Bearings for a gyroscope

I'm going to make a couple of 'toy' gyroscopes as last-minute Xmas pressies along the lines in this video: **LINK**

The author makes the gyro spindle from mild steel with 60 degree cones turned on the ends - these run in 120 degree (because it's easy to do with a drill) conical brass pivot holes. I'm sure this works OK in the short term at least - the performance of the gyroscope in the video is quite impressive - but I can't help wondering if this is the best choice of materials. I'd be interested in any opinions (barring jewelled bearings!)

Regards, Robin

Edited By Robin Graham on 13/12/2017 21:06:23

Small ball bearings...

**LINK**

I have a small low delta T stirling engine from the same stable sitting on top of my laptop PSU quietly ticking away using similar bearings, they are very low friction.

My guess is that a hardened steel point in a bronze cup would be pretty good.

N.

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Cone bearings are certainly the traditional method for 'toy' and 'demonstration' gyroscopes.

Much great work and play was done without recourse to "better" bearings.

Perhaps 'hard steel on hard steel' may be a little better than 'steel on bronze'.

MichaelG.

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For inspiration:

http://www.arts-et-metiers.net/musee/gyroscope

http://adsabs.harvard.edu/full/1855MNRAS..15..182P

Edited By Michael Gilligan on 13/12/2017 22:30:57

Hi I Havnt been on the forum for a while. I built replica early 20 th century gyroscopes in brass. I use silver steel for the spindles and leaded steel for the adjusting screws. If the screws wear I just make a couple extra. Allways use something harder for the spindles. Its easier to replace the adjusting screws.

The very early gyroscopes used a similar set up. I can get the spin to last for 8 minutes on one pull of the string.

Hope this helps

Manny

Quite a few years ago I. Bought a linaze super quality gyro as advertised in me it has miniature ball bearings, the trouble is the outer frame annoyingly spins around as well l've tried washing the bearings used dry, machine oil,diesel,wd40 & turret clock oil to no avail perhaps the bearings are u s any ideas please ?

Graham

Graham... while working at Sperry Gyroscope, Bracknell I was very close to the mechanical development. The oil was quite a topic of its own but from memory it was pretty thin stuff. I would suggest the nearest easily obtainable oil would a light grade of clock oil.

John

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Is it like the one shown here, Graham ?

**LINK**

https://www.gyroscopes.co.uk/Gyroscopes/

MichaelG.

The point and cone would seem to be simple and effective, ball races add a level of complication and will need some strategy to keep dirt out. The ZZ type with metal shields are available in small size and will not have any drag like rubber seals. I suspect the point and cone may have less friction than a ball race or clockmakers would use them.

Mike

If there is any friction in the bearings (and there must be), then the wheel will exert a torque on the bearings as it is slowed down. So if the gyro is for example standing on a low friction point the frame will tend to rotate.

In horology it seems to be recommended that for minimum friction and long life all the grease and oil is washed out, but not in an ultrasonic bath.

Hi Michael it's similar to one of them but not complete match John thanks for. The oil info & thanks for your help,the unfortunate thing is myworkshops 10,000 miles away at home in Yorkshite & I'm in Perth ozz. So will have to wait til march!!

Many of the best clocks now use ball bearings. For measured results of friction tests comparing ball bearings to plain pivots see **LINK**

That article persuaded me to use stainless steel ball bearings run dry in my regulator clock.

Russell

That's interesting Russell, I am not a clock man but many model engineering techniques seem to come from the clock and watch field. As a gyro is probably fairly fast some light lubrication may be in order I would think.

Mike

My display picture is actually of me, turning a new gimbal ring for somebody, I also made a few other bits anew. Such as the screws and the clasps. Heres a pic of what the final result was.

Was a very interesting exercise, if not a little hair raising boring the 8mm brass ring.

Michael W 

Edited By Michael-w on 14/12/2017 13:35:14

Graham,

"Quite a few years ago I. Bought a linaze super quality gyro as advertised in me it has miniature ball bearings, the trouble is the outer frame annoyingly spins around as well "

I had one these Linaze gyroscopes that did exactly the same. I quickly concluded that the miniature ball bearings could not be made to have low enough friction to enable the gyro to work properly. I tried them dry, slack, oiled with watch oil etc. all to no avail.

No small bearing can match a point and cone system for lowest friction for this very light and low powered application.

Eric

The frame ring will tend to rotate in the same direction as the flywheel due to the small amount of drag from the two bearings. Even with the best bearings know to man there will still be some drag. The classic way of preventing the drag disturbing a mechanical gyro is to use a closely matched pair of bearings and have the outer race of each motorised or driven so they rotating in opposite directions to each other. It doesn't eliminate the drag in each bearing, but it does cancel out the effect.

Ian P

Thanks for your replies chaps.

MichaelG - I'm not sure if the exhibit at the Musée des arts et métiers is inspirational or makes me want to give up! Maybe someday I'll make something as lovely as that... . perhaps not in the next week though.

As I have the materials to hand and can do it quickly, Neil's suggestion of hardened steel pivots running in bronze cups is the way I'll go. It doesn't really matter too much in that the recipients will probably spin them up a couple of times then lose interest, - but maybe they'll light a spark in a young person's head. More fun than Pokemon?

Thanks again - much useful information which will be carried forward to other projects.

Robin

Perhaps I'm being particularly dim this morning, but surely the frame is bound to rotate unless somebody has invented a totally frictionless bearing, which logic tells me is impossible. It's just a matter of keeping the frame rotation as slow as possible.............or is it?

Mike,

Perhaps I'm being particularly dim this morning, but surely the frame is bound to rotate unless somebody has invented a totally frictionless bearing, which logic tells me is impossible. It's just a matter of keeping the frame rotation as slow as possible.............or is it?

Properly designed and adjusted "point and cup" bearings will not create enough torque to overcome the inertia of the frame. Newton's third law of motion applies.

Eric

On aircraft gyros" the bearing consists of a cup with 3 (I think)ball bearings and the point that fits in this is about 60* and hardened.

Ian S C