Experiments With A Bowden Extruder Filament Force Sensor

We were excited to learn that someone had started working with force sensors on filament extruders, especially after we posted about a recent development in filament thickness sensors.

[airtripper] primarily uses a Bowden extruder, and wanted to be a little more scientific in his 3D printing efforts. So he purchased a force sensor off eBay and modified his extruder design to fit it. Once installed he could see exactly how different temperatures, retraction rates, speed, etc. resulted in different forces on the extruder. He used this information to tune his printer just a bit better.

More interesting, [airtripper] used his new sensor to validate the powers of various extruder gears. These are the gears that actually transfer the driving force of the stepper to the filament itself. He tested some of the common drive gears, and proved that the Mk8 gear slipped the least and provided the most constant force. We love to see this kind of science in the 3D printing community — let’s see if someone can replicate his findings.

 

16-Bobbin Rope Braiding Machine Inspired by Surplus Store Find

When the Red Bull Creation build days were past, [David] pulled us aside and asked if we wanted to see the mechanical hack he’s been working on. He built this rope braiding machine, which uses 16 bobbins, with help from his brother [Jed].

Ideas for projects always come from funny places. [David] came up with this one after finding a rope braiding machine at Ax-man Surplus. This outlet, located in the Twin Cities (Minneapolis/St. Paul, Minnesota) has been the origin for innumerable hacks. Just one that comes to mind is this electric scooter project from the ’90s.

[David] wanted to understand how the mechanism, which divides the bobbins up into groups of orbiting spools, actually works. It’s both mesmerizing and quite tough to visualize how it works without really getting in there and looking at the gearing. Thankfully you can do just that if he follows through with his plan to turn this into a kit.

In case you don’t recognize him, [David] was on the 1.21 Jigawatt’s team during this year’s Creation. We’ve also seen a couple of hacks from him in the past like this half-tone drum printer, and this bicycle frame welding jig.

Machining an Orrery

machining-an-orrery

What in the heck is an Orrery? If you’re looking at the image above we’re sure you’ve already figured it out (kudos to the big brains that knew the word). For those that don’t get it, an Orrery is a mechanical device that represents the movements of planets and moons. We never thought of building one ourselves. After seeing the machining process for what’s shown above we’re not sure if we’re excited, or scared off by all the work that went into it.

You might want to bust out the Chromecast and hit the sofa for this one. There are dozens of YouTube videos showing the build. From cutting sheet stock into round slugs, to making teeth, teeth, teeth, and more teeth it’s not just the gears that go into this one. You’re also going to needs the orbs themselves.

We have fond (perhaps scary) memories of the first time we saw an Orrery as a part of the set in The Dark Crystal.

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Automata and wooden gears

mechanism

While most animated machines we deal with every day – everything from clocks to cars to computers – are made of metal, there is an art to creating automated objects out of wood. [Dug North] is a creator of such inventions, making automata out of wooden gears, cogs, and cams.

[Dug]’s inventions are simple compared to turbine engines, but they still retain an artistry all their own. With just simple woodworking tools, he’s able to creating moving vignettes of everyday scenes, everything from a dog barking at a bird, to Santa Claus gracefully soaring over a house on Christmas Eve.

Below, you’ll find a video of [Dug]’s creation, ‘An Unwelcome Dinner Guest’ – an automated dog barking at a wooden bird. There’s also a video of him being interviewed by the awesome people at Tested last year at the World Maker Faire.

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Retrotechtacular: Mechanical targeting computers

retrotechtacular-mechanical-computer

The device that these seamen are standing around is a US Navy targeting computer. It doesn’t use electricity, but relies on mechanical computing to adjust trajectories of the ship’s guns. Setting up to twenty-five different attributes by turning cranks and other input mechanisms lets the computer automatically calculate the gun settings necessary to hit a target. These parameters include speed and heading of both the ship and it’s target, wind speed and bearing, and the location of the target in relation to this ship. It boggles the mind to think of the complexity that went into this computer.

The first of this seven part series can be seen after the break. The collection covers shafts,  gears, cams, and differentials. Sounds like it would be quite boring to sit through, huh? But as we’ve come to expect from this style and vintage of training film it packs a remarkable number of simple demonstrations into the footage.

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Printed machine does nothing until the heat death of the Universe

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A 2:1 gear reduction slows down a spinning shaft to half speed and doubles the torque. Repeat this a few times, and you’ve got a ludicrous amount of torque moving too slowly to see with even precision instruments. That’s the idea behind [Jeshua]’s project, a Printed Machine partially embedded in a block of concrete.

[Jeshua]’s build is a replica of one of [Arthur Ganson]’s kinetic sculptures. [Ganson]’s machine uses 50 sets of gears to reduce the rotation of 200 RPM motor more that 200  quintillion times. The final gear in the sculpture is embedded in a block of concrete, waiting to be freed by either erosion of the concrete block or the sun going nova.

Instead of metal gears, [Jeshua] used 3D printed gears in PLA. After assembling them on a stand, he cast concrete around the final, barely moving gear. It’s an impressively useless build that will turn to dust before the final gear makes even 1/10th of a revolution. This machine could have a longer life if it were printed with ABS instead of PLA, but with the time scales we’re talking about here it won’t make much difference.

Building a mechanical counter out of scrap wood

Watching [Matthias Wandel] fabricate this mechanical counter from scrap wood is just fascinating. He likens the mechanism to the counters you would find on decades-old cassette tape players.

You may recognize the quality of [Matthias’] work. We’ve seen several pieces, but his binary adder is still one of our favorites. This project gives us a very clear view of the development and fabrication process. He even posted a detailed guide if you want to build your own.

He started by prototyping a mechanism to increment and decrement the counter. With that proven design he started laying out the rest of the gears. These were cut from plywood scraps he had from other projects. Notice the small gears seen above which are missing parts of some teeth. Those sections were removed using a drill press with a Forstner bit. The missing teeth cause the next digit over to increment more slowly, resulting in a 1/10 ratio. This part of the design is demonstrated about three minutes into the video after the break.

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