I've been fiddling with the making of a version of the classic toy gyroscope that's been around for a very long time. Wanting one that would run for a long time I'm going for a weighty rotor and some robust construction. I've reached a stop point right now as I need to source some material for the rotor, and suss out how I'm going to handle the bearings. But for now I've used some offcuts to try a few things out, this is just an aluminium rotor on a stainless steel shaft, the final materials for these parts are yet to be decided, keeping options open there right now.

Anyway, here's where I am and how I got there.

One of the main challenges was the making of a 'cage'. This consists of two rings, one horizontal, one vertical, which have to intersect on the same plane where they meet. First stage in making these consisted of machining down a large Aluminium Bronze nut I happen to have:

This was bored out to a random dimension, derived from guessing the biggest ring size I could get out of the material:

The outside was then turned down to suit:

And two identical rings parted off:

The rings would intersect through a half lap joint, so one was mounted in a rotary table and a slot milled out to half depth. A clearance hole was included for a fixing bolt, and tapped holes added for bearing adjustment 90° to the slots:

The outer ring could have been machined by broaching, but it was easier to just do it by hand. So following some saw cuts and judicious filing the two rings could be coaxed together through many trial fits. Fortunately there is enough spring in the material to allow this distortion without permanent deformation:

A quick knock up of a temporary spindle and rotor has me at this stage so far:

Without proper bearings and too light a rotor it does not function properly, but it has served to allow me to check balance of the cage by hanging it from various points and seeing if it hangs true. So far it's reasonable, but the real challenge will be making a well balanced heavy rotor. Fortunately I have propeller balancers from modelling days which will make that easier, but it must be able to do a few thousand RPM without vibrating at all. First though, the bearings have to be sussed. There's a few options there, and if anyone has any ideas I'd love to hear them. From memory these toys use point bearings of dissimilar metal, i.e steel points in brass cups, which may suffice. Surprisingly I've not been able to find any real 'how to's' on the net for these.

Soundreflections said:

Hi Jerry,  Navigational gyros use ceramic ball bearings – if it would help I should be able to get some old ones – we service them here.  I have started collecting a number of small bearings for projects (I think they are normaly fine for "homebrew" use after their service replacement!).

 

Those sound very interesting Peet, what sizes are these things?