One more thing for the night here... Transfer screws and punches. If anyone is looking for a quick and easy way to mark holes on blind surfaces, do this.
I turned these in the lather quick. they are just a slip fit in the threaded tank mount. You could thread sharpened set screws in there if youve got em, but this will do for this job. These are brass, btw.
Then drop them into the tank mount.
The tank is plastic, so I cannot stress enough that the next step does not require great force.
Just color the side of the blind surface (bracket for me) with a sharpie, and gently put it on the surface where it will mount, and LIGHTLY tap it with a hammer. The tap will scuff the surface where the transfer punches are.
Then remove the part, and theres your marks on the back. Ready to drill.
This concept works really well with steel set screws because they actually thread into the mount for better accuracy and will actually prick the metal in case the scuff wears off. You can even buy special sets of screws and punches just for this. I have some at work, but for home I do this just as much. I should add that if you go with the scuff method, its good to get a spring punch to re-mark the scuffs after you make them. because it sucks to have to re-mark stuff when a oily hand wipes out the sharpie scuff.
Ok, it is late and I am tired.