Scissor Lift Update Issues

Since posting I have added elastics to the X’s of the scissor lift and know the lift goes up great but still having bad issues of it going down. I checked with my advisor and we can’t seem to get the idea where the friction is at anywhere and is hard to mess with because it tears the gears apart. I have attached some videos of how it goes up but going down is horrible and need some help with what could be causing this. :confused:

It seems that now you have elastics that allow it to go up well, but are too much for it to go down, which the motors can’t handle.

The reason they are stripping is because they are not tight enough to the racks, allowing them to move away from them and strip. Try to see if you can make them mounted more solidly.

I will have to try to create a tighter fit between the gears and the racks. Thanks!

Have you considered the suggestion of having the rack power between two centre pivots of the X’s rather than on centre pivot and the base?

You asked for clarification about what I meant on your previous thread on the topic

If we did a pivot point on the first and second one I don’t believe we have the height or room to do it to get the height we need to build the tower. I will see though if we do.

Skipping can be introduced by the length of that driven shaft having room to wiggle.

We’ve had some lifts like this and have a 12 tooth gears on top of the one driving the linear slides. So sandwiching this gear in place keeps the driven gear smashed on to the linear track. Putting another linear rack bracket on top or attaching C-channels gets you the room to do this. 81J is doing this type of rack design this year but with a different lift placement.

Another means of reducing shaft flex is to use bearing blocks as it passes through the rack brackets. This gives some bracing on the long shaft.

From a lift force perspective, using multiple smaller #32 rubber bands can get less force per rubber band allowing you to tune to a sweet spot of lift assist with what needs to come down. But stopping the skips is need number 1.