Author: Gerrit Coetzee

476 Articles

Copenhagen Suborbitals Launches Impressive Amateur Liquid Fueled Rocket

August 1, 2016 by 41 Comments

Copenhagen Suborbitals just launched their latest amateur liquid fuel rocket. Why? Because they want to strap someone to a bigger amateur liquid fuel rocket and launch them into space.

We’ve covered them before, but it’s been a while. While they make a big deal of being amateurs, they are the least amateurish amateurs we’ve come across. We’ll forgive a lot as long as they keep making great videos about their projects. Or posting great pictures of the internals of their rockets.

The Nexø I rocket they recently launched claims to be the first guided, amateur, liquid-fueled rocket. There is a nice post on the guidance system. It was launched from a custom built barge off the shore of Denmark, which allows them to escape quite a few legal hurdles around the launch. The rocket flew beautifully. That is, it went only away from the ground; no other directions. Also, it didn’t explode, which is a lot to expect from even the biggest players in the field.

Copenhagen Suborbitals continues to do amazing work. Hopefully their next rocket will be even more impressive… for amateurs, that is.

From Shop Floor Dust To Carbon Steel

August 1, 2016 by 15 Comments

[Chandler Dickinson] did his monthly sweep of the floor in his blacksmith’s shop when it occurred to him that all that metal dust had to go somewhere, didn’t it? So he did the only reasonable thing and made a crude foundry out of cinder blocks, melted his dirt in it, and examined what came out the other end.

His first step was to “pan” for steel. He rinsed all the dirt in a bucket of water and then ran a magnet at the bottom of the bucket. The material that stuck to the magnet, was ripe for reclaimation.

Next he spent a few hours charging a cinderblock foundry with coal and his iron dust. The cinderblocks cracked from the heat, but at the end he had a few very ugly brittle rocks that stuck to a magnet.

Of course there’s a solution to this non-homogenous steel. As every culture with crappy steel eventually discovered, you can get really good steel if you just fold it over and over again.  So he spend some time hammering one of his ugly rocks and folding it a bit. He didn’t get to two hundred folds, but it was enough to show that the resulting slag was indeed usable iron.

He did a deeper examination of the steel last week, going as far as to etch it, after discovering that the metal sparked completely differently when sanded on one side versus the other. It definitely needed work, but all seemed to have worked in the end.

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LastPass Happily Forfeits Passwords To Simple Javascript

August 1, 2016 by 37 Comments

Lastpass is a great piece of software when it comes to convenience, but a recent simple hack shows just how insecure software like it can be. [Mathias Karlsson] nabbed a nice $1000 bounty for its discovery.

Lastpass’s auto-fill works by injecting some html into the website you’re visiting. It runs a bit of Javascript to parse the URL. However, the parsing script was laughably vague. By changing the URL of the page, inserting a few meaningless-to-the server slugs into the URL, an attacker could get Lastpass to give it a password and username combo for any website.

The discussion in the HackerNews comment section more-or-less unilaterally agreed that most systems like this have their glaring flaws, but that the overall benefits of having secure passwords generated and managed by software was still worth the risk when compared to having a few commonly reused passwords over multiple sites.

One could get a more secure key manager by using software like KeePass, but it’s missing some of the convenience factor of remote-based services and relies on a user protecting their key files adequately.

Still, as scary as they are, openly discussing hacks like this after responsible disclosure is good because they force companies like Lastpass, who have some very big name clients, to take their code review and transparency more seriously.

Escalating To CNC Through Proxxon’s Tool Line

July 31, 2016 by 16 Comments

Proxxon is a mostly German maker of above average micro tools. They do sell a tiny milling machine in various flavors, from manual to full CNC. [Goran Mahovlić] did not buy that. He did, however, combine their rotary tool accessory catalog into a CNC mill.

Owning tools is dangerous. Once you start, there’s really no way to stop. This is clearly seen with Goran’s CNC machine. At first happiness for him was a small high speed rotary tool. He used it to drill holes in PCBs.

In a predictable turn of events, he discovered drilling tiny holes in PCBs by hand is tedious and ultimately boring. So he purchased the drill press accessory for his rotary tool.

Life was good for a while. He had all the tools he needed, but… wouldn’t it be better if he could position the holes more quickly. He presumably leafed through a now battered and earmarked Proxxon catalog and ordered the XY table.

A realization struck. Pulling a lever and turning knobs! Why! This is work for a robot, not a man! So he pestered his colleague for help and they soon had the contraption under CNC control.

We’d like to say that was the end of it, and that [Goran] was finally happy, but he recently converted his frankenmill to a 3D printer. We’ve seen this before. It won’t be long before he’s cleaning out his garage to begin the restoration and ultimate CNC conversion of an old knee mill. Videos after the break.

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Parent To The Power Wheels Rescue

July 31, 2016 by 13 Comments

If the [realjohnnybravo] is the one from the show, it appears he finally managed to get a girlfriend, marry her, and produce at least one son. As the old schoolyard rhyme goes, first comes love, then comes marriage, then comes filling the whole *!$&# backyard with brightly colored plastic garbage. One of these items, a Power Wheels quad bike,  suffered a blow from planned obsolescence leaving behind a traumatized child. [realjohnnybravo] decided to fix it.

He made frequent mention of how one could go to a store and purchase replacement gears for the toy. Perhaps it’s a German thing. Regardless, he shows experience with internet comments by justifying his adventure in gear manufacturing with, paraphrased, “I’m having fun and learning so back off you pedantic jerks.”

Resin casting is great, and is often overlooked vs 3D printing. He purchased some hardware store RTV silicone and some slow-cure resin. The faster cure resin would get too hot with this much volume and potentially burn.

Materials procured he took apart both gearboxes from the machine. He first made a silicone mold of the broken parts (from the good copies out of the working gearbox) and removed the master. Without a vacuum or pressure casting chamber, the molds came out a little rough and bubbly, but it’s nothing some work with a carpet knife can’t fix. For big gears like this it hardly matters. Next he poured the two part resin into the molds and waited.

After some finishing with regular woodworking tools the parts fit right into the voids in the defective gearbox. His son can once again happily whir around the lawn, until the batteries die anyway.

20kW Light Is As Bright As You’d Expect

July 28, 2016 by 37 Comments

[Photonicinduction] purchased a very very bright light. This 20,000 Watt half meter tall halogen will just about light the back of a person’s skull with their eyes closed. These are typically used to light film sets.

Most people couldn’t even turn such a light on, but [Photonicinduction] is a mad scientist. Making lightning in his attic, it’s easy to mentally picture him as the villain in a Sherlock Holmes novel. Luckily for us, if he has any evil tendencies, they are channeled into YouTube videos.

He gives a good description of the mechanical and electrical properties of the light. The body is as one would expect for an incandescent light. A glass filament envelope with the filaments supported within. The envelope is evacuated and filled with an appropriate gas. This light is dangerous enough that the outside must be thoroughly cleaned of fingerprints to keep a hot-spot from forming, which could cause the lamp to explode.

After some work, he managed to convince himself that the filaments within were not, in fact, garage door springs, and gave a demonstration of their properties. For example, their resistance goes up as they are heated. In order to keep from tripping the power supply, filaments this large must be preheated. Failure to do so passes a very large number of amps.

The next step was to hook the lamp up to his home-made 20 kW power supply. He gives a good demonstration of just how bright it is. Within seconds he’s sweating from the heat and definitely can’t even open his eyes to see with the tiny sun occupying the center of his abode. Video after the break.

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Repaired Manned Multicopter Flies Without Horrifying Crash

July 28, 2016 by 81 Comments

[amazingdiyprojects] has been making lots of test flights in his crazy eight propeller gasoline powered danger bucket.

We last covered the project when he had, unfortunately, wrecked the thing in a remote-controlled test flight.  He later discovered that the motor’s crankshaft bearings had, well, exploded. The resulting shrapnel destroyed the motor and crashed the drone. He described this failure mode as “concerning”.

Also concerning is the act of stepping into the seat once all the propellers are started up. He tags this as “watch your step or die”. Regardless, he also describes flying in the thing as so incredibly fun that it’s hard to stay out of it; like a mechanical drug. It explains why his channel has been lately dominated by videos of him testing the multicopter. Those videos are found after the break.

The device drinks 0.65-0.7 liters per minute of gasoline, and he’s been going through reserves working out all the bugs. This means everything from just figuring out how to fly it to discovering that the dust from the ground effect tends to clog up the air filters; which causes them to run lean, subsequently burning up sparkplugs. Dangerous, but cool.

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