Measuring the link.

[Azrael256]

Exactly how does one measure the link if it's not conveniently marked? I thought of measuring the ID of each hole, taking the radius, and adding both to the distance between the holes. 'Course, since that requires taking an ID on two different holes with a dial caliper, my margin of error is around .01 either direction, so that ain't workin'.

Anybody know a better way?

[1911Tuner]

Your way is accurate enough for comparing two links of unknown dimensions,
and I do it a lot. For an accurate measurement, you'll need to measure across two closely-fitting pins with a micrometer and subtract each pin's radius. If you have a full set of lettered and numbered twist drills, you can probbly find what you need there.

[Azrael256]

Ok, that works nicely.

The holes match up snugly with the #21 bit (.159) and the #5 (.205). I stuck 'em in and miked it to .457. So, subtracting radii (.1025 + .0759 = .1784) from the mike gives .457 - .1784 = .2786. That extra .0006 is probably measuring error, and it's way less than halfway to the next size, so it looks to me like this is a #3 link.

Thanks, Tuner!

[1911Tuner]

The .0006 extra falls pretty close to the allowed tolerance of such parts, which is usually plus/minus .0005 inch. Neat, huh? ;)

Just curious...what did it measure out to with the calipers and the rough method?

[Azrael256]

The rough method didn't give me anything accurate enough to even record. My caliper's jaws aren't small enough to get a proper bite, so I got several measurements. My smallest measurement came out as .271, and the largest was something around .290. If I wiggled this here, and tapped that there, and the moon is aligned with Jupiter, I could get it to come out just exactly right, but I couldn't duplicate it reliably. I could probably tell whether two links are the same, but not exactly what one is. With the +/- .01 error, there was just no way I could tell what it is.