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.

[BazyleParticipant @bazyle]

Today I picked up a 2x2x3 block of CI what was / is a weighing machine weight. What do think its chanced of being usable are? I’m thinking perhaps as it needed to be close to design weight it might have been cast with less dross for consistency.

[Bazyle]

On Bazyle Said:

Today I picked up a 2x2x3 block of CI what was / is a weighing machine weight. What do think its chanced of being usable are? I’m thinking perhaps as it needed to be close to design weight it might have been cast with less dross for consistency.

Always cast over-weight.  Just need (a) bigger hole(s) drilling to get the heavier ones down to weight.

[JasonBModerator @jasonb]

“What do think its chanced of being usable are”

Depends what use you want to put it to. If it were say a model cylinder then I would not want to put the time into it only to find a problem part way through but if it were just a box bed that required less work and no running surfaces then I would be tempted to at least take a skim off one face to see what hidden inside.

[Alan CharlestonParticipant @alancharleston78882]

I bought some weights to use for a flywheel. There were a lot of slag inclusions which resulted in a lot of sparks and broken carbide inserts. One problem you’ll have is putting a bushing in the centre to reduce the hole size down to that required. I hadn’t silver soldered cast iron before and had all sorts of problems with getting a good joint. In the end I didn’t proceed with the weights.

Of course the quality of the metal I encountered isn’t necessarily the case for your weights.

Getting through the hard skin on the casting isn’t easy, and if I were doing it again I’d try removing it with an angle grinder before trying to turn it.

Regards,

Alan C.

[JasonBModerator @jasonb]

Regarding the hole another option may be to just use the weight for the rim and bond that onto spokes cut from steel sheet with a bonded or soldered hub. If you trepan out the middle then you have a usable disc for another smaller rim.

But JBWeld will hold a hub bush in place as these sort of engines don’t have a lot of power and there is no violent jerk when they fire like you can get on a hit & miss engine. Loctite would even do the job, add a pin if you want belt and braces. If retaining with a grub screw then use a long one and that will serve a similar purpose to a pin as it passes through the joint.

The weights I showed did not have much if any skin but some I have seen look like they might.

[Mick BaileyParticipant @mickbailey28509]

The Leek engine is delightful. It became even more interesting after a little bit of searching to find that the company that originally made this type of engine was based in Leek, Staffordshire. I live just three miles away and was unaware of the existence of this company. I’d like to find where the factory was and if it still exists. Maybe there are some original engines lurking around the local area.

 

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