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On 12/01/2019 at 06:28, Stubby said:

A good example is when you switch from cord to a metal blade on your strimmer .  The blade takes a few seconds longer to spin up but the stored energy  , once up to speed takes longer to dissipate when off the gas .  

The words you're  looking for here, Stubby, are inertia/momentum. Torque is the measure of the turning force of a device. HP is the amount of work the device can do over a period of time. Momentum is the amount of kinetic energy an object has. Inertia is the object's resistance to motion.

In an engine, you need to balance all it's aspects and design it for whatever use you intend. If you remove a flywheel from a saw, you'll see it could easily be made thinner and lighter. It's the weight it is for a reason. The flywheel has to do a lot of things in a modern saw - redirect air, trip the coil, balance the crank assembly, set the timing, start the engine, add inertia, and store momentum. In fact, most cars had flywheels installed mainly for momentum. It made the engines run more smoothly, with less vibration, and hold RPM's better when a force was applied(whether external or internal).

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3 minutes ago, wyk said:

The words you're  looking for here, Stubby, are inertia/momentum. Torque is the measure of the turning force of a device. HP is the amount of work the device can do over a period of time. Momentum is the amount of kinetic energy an object has. Inertia is the object's resistance to motion.

In an engine, you need to balance all it's aspects and design it for whatever use you intend. If you remove a flywheel from a saw, you'll see it could easily be made thinner and lighter. It's the weight it is for a reason. The flywheel has to do a lot of things in a modern saw - redirect air, trip the coil, balance the crank assembly, set the timing, start the engine, add inertia, and store momentum. In fact, most cars had flywheels installed mainly for momentum. It made the engines run more smoothly, with less vibration, and hold RPM's better when a force was applied(whether external or internal).

Yep . Understood .

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Just regurgitating what google told me about all this nonsense ;)

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1 hour ago, Khriss said:

Where will it all end ! Am still getting over the fact you can have a plastic crankcase ?? ;/  k

Most " home owner " and some semi pro/farm saws have plastic crank cases . Its when we get a plastic crank shaft you need to worry  ! 😁

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54 minutes ago, Stubby said:

Most " home owner " and some semi pro/farm saws have plastic crank cases . Its when we get a plastic crank shaft you need to worry  ! 😁

A lot of plastic used in guns now- mind that SA80 was shite fr different reasons. K

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I’ve tried the ms500, it’s a definite step up, wouldn’t go above 25” on it or you’d lose the fun factor

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On 17/01/2019 at 20:51, john p said:

I’ve tried the ms500, it’s a definite step up, wouldn’t go above 25” on it or you’d lose the fun factor

What did you think of the build quality of the saw? anti vibe/ air filter/ back handle 

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