Hacked Car Axle Yields Custom 90° Gearbox

Need a sturdy angle gearbox to handle power transmission for your next big project? Why not harvest a rear axle from a car and make one yourself?

When you think about it, the axle of a rear-wheel drive vehicle is really just a couple of 90° gearboxes linked together internally, and a pretty sturdy assembly that’s readily available for free or on the cheap. [Donn DIY]’s need for a gearbox to run a mower lead him to a boneyard for the raw material. The video below shows some truly impressive work with that indispensable tool of hardware hackers, the angle grinder. Not only does he amputate one of the half axles with it, he actually creates almost perfect splines on the remaining shortened shaft. Such work is usually done on a milling machine with a dividing head and an end mill, but [DonnDIY]’s junkyard approach worked great. Just goes to show how much you can accomplish with what you’ve got when you have no choice.

We’re surprised to not see any of [DonnDIY]’s projects featured here before, as he seems to have quite a body of hacks built up. We hope to feature some more of his stuff soon, but in the meantime, you can always check out some of the perils and pitfalls of automotive differentials.

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Hackaday Prize Entry: 3D Printed Mini-Lathe

Lathes can be big, powerful, dangerous machines. But sometimes there’s a call for making very small parts out of soft materials, like plastic and wood. For jobs like this, you could use something like this 3D printed mini-lathe.

The benefits of 3D printing a tool like this are plentiful. The design can be customized and refined by the end user; [castvee8] notes that the machine can be made longer simply by increasing the length of the lead screw and guide rails. The machine does rely on some metal parts and a motor; but the real power here is that if you can’t source the exact components, you can always customize the files to suit what you have on hand.

[castvee8] aimed to make the entire build as easy as possible for the novice – even the motor and speed controller are off-the-shelf modules. It’s a testament to the golden age we live in that an entire lathe can be built out of modules and 3D printed parts. The project makes up another member of the family of 3D printed tools [castvee8] is showing off on Hackaday.io.

Making an Inexpensive DRO

[Andrew] wanted a digital readout (DRO) for his mini lathe and mini mill, but found that buying even one DRO cost as much as either of his machines. The solution? You guessed it, he built his own for cheap, using inexpensive digital calipers purchased off eBay.

The DRO he created features a touch screen with a menu system running on an LPCXpresso, while smaller OLED screens serve as labels for the 7-segment displays to the right. The DRO switches back and forth between the lathe and mill, and while the software isn’t done, [Andrew] hopes to be able to transfer measurements from one machine to the other.

In a very sweet touch, [Andrew] hacked cheap digital calipers to provide measurements for each axis, where they provide a resolution of 0.01mm. There are six daughter boards, one for each caliper, and each has a PIC that converts from serial to I2C, freeing the main firmware from dealing with six separate data streams.

The DRO doesn’t have a case, [Andrew] has it positioned out of chip-range from either machine.

A previous DRO we featured in 2012 used an Android tablet as its display.

New Wisdom on Old Practices

Getting into machining is hard. From high-speed seel versus carbide to “old US iron” versus “new Asian manufacture” to simply choosing which drill bits to buy, many hard decisions must be made before one even has a chance to gain experience. Fear not, [Quinn Dunki] has created “a roadmap for how to get involved in this hobby.

We saw [Quinn’s] first entry in her lathe series back in January, and now the series is complete! Starting with the definition of a machine tool and ending with the famous Clickspring scriber and a multi-material pen, [Quinn] leaves no stone unturned. [Quinn’s] style contrasts with the likes of [ThisOldTony], [AvE] or [Clickspring], as she makes sure to include the gory details of everything, citing her dissatisfaction with most YouTube machinists as motivation:

they’re all about the money shots of chips flying, but thin on the actual work of machining, which is mostly work-holding setups, changing bits and dies around, etc. That’s where all the knowledge is. The machine does the work once you spend 20 minutes setting it up properly for the operation. Everyone skips that part. I scour Tubalcain videos for details like the angle of the compound for a facing operation, or how to drill a deep hole with a short tail stock without the carriage getting in the way. Simple things like that get glossed over, but stump a beginner.

Of the series, our favorite part was “Grinding tool bits.” When combined with [ThisOldTony’s] Grinding HSS Tools, the two form an education in high-speed steel tool grinding fit for a hacker. Need more than high-speed steel? We’ve got you covered.

Welcome… To Resin Cast Park

From animatronic dinosaurs to [Jeff Goldblum]’s prosthetic chest hair, Jurassic Park is known for its practical effects and props. While it’s not as fancy as a breathing triceratops, YouTube’s god of resin casting has recreated one of the more endearing props from this movie. [Peter Brown] and [Pocket83] made a replica of the amber-topped cane carried by John Hammond, and it took him two years to do it.

The ‘mosquito in amber’ walking cane prop from Jurassic Park is just what you think it is – a large mosquito-looking bug trapped in 100 million year old amber. Of course, finding such a chunk of amber with the included mosquito would cost a fortune, so [Peter] turned to polyurethane resin. This block of resin was cast in two halves, with a ‘mosquito eater’ (or a crane fly) embedded in the middle. It took two years for [Peter] to cast this block of amber, but really all but two weeks of that was waiting for a few adult crane flys to appear.

With a bug encased in resin, the project went over to [Pocket83] who turned the walking cane on his lathe. There’s not much to this part of the build except for drilling a three-foot long hole down the center of a piece of wood, although the finish does make this cane look spectacular.

The long wait for crane fly breeding season was worth it. This is one of the best looking functional props from Jurassic Park. You can check out the videos for this build below.

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Bulking up a Lightweight Lathe with a Concrete Cart

When it comes to machine tools, a good rule of thumb is that heavier is better. A big South Bend lathe or Bridgeport mill might tip the scales at ludicrous weight, but all that mass goes to damping vibration and improving performance. So you’d figure a lathe made of soda cans could use all the help it could get; this cast concrete machine cart ought to fit the bill nicely

Perhaps you’ve caught our recent coverage of [Makercise]’s long and detailed vlog of his Gingery lathe build. If not, you might want to watch the 5-minute condensed video of the build, which shows the entire process from melting down scrap aluminum for castings to first chips. We love the build and the videos, but the lightweight lathe on that wooden bench never really worked for us, or for [Makercise], who notes that he was never able to crank the lathe up to full speed because of the vibrations. The cart attempts to fix that problem the old fashioned way – more mass.

There are a few “measure twice, cut once” moments in the video below, as well as a high pucker-factor slab lift that could have turned into a real disaster. We might have opted for a countertop-grade concrete mix that could be dyed and polished, but that would be just for looks. When all is said and done, the cart does exactly what it was built to do, and there’s even room on it for the shaper that’s next on the build list. We’re looking forward to that.

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The Elements Converge for ±.002 in Tolerance

What can be accomplished with just a torch and compressed air? We can think of many things, but bringing a 17-foot-long marine shaft into ±.002 in tolerance was not on our list.

Heat straightening (PDF) utilizes an oxy-acetylene flame that is used to quickly heat a small section of a workpiece. As the metal cools, it contracts more than it expanded when heated, resulting in a changed volume. With skill, any distortions on a shaft can theoretically be straightened out with enough time (and oxy-acetylene). Heat straightening is commonly applied to steel but works on nickel, copper, brass and aluminum additionally.

[Keith Fenner’s] standard process for trueing stock is sensitive enough that even sunlight can introduce irregularities, but at the same time is robust enough to carry out in your driveway. However, even though the only specialty tools you need are a torch, compressed air and work supports, watching [Keith] work makes it clear that heat straightening is as much an art as it is a science. Check out his artistry in the video below the break. Continue reading “The Elements Converge for ±.002 in Tolerance”