You
may be familiar with the small gyroscope tops that used to be sold in most toy
shops. They consisted of a heavy
wheel which could be spun into rapid motion and balanced on the edge of a glass
rim for example.An Oldie but a Goodie - A Meccano Gyroscope
by Bob Prescott
You
may be familiar with the small gyroscope tops that used to be sold in most toy
shops. They consisted of a heavy
wheel which could be spun into rapid motion and balanced on the edge of a glass
rim for example.
My Reader’s Digest Library of Essential Knowledge defines a gyroscope as a “device consisting of a flywheel mounted inside a ring on an axis that leaves it free to pivot in any direction, without suffering disturbance from outside forces”.
When I spotted the Meccano Gyroscope in the April 1929 magazine I was curious to see how well it worked. As the article pointed out this was no toy and it had many applications such as the gyrocompass.
I have included the MM instructions in italics and added my own comments in plain text.
“The gyroscope
proper consists of two Hub Discs 1 mounted face to face and secured to an Axle
Rod by means of two Bush Wheels. In order to increase the mass of the gyroscope
near the periphery, four 50-gramme Weights 2 are secured to the inside of each
Hub Disc in the positions shown.”
Eight 50-gramme Weights? I don’t own any of these rare items but I do have plenty of Wheel Discs. I built up eight piles of 6 Wheel Discs which weighed approximately 35 grams per pile and secured these evenly around the Hub Discs at the periphery.
“The swinging frame
consists of a Circular Strip 3 that is attached by 1/2” x 1/2”
Angle Brackets and lock-nuts to a Strip bent in the form of a U. The
U-shaped Strip has a Double-arm Crank bolted to its lower extremity to form a
means of connection with a 11/2”
Rod. This Rod, which forms a pivot, is free to turn in a reinforced bearing
consisting of a Double Bent Strip and a 11/2”
Strip bolted to the 51/2”
x 21/2”
Flanged Plate forming the base of the model.”
I used two shaped 51/2” Perforated Strips to form my U frame and joined them at the base using the Double Arm Crank overlapping three holes and I used P/N 37h captive lock nuts for lock nutting at the Angle Brackets. In my view it needs a bigger base for stability so I used a P/N 236 131/2” x 41/2” Flanged Plate (lid for parts box). The same could be achieved by using three P/N 52 51/2” x 21/2” Flanged Plates joined together.
“To start the
gyroscope, a length of string is wound on to the spindle and its end is then
given a smart pull so that the wheel is set spinning in a clockwork direction.
If now the U-frame is turned also in a clockwork direction the edge of the
Circular Strip remote from the observer dips. When a reverse movement is given
to the U-frame, the same end of the Circular Strip rises. This is due to the
tendency of the axis of rotation of the gyroscope always to point in the same
direction in space.”
I decided that the “length of string” trick was too
cumbersome. Instead I used two P/N 27f Multi Purpose Gear Wheels on the end of
the flywheel Axle Rod and turned these to achieve the spinning motion and sure
enough, it performed “as advertised“.
After checking Bruce Neilson’s Index I discovered that the same model had been mentioned again in the September 1944 MM but this time it had been constructed without weight in the flywheel. I doubt that it would work so well because you need weight to achieve a reasonable amount of spinning motion. An interesting model - build it and see how it works.
