Z-axis on ADXL 335 accelerometer

Hi

I’m just messing around with this accelerometer. Trying to interpret the values it gives, when I use analogRead() on the pins. I understand how the X-axis and Y-axis work. They give roughly 512 at 0 degrees, 300-something at 90 degrees and 600-something at -90 degrees.

But I can’t seem to get any change in the Z-axis. No matter which way I move the accelerometer it only ever changes value between about 410 and 440…

Also I was hoping to use the accelerometer to detect up/down and left/right movements. But I get the impression all I can measure is tilt. Is that about right?

Thanks.