A Hobson’s Coupler Leads To A Weird Engine

You want to join two shafts. What do you need? A coupler, of course. If the shafts don’t line up, you might consider an Oldham coupler. But what if the shafts are at a 90-degree angle to each other? Then you need a Hobson’s coupler. [Robert Murray-Smith] has the 3D printed hookup for you and a video that you can see below.

The part isn’t all 3D printed, though. You do need some bearings and steel rods. [Robert] proposes using this to couple a windmill’s blades to a generator, although we assume some loss is involved compared to a standard shaft. However, we’ve heard that the coupler, also called a Hobson’s joint or a stirrup joint, is actually pretty efficient. However, you rarely see these in practice because most applications will use a gear train employing a bevel gear.

While it may not be practical, the second video below shows an elbow engine that would look undeniably cool on your desk. By making some changes, you can create a Cardan joint which happens to be half of what you think of as a universal joint. The Hobson coupler and the Cardan joint seem to be made for each other, as you’ll see in the video.

We aren’t sure what we want to make with all these mechanisms, but as [Robert] points out, with new materials and techniques, these mechanisms might have a role to play in future designs, even though they have been mostly discarded.

There are, of course, many kinds of couplings. Then again, not all useful joints have to move.

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Wooden Machine Belongs In Willy Wonka’s Factory

Behold the wooden machine (translated) that is used for… well it does… it was built because… Okay, this is a case where asking what it does or why it was built is the wrong question. [Erich Schatt] began building the piece that he calls “Wheels” back in 1995. It took just seven years to complete, and is made entirely of wood. The video after the break shows a multitude of moving parts.

The chains were modeled after bicycle chains, which are used to transfer motion from the “rider” throughout the machine. The gearing for each segment was meticulously calculated, then perfected through trial and error. The complexity even calls for a differential and universal joints. It’s mesmerizing to watch and for that reason it’s made appearances at conventions and been featured in art exhibitions.

It’s also worth mentioning that this comes from a very humble-looking shop. [Erich] posted some pictures of his studio and aside from the abundance of bar clamps, it’s just your average garage or basement setup.

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