Good thread, but seriously.... A spirit level to get the valve angle... there's drawings with dimensions on. Set it to that angle.
A air bubble is pissing in the wind mate.
Each to their own
The spirit level is only needed as a rough guide as the Serdi uses a self centering floating head arrangement. Aside from a CNC machine with a good operator, i'd say this is probably the best seat cutter on the market. Feel free to take a look at the machine at
http://www.serdi.co.uk/serdi2/portal...20Serdi%20S3.0 . I've used this one for over 7 years now including cutting thousands of seats and rarely have any issues.