Glue Your Sumo Robot to The Mat With Custom Sticky Tires

Mini Sumo seems like one of those hobbies that starts out innocently enough, and ends up with a special room in the house dedicated to it. One day you’re excitedly opening up your first Basic Stamp kit, and the next you’re milling out mini molds on a mini lathe to make mini extra sticky tires.

[Dave] started out trying to find a part from the local big box store that was just a little bigger than the wheel he wanted to rubberize. He set the wheel inside a plumbing cap and poured the urethane in. It worked, but it required a lot of time with a sharp knife to carve away the excess rubber.

In the meantime he acquired a Sherline Mini Mill and Lathe. With the new tools available to him, he made a new mold out of a bit of purple UHMW and some acrylic. This one produced much nicer results. Using a syringe he squeezed resin into the mold through a hole in the acrylic. Much less cleanup was needed.

He later applied these methods to smaller, wider wheels as his mini sumo addiction took a stronger hold on his life.

Casting A Lathe Out Of Concrete

Look up ‘concrete lathe’ and you’ll quickly find yourself reading the works of [David Gingery]. His series of books on building a machine shop from scrap begin with a charcoal foundry, and quickly move to creating a metal lathe out of concrete. Before [Gingery]’s lathe, around the time of World War I, many factories created gigantic machine tools out of concrete. It’s an old idea, but you’ll be hard pressed to find anyone with a shop featuring concrete machine tools. Cheap lathes are plentiful on Craigslist, after all.

Building a metal lathe from concrete is more of a challenge. This challenge was recently taken up by [Curt Filipowski] in a five part YouTube series that resulted in a real, working lathe made out of concrete, scrap, and a lot of bolts.

The concrete lathe begins with a form, and for this [Curt] cut out all the parts on a CNC router. Creating the form isn’t quite as simple as you would think – the concrete form included several bolts that would alow [Curt] to bolt bearings, ways made out of gas pipe, and angle iron. This form was filled with concrete in [Curt]’s kitchen, and after a nice long cure, the lathe was moved up to the upstairs shop. That’s a five hundred pound block moved up a flight of stairs by a single person.

The rest of the build deals with the cast concrete carriage which rides along the polished gas pipe ways, a tool post holder milled out of a block of aluminum, and finally making some chips. While it’s not the most practical lathe – the carriage moves along the ways by turning a wheel underneath the tailstock – it does demonstrate a concrete lathe is possible.

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Machines That Build Other Machines

When the RepRap project was founded in 2005, it promised something spectacular: a machine that could build copies of itself. RepRaps were supposed to be somewhere between a grey goo and a device that could lift billions of people out of poverty by giving them self-sufficiency and the tools to make their lives better.

While the RepRap project was hugely successful in creating an open source ecosystem around 3D printers, a decade of development hasn’t produced a machine that can truly build itself. Either way, it’s usually easier and cheaper to buy a 3D printer than to build your own.

[castvee8]’s entry into the 2016 Hackaday Prize does just what the RepRap project promised ten years ago. It’s all about building machines with the ability to reproduce, creating an ecosystem of machines to build household goods. The best part? You can 3D print most of the machines. It’s the RepRap project, but for mills, lathes, microscopes, and routers. It’s an entire shop produced entirely in a 3D printer.

The idea of creating a machine shop from the most basic building materials has been around for a while. At the turn of the last century, concrete lathes and mills bootstrapped industrial economies. Decades later, [David J. Gingery] created a series of books on building a machine shop starting with a charcoal foundry. The idea of building a shop using scrap and the most minimal tools is very old, but this idea hasn’t been updated to the era where anyone can buy a 3D printer for a few hundred dollars.

So far, [castvee8] has a few homemade machine tools on the workbench, including a lathe, a tiny mill easily capable of fabricating a few circuit boards, and a little drill press. They’re all machines that can be used to make other useful items, and all allow anyone to create the devices they need.

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Spark Plug Lights the Darkness

When you have an idea, just go build it. That’s the approach that [GordsGarage] takes with most of his projects, and he’s back in the machine shop again. This time it’s with a rather unique oil candle that uses a spark plug as inspiration. We have to say, the results are on fire.

thumbThe spark plug candle was fashioned out of a single piece of 6061 aluminum. To create the scale model, first the stock metal hit the lathe to create the “insulator” section of the plug. From there, he milled in the hex bolt section, then it hit the lathe again to create the threaded section. The inside was bored out to create space for the wick and oil, and then the electrode was installed just above the flame.

This is a pretty impressive scale model and has a great finished look. The only thing that isn’t to scale is the gap for the electrode which is completely necessary to keep the candle from getting smothered. It’s an interesting, unique idea too, which is something that [GordsGarage] excels at. And, if you want to scale his model up a little bit, perhaps you can find some inspiration from this other candle.

Custom Machined Triple Threat Slingshot

Time was when a lad in need of a ranged weapon would hack a slingshot together out of a forked tree branch and a strip of inner tube. Slingshot design has progressed considerably since [Dennis the Menace]’s day, but few commercially available slingshots can match up to the beauty and functionality of this magnificently machined multipurpose handheld weapon system.

Making it clear in his very detailed build log that this is but a prototype for a design he’s working on, [Gord] has spared little effort to come up with a unique form factor that’s not only functional as a slingshot, but also provides a few surprises: a magazine that holds nine rounds of ammo with magnets; knuckle protection on the hand grip that would deal a devastating left hook; and an interchangeable base that provides a hang loop or allows mounting a viciously sharp broadhead hunting arrow tip for somewhat mysterious purposes. There’s plenty to admire in the build process as well – lots and lots of 6061 billet aluminum chips from milling machine and lathe alike. All told, a nice piece of craftsmanship.

For a more traditional slingshot design with a twist, check out this USB-equipped slingshot that talks to Angry Birds. And when your taste in slingshots run more toward the ridiculously lethal, [Jörg Sprave]’s machete launcher never disappoints.

[Thanks Leslie!]

Making A Wooden Bowl Without A Lathe

Typically, when creating a wooden bowl a crafts person would do so on a lathe. A chunk of wood would be bolted to the head stock and the bottom of the bowl turned to an appropriate shape. Then the half-bowl-shaped wood is flipped around on the lathe so that the material on the inside of the bowl can be removed. This traditional method of bowl turning requires a lathe, turning tools, and the serious technique and skill required for the task.

The master maker of weird wood working tools, [Izzy], decided to make a wooden bowl without the use of a lathe. He created a unique fixture to cut the shape of the bowl on a table saw, a piece of equipment that is a bit more common for the average DIYer to have. The fixture itself is made of wood and supports a standard hand drill in a vertical position. The soon-to-be bowl is bolted to the drill and hovers just above the table saw blade. The table saw is turned on and the fixture allows the work piece to rock back and forth creating the bowls outside shape. The drill rotates the piece so that the contours are consistent around the bowl.

The bowl is then flipped over and re-attached to the drill. This time to cut the inside of the bowl, the fixture is locked in the vertical position and the wood is dropped straight down on the spinning blade while being rotated. The saw blade cuts a perfectly hemispherical cavity in the wood. The final bowl looks great after a little sanding and an application of oil. Check out the video after the break.

This isn’t the first time [Izzy’s] projects have been here on Hackaday, check out his DIY Band Saw and Wooden Sphere Cutter.

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Miniature Cannon Packs a Punch, Shows off Manual Machining Skills

CNC machine tools are getting ever more affordable for the amateur machinist, and they’re an enabling technology for many projects. But you’ve got to respect the old school approach to turning hunks of metal into finished parts with no computer control. [Ticktock34] shows off his skills on a WWII vintage manual lathe with a photo album of his .75 caliber miniature black powder cannon build. What starts as a 3″ diameter actuator from a front end loader ends up as a beautiful replica of a full-sized cannon, along with a half-filled barrel of nicely blued scrap metal. Particularly impressive is the nicely proportioned ball end, cut by hand with no more instrumentation than a set of calipers. [Ticktock34] also shares a few tips for getting the trunnions exactly squared and aligned.

Good looking, and functional – stay tuned after the break for a video with the impressive blast from a test firing – with only a quarter charge of powder, mind you.

Want something a little safer for the kiddies and less likely to result in a visit from the police? Perhaps this PVC pirate cannon is more your speed.

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