David I bought one of these a few years ago lot better than mentioned above
http://www.ebay.co.uk/itm/Smart-Level-Digital-Protractor-Inclinometer-Laser-Angle-/330431193494?pt=LH_DefaultDomain_0&hash=item4cef3be196 Ignore the price.
I bought it for sole purpose of setting precision machinings at a specific angle within seconds to machine opposite side.
Though can be zeroed on table setting remotely accurate is a tall order. Fractional touches on workpiece you want to move in seconds not minutes or degrees send it a mile and too hard to control. Far easier and more accurate going against the grain working out the tilt by maths and trial and error taking a cut.
Flat surfaces are the worst with no runout guaranteed but place unit on different areas and get different measurements. Placing on round bar a lot better.
Best part is USB charging and the laser.
If doing aluminium work forget it. Give you some idea of what s going on lightly press down on one side or end of the unit, watch it read different without job deflecting, that should tell you something.