DIY Car Wheel Bearing Puller

March 21, 2015 by Rich Bremer 24 Comments

Cars are the greatest. They get you to where you need to go… most of the time. They can also let you down at the worst moment if a critical part fails. Wheel bearings get a lot of use while we drive and [Dmitriy] found out the hard way how quickly they can fail. Instead of getting cranky about it, he set out to change the damaged bearing himself. In the process he made a pretty neat DIY bearing puller.

Some wheel bearings, on the front of a 2WD truck for example, are only held on by one large nut and easily slide off the spindle. This was not the case for the rear of [Dmitriy’s] AWD Subaru. The rear bearings are press-fit into a bearing housing. These are hard to remove because Outer Diameter of the bearing is actually just slightly larger than the Inner Diameter of the bearing housing. This method of retaining parts together is called an ‘interference fit‘.

[Dmitriy’s] gadget uses one of Hackaday’s favorite simple machines, the screw, to slowly force the bearing out of its housing. It works by inserting a threaded rod through the bearing and bearing housing. Each side has a large washer and nut installed as well as a PVC pipe spacer providing support for the threaded rod. As the opposing nuts are tightened, one washer presses against the bearing and the bearing slowly slides out of the housing. Installation of the new bearing is the same except the tool is reversed to press the bushing into the housing.

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Your Marble Machine Doesn’t Need To Change The World

March 21, 2015 by Mike Szczys 21 Comments

It’s easy to get sucked into the increasing the complexity when sometimes the craftsmanship can be what makes the project. [Alex Weber] proves the point with his minimalist marble machine. There are no death-defying twists and turns, no convoluted path forks or overly-complex lifting mechanisms. This is about a clean and simple design that looks amazing whether running or stationary.

For the uninitiated, marble machines route marbles (or quite often steel ball bearings) through a set of paths usually guided by gravity for the delight of onlookers. Traditionally, making them complicated is the point. Take this offering which highlights years worth of marble machine builds all exercising different concepts. Sometimes they occupy entire rooms. We’ve seen them make a clock tick. And who can forget marble-based flip-flops that combine to form things like binary adders?

Have we scared you off from building these yourself yet? No, that’s the entire point of this one… it can be excruciatingly simple, while elegantly crafted. Check out the video demo below to see how one oval, one battery, and one motor have no problem bringing a smile to your face.

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Active “Dart-Sensing” Makes Your Nerf Gun Smarter

March 21, 2015 by Sonya Vasquez 5 Comments

When choosing weapons to defend yourself in the next zombie apocalypse, dart jamming whilst firing your Nerf Gun can be a deal-breaker. This clogging is an issue with many “semi-automatic” Nerf Guns. When our trigger-happy fingertips attempt to shoot a dart that hasn’t finished loading into the firing chamber, the halfway-loaded dart folds onto itself and jams the chamber from firing any more darts. The solution, as intended by Nerf, would be to open the chamber lid and manually clear the pathway. The solution, according to [Technician Gimmick], however, is active sensing, and the resulting “smart” dart gun is the TR-27 GRYPHON.

To prevent jamming from occurring altogether, [Technician Gimmick] added a trigger-disable until the dart has fully loaded into the firing chamber. An IR LED, harvested from a mouse scroll wheel, returns an analog value to the microcontroller’s analog-to-digital converter, allowing it to determine whether or not a dart is ready for firing. The implementation is simple, but the results are fantastic. No longer will any gun fire a dart until it has completely entered the chamber.

The TR-27 GRYPHON isn’t just a Nerf Gun that enables “smart” dart sensing. [Technician Gimmick] folded a number of other features into the Nerf Gun that makes it a charmer on the shelf. First, a hall-sensor array identifies the current cartridge loaded into the Nerf Gun and it’s carrying capacity. To display this value and decrement appropriately, [Technician Gimmick] added a dual-seven segment display, a trick we’ve seen before. Finally, a whopping 3S LiPo battery replaces the original alkaline batteries, and the voltage-reducing diodes have been cropped, enabling a full 12.6 Volt delivery to the motors at full charge.

We’re glad to see such a simple trick go such a long way as to almost entirely eliminate Nerf dart jams. For all those braving the Humans-Versus-Zombies frontier this season, may this clever trick keep you alive for just a bit longer.

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Portable 120V To 240V Converter; Or How To Fast Charge At Your In-Law’s House

March 21, 2015 by Mike Szczys 73 Comments

[Nick Sayer] falls into the “would rather build it than buy it” category. This particular project is a clone of a fast electric vehicle charger. There are commercially available versions sold under the Quick 220 brand name. The idea is that for fast charging, some electric vehicles call for a 240V outlet and Americans without electric cars often don’t have one. If they do it’s for an appliance like a stove or clothes dryer and probably not found in the garage.

The device uses two hot and one ground to supply the 240V output which is, in some business where there is three phase power this will be closer to 208V but should still work. Obviously you shouldn’t be doing this unless you know exactly how it works, and we applaud [Nick] for airing these hazards while at the same time supplying the knowledge behind the concerns.

Two inputs for the beefy converter are supplied from outlets not just on separate circuits, but on two circuits whose hot lines are 180 degrees out of phase. That means identifying where there are two plugs, not protected by GFCI outlets or breakers, which are on two separate hot lines of split phase power. To protect the user, [Nick] designed in a set of relays which kill the circuit when one of the two supplies is unplugged. A system that didn’t have these protections would have mains voltage on the prongs of the disconnected plug.

We’ve seen very few car charging hacks. If you know of one, or have been working on your own, let us know!

MRRF: (not Quite) Chocolate Clock

March 21, 2015 by Kristina Panos 25 Comments

[Jason] is a woodworker. At least, he was until he saw his first 3D printer. While he may still work in wood, he particularly likes adapting scroll saw patterns for 3D printing. His clock started as a woodworking pattern for use on a scroll saw. To adapt it for 3D printing, [Jason] scanned the plotter-sized pattern pieces into Inkscape, where he was able to do things like add bevels before sending the pieces to OpenSCAD.

As you might imagine, a great deal of work went into this build, beginning with the scanning. [Jason] starting scanning last October and finished in January. Printing started January 9th, and he told me the final pieces were printed early this morning. We know you want all the details, so here goes: this build took just over six rolls of PLA at 20% infill. It’s 48″ tall and about 24″ wide. It was printed on what [Jason] referred to as his “very modified” Replicator 2. He glued the pieces together with Testor’s, and that took about 30 hours. All through the project, he kept meticulous notes in a spreadsheet of print times and filament used.

We were honored to be among the first to see [Jason]’s incredible clock build at this year’s Midwest RepRap Festival. He would like to take it on tour this year to the nearby Maker Faires. If he can figure out how transport it safely, he’d like to show it at World Maker Faire in NYC.

GT2 Belt Drive Conversion Of Printrbot Simple

March 21, 2015 by Anool Mahidharia 5 Comments

The early versions of the Printrbot Simple at about $300 were cheap enough for even the most cash-strapped hackers to put on their desks. Obviously, for that cost, a lot of design compromises were needed to keep it cheap. Sometimes, changes carry forward to the next iteration at no cost increase. One such improvement in the current version of the Printrbot is the belt drive. Unfortunately, if you have one of the late 2013 – early 2014 wood models, it is most likely being driven by a fishing line that loops over a rubber hose attached to the stepper motor. [jason] describes the process of upgrading the Printrbot Simple to a GT2 belt drive , using the designs posted by Thingiverse contributor [iamjonlawrence].

The trouble with the fishing line drive was that it would tend to get loose over time and needed to be pulled taut. Also, it affected precision when the line tended to wander over the drive shaft. The good thing with having rapid prototyping tools is you can make bootstrap improvements using them. Once the parts for the upgrade were printed, [jason] only needed some bearings, GT2 belts and pulleys to complete the upgrade. For those wanting to upgrade their old Printrbot Simple machines, [jason] guides you through the whole process via some detailed photographs and listing out the gotcha’s that you need to be careful about.

Rebraining An LED Marquee With A SparkCore

March 20, 2015 by Mike Szczys 6 Comments

Wires? Where this LED scroller is going we don’t need wires. Well, except for power but everything needs power. The 90×7 LED marquee hangs over the entrance to NYC Resistor’s laser cutter room. Thanks to a Spark Core and a bit of work from [Trammell Hudson], the sign is working and attached to the network.

The original unit called for an RS485 connection for input. Other than that there wasn’t really a reason it had been collecting dust. Closer inspection of the internals proved that the display is driven exactly as you would expect: transistors for the rows and shift registers for the columns. Well, actually the columns are split into separate shift registers for the even and odd but that doesn’t complicate things too much. GPIO takes the seven row-driving transistors, two shift register clocks, data, latch, and enable for a total of twelve pins.

The Spark Core completely replaces the Atmel 80C32X2 and its RTC by pinging the network for UTC time synchronization once per day.

[via NYC Resistor]