Originally Posted by
dabac
Plenty of those around. You can use a hose / jubilee clamp. You can take a fairly non-stretchy tape and wrap it a couple of turns. If you get it to align edge-to-edge it'll be a straight line.
Or you can buy one of those purpose made saw guides. Or a dirt cheap miter box from any DIY store.
Thank you, and Airburst.
How about those pipe cutter tools? They only seem to cut copper, and I am not sure if they are made to the needed diameter for a fork, but I was toying with the idea of buying one and try to see if I can at least mark the circumference precisely with it.