3D-Printed Punch and Die Stand up to Steel

When you think of machine tooling, what comes to mind might be an endmill made of tungsten carbide or a punch and die made of high-speed steel. But surely there’s no room in the machine tool world for 3D-printed plastic tools, especially for the demanding needs of punching parts from sheet metal.

As it turns out, it is possible to make a 3D-printed punch and die set that will stand up to repeated use in a press brake. [Phil Vickery] decided to push the tooling envelope to test this, and came away pleasantly surprised by the results. In fairness, the die he used ended up being more of a composite between the carbon-fiber nylon filament and some embedded metal to reinforce stress points in the die block. It looks like the punch is just plastic, though, and both were printed on a Markforged Mark 2, a printer specifically designed for high-strength parts. The punch and die set were strong enough to form 14-gauge sheet steel in a press brake, which is pretty impressive. The tool wasn’t used to cut the metal; the blanks were precut with a laser before heading to the press. But still, having any 3D-printed tool stand up to metal opens up possibilities for rapid prototyping and short production runs.

No matter what material you make your tooling out of, there’s a lot to know about bending metal. Check out the basics in our guide to the art and science of bending metal.

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Smooth and Steady Cuts with an Improvised Power Feeder

Some woodworking operations require stock to be fed at a smooth, steady rate, for which purpose a power feeder is usually employed. They’re expensive bits of gear, though, and their cost can usually be borne only by high-output production shops. But when you need one, you need one, and hacking a power feeder from a drill and a skate wheel is a viable option.

It should come as no surprise that this woodshop hack comes to us from [Matthias Wandel], who never seems to let a woodworking challenge pass him by. His first two versions of expedient power feeders were tasked with making a lot of baseboard moldings in his new house. Version three, presented in the video below, allows him to feed stock diagonally across his table saw, resulting in custom cove moldings. The completed power feeder may look simple — it’s just a brushless drill in a wooden jig driving a skate wheel — but the iterative design process [Matthias] walks us through is pretty fascinating. We also appreciate the hacks within hacks that always find their way into his videos. No lathe? No problem! Improvise with a drill and a bandsaw.

Surprised that [Matthias] didn’t use some of his famous wooden gears in this build? We’re not. A brushless motor is perfect for this application, with constant torque at low speeds. Want to learn more about BLDC motors? Get the basics with a giant demo brushless motor.

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Making a Gun Without a 3D Printer

Around four years ago the world was up in arms over the first gun to be 3D printed. The hype was largely due to the fact that most people don’t understand how easy it is to build a gun without a 3D printer. To that end, you don’t even need access to metal stock, as [FarmCraft101] shows us with this gun made out of melted aluminum cans.

The build starts off by melting over 200 cans down into metal ingots, and then constructing a mold for the gun’s lower. This is the part that is legally regulated (at least in the US), and all other parts of a gun can be purchased without any special considerations. Once the aluminum is poured into the mold, the rough receiver heads over to the machine shop for finishing.

This build is fascinating, both from a machinist’s and blacksmith’s point-of-view and also as a reality check for how easy it is to build a firearm from scratch provided the correct tools are available. Of course, we don’t need to worry about the world being taken over by hoards of angry machinists wielding unlicensed firearms. There’s a lot of time and effort that goes into these builds and even then they won’t all be of the highest quality. Even the first 3D printed guns only fired a handful of times before becoming unusable, so it seems like any homemade firearm, regardless of manufacturing method, has substantial drawbacks.

Thanks to [Rey] for the tip!

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Maywa Denki’s Nonsense Machines

We just spent a few hours trying to figure out Japanese techno-performance-art-toy company [Maywa Denki]. As self-described “parallel-world electricians”, the small art collective turns out strange electro-mechanical instruments, creates bellows-powered “singing” sculptures, and puts on concerts/demos/lectures. And if you desperately need an extension cord in the shape of a fish skeleton, [Maywa Denki] has you covered. Writing about art is like dancing about economics, so first we’ll just drop a few of our favorites and let you decide.

On the serious art front are “nonsense machines” like SeaMoonsII and Wahha Go Go. The most iconic performance piece is probably the Pachi-Moku, a set of finger-snap-activated wooden gongs mounted on anime-style wings. And then there are “toys” like Mr. Knocky and the Otamatone, here demonstrated playing some DEVO.

There’s a lot going on here. The blue suits of the assembly-line worker, the back story as a small-electronics “company”, and the whole art-as-commodity routine is a put into contrast with the mad-inventor schtick make sense both as a reaction against conformist, corporatist postwar Japanese culture or as a postmodern hat-tip to the realities of the modern art scene. But mostly, what comes across is the feeling that [Novmichi Tosa], the “president” of [Maywa Denki] just loves to make crazy gizmos.

How else do you explain the gas-powered, chomping mouth-full-of-knives, Poodle’s Head?

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Marvelous Mechanisms: The Ubiquitous Four Bar Linkage

The four bar linkage is a type of mechanical linkage that is used in many different devices. A few examples are: locking pliers, bicycles, oil well pumps, loaders, internal combustion engines, compressors, and pantographs. In biology we can also find examples of this linkage, as in the human knee joint, where the mechanism allows rotation and keeps the two legs bones attached to each other. It is also present in some fish jaws that evolved to take advantage of the force multiplication that the four bar mechanism can provide.

How It Works

Deployable mirror with scissor linkages. By [Catsquisher] via Wikimedia Commons
The study of linkages started with Archimedes who applied geometry to the study of the lever, but a full mathematical description had to wait until the late 1800’s, however, due to the complexity of the resulting equations, the study and design of complex linkages was greatly simplified with the advent of the digital computer.

Mechanical linkages in general are a group of bodies connected to each other to manage forces and movement. The bodies, or links, that form the linkage, are connected to each other at points called joints. Perhaps the simplest example is the lever, that consists of a rigid bar that is allowed to pivot about a fulcrum, used to obtain a mechanical advantage: you can raise an object using less force than the weight of the object.

Two levers can be connected to each other to form the four bar linkage. In the figure, the levers are represented by the links a (A-D) and b (B-C).  The points A and B are the fulcrum points.  A third link f (C-D) connects the levers, and the fourth link is the ground or frame g (A-B) where the mechanism is mounted. In the animation below, the input link a (the crank) performs a rotational motion driving the rocker rod b and resulting in a reciprocating motion of the link b (the rocker).

This slider-crank arrangement is the heart of the internal combustion engine, where the expansion of gases against a sliding piston in the cylinder drives the rotation of the crank. In a compressor the opposite happens, the rotation of the crank pushes the piston to compress the gas in the cylinder. Depending on how the mechanism is arranged, it can perform the following tasks:

  • convert rotational motion to reciprocating motion, as we just discussed above.
  • convert reciprocating motion to rotational motion, as in the bicycle.
  • constrain motion, e.g. knee joint and car suspension.
  • magnify force, as in the parrotfish jaw.
Locking pliers mechanism. Image from [Engineering made easy]

Some Applications

One interesting application of the four bar linkage is found in locking pliers. The B-C and C-D links are set at an angle close to 180 degrees. When force is applied to the handle, the angle between the links is less than 180 (measured from inside the linkage), and the resulting force in the jaws tries to keep the handle open. When the pliers snap into the locked position that angle becomes less than 180, and the force in the jaws keeps the handle in the locked position.

In a bicycle, the reciprocating motion of the rider´s legs is converted to rotational motion via a four bar mechanism that is formed by the two leg segments, the bicycle frame, and the crank.

An example from nature, the Moray eel. Image from [Matthew West]
As with many other inventions of humankind, we often find that nature has already come up with the same idea via evolution. The parrotfish lives on coral reefs, from which it feeds, and has to grind the coral to get to the polyps inside. For that job, they need a very powerful bite. The parrotfish obtains a mechanical advantage to the muscle force by using a four bar linkage in their jaws! Other species also use the same mechanism, one is the Moray eel, shown in the image, which has the very particular ability to launch its jaws up in the mouth to capture its prey, much like the alien from the film series.

The joints connecting the links in the linkage can be of two types. A hinged joint is called a revolute, and a sliding joint is called a prismatic. Depending on the number of revolute and prismatic joints, the four bar linkage can be of three types:

  • Planar quadrilateral linkage formed by four links and four revolute points. This is shown in the animation above.
  • Slider-crank linkage, formed by three revolute joints and a prismatic joint.
  • Double slider formed by two revolute joints and two prismatic joints. The Scotch yoke and the trammel of Archimedes are examples.

There are a great number of variations for the four bar linkage, and as you can guess, the design process to obtain the forces and movements that we need is not an easy task. An excellent resource for the interested reader is KMODDL (Kinematic Models for Design Digital Library) from Cornell University. Other interesting sites are the 507 mechanical movements, where you can find nice animations, and [thang010146]’s YouTube channel.

We hope to have piqued your curiosity in mechanical things. In these times of ultra fast developments in electronics, looking at the working of mechanisms that were developed centuries ago, but are still present and needed in our everyday lives can be a rewarding experience. We plan to work on more articles featuring interesting mechanisms so please let us know your favorites in the comments below.

Silicon Wafer Transfer Machine Is Beautifully Expensive

There’s nothing more freeing than to be an engineer with no perceptible budget in sight. [BrendaEM] walks us through a teardown of a machine that was designed under just such a lack of constraint. It sat inside of a big box whose job was to take silicon wafers in on one side and spit out integrated circuits on the other.

[BrendaEM] never really divulges how she got her hands on something so expensive that the engineer could specify “tiny optical fiber prisms on the end of a precision sintered metal post” as an interrupt solution for the wafer.  However, we’re glad she did.

The machine features lots of things you would expect; pricey ultra precise motors, silky smooth linear motion systems, etcetera. At one point she turns on a gripper movement, the sound of it moving can be adequately described as poetic.

It also gives an unexpected view into how challenging it is to produce the silicon we rely on daily at the ridiculously affordable price we’ve come to expect. Everything from the ceramic plates and jaws that can handle the heat of the silicon right out of the oven to the obvious cleanliness of even this heavily used unit.

It’s a rare look into an expensive world most of us peasants aren’t invited to. Video after the break.

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Battery Powered Fog Machine Just in Time for Halloween

[makendo] needed a portable fog machine for an upcoming project. It seemed like the kind of a thing a liberal application of money on the Internet could fix in no time. But quality fog machines are too expensive, and the cheap machines are just, well, cheap. Stuck between $800 and quickly broken crap, he decided instead to fashion his own.

Fortunately for him, a recent fad has made it so that a certain segment of the populace absolutely require dramatic clouds of scented drug fog or they get cranky. The market saw an opportunity, cost optimized, and now there are many portable fog machines just waiting to be born in the form of an e-cigarette. However, an e-cigarette needs interaction from a person’s lungs to provide an annoying cloud. So he modeled up a 3D printable case that would blow air into the intake of the e-cigarette. Instead of filling a person’s lungs with a cloud of eye drops and nicotine, it would let out a steady stream of fog.

This device does burn through emitters, because the e-cigarette was not designed for this kind of heavy duty. Even reading the Amazon comments for the $800 dollar version, this is fairly normal for these things. So now [makendo] is able to produce a nice cloud of smoke whenever he needs and it only set him back around $40 US dollars.