Hello everybody.
Can anyone give me the exact outer diameter of the metallic horns?
Digital caliper says: 24.00mm exactly, +/- 0.01mm
(0.9455 inch)
(That 0.01mm figure is within the degree of precision of my device - I can get it to ‘wiggle’ up and down a bit by applying pressure to the measurement slide - but it consistently reads 24.00mm when left to its own devices, so unless you’re looking to machine an airtight seal around the outer circumference of the servo horn, I’d call it “close enough”.)
thx man. And correct me if i’m wrong but the distance between the centers of two opposing tapped holes is 16.66mm?!
It’s harder for me to read a between-centers position properly, but yes, 16.66mm is correct, or at least accurate enough to be within tolerance for the hardware.
thanks again man.
By the way, in order to get a good reading, measure the innermost distance between the two holes and add one diameter of one of the holes. that way you can get a measurement of the distance between the centers (within tolerance), but you probably know that already. 
thx
Eren,
Even better, use the centering points (CENTERLINE GAGES) on your dial calipers. Not that expensive an accessory to add.
Alan KM6VV