1:21? How much time does it take for your lift to raise all the way? And how many cubes are you lifting with that ratio?
Our robot is still under construction, but from our very early scissor lift testing, I’ve gotten our lift fully extended in about 7-8 seconds, with elastics. We’re still waiting on our cross-bars to come in, so we can stabilize our lift further. We’ve designed our bot to lift 5 cubes, but our intake is still under construction.
Edit: our lift raises up to approx. 75" tall
Hmm, OK. If your lifting 5 cubes then I guess that’s about right.
We are going for 1:7 for pure speed. Capable of going to full height in about 2 seconds. We found that the slack is one huge issue for a multi stage lift. For our 4 stage lift experiment, even though we over tensioned our lift so much that it cannot even fold down, the motors still have trouble handling the initial breakpoint. I guess it could have been better if we powered a higher stage. But for 4 motor rotational lift 1:7, my empirical result tells me never go for 4 stages or higher.
Actually 3 stages is not that bad… at this point of the season. We have 56 inch for max, high goal capability and decent skyrise building ability.
You might want to consider changing from a 1:7 lift to a lift with more torque. At max speed with no load, a 1:7 should go extremely fast (BNSw 4 stage lift: BNSw - 4 Stage Scissor Test - YouTube). However, since there is a load on the lift, it ends up going at around 50% of its max speed–especially at the beginning, as you’ve noticed.
If you change the lift to have more torque, you’d lower the max speed but it would respond better to greater loads without losing as much speed. Our 1:15 lift can go up to full height in 2-3 seconds since it lifts at about (estimated) 80% of its max speed. You can get a comparable lift speed while also increasing torque and reliability when the lift starts at the bottom if you switch to a higher gear ratio. 