Originally Posted by Speedy2222
if these were made right the splines are probably flame hardened
Flame hardened to what Rc hardness? What material is it and is it flame hardened or another heat treat process? Made right is flame hardening? Not necessarily. There is nothing wrong with flame hardening but it's not the best process.
Most spline cutters can cut up into the mid 30's. Some as much as low 40's.