shafting question

Hi,
Could anyone point me to a resource telling me how much a certain material will bend if it is X long and has Y load applied to it? I'm trying to decide if I can get away with using 1/2" dia. end supported shafting on my mill or if I'm going to need continuously supported shafting.
I'm concerned the end-supported may bow too much under load, causing innacuracy or leading to things binding up on me. The continuously supported shafting though is much more expensive.
Also, has anyone had any experience using frelon bearings?

Thanks,
Rick



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