TechyMagThings

In this era of consumer-grade FDM printers that have automatic bed levelling, automatic pressure advance tuning, automatic temperature regulation and so on buttoned away behind bullet-proof presets and automation, something as archaic as manual filament tuning does seem a bit out of place. Unless you’re running that hot rod Voron FDM printer, does it make sense to ‘waste time’ with manual tuning your off-the-shelf FDM printer? In a recent video [MandicReally] argues that it still makes sense to unlock more performance.

Up front it’s made clear that these auto-tuned configurations are perfectly fine for the average user, who will be perfectly happy with something like a ‘generic PLA’ preset combined with whatever auto-configuration the printer did. That said, not every filament is the same, nor is each heating element, nozzle and feeding system. In that sense it can be worth it to take a deeper look.

In the video basic aspects like preparing the material, such as properly drying, are looked at, before running through tests for temperature, flow ratio and rate, pressure advance, retraction speeds, material shrinkage etc. before doing a test between such a tuned profile versus a generic preset for ASA filament.

Although the difference isn’t night and day, the tuned profile was faster due to less conservative settings and had better accuracy on the final print due to taking the target FDM printer’s performance into account. Even if not something that the average hobbyist would be interested in, if you’re doing something like production runs with FDM, this might be something you’d want to look at.

It’s no real secret that battery packs for power tools aren’t the foremost when it comes to user serviceability, so if said battery pack suddenly stops charging outside of warranty, you generally just e-waste it. That’s what [The Repair Forge] could have done for the Makita battery pack in question, but instead it was opened up for a diagnosis and fix.

Rather than the charger throwing up an error with this specific battery, it would flash its red LED and run its fan, but never actually start the charging process. Apparently the charger seems to think that the battery is either too hot or cold to be charged, which already gives a big hint as to what might be wrong.

Using the open source PocketOBI tool it’s possible to query the battery, which showed that one of the internal thermistors reported the battery being at a chilly -30°C while the other a more reasonable 28°C. After popping open the pack and measuring the thermistors, the faulty one registered as infinite resistance thus confirming that it had failed.

By putting in a temporary resistor this diagnosis was confirmed, thus the next step will be to replace said thermistor. This same procedure was then used with a second battery, whose thermistor read a wild 64°C.

Overall it’s a pretty easy fix, using a 20 cent part, with the entirety of diagnosis to repair taking maybe ten minutes when using a tool like PocketOBI, itself based on the great Open Battery Information project that originally reverse-engineered the Makita battery protocol.

Gears are usually the biggest contributors to backlash in a mechanical system, but they’re far from the only culprits. Ball bearings are a less obvious source of imprecision, since any gaps between the balls and the races can lead to axial wobble. Precision mechanisms can eliminate this by pairing two ball bearings, holding the outer races fixed, and applying a preload force to the inner traces. [Chronova Engineering], however, has a different solution, for which he split a ball bearing in half.

Besides taking up more room, thermal expansion also means that it’s difficult to apply a consistent preload force between two ball bearings. Instead, to make a self-contained preloaded bearing, [Chronova Engineering] first disassembled a single ball bearing. The most difficult part of this is taking apart the ball cage; the two parts of this are normally riveted together, but he managed to find a crimped cage and pry it apart. After taking the bearing completely apart, he cut the outer trace in half along the circumference, then reassembled the bearing. The split outer trace makes it possible to press the two halves together, preloading it and removing slop.

To see how well this worked, [Chronova Engineering] replaced the the ball bearing supporting one end of the feed screw for a milling machine with this new bearing. Before the replacement, it had a backlash of 0.1 to 0.2 millimeters; after the modification, it dropped to 30 to 40 microns. This kind of bearing is already known in the machining world – four-point-contact bearings use a very similar principle – but they don’t seem to be well known.

For more about these common yet remarkable rotary mechanisms, check out our article on bearings. If, on the other hard, precision isn’t a priority, you can always 3D print ball bearings.

In the world of children’s toys there are many offerings which are meant to look like devices used by older kids or even adults, with the Fisher Price Laugh & Learn Lil’ Gamer toy bearing quite the resemblance to Nintendo’s iconic Game Boy. Although this factoid could be filed away as amusing trivia before passing said toy to a child for its requisite physical abuse by said child, a purported adult can still have a lot of fun with this toy by modding it into a real Game Boy, as [KOUZEX] recently did.

Part of the challenge here is to not just treat it as an unconventional replacement shell for a genuine Game Boy, but to retain as much of the child toy’s look and feel as possible. This includes things like buttons and even the weird sliding blocks on the side.

For the functional components a Game Boy Color with a busted screen was chosen as a donor, with the GBC mainboard fitting almost perfectly inside its new shell. Wires were then soldered to bridge Nintendo’s PCB with the toy’s PCB to make the original buttons and speaker work. After blowing a fuse on the GBC mainboard due to likely some power back feeding, the toy’s PCB had its non-essential parts stripped, but fortunately without further damage to the grafted in electronics.

Most of this mod is quite straightforward, just with some creativity required to add a Select and Start button as these were notably absent from the original. The new, rather large replacement OLED screen is a nice upgrade too and actually fits pretty well with the chunky look of the child’s toy. Even as mostly a joke mod, it seems surprisingly functional.

The formula for a Raspberry Pi camera is by now a straightforward one: take a Pi and camera module, add a display, buttons, and battery, and you’re done. This doesn’t mean that there’s no scope for more though, and [Irtaza2009] has one in the PiShot. It’s a few months old now but the repository is still being updated.

The 3D printed case follows a compact camera form factor with the screen on the rear, and a cold shoe on top. Inside is a Pi Zero 2 W and a Camera Module 3, with an 18650 cell and battery management/power supply board. The buttons are tactile switches hooked up to GPIOs, and the screen is an ST7789 SPI display.

For software there’s a Python script, which should do the job. We’ve not tested this one, but our experience is that slowness is the Achilles’ heel of Python based Pi cameras. We hope this one has managed to eke out some performance.

An interesting upgrade to this device would be to use an HQ camera module, for a mirror-less compact. It wouldn’t be the first such camera we’ve seen.

You’ve seen fiber-reinforced-plastic before, no doubt, but perhaps never quite like in this video by [Whitburn Studio]: it’s still got the usual resin, but instead of glass or carbon fibers, he’s using printed Japanese cotton to create strong, lightweight and good looking parts for the interior of his RV– specifically the countertops.

The technique is very similar to the sort of moldless composite work Burt Rutan pioneered in aircraft use. The fiber-reinforced plastic is formed around a positive ‘buck’ that remains inside the final part, adding stiffness and some backing. Unlike Rutan’s designs, which used pure Styrofoam inside, [Whitburn] is using a sandwhich of two layers of thin ply (3.6 mm) with XPS foam in between. Adding plywood means you don’t need many layers of fiber– again, that’s a decorative cotton, here– to get a surface that won’t dent into the styrofoam when you drop a coffee cup on it.

Indeed, with the plywood providing much of the strength, he’s only using a single layer of cotton and a second of fiberglass– though the glass fibers are really there to protect the pretty print from oopsies while sanding, rather than for their mechanical properties, by the sounds of it. Everything is held together with clear epoxy resin, which also fills the weave of the fabrics. Multiple coats of that are required to get the smooth, shiny surface he shows off at the end, but all that sanding and buffing really pays off. That’s also where you have to be really careful to avoid oopsies– go through the cotton and you have to start over.

Aside from the aesthetics, since this is going in a vehicle the weight is an important consideration– the bigger of the two counters he makes, pictured here, weighs in at only 2.4 kg or 5.2 lb including the cutout covering the sink. That’s pretty good all things considered– a lot lighter than a cement countertop, or even one made of DIY resin tiles.

A recent addition to mountain bikes is the dropper seat post. This invention is in the vein of office swivel chairs, allowing the seat height to be adjusted with a simple handlebar mounted lever. They are rather fascinating inventions ranging in complexity from simple mechanical systems, to electronic monstrosities actuated by Bluetooth. Inspired by the panoply of possibilities, [kane components] set forth to create such a home-built dropper post. 

Inspired by woodworking bar clamps, [kane’s] design utilizing angled plates binding against a rail inside the dropper post. Two pairs of plates sitting at opposite angles resist opposite forces from either the rider sitting on the post, or the return spring. A simple cable actuated cam moves the plates to a nonbinding position when the lever is actuated, and springs return the plates to a binding rest-state. The return is handled by an air spring pressurized against a piston at the bottom of the shaft.

Though 3D printing could be used for a cursory test the mechanism, properly machined parts are needed to handle the loads running through a typical seat post. But instead of machining everything from scratch, [kane] reused the lower post and bushings from a broken post. To fit everything together, the lower post got thread milled so the entire mechanism can be threaded into the seat post as a replaceable cartridge. The upper telescopic section consists of aluminum tubing and a custom machined seat clam mechanism press-fit together.

As is the case with all engineering projects, a number of issues came forth once the dropper post made it onto a bike. Issues ranged from the cable pull causing the seat post to move slightly, to all manner of mechanical jamming. Filing down the ball end of the cable so it didn’t rub against the outer-housing of the seat post fixed that particular issue. The two-piece upper design also proved problematic with the press-fit having a bad tendency to come apart.

Despite these particular issues, did it end up working? No, not consistently. The binding mechanism does not consistently produce enough force to keep the dropper post from falling under a rider’s weight. Regardless, we really enjoyed following along with [kane] for the journey of creating such a mechanically complicated bicycle component!

To our surprise, this isn’t the first dropper post hack we have come across. So make sure to check out this bodge of a fix for a far more complex (and expensive) dropper next!