So this is the seemingly feasible lift we did in inventor. A lot of way to build and power a scissor, we primarily chose the most lightweight and stable way to build and power it.
https://vexforum.com/attachment.php?attachmentid=8393&stc=1&d=1400177509
Any opinions or criticism, welcome to discuss.
Martin, team 3921
The prototype is yet not completely finished, just an idea~
Be careful with those long axles. I suspect that, in practice, they will bend slightly and the gears will slip under heavy loads. Is it really necessary to have the metal strips so far apart?
Personally, I’ve always been wary of using the metal strips on a scissor lift, particularly now when bots will be loading these lifts with 6+ lbs of components and scoring objects.
Also, I note that you have your bars too close together - especially at the base, you will not be able to fit screws into the bearings properly. Throw a 1/4" spacer in there and you’ll be fine.
Your motors are attached directly to the bearings, which doesn’t work very well at all; place a strip of metal 9 holes long across the 3 bearings in the center, and screw the motors in and any other screws through that strip, into the bearings, and out on the other metal strip which makes up your lift.
I’ll see about getting a picture up.
EDIT: Got it. The motors are backwards from how you have them, but I’m too lazy to go back and fix them XD
[ATTACH]8396[/ATTACH]
BTW don’t mind the recolored bearings and weird metal; those are just changes I made to the VEX library to make it easier to use. Makes constraining things waaay easier than with square holes…
Anyways, I hope you get the idea - mount the motors onto a second metal strip with the bearings sandwiched in between.
The scissor lift is great for height, however it is very hard to build it to be sturdy. When the lift is fully extended it is likely to sway making it difficult to score when someone is playing defence. You could try adding more cross-bars to help with stability if you are set on this design.
I would be very careful using single strips on a scissor lift like that. I’ve seen teams pull it off, but I won’t be doing it any time soon. If you want a very light but durable lift, you can make some custom 1x1x25 L-Bars like TVEX did. If you stick with this, I would suggest getting a lot of threaded beams.
Has anyone found adding bearings at ALL the joints to be helpful? Our scissor had bearings at the joints where we used a shaft, but not where there were screws.
Best of Luck!
(PS. you might want a few more tiers to reach some of the higher goals:p)
Thanks very much about the feedback.
Yes, next thing to concern is to reduce the overall width. Still haven’t decided on the exact plan yet, but that is to be concerned.
Thanks a lot on the motor mounting tip. Yes, I was struggling about that. I want the lift to fold as low as possible, so I placed the bearing outside.
At the base, I designed not to use any additional screws to secure the bearing flats. Probably you cannot see, but I am planning to use nylon nut and screw to make the joint. This way maybe I can adjust the tightness so that it has minimal friction and holds the bearing on the bar without any additional screws and poppers. We did that with our toss up 8 bar, and it worked well. Not sure about the scissor.
Note that I tried really hard to keep the space between the bars standard… So using standoffs to support will be less of a pain. No need to worry about adding spacers…
Thanks 400X. First of all, your toss up anti tip design was delightful! I love that design.
About TVEX’s design, yes I have thought of that. But you know, budgeting is always the problem. We cannot afford cutting that many bars.
Yes, we are not sure about our aluminum purchase plan, so we are trying to make the lightest scissor out of steel.
Although probably not very helpful, I insist to put bearings at all joints…
For a similar rotationally powered scissor lift built with all bars and standoffs, check team 8192 gateway robot. Not sure how they did, but people have done this.
Why 4 motors?
Oh, yeah, I completely forgot about that… The one screw you are using for a pivot is going to hold the bearing in place.
Thanks!
We originally planned on cutting the C-Channels as well, but it was not in the budget either! 
I’m sure if you add enough support with threaded beams, etc. You’ll be fine.
If you guys end up attending Nationals or Worlds, be careful with the TSA, when we returned from the Open, almost every C-Channel on our lift was bent badly and had to be replaced before worlds. Put foam in between the scissors to keep it from hyper-compressing and getting damaged.
Hope to see you guys around.
The Idea itself seems good. The only problem I see with it is the metal used to make the lift, its very flimsy. If a robot was to knock into it or something along those lines it could potentially bend that metal very easily, therefor possibly disabling you for the entire match. But on the other side it because how light it is it will be able to be as fast as possible. Its jus something to think about.
Best Of Luck,
Luke Anderson, Team Captain/Builder of team 5686C
I wouldn’t trust that. There is a ridiculous amount of force on the joint.
On the first version of our robot, where the scissor lift was mounted, there were a few bearings that were bent out of place and wearing on the metal itself. Because of the force, the joint had moved the bearing despite the tabs AND an extra screw holding it as well.
Careful with that… scissors require an extremely large amount of torque at the bottom.
This cannot be stressed enough, especially with over lifts over 5 ft tall.
Just to clarify, we used what were essentially 1x1 aluminum angles.
There were very few bearings on our Toss Up lift. Though perhaps I’ll explore using more bearings with the additional stages needed in Skyrise.
I used the 25X1 bars succsesfully on a scissor lift powered from the center. The width of the scissor lift is only 0.75" wide + width of motor. If plenty of stanoff’s are used, I find it plenty strong.
I have to stress 0.75" thick and powered from the center is only feasable through a few methods, one of them using 1X25 bars.
How did you make those? Did you bent a 2x plate or cut a 1x2 C Channel in half?
That how we mad some of those.
We made some lightweight 1x1 L’s by cutting a C-Channel in half - just be careful, because the 7:1 4-motor lift that it was using bent the small L’s easily when they got caught on part of the robot during a match.
Better be a little bit careful at the beginning~ We don’t want our lift to die just because the rubber bands got stretched too long. Lift is basically everything in skyrise. Well, from a normal mind’s opinion~
Thanks for sharing the experience. Not sure whether i am right or not, but don’t you gain some more stability when your lift is wider? We decided not to cut the 84 tooth gear, not to spend money on high strength 84 tooth gear, and to fold two together to make a high strength one, so we might be needing about 1.5 inch for the best clearance in our next design.
Thanks.
Martin