Anybody Know About Linear Motion Rail Sizing?

I've seen a similar question here these days. But asking about how to calculate the tip displacement under load.

Your question is: what would be the appropriated deflection of the device so I can choose the correct commercial equipment to assemble. The answer is: depends on your application. If you'd like to raise sand bags from the ground to an upper level with nobody behind the machine, you can choose a device only paying attention to its nominal capacity, install and that's it. The deflection will be compensated by an increase in the vertical range you will have to install.

If you have precision in your movement, I'd choose and size a system that would give me at least the ability to stay within 1/10 of the positioning tolerance. There's no magic about it, the cost increases exponentially. So, evaluate your needs corrently, that's where the engineering works in your case.

Best thing is to call your local igus office. Our local igus salesperson gave me a copy of their software, which predicts lifetime - it also has a shaft deflection calculator that is pretty cool. a 2-inch aluminum might be fine. check it out.