Adjusting truss rod on a strat

[bjjp2]

I know you have to take off the neck. Is it possible to do this and adjust the truss rod without removing the strings? Or if I am looking for right adjustment by trial and error, do I have to waste a set of strings each time?

[Rosewood]

Just loosen the strings, loosen the neck enough to access the truss rod.

[57paf]

I tried this technique successfully: http://www.andersonguitars.com/questions.html
You should follow his advice & grind the sides of the screwdriver, though.

[Mike9]

If you have Kluson tuners here's what I do:

Cut round toothpicks in half

Lock the string in the hole with a half of the toothpick and detune

Capo at the nut

Capture the strings around the 17th fret in between two strips of velcro

Loosen the neck & make your adjustment

Reassemble, tune to pitch and check your relief.

If you have standard Ping type tuners omit the toothpicks, but everything else is the same.

One of the reasons you see a half round hole in the pickguard on vintage Strats is to access the truss nut without going through all that trouble. It requires a little alteration to the body and pickguard, but nothing bad.