Spoke-end diameter
How to measure "Spoke-End-Diameter"
Spoke-end diameter depends on your rim and nipple type and length.
Below you see how to measure SED for both nipple types:
External nipple configuration
Internal nipple configuration
Take measures very precisely because a well correct nipple/spoke assembly accepts a spoke-length tolerance of +/-1mm only.
(All measures are expressed in mm)
External nipple configuration
1) Insert two J-spokes (random size) with the nipples (of your final build) into 2 opposite rim holes.
This simple trick helps to keep spokes aligned and slightly tensioned.
2) Precisely measure distance between nipples.
Be careful to take measure between the 2 nipple-ends.
3) Add 2x by the nipple height (of your final build) to the measure above.
This gives "Spoke-End-Diameter".
Note: with slotted nipples measure height inside the cut.
Internal nipple configuration
You can get the necessary data following the procedure below:
1) Precisely measure outer rim diameter (A).
2) Insert a nipple of your final build into a hole (use a spoke to hold nipple in position).
3) Precisely measure distance between nipple-top and outer rim diameter (B).
This is the correct caliper positioning inside the rim (don't cut your rim!)
4) A-2B = "Spoke-End-Diameter".