Over the last century, very little of the basic design of firearm cartridges has changed, but the mechanics of firearms themselves have undergone many upgrades. The evolution of triggers, safeties, magazines, and operating mechanisms is a fascinating field of study. Hands-on experience with these devices is rare for most people, but thanks to people like [zvc], you can 3D print accurate replicas of historical firearms and see how all the parts fit together for yourself.
[zvc] is slowly building up a library of 3D models, with nine available so far, from the Mauser C96 “Broomhandle” pistol to the modern M4 rifle. Except for springs and some fasteners, almost every single part of [zvc]’s models are 3D printed, down to the takedown pins and extractors. With the obvious exception of being able to fire a live round, it looks like all the components fit and work together like on the real firearms. None were ever designed with 3D printing in mind, so a well-tuned printer, lots of support structure, and post-processing are required to make everything work. The surface finish will be a bit rough, and some smaller and thin-walled components might be susceptible to breaking after the repeated operation or excessive force. The models are not free, but all prices are below €10.
These models do demonstrate one of the real superpowers of 3D printing: functional mock-ups and prototypes. The ability to do rapid iterative design updates and to have the latest design in hand within a few hours is invaluable in product development. [Giaco] used this extensively during the development of his kinetic driver. When you buy 3D printable models online, always make sure what possible pitfalls exist.
Did you think your printer stayed the same size when it heated up? Well, think again! According to [Mark’s] calculations, when heated, the bed can expand by as much as half a millimeter in the x/y direction. While x/y deformation seems like something we can ignore, that’s not always true. If our bed is rigidly fixed in place, then that change in dimension will only result in a warped bed as it tries to make space for itself.
Don’t give up yet though. As sinister as this problem may seem, [Mark] introduces a classic-but-well-implemented solution: and adjustable kinematic coupling. The kinematic coupling holds the bed at the minimum number of points to keep it rigid while exposing thumbscrews to dial in a level bed. What’s special about this technique is that the coupling holds the bed perfectly rigid whilst allowing it to thermally expand!
This is the beauty of “exact constraint” design. Parts are held together only by the minimum number of points needed to guarantee a specific relationship. Here that relationship is coplanarity between the the nozzle’s x/y plane and the bed. Even when the bed expands this relationship holds. Now that is magic.
With such a flood of 3D printed parts on the market, building a printer has never been easier! Nevertheless, it’s easy to pin ourselves into a corner re-tuning a poor design that skips a foundation on the base principles. If you’re curious about more of these principles behind 3D printer design, check out [Mark’s] thorough walkthrough on the CoreXY design.
Ah, the great outdoors. Rejuvenating air rife with mosquitoes and other nasties, and spending some time hanging out in the woods sleeping in a 3D printed camper. Wait– what was that last one again?
Yep, it’s exactly what it sounds like. A Canadian team headed by [Randy Janes] of Wave of the Future 3D, printed a camper at [Create Cafe] in Saskatoon, Saskatchewan, using high-flow nozzles on one of the largest 3D printers in North America. These layers are 10.3mm thick!!
This trailer is one single printed piece, taking 230 hours — nine and a half days — of straight printing with only a few hangups. Weighing 600lbs and at 13 feet long by six feet wide — approximately 507 cubic feet, this beats the previous record holder for largest single piece indoor print in size by three times over.
Let’s build a robot that gets hot. Really hot — like three times hotter than McDonald’s coffee. Then make it move around. And let’s get the cost in at around $100. Sounds crazy? Not really, since that describes the cheap 3D printers we all have been buying. [John] found out the hard way that you really need to be careful with hot moving parts.
The short story is that [John’s] Anet A8 caught on fire — significantly caught on fire. Common wisdom says that cheap printers often don’t have connectors for the heated bed that can handle the current. There have been several well-publicized cases of those connectors melting, especially on early production models of several printers. However, this printer had an add-on heater with a relay, so that shouldn’t be the problem. Of course, a cheap power supply could do it, too, but the evidence pointed to it being none of those things.
The holidays are almost here, and with that comes the traditional Mass Consumption of Consumer Goods and Gift Exchange. 3D printers are getting really good and really cheap, and it’s inevitable that a lot of 3D printers will be given as gifts this year. Be careful if you’re giving or receiving one of these printers: they can cause fires as [Ben Hencke] found out when diagnosing a problem with a printer he bought this year.
The printer in question is the Monoprice Maker Select V2, a Prusa i3 clone with impressive specs for a $300 printer. This printer is a rebranded Wanhao Duplicator i3, and we’ve reviewed it favorably. It’s a capable printer that beats the pants off of any Kickstarter printer in quality (and for the fact that you can buy it right now). We’re pretty sure there are going to be more than a few of these printers under the Saturnalia tree this year.
After a few weeks, [Ben] noticed a bit of smoke coming from the printer while the bed was preheating. This wasn’t blue pixie smoke, like you’d find from an exploded capacitor. There was a lot of smoke.
After a closer inspection and help from [Elecia White] from embedded.fm, the problem was traced to the power connector for the heated bed. The green, bromine-infused plastic for this connector was charred and there’s little doubt this could have caused a fire.
3D printing is a fantastic tool, and has enabled more hacks and builds over the last few years than we could have ever imagined. 3D printers are getting very good, and very cheap, and of course this will eventually mean someone losing their workshop to a printer fire. Until someone figures out how to build a ‘thermal fuse’ or something of that nature, 3D printers — from the high-end ones to the still very good Monoprice and Wanhao units — have the potential to start a fire.
A while ago Wanhao was reaching out to its customers and resellers, warning them of a design flaw in their Duplicator i3 that may cause fires. The printers suffered from an issue that caused crimp connections of the nozzle heater cartridge’s supply line to fail due to the mechanical stress in the cable drag chain. In their “Recall” titled note, Wanhao provides instructions on how to fix the issue.
[Jay] out of the River City Labs Hackerspace in Peoria, IL cleared out a jam in his printer. It’s an operation most of us who own a 3D printer have performed. He reassembled the nozzle, and in a moment forgot to tighten down the grub nut that holds the heater cartridge in place. He started a print, saw the first layer go down right, and left the house at 8:30 for work. When he came back from work at 10:30 he didn’t see the print he expected, but was instead greeted by acrid smoke and a burnt out printer.
As far as he can figure, some time at around the thirty minute mark the heater cartridge vibrated out of the block. The printer saw a drop in temperature and increased the power to the cartridge. Since the cartridge was now hanging in air and the thermistor that reads the temperature was still attached to the block, the printer kept sending power. Eventually the cartridge, without a place to dump the energy being fed to it, burst into flame. This resulted in the carnage pictured. Luckily the Zortrax is a solidly built full metal printer, so there wasn’t much fuel for the fire, but the damage is total and the fire could easily have spread.
Which brings us to the topics of discussion.
How much can we trust our own work? We all have our home-builds and once you’ve put a lot of work into a printer you want to see it print a lot of things. I regularly leave the house with a print running and have a few other home projects going 24/7. Am I being arrogant? Should I treat my home work with a lesser degree of trust than something built by a larger organization? Or is the chance about the same? Continue reading “Ask Hackaday MRRF Edition: 3D Printers Can Catch Fire”→