Up Close And Personal With An Unusual 3D Printer Kit

While there are still plenty of folks out there tinkering with custom 3D printers, it’s safe to say that most people these days are using a commercially-available machine. The prices are just so low now, even on the resin printers, that unless you have some application that requires exacting specifications, it just doesn’t make a whole lot of sense to fiddle around with a homebrew machine.

As it so happens, [Nicolas Tranchant] actually does have such an application. He needs ultra-high resolution 3D prints for his jewelry company, but even expensive printers designed for doing dental work weren’t giving him the results he was looking for. Rather than spend five-figures on a machine that may or may not get the job done, he decided to check out what was available in kit form. That’s when he found the work of [Frédéric Lautré].

A look at the heavy-duty Z axis.

He purchased the unique “Top-Down” SLA kit from him back in 2017, and now after four years of working with the machine, [Nicolas] decided he would share his experiences with the rest of the class. The basic idea with this printer is that the light source is above the resin vat, rather than below. So instead of the print bed being pulled farther away from the resin on each new layer, it actually sinks deeper into it.

Compared to the “Bottom-Up” style of resin printers that are more common for hobbyists, this approach does away with the need for a non-stick layer of film at the bottom of the tank. Printing is therefore made faster and more reliable, as the part doesn’t need to be peeled off the film for each new layer.

[Nicolas] goes into quite a bit of detail about building and using the $700 USD kit, including the occasional modifications he made. It sounds like the kit later went through a few revisions, but the core concepts are largely the same. It’s worth noting that the kit did not come with the actual projector though, so in his case the total cost was closer to $1,400. We were also surprised to see that [Frédéric] apparently developed the software for this printer himself, so the tips on how to wrangle its unfamiliar interface for slicing and support generation may be particularly helpful.

Unfortunately, it sounds like [Frédéric] has dropped off the radar. The website for the kit is gone, and [Nicolas] has been unable to get in touch with him. Which is a shame, as this looks to be a fascinating project. Perhaps the Hackaday community can help track down this mysterious SLA maestro?

Resin print before and after paint injection.

Resin 3D Prints Get A New Look With Paint Injection

As cool as resin-based 3D printers are, they’re not without their shortcomings. One sore point, especially for those looking to document their prints, is that the translucent resins often favored for stereolithography can make the finest details difficult to see. Injecting paint into the model is how [Andrew Sink] decided to attack this problem, and the results are pretty striking.

For sure, this isn’t a problem that everyone making resin prints is going to face. Some resins are nicely opaque, and the fine details of a print show up just fine. But transparent resins lend a nice look to some projects, and might benefit from [Andrew]’s technique. It’s pretty much as simple as it sounds: choose a hollow model — or modify an existing one — print it up in the usual way, and clean thoroughly inside and out with isopropanol before curing under UV. Using a curing station that can get UV light up into the voids is probably a smart idea.

To finish off, the cured model is injected with acrylic paint. Nothing special here, just craft store acrylic in a syringe. [Andrew] seemed to prefer a thicker paint; we don’t want to second guess, but intuitively a thinner paint would seem to have some advantages. In any case, be sure to provide adequate vent holes for the displaced air. The video below has a few before and after shots, and the technique really works well to show off surface detail. Plus it just plain looks cool.

This seems like a good technique to keep in mind, and might even work well for hollow FDM prints done with transparent filaments. Still on the fence about FDM vs. SLA? We can help with that.

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How To Make Resin Prints Crystal Clear

[Matou] has always been entranced by the beauty of natural crystal formations [and has long wished for a glowing crystal pendant]. Once he got a resin-based 3D printer, he was majorly disappointed to find out that although transparent resin prints look like delicious candy when they’re still wet, they turn cloudy and dull after being washed in an isopropyl bath and cured with UV light. There must be a way to either polish pieces back to clear, or keep them clear in the first place, [Matou] thought, and set about experimenting with some test crystals (video, embedded below).

As [Matou] found out, the dullness is caused by surface imperfections. Resin prints have layer lines, too, and although they may be super fine and invisible to the naked eye, they will still scatter light. The choices seem obvious — either polish the proud parts down with many grits of sandpaper, or fill the valleys with something to smooth everything out. As you’ll see in the video after the break, [Matou] tried it all, including a coat of the same resin that made the print. It’s an interesting look at the different ways to smooth out resin prints, though you may not be surprised to find that the one with the most work put into it looks the best.

We were hoping to see [Matou] try a green LED in the pendant, but it didn’t happen. If you’re dying to know what that looks like, you can get one of these pendants for yourself by supporting [Matou] on Patreon.

We think crystals are pretty cool, too — especially crystal radios. Here’s the hack-iest one of those we’ve ever seen, free of charge.

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Off-The-Shelf Parts Make A Tidy Heater For Resin Printer

Resin printers can offer excellent surface finish and higher detail than other 3D printing technologies, but they come with their own set of drawbacks. One is that they’re quite sensitive to temperature, generally requiring the resin chamber to be heated to 25-30 degrees Celsius for good performance. To help maintain a stable temperature without a lot of mucking around, [Grant] put together a simple chamber heater for his printer at home.

Rather than go for a custom build from scratch with a microcontroller, [Grant] was well aware that off-the-shelf solutions could easily do the job. Thus, a W1209 temperature control board was selected, available for under $5 online. Hooked up to a thermocouple, it can switch heating elements via its onboard relay to maintain the set temperature desired. In this case, [Grant] chose a set of positive-temperature coefficient heating elements to do the job, installing them around the resin chamber for efficiency.

The heater can preheat the chamber in under fifteen minutes, much quicker than other solutions using space heaters or heat mats. The time savings will be much appreciated by [Grant], we’re sure, along with the attendant increase in print quality.  If you’re still not sure if resin printing is for you, have a read of our primer. And, if you’ve got your own workflow improvements for resin printing, drop us a line!

These Micro Mice Have Macro Control

Few things fascinate a simple Hackaday writer as much as a tiny robot. We’ve been watching [Keri]’s utterly beguiling micromouse builds for a while now, but the fifth version of the KERISE series (machine translation) of ‘bots takes the design to new heights.

A family of mice v1 (largest) to v5 (smallest)

For context, micromouse is a competition where robots complete to solve mazes of varying pattern but standardized size by driving through them with no guidance or compute offboard of the robot itself. Historically the mazes were 3 meter squares composed of a 16 x 16 grid of cells, each 180mm on a side and 50mm tall, which puts bounds on the size of the robots involved.

What are the hallmarks of a [Keri] micromouse design? Well this is micromouse, so everything is pretty small. But [Keri]’s attention to detail in forming miniaturized mechanisms and 3D structures out of PCBs really stands out. They’ve been building micromouse robots since 2016, testing new design features with each iteration. Versions three and four had a wild suction fan to improve traction for faster maneuvering, but the KERISE v5 removes this to emphasize light weight and small size. The resulting vehicle is a shocking 30mm x 32mm! We’re following along through a translation to English, but we gather that [Keri] feels that there is still plenty of space on the main PCBA now that the fan is gone.

The KERISE v5 front end

The processor is a now familiar ESP32-PICO-D4, though the wireless radios are unused so far. As far as environmental sensing is concerned the v5 has an impressive compliment given its micro size. For position sensing there are custom magnetic encoders and a 3 DOF IMU. And for sensing the maze there are four side-looking IR emitter/receiver pairs and one forward-looking VL6180X laser rangefinder for measurements out to 100 or 150mm. Most of these sensors are mounted on little PCB ‘blades’ which are double sided (check out how the PCB shields the IR emitter from it’s receiver!) and soldered into slots perpendicular to the PCBA that makes up the main chassis. It goes without saying that the rest of the frame is built up of custom 3D printed parts and gearboxes.

If you’d like to build a KERISE yourself, [Keri] has what looks to be complete mechanical, electrical, and firmware sources for v1, v2, and v3 on their Github. To see the KERISE v5 dance on a spinning sheet of paper, check out the video after the break. You don’t want to miss it!

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Building A UV Curing Station For Resin Prints

Resin printers have a lot going for them – particularly in regards to quality surface finishes and excellent reproduction of fine details. However, the vast majority rely on UV light to cure prints. [douwe1230] had been using a resin printer for a while, and grew tired of having to wait for sunny days to cure parts outside. Thus, it was time to build a compact UV curing station to get the job done.

The build consists of a series of laser-cut panels, assembled into a box one would presume is large enough to match the build volume of [douwe1230’s] printer.  UV LED strips are installed in the corners to provide plenty of light, and acrylic mirrors are placed on all the walls. The use of mirrors is key to evenly lighting the parts, helping to reduce the likelihood of any shadows or dead spots stopping part of the print from curing completely. In the base, a motor is installed with a turntable to slowly spin the part during curing.

[Douwe1230] notes that parts take around about 10 minutes to cure with this setup, and recommends a flip halfway through to make sure the part is cured nice and evenly. We’ve seen other similar DIY builds too, like this one created out of a device aimed at nail salons. If you’re struggling with curing outside, with the weather starting to turn, this might just be the time to get building!

Repurposed UV Curer Makes Your Prints Hard As Nails

The price of resin printers has dropped significantly in the last couple of years, and it’s down to the point where you can pick up a fairly decent DLP machine for less than $500. While this is great news, you still need several things beyond resin for successful prints, like a way to do post-process UV curing.

[Inhibit] picked up the formidably-priced Wanhao D7 awhile back. Rather than spending another printer’s worth of paper on a UV curing box, he rescued and repurposed a small commercial curing device meant for gel-based nail polish. You stick your fingertips in, switch it on, and it runs for 60 seconds and then shuts off.

It’s a great idea, but unfortunately prints don’t cure as fast as fingernails. So the first order of business was to bypass the dual 555-based timing system by wiring the UV LEDs directly to power. The manufacturer never intended for the lights to run continuously, so to keep the board from melting, [Inhibit] added in a small 12 V computer fan for cooling. There’s even a little printed grille with angled fins to keep UV light from leaking out and burning nearby retinas.

[Inhibit] also designed and printed a tray for the prints to sit on, and a front enclosure piece to focus as much light on the parts as possible. Files for both parts are floating around the Thingiverse, and we’ve got the build video all cured queued up after the break.

These little commercial boxes don’t cost all that much, but you could always just build your own.

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