Mini Retro PET Computer

There was a time that the Commodore PET was the standard computer at North American schools. It’s all-in-one, rugged construction made it ideal for the education market and for some of us, the PET started a life-long love affair with computers. [Ruiz Brothers] at Adafruit has come up with a miniature PET model run on a microcontroller and loaded up with a green LED matrix for a true vintage look.

While not a working model of a PET, the model runs on an Adafruit Feather M0 Basic Proto which is an Atmel ATSAMD21 Cortex M0 microcontroller and can display graphics on Adafruit’s 16×9 charlieplexed led matrix.The ATSAMD21 is the chip used in the Arduino Zero, so I’m sure we’ll see more of this chip in the future. Like all of the tutorials at Adafruit, this one is very detailed with step-by-step animated pictures to help you along. Obviously, you don’t need the exact hardware that they’re using, but if you’re putting in an order from Adafruit anyway, why not?

The plans for the 3D printed PET are available for free, so even if you don’t want to put their LED matrix and microcontroller in it, you can still print yourself out a great looking prop and 3D printing the PET will only use about a dollar’s worth of filament. Of course, while this is a cool retro model, if you have a Commodore PET lying around, you could probably do something else with it. We don’t, so that sound you hear is the sound of our 3D printer printing up the past.

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Thirty Days Of 3D Printing Filament

Our first 3D printers only printed ABS and PLA plastic. Yeah, we heard about PVA for support structures, but no one could get them to stick. There was also polycarbonate, but you had to have an all metal hot end with a fan to print that stuff. Now there’s a lot of variety out there: flexible, wood and stone, nylon, PETG, and more.

If you are still printing with just the old standards, you might enjoy [all3dp’s] comparison chart of 30 different filament types–that’s enough for one day a month–well at least for four months. It is too many for February, and a day short for the rest of the months. In addition to a table, there’s a short write-up about each type of plastic, its characteristics, and its technical data. There’s even magnetic PLA (see video below) which, in addition to being magnetic, will actually rust in water which might be good for some artistic prints.

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Speed Run [James Bruton’s] Star Wars Builds

We’ve been following [James Bruton]’s builds here on Hackaday for quite a while and he has built some impressive stuff. We love how he often doesn’t cover everything up, leaving enough room to admire the working bits under the hood. Just in time for the release of the new Star Wars movie, Rogue One, [James] put together an overview of his Star Wars robot builds.

The build summary includes his R6 droid, his GNK walking droid and the third revision of his BB-8 droid. [James Bruton]’s videos have tons of detail in them over many, many parts (for example, his BB-8 R3 playlist is 15 parts and his Ultron build currently has 26 episodes and counting!)

There’s a quick overview of each of the three robot builds in this video, and it includes links to the playlists for each build for those who want more detail. This is just what you need to glimpse all of the clever design that went into these wonderfully crafted droids. And if you haven’t seen it yet, you should check out his series elastic actuators that he’s working on for the Ultron build, they give a robot some relief from rigidity.

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Maybe You Can Print In Metal

Let’s face it. Printing in plastic is old hat. It is fun. It is useful. But it isn’t really all that exotic anymore. The real dream is to print using metal. There are printers that handle metal in different ways, but they aren’t usually practical for the conventional hacker. Even a “cheap” metal printer costs over $100,000. But there are ways you can almost get there with a pretty garden-variety printer.

There’s no shortage of people mixing things into PLA filament. If you have a metal hot end and don’t mind wearing out nozzles, you can get PLA filament with various percentages of metal powder in it. You can get filament that is 50% to 85% metal and produce things that almost seem like they are made from metals.

[Beau Jackson] recently had a chance to experiment with a metal-bearing filament that has a unique twist. Virtual Foundry’s Filamet has about 10% PLA. The remaining material is copper. Not only do you have to print the material hot, but you have to print it slow (it is much denser than standard PLA). If it were just nearly 90% metal, that would be impressive, but nothing too exciting.  The real interesting part is what you can do after the print is complete. (If you don’t want to read, you can always skip to the videos, below.)

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This Old Mouse Keeps Track Of Filament Usage

Keeping track of your 3D-printer filament use can be both eye-opening and depressing. Knowing exactly how much material goes into a project can help you make build-versus-buy decisions, but it can also prove gut-wrenching when you see how much you just spent on that failed print. Stock filament counters aren’t always very accurate, but you can roll your own filament counter from an old mouse.

[Bin Sun]’s build is based around an old ball-type PS/2 mouse, the kind with the nice optical encoders. Mice of this vintage are getting harder to come by these days, but chances are you’ve got one lying around in a junk bin or can scrounge one up from a thrift store. Stripped down to its guts and held in place by a 3D-printed bracket, the roller that used to sense ball rotation bears on the filament on its way to the extruder. An Arduino keeps track of the pulses and totalizes the amount of filament used; the counter handily subtracts from the totals when the filament is retracted.

Simple, useful, and cheap — the very definition of a hack. And even if you don’t have a 3D-printer to keep track of, harvesting encoders from old mice is a nice trick to file away for a rainy day. Or you might prefer to just build your own encoders for your next project.

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Sintering Sand WIth A Laser Cutter

We are all used to Fused Deposition Modeling, or FDM, 3D printers. A nozzle squirts molten material under the control of a computer to make 3D objects. And even if they’re usually rather expensive we’re used to seeing printers that use Stereolithography (SLA), in which a light-catalysed liquid monomer is exposed layer-by layer to allow a 3D object to be drawn out. The real objects of desire though are unlikely to grace the average hackspace. Selective Laser Sintering 3D printers use a laser on a bed of powder to solidify a 3D object layer by layer.

The laser creating a ring.
The laser creating a ring.

While an SLS printer may be a little beyond most budgets, it turns out that it’s not impossible to experiment with the technology. [William Osman] has an 80 W laser cutter, and he’s been experimenting with it sintering beach sand to create 2D objects. His write-up gives a basic introduction to glassmaking and shows the difference between using sand alone, and using sodium carbonate to reduce the melting point. He produces a few brittle barely sintered tests without it, then an array of shapes including a Flying Spaghetti Monster with it.

The results are more decorative than useful at the moment, however it is entirely possible that the technique could be refined. After all, this is beach sand rather than a carefully selected material, and it is quite possible that a finer and more uniform sand could give better results. He says that he’ll be investigating its use for 3D work in the future.

We’ve put his video of the whole process below the break, complete with worrying faults in home-made laser wiring. It’s worth a watch.

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Don’t Leave 3D Printers Unattended – They Can Catch Fire

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.

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