I had a genius idea; I needed to mark the notch for the hatch weather stripping. I tried to use a square but it wasn’t accurate enough because it rocked back and forth while striking the scribe. I figured that 2 points would be best so that it wouldn’t rock yet still follow the arc.
I took a U-bolt and notched it in 2 places, then I tie wrapped it to a compass. The 2 legs of the u-bolt followed the arc while the pencil marked the amount of sidewall I needed to remove. This was all done using the hatch as the reference.
Click thumbnails for larger pic.
Modding the compass:
The mark: