space in winding @ bridge

[Ken Smith]

Round over the slots in the bridge. Make the slots with a round file at no more than about .010" of an inch bigger than the measured diameter of the string. Never under the string diameter! I like the depth of the slots to be about 1/2 - 3/4 the diameter of the string at most. Then, lubricate the maple bridge slot with a pencil. The Nut usually being ebony is self lubricating as well but a little pencil there wont hurt.

I measure the string diameters with a dial caliper or micrometer and then I measure the file and mark the same diameter on the round rat-tail file. Then, just filing them to the measured line on the file will make them slightly bigger as you need with the motion of the human hand.

Fixed diameter files sold as luthier supplies do not allow for the variance in gauges of the various string brands or gauges within them. I have cut 1,000s of slots in brass, bone, plastic, composite, ebony and maple that I can remember.

Diameter is one thing but you must angel it towards the tailpiece and fingerboard to avoid sharp edges that grab the windings. Still, the string centered under pressure over the top of the bridge might separate by nature anyway. Cutting the best possible slots will help to avoid any excess distortion of the string.