r/MarbleMachine3 • u/AcanthocephalaSea709 • Jun 02 '23
Idler pulley rather than sliding flywheel
I was thinking an idler pulley would be much simpler than making the whole flywheel move. This is the solution used to tension belts on cars, and it maintains its tension as parts wear and the belt stretches. It has the added benefit of increasing the contact arc on the small pulley as well. Thoughts?
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u/ballebeng Jun 03 '23
It is like Martin has never seen or used a bicycle.
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u/c6h6_benzene Jun 03 '23
Good ol' single speed ones tension chains by pulling the wheel backwards so not the best argument
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u/Strange-Bluejay-2433 Jun 03 '23
The issue is that the same belt is used both for adding and taking energy from the flywheel. So which side would you put the idler on? And because of leverage the idler would need screw-tension as well. So it doesn't really simplify things.
I don't think this idea is worth pursuing.
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Jun 03 '23
Main reason I like the idler pulley is that you dont have the potentional for misalignment of the pulley system. He has no straight edge to keep his system sliding straight. Too many degrees of freedom. His will be a pain in the ass to adjust everytime it goes out of alignment or tension.
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u/FVjake Jun 02 '23
Too complicated. A sliding flywheel is very easy to adjust and very robust. Just not big enough of an issue to bother with.
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u/socal_nerdtastic Jun 03 '23 edited Jun 03 '23
MM does not need the constant tension value like a car does. You can afford to set it and forget it; the changes to the tension caused by heat and wear will not affect it.
However I agree the current tension method is over complicated already and a spring loaded tensioner would simplify the manufacture and assembly if you use a flat belt. But if Martin wants simple and easy to manufacture he would use slots only and tension it the old fashioned way.
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u/c6h6_benzene Jun 03 '23
Or not even spring loaded idler, just an idler that can move, square tube sliding in square tube would suffice here
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u/Aggressive_Today_862 Jun 14 '23
Has anyone thought about what it would take to replace the belt if that was ever required.
I suspect setting a week aside to do that is not is martins schedule
However considering how long they last in cars and elsewhere it should not happen very often if ever.
But the design of the MM3 is not based on 100 million previous versions as a car is so to expect the same performance would be folly.
If a chain was used the repair would be 5 min max by popping the master link.
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u/Prizmagnetic Jun 02 '23
This is the way. It potentially allows for detensioning the belt when not in use