Here’s how I make sure my strings stay locked on the post with a minimum number of windings and slippage (as little as .5 works)
If you don’t want to watch the video, I’ll just explain:
1. Pull the string straight through the post. Pull it taught and let it relax.
2. Start winding.
3. Pass the free end of the string UNDER the standing end as it comes around.
4. The string should be in tune before the free end comes around a second time, but DO NOT CUT THE STRING YET!
5. The strings will settle a little bit. Play for a few minutes, then check the tuning again.
6. When the free end comes around a second time, pass it OVER the standing end.
7. Cut off the excess string.
The concave shape of the post will force the two windings towards the center, where they will grip the end of the string quite tightly. The strings tend to lock in well before that second winding though. I usually only have a 3/4 wrap around with the E A & D strings, but I can’t remember the last time I had a string slip out of the post.