Let's just go over the basic idea:

Center position of futaba servo is 1.52ms puls length sent approx every 20 ms. To move it to min position 1 ms and to max position 2 ms.

But when I recently did a thingy for a RC receiver I found out that the pulses are acctually more in the 0.8 ms - 2.2 ms range to allow for trim settings.

If you plan to have more than one servo I would recommend you to have a look at DT software PWM.

If you want to have bigger movement try to change your limit values.

/me