next they will be dry installing them and fitting the axle to a drill to simulate miles like roadies do
do you have a lathe handy ?
its likely that the hubs will be a simple tube with 2 steel cones pressed into either end , get your little finger in the hole and feel what its like inside
in an ideal world you could knock the 2 cones out and be left with a nice hollow tube . go to the local sealed bearing merchant and with the diameter you got from the vernier caliper get some that will just pop in
all well and good until an axle is slotted in and the bearings get pushed in , you will be needing a spacer tube too ( think how your sealed cranks work
)
thats only if the inside diameter of the hub is a standard sealed bearing size , if not itl need to be machined to suit
next will be a nice new standard industries heat treated axle
use some cone nuts to stop the whole hub shifting side to side on the axle