Vertical sundial - work in progress! 11.20hrs.

If you are tempted to try making a vertical sundial, there are only two major considerations: the angle of the rod making up the gnomon, to the vertical, and the compass point it needs to be set to.
Your latitude is the prime determinant for the angle. Imagine the rod you see is the hypotenuse of a right-angled triangle.the right angle is at the bottom of the vertical part of the imaginary triangle. The other base angle must be equal to your latitude. For instance if you are living at 57 degrees North, the base angle would be 57 degrees. As we are dealing with an imaginary right-angled triangle, the angle at the top between the vertical and the rod itself, then has to be 180 - (90+57) = 33 degrees.
The next issue is the direction it is set to. It needs to point at True North, as opposed to magnetic North. Tables are on the web which will show you the amount of declination for your particular longitude. But an easy way to resolve this is to set it up to point directly at the North Star (Polaris) which is the direction of true north.
You can figure out the hour lines by checking where the shadow falls on the hour, for each hour of sunlight, and marking the surface.