Gym weight flywhels

[Mick BaileyParticipant @mickbailey28509]

I have quite a few weights that I’ve collected and the 1kg sizes look to be candidates for flywheel construction. There isn’t much information on using them, but what I’ve seen looks to be quire negative in the unpredictability and inconsistency of the iron. Any success stories here, or should I not bother?

[Brian WoodParticipant @brianwood45127]

They are made to be a particular weight, so expect blow holes and other casting faults that may render them as unsuitable material for an application which will subject them to stresses they were never designed to meet.

Of course, common sense must apply and much will depend on dimensions of the disc part of any such wheel, the anticipated rotational speed and other such factors. A small model wheel that will do minimal damage if it ruptures is one thing, something larger or harder pressed in service is rather different.

For a critical application, I strongly recommend using offcuts of continuously cast bar that should be free of such casting faults.

I am reminded of an old course on industrial X ray inspection held at the Welding Institute. Various examples of faults were shown to the students to comment on the component acceptability for use. One such item was riddled with blow holes, cracks and unfused material, to be soundly condemned by all the students except one who asked what it was to be used for. It was a paper weight!

Brian

[SillyOldDufferModerator @sillyoldduffer]

The only way to find out is to open one up.   Problem is there is no need for gym weights to be machinable, and a strong desire for them to be dirt cheap.   Last one I tried was compressed steel swarf in resin.

Old-fashioned sash weights have a similar problem.   They were often knocked out by foundries using left-overs, a random mix of good metal and slag, super-hard because they’d been hosed down with cold water to get them out of the way.

Worth a try, but not a source of reliable metal.

Dave

[JasonBModerator @jasonb]

A while ago I got several weights from a Yokk Multi-gym and have used them for various non-critical items such as engine bases, valve cheats and a flywheel pully. The iron is a bit grainy but otherwise machines OK with carbide tools.

 

Probably not the best if your engines will be doing 10k rpm but for a hit & Miss or steam engine running just for display shoild be OK You may need to bond in a hub as the round weights usually have quite a large hole.

Engine base

Pulley 70mm dia

[Mick BaileyParticipant @mickbailey28509]

Those parts look to have machined quite nicely. Not bad at all and I’d be pleased with that kind of result. I’ll try a facing cut across a sample weight and take a look. The size of the hole may be the deciding factor even if my weights are OK, as even with a pressed/bonded centre it may look wrong. I’m intending to use them for a part-completed vacuum engine that I want to complete, but as a Loyal cycle engine. Perhaps 400 to 700 RPM or thereabouts. Or slower if possible.

 

[JasonBModerator @jasonb]

You should be safe with that use. They can be made to run quite slowly, this is Graham Corry’s LEEK non compression engine on spark plug rather than flame ignition which really needs the old town or illuminating gas.

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