Our scissor problem pt1

[Al Skierkiewicz]

Jacob,
I go along with Chris on his assesment and the others. You have a tremendous amount of force that you are trying to overcome. As you start to raise the scissors, you are encountering some rather exceptional friction in the horizontal direction and well as trying to raise the weight of the assembly. That in of itself is bad enough, but it also appears that you trying to lift a motor, gearbox and shaft as well. That throws all the forces off balance and multiplies the work that the lead screw and motor must perform. When you try this again, take the motor and other parts off the top section and see if balancing helps. As pointed out, try lifting a few inches by hand and see if the motor can take over from there.
Lastly, the joints in a scisor lift must stay in position and have low friction. As you can see in one of your stress photos, the bottom of the scissor has started to move but the top layers have not yet moved at all. This is the free play in your joints adding up. When the joints have little free play, all layers should move about the same. It is hard to tell from here, but a washer between bars helps reduce the friction of the joint. I would also recommend you use a lock nut (nylon insert) instead of the dual nuts. That will give you some additional control over the friction of each joint.