Reproducing A Reproducer: Servicing A Cylinder Phonograph In The Year 2021

[Jan Derogee] pulled out his phonograph the other day to hear the 100+ year old wax cylinder warble of “It’s a Long Way to Tipperary”, but couldn’t locate the reproducer — this is the small circular bit that holds the stylus and transfers the groove-driven vibrations to the center of a thin diaphragm, which vibrates into the sound horn. It’s easily the most important part of a cylinder phonograph. What do you do when you lose your reproducer? You could search ebay for a replacement, but that wouldn’t be nearly as fun as reproducing your reproducer yourself.

Traditionally, diaphragms were made from mica or celluloid, and the Edison disk phonograph used seven layers of shellac-soaked rice paper. Reproducers typically have a Dagwood sandwich of gaskets surrounding the membrane, but they don’t have to be so convoluted to work — a single strong membrane will do just fine. Just ask [Jan], who made a new reproducer with a 3D-printed case, a hand-pulled glass stylus, and a disposable aluminum foil pan for the diaphragm.

It’s difficult for us to say which part looks more fun — stretching the glass shard over a gas kitchen stove with the flame focused by a stack of wrench sockets, or cutting up a bicycle inner tube and using a car jack to press the aluminum into shape against a 3D-printed mold. The whole video is awesome and you can check it out after the break.

As [Jan] notes in the video and on the project site, the glass stylus should really be made from borosilicate because it’s harder than regular soda lime glass (that’s why they often make vaccine vials out of it). Regular glass will work and takes much less time and gas to reach the pull-able stage, so that’s what [Jan] used in the video, but it will wear out much more quickly. Fortunately, this was a temporary solution, because as soon as [Jan] made a replacement, the missing reproducer showed up.

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Finely Machined Valve Controls Miniature RC Hydraulics

Hydraulic components are the industrial power transmission version of LEGO. Pumps, cylinders, valves – pretty much everything is standardized, and fitting out a working system is a matter of picking the right parts and just plumbing everything together. That’s fine if you want to build an excavator or a dump truck, but what if you want to scale things down?

Miniature hydraulic systems need miniature components, of which this homebrew hydraulic valve made by [TinC33] is a great example. (Video embedded below.) If you’re curious about why anyone would need these, check out the tiny hydraulic cylinders he built a while back, wherein you’ll learn that miniature RC snowplows are a thing. The video below starts with a brief but clear explanation about how hydraulic circuits work, as well as an explanation of the rotary dual-action proportional valve he designed. All the parts are machined by hand in the lathe from aluminum and brass stock. The machining operations are worth watching, but if you’re not into such things, skip to final assembly and testing at 13:44. The valve works well, providing very fine control of the cylinder and excellent load holding, and there’s not a leak to be seen. Impressive.

[TinC33] finishes the video with a tease of a design for multiple valves in a single body. That one looks like it might be an interesting machining challenge, and one we’d love to see.

Thanks to [mgsouth] for the tip.

CNC Machine Rolls Up An Axis To Machine PVC Pipe

Whether it’s wood, metal, plastic, or otherwise, when it comes to obtaining materials for your builds, you have two choices: buy new stock, or scrounge what you can. Fresh virgin materials are often easier to work with, but it’s satisfying to get useful stock from unexpected sources.

This CNC router for PVC pipe is a great example of harvesting materials from an unusual source. [Christophe Machet] undertook his “Pipeline Project” specifically to explore what can be made from large-diameter PVC pipe, of the type commonly used for sewers and other drains. It’s basically a standard – albeit large-format – three-axis CNC router with one axis wrapped into a cylinder. The pipe is slipped around a sacrificial mandrel and loaded into the machine, where it rotates under what looks like a piece of truss from an antenna tower. The spindle seems a bit small, but it obviously gets the job done; luckily the truss has the strength and stiffness to carry a much bigger spindle if that becomes necessary in the future.

The video below shows the machine carving up parts for some lovely chairs. [Christophe] tells us that some manual post-forming with a heat gun is required for features like the arms of the chairs, but we could see automating that step too. We like the look of the pieces that come off this machine, and how [Christophe] saw a way to adapt one axis for cylindrical work. He submitted this project for the 2019 Hackaday Prize; have you submitted your entry yet?

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Hacked Electric Toothbrush Defeats Locks With Ease

The movie version of lockpicking tends to emphasize the meticulous, delicate image of the craft. The hero or villain takes out a slim wallet of fine tools, applies them with skill and precision, and quickly defeats the lock. They make it look easy, and while the image isn’t far from reality, there are other ways to pick a lock.

This expedient electric toothbrush lockpick is a surprisingly effective example of the more brute force approach to lockpicking. As [Jolly Peanut] explains, pin tumbler locks work by lining up each pin with the shear line of the cylinder, which allows the lock to turn. This can be accomplished a pin at a time with picks, or en masse by vibrating the pins until they randomly line up with the shear line just long enough for the lock to turn. A locksmith might use a purpose-built tool for the job, but a simple battery-powered electric toothbrush works in a pinch too. [Jolly Peanut] removed the usual business end of the brush to reveal a metal drive rod that vibrates at a high frequency. The rod was slimmed down by a little grinding to fit into the keyway of a lock, and with the application of a little torque, the vibration is enough to pop the pins into the right position. He tries it out on several locks in the video below, and it only takes a few seconds each time.

Such brute force methods have their drawbacks, of course. They’re not exactly subtle, and the noise they create may attract unwanted attention. In that case, hone your manual lockpicking skills with a giant 3D-printed see-through lock.

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Shop-Made Pneumatic Cylinders From PVC And Plywood

You see a lot of pneumatic actuators in industrial automation, and for good reason. They’re simple, powerful, reliable, and above all, cheap. Online sources and fluid-power suppliers carry a bewildering range of actuators, so why would anyone bother to make their own pneumatic cylinders? Because while the commercial stuff is cheap, it’s not PVC and plywood cheap.

Granted, that’s not the only reason [Izzy Swan] gives for his DIY single-acting cylinder. For him it’s more about having the flexibility to make exactly what he needs in terms of size and shape. And given how ridiculously easy these cylinders are, you can make a ton of them for pennies. The cylinder itself is common Schedule 40 PVC pipe with plywood endcaps, all held together with threaded rod. [Izzy] cut the endcaps with a CNC router, but a band saw or jig saw would do as well. The piston is a plywood plug mounted to a long bolt; [Izzy] gambled a little by cutting the groove for the O-ring with a table saw, but no fingers were lost. The cylinder uses a cheap bungee as a return spring, but an internal compression spring would work too,. Adding a second air inlet to make the cylinder double-acting would be possible as well. The video below shows the cylinder in action as a jig clamp.

True, the valves are the most expensive part of a pneumatic system, but if nothing else, being able to say you made your own cylinders is a win. And maybe you’ll get the fluid-power bug and want to work up to DIY hydraulics.

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The Magic That Goes Into Magnets

Every person who reads these pages is likely to have encountered a neodymium magnet. Most of us interact with them on a daily basis, so it is easy to assume that the process for their manufacture must be simple since they are everywhere. That is not the case, and there is value in knowing how the magnets are manufactured so that the next time you pick one up or put a reminder on the fridge you can appreciate the labor that goes into one.

[Michael Brand] writes the Super Magnet Man blog and he walks us through the high-level steps of neodymium magnet production. It would be a flat-out lie to say it was easy, but you’ll learn what goes into them and why you don’t want to lick a broken hard-drive magnet and why it will turn to powder in your mouth. Neodymium magnets are probably unlikely to be produced at this level in a garage lab, but we would love to be proved wrong.

We see these magnets everywhere, from homemade encoder disks, cartesian coordinate tables, to a super low-power motor.

Mini Lathe Makes Tiny Hydraulic Cylinders For RC Snow Plow

You can get pretty much any part you need online these days, but some specialty parts are a little hard to come by. So if your needs are esoteric, like tiny hydraulic cylinders for RC snow plows, you might just have to roll your own.

To be honest, we never really knew that realistic working hydraulics on such a small scale were a thing, but [tintek33]’s video below opened our eyes to a new world of miniature mechanicals. You’d think a linear actuator would be a fine stand-in for the hydraulic ram on a tiny snow plow for an RC truck, but apparently no detail is too small to address in painstaking detail. And as with many things in life, the lathe is the way to get there. Every part is scratch-built from raw brass, aluminum and steel on a mini lathe, with the exception of a few operations that were sent over to the mill that could have been done with hand tools in a pinch. The video is longish, so if you’re not into machining you can skip to 16:40 or so and pick the action up at final assembly. The finely finished cylinder is impressively powerful when hooked up to [tintek33]’s hydraulic power pack, and looks great on the plow. He’s got some other videos on his site of the RC snow plow in action that are worth a look, too.

Ready to take the plunge with a lathe but don’t know where to start? We’ve covered the basics of adopting a new lathe before.

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