Standard hole saw arbors generally are pretty flemsy. They don’t hold the saw securely, so when it first hits the surface it tends to wander around and score up the material sounding the hold. Also when doing any kind of heavy duty drilling the little pins that drive the saw tend to shear off. I have a job coming up where I will need to drill reasonably neat holes in cast iron with a hole saw, so I made up this “Heavy Duty” arbor.