Hackaday Links: February 12, 2023

February 12, 2023 by Dan Maloney 24 Comments

So, maybe right now isn’t the best time to get into the high-altitude ballooning hobby? At least in the US, which with the downing of another — whatever? — over Alaska, seems to have taken a “Sidewinders first, threat identification later” approach to anything that floats by. The latest incident involved an aircraft of unknown type, described as “the size of a small car” — there’s that units problem again — that was operating over Prudhoe Bay off the northern coast of Alaska. The reason that was given for this one earning a Sidewinder was that it was operating much lower than the balloon from last week, only about 40,000 feet, which is well within the ceiling of commercial aviation. It was also over sea ice at the time of the shootdown, making the chance of bothering anyone besides a polar bear unlikely. We’re not taking any political position on this whole thing, but there certainly are engineering and technical aspects of these shootdowns that are pretty interesting, as well as the aforementioned potential for liability if your HAB goes astray. Nobody ever really benefits from having an international incident on their resume, after all.

Continue reading “Hackaday Links: February 12, 2023” →

Continuous Printing On LCD Resin Printer: No More Wasted Time On Peeling? Is It Possible?

January 3, 2023 by Maya Posch 20 Comments

Anyone who has done any amount of 3D printing with SLA printers is probably well aware of the peeling step with each layer. This involves the newly printed layer being pulled away from the FEP film that is attached to the bottom of the resin vat. Due to the forces involved, the retraction speed of the build plate on the Z-axis has to be carefully tuned to not have something terrible happen, like the object being pulled off the build plate. Ultimately this is what limits SLA print speed, yet [Jan Mrázek] postulates that replacing the FEP with an oxygen-rich layer can help here.

The principle is relatively simple: the presence of oxygen inhibits the curing of resin, which is why for fast curing of resin parts you want to do so in a low oxygen environment, such as when submerged in water. Commercial printers by Carbon use a patented method called “continuous liquid interface production” (CLIP), with resin printers by other companies using a variety of other (also patented) methods that reduce or remove the need for peeling. Theoretically by using an oxygen-permeating layer instead of the FEP film, even a consumer grade SLA printer can skip the peeling step.

The initial attempt by [Jan] to create an oxygen-permeating silicone film to replace the FEP film worked great for about 10 layers, until it seems the oxygen available to the resin ran out and the peeling force became too much. Next attempts involved trying to create an oxygen replenishment mechanism, but unfortunately without much success so far.

Regardless of these setbacks, it’s an interesting research direction that could make cheap consumer-level SLA printers that much more efficient.

(Thumbnail image: the silicone sheet prior to attaching. Heading image: the silicone sheet attached to a resin vat. Both images by [Jan Mrázek])

Toilet Paper Tube Pulls Dissolved Resin From IPA, Cures It For Disposal

October 12, 2022 by Donald Papp 53 Comments

SLA 3D printing with resin typically means rinsing parts with IPA (isopropyl alcohol). That process results in cloudy, used IPA containing a high concentration of dissolved resin. The dual goals of cleaning and reusing IPA are important ones, and we have to say, [Jan Mrázek]’s unusual experiment involving a UV source and slowly-rotating paper tube to extract and cure dissolved resin might look odd, but the results are definitely intriguing.

Dissolved resin successfully pulled from IPA and cured onto a cardboard roll. This particular one rotated a bit too quickly, trapping IPA in the curing process and yielding a slightly rubbery wad instead of a hard solid.

The best way to dispose of liquid resin is to cure it into a solid, therefore making it safe to throw away. But what about resin that has been dissolved into a cleaning liquid like IPA? [Jan] felt that there was surely a way to extract the dissolved resin somehow, which would also leave the IPA clean for re-use. His solution? The device shown here, which uses a cardboard tube to pull dissolved resin from an IPA bath and a UV source to cure it onto the tube.

Here’s how it works: the tube’s bottom third sits in dirty IPA, and UV LEDs shine on the top of the tube. The IPA is agitated with a magnetic stirrer for best results. A motor slowly rotates the cardboard tube; dissolved resin gets on the tube at the bottom, UV cures it at the top, and the whole thing repeats. Thin layers of cured resin slowly build up, and after long enough, the roll of cured resin can be thrown away and the IPA should be clean enough for reuse.

So far it’s a pretty successful test of a concept, but [Jan] points out that there are still some rough edges. Results depend on turning the tube at a good rate; turning it too quickly results in IPA trapped with the cured residue. On the plus side, the UV source doesn’t need to be particularly powerful. [Jan] says that Ideally this would be a device one could run in a sealed container, cleaning it over one or two days.

Resin printing is great, but it’s a messy process, so anything that makes it less wasteful is worth checking out. Got any ideas for improving or building on this concept? If so, don’t keep ’em to yourself! Let us know in the comments.

When 3D Printing Gears, It Pays To Use The Right Resin

September 26, 2022 by Donald Papp 9 Comments

There are plenty of resins advertised as being suitable for functional applications and parts, but which is best and for what purpose?

According to [Jan Mrázek], if one is printing gears, then they are definitely not all the same. He recently got fantastic results with Siraya Tech Fast Mecha, a composite resin that contains a filler to improve its properties, and he has plenty of pictures and data to share.

[Jan] has identified some key features that are important for functional parts like gears. Dimensional accuracy is important, there should be low surface friction on mating surfaces, and the printed objects should be durable. Of course, nothing beats a good real-world test. [Jan] puts the resin to work with his favorite method: printing out a 1:85 compound planetary gearbox, and testing it to failure.

The results? The composite resin performed admirably, and somewhat to his surprise, the teeth on the little gears showed no signs of wear. We recommend checking out the results on his page. [Jan] has used the same process to test many different materials, and it’s always updated with all tests he has done to date.

Whether it’s working out all that can go wrong, or making flexible build plates before they were cool, We really admire [Jan Mrázek]’s commitment to getting the most out of 3D printing with resin.

Make Multi-Material Resin Prints With A Syringe (And A Bit Of Patience)

August 22, 2022 by Donald Papp 15 Comments

Resin printing is a fantastic way to create parts, but multi-material printing isn’t really a possibility with resin. That is, unless you use [Cameron Coward]’s method for creating multi-material resin prints.

[Cameron]’s idea relies on the fact that handling and curing UV resin can easily be done outside of the printer itself. First, one prints what we’ll call the primary object. This object has empty spaces representing the secondary object. Once the primary object is printed and finished, these voids are carefully filled with a different resin, then cured with UV light. The end result is a single multi-material object that is, effectively, made from two different resins.

Continue reading “Make Multi-Material Resin Prints With A Syringe (And A Bit Of Patience)” →

3D Printering: Today’s Resins Can Meet Your Needs

June 13, 2022 by Donald Papp 27 Comments

Filament-based 3D printers spent a long time at the developmental forefront for hobbyists, but resin-based printers have absolutely done a lot of catching up, and so have the resins they use. It used to be broadly true that resin prints looked great but were brittle, but that’s really not the case anymore.

A bigger variety of resins and properties are available to hobbyists than ever before, so if that’s what’s been keeping you away, it’s maybe time for another look. There are tough resins, there are stiff resins, there are heat-resistant resins, and more. Some make casting easy, and some are even flexible. If your part or application needs a particular property, there is probably a resin for it out there.

Continue reading “3D Printering: Today’s Resins Can Meet Your Needs” →

New Resin Printing Method Creates Objects In Seconds

June 1, 2022 by Bryan Cockfield 20 Comments

For anyone looking to buy a 3D printer at home, the first major decision that needs to be made is whether to get a resin printer or a filament printer. Resin has the benefits of finer detail, but filament printers are typically able to produce stronger prints. Within those two main camps are various different types and sizes to choose from, but thanks to some researchers at Switzerland’s École polytechnique fédérale de Lausanne (EPFL) there’s a new type of resin printer on the horizon that can produce prints nearly instantaneously.

The method works similarly to existing resin printers by shining a specific light pattern on the resin in order to harden it. The main difference is that the resin is initially placed in a cylinder and spun at a high speed, and the light is shined on the resin at different angles with very precise intensities and timings in order to harden the resin in specific areas. This high-speed method allows the printer to produce prints in record-breaking time. The only current downside, besides the high price for the prototype printer, is that it’s currently limited to small prints.

With the ability to scale in the future and the trend of most new technologies to come down in price after they have been on the market for some amount of time, it would be groundbreaking to be able to produce prints with this type of speed if printers like these can be scalable. Especially if they end up matching the size and scale of homemade printers like this resin printer.

Thanks to [suicidal.banana] for the tip!