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How to calculate the mechanical advantage of a lever?
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My recommendation?
No matter what I tell you, get a second opinion.

In one case it is a straight ratio, in the other there is an additional "1" in there...
If the lever is 9 units long, fulcrum 1 unit in, then you have in one case 8:1, but the other case you have 9:1.CNC machines only go through the motions.
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You could use moments, simple force x distance clockwise, equals force x distance anticlockwise, fulcrum is the datum or where moments are calculated about.
(Works really well with beams and cantilevers, saves going all bows notation and vectors, though levers can be treated as vectors instead of scalars, ie magnitude and direction)
More than one way to do most things though memory is fuzzy about it!
Mark
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It is a simple ratio, as Jim Williams suggested. But you have to null out the difference in the weight of the lever on either side of the balance point as you change the balance point. Making the lever lightweight minimizes the need to do this, but there is still an error. Marv Klotz may have a formula that includes this factor, I don't know. I know that this leverage idea is great for weighing heavy things with a bathroom scale. It doesn't take a lot of figuring to set the position of the balance point to say 1 to 10. Every 100 you read on your scale is then 1000 lbs or kgs, doesn't matter.
As I can see it, it's a matter of the ratios plus the balancing of the lever.I seldom do anything within the scope of logical reason and calculated cost/benefit, etc I'm following my passion
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So many things that factor in  and like Darryl stated the weight of the lever is everything  technically the red diagram might lift the weight itself just with the lever  and assuming the lever is made of the same thing the blue might take double the effort than just lifting the weight without even figuring in the leverage ratios...
and why does the blue have an unusable hole drilled in it?
but for strictly ratio's sake  measure the amount of travel that the handle end moves, in comparison to the amount the weight gets lifted  done deal,
keep in mind even if you get identical there's also a friction formula as not all fulcrums and pivots are created equal and some have more "bearing speed" and pivot travel in comparison to others even though it "appears" that the work load is identical...
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Originally posted by A.K. Boomer View PostSo many things that factor in  and like Darryl stated the weight of the lever is everything  technically the red diagram might lift the weight itself just with the lever  and assuming the lever is made of the same thing the blue might take double the effort than just lifting the weight without even figuring in the leverage ratios...
and why does the blue have an unusable hole drilled in it?
but for strictly ratio's sake  measure the amount of travel that the handle end moves, in comparison to the amount the weight gets lifted  done deal,
keep in mind even if you get identical there's also a friction formula as not all fulcrums and pivots are created equal and some have more "bearing speed" and pivot travel in comparison to others even though it "appears" that the work load is identical...Location: The Black Forest in Germany
How to become a millionaire: Start out with 10 million and take up machining as a hobby!
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An additional one? I think I know where you got that, but there is no reason to add that complication. If you measure FROM THE FULCRUM to points where you have the LOAD and the FORCE, then it is a simple ratio of those two lengths, as has been stated several times already.
You are talking about a lever with TWO assumptions: 1. the length of the lever is fixed (9 in your example) AND 2. the distance to the load is fixed at ONE. If you place those TWO constraints on the levers, then yes, you will get different ratios and different mechanical advantages. BUT, the simple ratios of the two distances are still the way to calculate the 8:1 and 9:1 ratios that you cite. If you just follow that simple rule, you will get the correct result for ALL types of lever.
It IS a simple ratio. You just must measure your distances correctly in each case.
Originally posted by J Tiers View PostIn one case it is a straight ratio, in the other there is an additional "1" in there...
If the lever is 9 units long, fulcrum 1 unit in, then you have in one case 8:1, but the other case you have 9:1.Paul A.
SE Texas
And if you look REAL close at an analog signal,
You will find that it has discrete steps.
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