from springs to couplings, and even more complex mechanisms like zippers and solenoids, we’ve covered the gamut. But we haven’t talked about one of the very earliest mechanisms, captured from nature by our clever ancestors to do useful work like grinding grain and shaping materials into tools: grit, sand, abrasives.

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Slipcasting Resin Prototypes

[Eric Strebel] doesn’t need an introduction anymore. If there is a picture of an elegantly designed part with a professional finish on our pages, there is a good chance he has a hand in it. This time he is sharing his method of making a part which looks like it is blow-molded but it is not. Blow-molded parts have a distinctive look, especially made with a transparent material and [Eric’s] method certainly passes for it. This could upgrade your prototyping game if you need a few custom parts that look like solidified soap bubbles.

Mold making is not covered in this video, which can also be seen below the break, but we can help you out with a tip or two. For demonstration’s sake, we see the creation of a medical part which has some irregular surfaces. Resin is mixed and degassed then rolled around inside the mold. Then, the big reveal, resin is allowed to drain from the mold. Repeat to achieve the desired thickness.

This is a technique adapted from ceramics called slipcasting. For the curious, an elegant ceramic slipcasting video demonstration can be seen below as well. For an added finishing touch, watch how a laquer logo is applied to the finished part; a touch that will move the look of your build beyond that of a slapdash prototype.

More education from this prolific maker can be seen in his video on painting with a professional-looking finish and his tips for working with foam-core.

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Review of the Moai SLA 3D Printer

It is funny how we always seem to pay the same for a new computer. The price stays the same, but the power of the computer is better each time. It would appear 3D printers may be the same story. After all, it wasn’t long ago that sinking a thousand bucks or more on a 3D printer wouldn’t raise any eyebrows. Yet today you can better printers for a fraction of that and $1,300 will buy you an open source Moai SLA printer as a kit. [3D Printing Nerd] took a field trip to MatterHackers to check the machine out and you can see the results in the video below.

The printer uses a 150 mW laser to make parts up to 130 mm by 130 mm by 180 mm. The laser spot size is 70 micron (compare that to the typical 400 micron tip on a conventional printer). The prints require an alcohol bath after they are done followed by a UV curing step that takes a few hours.

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