I have a stepper motor that claims 425 oz*inches torque. I want the lead screw to span 2' supported on both sides. I'm trying to decide what diameter lead screw is strong enough to not be damaged by the motor, in other words I'd rather the motor started skipping steps before it caused damage to the lead screw. Equations and handy calculators for what force I could apply with a given lead screw are readily available. I suspect my motor would skip steps before it damaged any t8 lead screw if it were pushing against an unstoppable barrier.
However all the lead screws I've been browsing don't have a listed metric that says how much force it can handl.
From what I've read, the longer the unsupported stretch of lead screw, the less force it can push before it bends instead of moving. I also gather that a longer stretch of contact between the nut and lead screw increases the amount of force that can be withstood before the threads break.
Is there some way of estimating what the maximum force a lead screw can safely push at a given length, lead length, diameter, etc?