Making nylon plastic from raw chemicals used to be a very common demo; depending where and when you grew up, you may well have done it in high school or even earlier. What’s not common is taking that nylon and doing something with it, like, say extruding it into filament to make a benchy. [Startup Chuck] shows us there might be a reason for that. (Video, embedded below.)

It starts out well enough: sebacoyl chloride and hexamethaline diamine mix up and do their polymerizing tango to make some nylon, just like we remember. (Some of us also got to play with mercury bare-handed; safety standards have changed and you’ll want to be very careful if you try this reaction at home). The string of nylon [Chuck] pulls from the beaker even looks a little bit like filament for a second, at least until it breaks and gets tossed into a blobby mess. We wonder if it would be possible to pull nylon directly into 1.75 mm filament with the proper technique, but quality control would be a big issue. Even if you could get a consistent diameter, there’d likely be too much solvent trapped inside to safely print.

Of course, melting the nylon with a blowtorch and trying to manually push the liquid through a die to create filament has its own quality control problems. That’s actually where this ends: no filament, and definitely no benchy. [Chuck] leaves the challenge open to anyone else who wants to take the crown. Perhaps one of you can show him how it’s done. We suspect it would be easiest to dry the homemade nylon and shred it into granules and only then extrude them, like was done with polypropylene in this mask-recycling project. Making filament from granules or pellets is something we’ve seen more than once over the years.

If you really want to make plastic from scratch, ordering monomers from Sigma-Aldrich might not cut it for ultimate bragging rights; other people are starting with pulling CO2 from the atmosphere.

Thanks to [Chaz] for the tip! Remember that the tips line isn’t just for your successes– anything interesting can find its home here.

The good part about FDM 3D printing is that there are so many different filament types and parameters to choose from. This is also the bad part, as it can often be hard to tell what impact a change has. Fortunately we got destructive testing to provide us with some information here. Case in point [Functional Print Friday] on YouTube recently testing out a few iterations of a replacement part for a car.

The original part was in ABS, printed horizontally in a Bambu Lab FDM printer, which had a protruding element snapped off while in use. In addition to printing a replacement in carbon fiber-reinforced nylon (PAHT-CF, i.e. PA12 instead of the typical PA6), the part was now also printed at a 45° angle. To compare it with the original ABS filament in a more favorable way, the same part was reprinted at the same angle in ABS.

Another change was to add a machine screw to the stop element of the part, which turned out to make a massive difference. Whereas the original horizontal ABS print failed early and cleanly on layer lines, the angled versions put up much more of a fight, with the machine screw-reinforced stop combined with the PA12 CF filament maxing out the first meter.

The take-away here appears to be that not only angles are good, but that adding a few strategic metal screws can do wonders, even if you’re not using a more exotic filament type.

[Ben Krasnow] of the Applied Science channel recently released a video demonstrating his process for getting copper-plated traces reliably embedded into sintered nylon powder (SLS) 3D printed parts, and shows off a variety of small test boards with traces for functional circuits embedded directly into them.

Here’s how it works: The SLS 3D printer uses a laser to fuse powdered nylon together layer by layer to make a plastic part. But to the nylon powder, [Ben] has added a small amount of a specific catalyst (copper chromite), so that prints contains this catalyst. Copper chromite is pretty much inert until it gets hit by a laser, but not the same kind of laser that sinters the nylon powder. That means after the object is 3D printed, the object is mostly nylon with a small amount of (inert) copper chromite mixed in. That sets the stage for what comes next.

Activating the copper chromite is all about dumping enough energy into the particles, and that gets done with a pulsed laser. This is how the traces are “drawn” onto the printed object, and these traces will be copper-clad in the next step.

Once the copper chromite catalyst is activated by the second laser, the whole 3D printed object is put into a chemical bath for electroless copper plating. Again, only the places hit by the pulsed laser end up plated. Places not hit by the second laser remain inert.

There’s an interesting side note here. Electroless copper plating is a well understood process used by every PCB manufacturer in the world. But the recipes are all proprietary and [Ben] tried without success to mix up an effective batch. In the end, a talk with OpenAI’s ChatGPT helped crack the case by suggesting a procedure that worked, saving [Ben] a ton of time. Skip to 8:10 in the video if you want to know all about that.

The result is a 3D printed nylon object into which solder-able copper traces are well and truly embedded. The test pieces work out great, but even better, there’s no reason the objects and traces even have to be planar. All it would take is a pulsed laser able to focus on a curved surface in order to create curved traces on a 3-dimensional part.

We’ve seen copper-plated 3D printed PCBs before, but this is something very different and really elegant. The whole workflow has a lot of moving parts, but once controlled it’s remarkable repeatable.

[Ben] has actually tried putting copper traces on SLS printed parts before, but with only limited success. Recent advances in technology and tools have really made the process sing. Watch it all in action in the video, embedded below.

[Electrosync] is the creator and driver of the world’s fastest robotic vaccum cleaner, the Vroomba. It’s a heavily modified roomba capable of speeds of around 60 kph, well beyond the pedaling speed of most bicyclists. Despite being rejected by Guinness for a world record, we’re fairly confident that no other vacuum cleaners have gotten up to these speeds since the Vroomba first hit the streets. That’s not going to stop [electrosync] from trying to top his own record, though, and he’s brought the Vroomba some much needed upgrades.

The first, and perhaps most important, upgrades are to some of the structural components and wheels. The robot is much heavier than comparable RC vehicles and is under much greater strain than typical parts are meant to endure, so he’s 3D printed some parts of the chassis and some new wheels using a nylon-carbon fiber filament for improved strength. The wheels get a custom polyurethane coating similar to last time.

Controlling the robot a handful with previous versions. This is because Roombas use differential steering, controlling direction by sending more or less power to one of a pair of wheels. This is great for maneuverability at low speeds but becomes nightmarish at 60 kph, so [electrosync] added an onboard gyroscope to help the controller maintain a stable direction.

The final improvement was a full aerodynamic body kit including a front splitter and a rather large spoiler. With those improvements, it was ready to hit the track. After some fine-tuning the Vroomba is nearly as fast as its previous record. This is presumably because of a combination of higher weight and losses due to downforce from the spoiler, but [electrosync] plans to continue this pursuit by building a new lightweight chassis for future versions. In the meantime, be sure to check out the first prototypes of the Vroomba.

Thanks to [Wouter] for the tip!

Last time we talked about a video that purported to do plastic welding, we mentioned that the process wasn’t really plastic welding as we understood it. Judging by the comments, many people agreed, but it was still an interesting technique. Now [Inventor 101] has a video about plastic repair that also talks about welding, although — again, we aren’t sure all of the techniques qualify.

That’s not to say there aren’t some clever ideas, though. There are several variations on a theme, but the basic idea is to use a bolt or something similar in a soldering iron, metal reinforcement from things like wires and staples, and donor plastic from a zip tie. While we don’t think the nylon in a typical zip tie is the best way to repair anything other than nylon, if you were repairing something 3D printed, you could easily swap out the tie for filament of the same material, which — we think — would bond better.

The custom soldering iron tips made from copper wire probably have a few uses, too. Every time we see one of these videos, we think less about repairing plastic and more about reinforcing 3D prints, but maybe that’s just us.

If you want to grab the comments about the other post we saw someone using zip ties and a glue gun to “weld”, you’ll have a bit of reading to do. We think of proper welding as having a compatible kind of plastic and some form of heat, even if it is from friction.

The world of DIY circuits for STEM and wearables has a few options for conductors. Wire with Dupont connectors is a standard, as is adhesive copper tape. There’s also conductive nylon/steel thread or ribbon. Which you choose depends on your application, of course, but as a general rule wire is cheap and ubiquitous while making connections is more challenging; copper tape is cheap and simple to use, but delicate and rips easily, so is best used for flat surfaces that won’t see a lot of stress or temporary applications; and conductive nylon thread or tape is better for weaving into fabrics.

The Brown Dog Gadgets team wanted to respond to a frequent question they are asked, what are the current limits for their Maker Tape (nylon/steel ribbon), so they ran some experiments to find out. In the name of Science you’ll see some flames in the video below, but only under extreme conditions.

You may already have bits of each of these options lying around in your bins, and if you don’t it may be worth it. Each connection option has its benefits.

Their scientific process yielded sound results. While not as capable as copper tape, which could easily handle 5A (the limit of their power supply), their Maker Tape endured 3A before the adhesive started to struggle, and at 3.5A the tape acted like a fuse and burned itself out. It was only under very specific unusual conditions that took them a long time to recreate that they were able to get flames. For them this was a huge success, as most of their users are powering their circuits with coin cell batteries and only driving a motor or some LEDs, and this current consumption was at least an order of magnitude greater than most of their use cases. Anyone trying to use the nylon/steel tape at the level that can fry the tape likely knows what they’re doing enough to avoid the potential problem.

Incidentally, if you’re wondering why wire rating is measured in amps and not watts, here’s some physics. Power = Current * Voltage, and Voltage = Current * Resistance. These are the two formulas we all learn from the beginning of electronics lessons. When it comes to wires, resistance is measured as ohms per length. What we’re interested in is not the power that can flow through the wire, but the amount of power that the wire can safely dissipate before failing as it heats up through its own resistance.

Doing some algebra, Power dissipated by the wire as heat = Current*Current*Wire Resistance*Length. We don’t need the voltage. But also notice that if the length doubles then the power dissipated by the wire doubles but so does the amount of surface area of the wire to dissipate that heat. If you were to rate a wire by power, you’d have to include the length. To simplify things and keep the length out of the rating, and relate the rating back to how much energy is transferred across the wire (and not dissipated by it), and since source voltage doesn’t matter, the wire is thus rated with the amount of current.

[youtube https://www.youtube.com/watch?v=3Vt0bbB_A-w?start=5%5D

Manufacturers dye all sorts of 3D printer filaments on their factory lines; why can’t we? [Richard] takes this idea one step further by creating his own custom multicolored reels of nylon. Printing with these reels produces a vibrant pattern that simply demands our attention and  begs us to ask: how on earth..?

[Richard’s] tie-dye adventure is cleanly documented on the blog.  He simply spools a reel of nylon together and dyes subsections of the spool with a different color. With the filament “paletted” to taste, parts pop of the printer with an eye-catching rib pattern of color.

It’s worth mentioning that nylon is extremely hygroscopic, and dyeing filament in a bath full of colored liquid is sure to get it full of moisture. Then again, nylon’s capacity to absorb water might be why it dyes so well. Nevertheless, filament must be oven-dried (or equivalent) for a successful print. Post-drying, [Richard] doesn’t seem to be having any printing problems, and the results speak for themselves.

3D printers might be frequent fliers on these pages, but we still love seeing small modifications that enhance the visual appeal. What’s more, this trick delivers spectacular results with no modifications to the printer itself. Then again, if this job sounds like just too much work for you, we’d suggest using a sharpie.