Rings

[solek]

Lost the person who made the less then 1" rings, I used in my smaller engines, so set up to make cast iron rings. What a pain it was to make 2 or 3 .750" rings. Friend had be use X type o-rings, in place of cast iron rings, so I tried them in a .750" bore engine. The engine has a good 10 hours of run time on it and the same o-ring is still got good compression. Has anyone else have experance using an o-ring to replace the cast iron rings?
Safety note: Friend was cutting some titanium and the chips burst into flames. Never worked with it, but he is making sure chips do not build up as he cuts it.