Measuring rope diameter

[banjo]

How do rope manufacturers measure the diameter of a rope?
I know they use a micrometer, but I'm wondering if the rope is tensioned when they measure it. I'm also wondering why I have four different half inch ropes(new ones) that are clearly different sizes.

 

[Tom Dunlap]

'Nominal' should be attached to most half inch diameter ropes. When I climbed on them I found that NE Safety Blue 16 strand in plain white was the smallest diameter. On the other end True Blue was the largest half inch, it's almost 5/8" until it gets worked for a while.

Look in the printed Sherrill catalog. I think that they have a chart with actual rope specs.

 

[banjo]

I have looked at that chart with the "actual" rope sizes but they still seem pretty far off the mark. Do you know what the standards are for determining diameter?

 

[Jman]

I had the same thought. I just recently saw lava next to the fly and the fly looks a lot larger than the lava. The lava looks to be 11mm while the fly looks close to 13mm (1/2").

That just makes me think they put a working load on the line then measure it.