Belt measurement resource idea.

I'd like to create a resource here. But It'll take all of us adding info to it as it goes...



Looking at the image: The half circle is half of a pulley.

What I need:

I believe the two most commonly used belt sizes are 1/2" and 5/8". So I'll need someone with a belt of each size. Just a piece of the belt will probably be ok, as long as it's long enough.

Now what I need, is for you to wrap that belt around pulleys of sizes from maybe 2 and a half inches, up to whatever size is the largest trans pulley.

Make sure the pulley is the right groove size, (pitch) for the belt.

Now make a mark on the belt, at the halfway mark, where I have the green arrows.

Now take the belt off, and lay it flat, and measure between the marks.

This will probably work better if you make marks on the pulley first. Just lay a straightedge across the pulley and center the edge on the center of the bore. Then mark the pulley at the point where the same edge crosses the outside lips of the pulley.

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The idea of the resource...

With those measurements, we will be able to figure out belt sizes without a lot of cutting old belts, or making belts out of ropes, or whatever.

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To explain...

Let's say we have two pulleys. If we measure them, center to center, and the centers are 48 inches apart. Automatically we double that measurement, to get 96 inches.

Now all we have left is how much belt is on the two pulleys.

If it is a 1/2" belt, and one pulley is 4 inches, and the other is 5...

Let's pretend that the measurement someone has given us from the above method, is 7 inches for the 4 inch pulley and 9 inches for the 5 inch pulley.

We would then add 16 inches to the 96 inches, for a total of 112 inches.

That's your basic belt size.

Add some length to allow for the idler pulley/s.



And I suppose that some research into deflection by idler/clutch pulleys, and how much that adds to the length of the belt, would also be in order.