Jewel Bearings: Not as Expensive as You Might Think

Jewel bearings have always been relegated to use in things like watches and instruments, where their remarkable properties (very low stick-slip, virtually no thermal expansion, low wear) have distinct advantages.

But these bearings have other advantages: They run dry (no lube) and clean (generate virtually no particles), and their cost makes them competitive with ABEC-5 instrument bearings. Recent advances in synthesizing crystals, including sapphire, have made them more economical than they've been in the past.

Perhaps these pretty little bearings should be considered for general applications too.

A Remarkable Flexible Shaft Coupling

OEP Couplings offers a shaft coupling that is unique and remarkable: Their type UI coupling has all of the flexibility of an Oldham coupling, with smooth angular misalignment accomodation of up to 6 degrees.

This has been done before, but to my knowledge, never so well or so robustly: The hubs are a single piece, machined from bar, and so is the plastic midsection. The hubs can be machined from aluminum, and then anodized (for low friction), or stainless steel. Midsections are available in either Delrin, or a remarkable 30% carbon-fiber-filled PEEK. Quality is outstanding -- all subcomponents are machined in the US, with an eye toward detail.

The axes of the two cylindrical fins actually intersect one another -- they lie in one plane, instead of being offset. The result is a remarkably efficient and smooth flexion -- there's a flash video of one of these couplings rotating at the website.

A Gyroscopic Joint

The Wolfram Demonstrations Project has several interesting flash depictions of mathematical phenomena, but they also have quite a few interesting abstractions of simple machines.

The gyroscopic joint is an interesting concept -- essentially a double-universal joint with the joints nested within one another. This clearly wouldn't be a very strong shaft coupling, but for certain low-torque applications where axial space is at a premium, where a large angular misalignment must be accomodated, and where a constant-velocity (homokinetic) joint is necessary, this concept might find a niche.

Building a Scanner out of LEGOs

Here's a project for a rainy day (or more like a week, for me, at least): A working color scanner made mostly out of LEGOs.

There are other interesting projects at this site, including a LEGO rover and a candy machine.