I have a home made elevator that is technically rated for 5000 LBS. I limit it to 1200 lbs and never ride it. I build a circular staircase next to it. The Elevator will hold 6' x 4' and is used for putting machinery and heavy goods in the basement. I put the controls in such a place that I can't stand near it and use it. Its extremely handy, and can do all sorts of things. I can use it as a hoist as well. Its all about common sense, if I ever sold the place I would disable the lift so it could never be used again.
An office building I worked on this winter has a simple little wheelchair elevator. The lift is a gear motor and an Acme screw. I think a clever tinkerer could come up with something fairly safe using a screw. I will get an image next time I am there.
5-1 sounds a lot like the testing for an aircraft wing which is a pretty dynamic environment. Noramally elevators are not imprudently made to do acrobatics, or encounter hurricanes... Of course they don't have to be terribly light either, so why not build them stout. Just wondering if 5-1 is the actual load spec, or just a prudent call.
'Most' screw threads with typical TPI's are self locking, so give you considerable safety margin against auto-rotation (induced by load), and the gear motor adds even more friction to the system. A ball screw can be an exception, it will often auto-rotate, and probably needs a brake.
A (elevator) lead screw long enough to span 2 or more floors will have 2 big disadvantages: it will be expensive and slow. Generally speaking of course.
The shaft coupling between such a screw and gear motor would need to be bullet proof and immortal for me to ride. Then we'll talk about the running nut....
A ladder is looking better and better.
The screw elevator is indeed slow, noisy too. It is in a two story in a building with 8 foot walls. The door mechanism may be the most complicated part. It looks like a "buzz to let me in" lockset, without the intercom. It took me a while to figure out that the door knob (lever) does not turn, Just pull hard to open when the elevator is in position.
Last edited by Maurice Mcmurry; 04-23-2022 at 8:33 PM.