Originally Posted by
DaveSSS
This thread has become amusing. Not many familiar with precision measurement. In a machine shop, the least accurate way to measure something is with the most precise ruler that you can buy - a thin steel rule, with .010 inch increments, but for some jobs, it's good enough.
You don't even need to read the markings, when measuring a chain, since it's precisely 12 inches long. Just lay one end on the edge of a pin and see how much of the pin at the opposite end is exposed. If it's less than half, the elongation is still under .5%. The rule is made thin, so the markings that most people need to use can be placed close to the item being measured, to minimize error. Tape measures are worthless.
Here's an adequate rule that's cheap:
https://www.amazon.com/General-Tools.../dp/B00004T7SR
I'm not unfamiliar with accuracy and precision...they aren't the same thing. I'm also familiar with when something needs to be very precise and when it can be just good enough. Chain checking tools, in my experience, are good enough. On the other hand, putting a chain on a 12" rule and estimating how far off the rule the chain hangs off isn't all that "precise" nor accurate. It's an estimate.
I would also point out that no one in this entire thread has said what the value one is supposed to be looking for with a 12" rule. 0.5% wear is 1/16" and 0.75% wear is slightly less than 3/32". For the rest of the world, that's 1.6mm and 2.3mm over 30.48 cm. But those are only estimates as well.
Aw, hell, I'll just use the chain checker and buy cheap chains. It won't matter that much in the end. A more expensive chain wears out at about the same rate as a cheap one.