Scissor Lift Sliding Mechanism

SO this year we are using a scissor lift to reach all the very tall goals in the skyrise. WE are having trouble with the sliding part of the scissor lift at the base. We are using the new linear rail with the small inside “truck” to have it slide on. When we apply power, the "truck slightly gets pulled out of the rail and that causes was to much friction and the bot cant lift anymore. Can someone help us. We are runnng out of idea and could use a little outside help.
Thanks!

Also here is kind of a picture of what we are doing. (sorry this is before the motor was added but the motor is the kind that is in the middle of the “X”)
IMG_3559.jpg

what is the pro of the scissor lift sliding mechanism?

Wait what do you mean?

I personally have no experience with scissor lifts, but have used the sliders before.

Have you considered changing the orientation of the slider? you have your arm pivoting on one of the brackets from the slider kit with the truck bolted on the bottom, but having the truck on the side of the bracket and the slider rotated 90 degrees about it’s longest length may help.

Also, do you use any elastics on the lift? it could be that the friction isn’t the main problem but the weight of the arm is. Take the axles out of your motors so the motors don’t turn when you move the lift, then spend some time playing around with rubber bands. Try get it so that your lift’s weight is putting almost no strain on your motors and all they are doing is lifting the weight of scoring objects.

Finally, this is completely unrelated to your lift, but what is that angle at the back of your robot? I didn’t know there was any wider metal like that

Well before we attached the lift to the bot, the motor were able to lift it easily while we just held it. And if we manually make sure the truck doesnt get pulled up and jam then it will work. We want to use the old discontinued inner sliding rail that a lot of teams use but we cant find it anywhere at all! So any other ideas?

Also the giant angle bracket that we are using comes from the 3535 Super kit. It is like the normal 3535 kit but all the pieces are just bigger and stronger.

It sounds as though your static point of the scissor lift is mounted higher then the moving part within the linear slide. An uneven mount would exert force to lift the truck out of the slide thus causing friction as the lift expanded.

We had similar issues when prototyping scissor lifts robot in the past.

Hey there,
We are using a scissor lift this year too and used a linear lift last year so I have a few ideas on how you might fix this:

1.) As stated above make sure the mounting points are the same (put a spacer or something to make the non-moving one higher)
2.) Also make sure that the intake/whatever is on top is balanced or leaning the way of the moving piece
3.) We noticed that a little bit of grease (lithium grease seems to be the best) helps a lot
4.) If you want the old ones we can try to get them for you

Hope this helps,
X

For us screwing a pillow bearing block on top of the inner slide and then mounting scissor from there with screws and nylock nuts worked well, if this helps.
scissor mount.png

How did Yall do the rest of the scissor lift…like the motors and what not? We want to find the best combination that we can do!

Our scissor lift only goes up once, so its quite a bit different, but we use the 60 and 12 tooth gears mounted in the center of the bottom “cross.” This also looks like it works well: https://www.youtube.com/watch?v=u0feOUGTrAI

Just look around on Youtube/forum/Google and see what everyone else says.

X

My scissor lift only goes up once but is only tension powered. I am wondering why you have gears at the bottom if it only goes up once.

Alrighty, thank you everyone for you input and ideas. Using several different ideas from yall and the internet we were able to get the scissor lift working great! We will add the other half and a clay tomorrow.

Here is a video is you want to see:

Each side of our scissor is powered by 2 motors attached to a vertical slide and the midpoint of the 2nd X (we are using 4 stage scissor with 25 hole C-channels). The motors are HS, and can lift the mechanism in 3 seconds to the height of 45 in.

We used only 1 vertical slide per side, but we didn’t have any issues of gears breaking even when lifting 3 cubes.

Our lift uses four motors geared at 21:1. We’re using 5 stages on our lift and we have a planned capacity of 5 cubes. Very early testing showed our scissor reaching full height in about 7-8 seconds, with elastics being fully taken advantage of (A good method we use to tune our lift: completely remove the motors and add enough elastics to the point where you can hold the lift at any position and have it stay, this way the motors aren’t holding any more than they need to. Also, we recommend elastic tubing in lieu of rubber bands. It’s much stronger.)

Also, when you guys get to building both sides of the lift, don’t forget to use cross bars to support it! The difference was immediately noticeable for us once we added ours. Much less wobbling than before, and the lift stays pretty stable at heights of 75". (we used lexan, but we had to wait a few weeks longer than anticipated to make our cross bars due to a shipping error)

Isnt 75 inches a little over kill because the 7 sky rise section is 60 inches?:confused:

You do have a point, however, our intake is more towards the inside the lift instead of directly on top, so we can still be within the 18" volume. This is why we allowed for more height, so that we would not accidentally come up short when scoring on a fully built skyrise. Besides, it’s not like we’ll always be at max height. We plan to have control systems in place that will get us to the specified heights we need (using different height setpoints on a potentiometer), and ensure the lift stays stable while doing so (Potentiometers are on both sides of the lift).