Just watching the assembly of an engine on u tube and it jogged a memory. I use the type of piston ring compressor that is basically multi sheave thin sheet steel wrapped in a circle with a ratchet device on the outside that is tightened with an L shaped key. It worked well for a while and then I managed to break two successive piston rings whilst using it. I couldn’t understand why. I had tightened the ratchet as much as it would go, even using the small wrench from my socket set. The answer was, that as an amateur, the tool probably only gets used once a year (if that) and the layers of steel had dried out preventing the tool from fully tightening. A smear of oil between the layers made an enormous difference. I recommend it if you use this type of tool