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Provided that the generator's shaft and bearings are strong enough, the
weakest part of the system is the crank's hand-grip part.

We initially tried a large, immensely strong-looking, heavy-duty, industrial
quality, solid-disc-shaped crank moulded from tough engineering plastic.
Kids completely snapped the projecting handle off the 'wheel' part within a
few days!

Subsequently, the metal alloy cranks never snapped like this, but after
considerable use, we found that the standard rotating plastic grip wears
badly against its internal metal shaft, until it eventually breaks or slides
off. So now this is the part we modify by replacing it with a tough red
plastic ball.

Promoting public engagement with science
through a contagious delight in phenomena
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[log in to unmask] * http://www.interactives.co.uk
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http://uk.linkedin.com/pub/ian-russell/0/636/305
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Give people facts and you feed their minds for an hour.
Awaken curiosity and they feed their own minds for a lifetime.
*
Ian Russell

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