It is extremely nice to be able to use a caliper to measure screw/bolt major diameter (and length) to find correct replacements. However I am struggling to come up with a good way to determine accurate threads per inch (TPI; eyeball counts are difficult for me to get right, especially for smaller screws/etc).
What would folks here recommend for accurately determining TPI? I would prefer something other than prebuilt thread gauges, which based on my research are relatively expensive, dedicated-use, and of surprisingly variant build quality/accuracy (e.g., folks have complained about such gauges not being tapped correctly!!!). Thanks for any advice.
Best Answer
A thread gauge is not tapped. A tapped gauge is attempting to show both size and threading, and can be limited by being too thin to correctly discern close metric/inch threads, for instance.
A thread gauge lets you worry about size, while it concentrates on accurately determining threading. Of course, you need to buy one that's not a hunk of poorly made junk...
You might "prefer something else" but your title asked for best practices. This is a problem with a tool that solves it; that is the best practice.