Is Scissor Lift viable for Starstruck?

VEX V5 Technical Support
1

Is scissor lift a viable design for starstruck? literally everybody I know and every one of my tech teachers HIGHLY discourages scissor lifts because apparently it’s a pain in the ■■■ make it work perfectly with reasonably good sustainability and reliability. But the starstruck fence is only 24 inches in height so I personally don’t think it’s that big of a risk. Also, in this video (2016-2017 VEX Starstruck Asia-Pacific Robotics Championship China Qualifier - YouTube), as most of you have probably seen, 666U seems just fine. Though my engineering teacher says that 666u may seem fine that match, but as the robot continues to be used, it will have a very hard time sustaining through the whole tournament. Because of things like, loose screws, wobbling, uneven lift speed on both sides of the scissor, and fragile. Also it’s very hard to program a scissor lift according to him and a couple of my school mates. All of that may be true but I don’t know because I never built one before, nor have I seen them last year in Nothing but Net and this year so far in my competitions (this is my second and last year… :'(…). I have huge interest in scissor lifts because it’s a vertical lift and it’s the sexiest looking and rarest lift that I know of.

why else are scissor lifts a bad idea?
is there really not a way to build a successful scissor lift given the Vex parts?
what other vertical lifts are do-able in Vex? (besides the cascade/elevator lift and of course the scissor lift)

while(true) {
if(build scissor lift == true) {
any tips for building a good one?
}
}

2

This is true. Once you can make a reliable one, they work quite well.

Build quality plays a major affect in the functionality of a robot.

As for building one, you can always search for “vex scissor lift”. Google is your friend.

3

There’s really no point in building a scissor. The robot in the video has very good build quality. If you mess up a tiny bit on a scissor, they don’t act like you want them to. Your teacher is about half right. Scissors do need a lot of maintenance, but every type of lift needs maintenance. It’s just that with scissors, every detail counts. For Starstruck, why would you go through the turmoils of a scissor when a 2-bar can get the game elements over the fence? As for other linear lifts, does the reverse 4-bar count?

4

The scissor lift is doable, but completely unnecessary. It would be like trying to have 4 launchers last year. It could happen, but is complete overkill. Like you said, the fence is two feet tall. You almost don’t need a lift at all, but since you do you should keep it as simple as possible, like a 4 or 2 bar (think clawbot style) lift. The main challenge of starstruck is expanding and grabbing the objects. Don’t make one of the easiest parts of the game too complicated.

5

Other vertical lifts:
Reverse double four bar, reverse double six bar, reverse double eight bar, and peaucellier lift (those last two are extremely rare)

6

what are those? Google won’t tell me

7

For the reverse double six bar, think of a 6-bar that starts out in the opposite standard starting position that is connected to another 6-bar. When the 1st 6-bar lifts, the other 6-bar lifts as well, more than doubling the max height.

For the reverse double 8-bar, think of the same design, but as 8-bars instead.

The peaucellier is a bunch of geometry that can be explained with this video:

8

This is a good example of a dr6b (double reverse 6 bar). It’s a double reverse 4 bar, but the top and bottom are six bars lifts, not 4s. Same goes for dr8b.

9

thanks

(i know what peaucellier lifts are, i accidentally left it in, but thanks!)

10

Also, don’t go for it because "it’s the sexiest looking and rarest lift " that you know of. When I started robotics I built a U-drive for that same reason because no one I knew had ever seen it before and because it would be “unique”. It is still to this day the worst robot that I have ever seen just so that it could be “special”.

Edit: I am definitely not saying don’t do it. It is a viable strategy and can be executed well as shown in that video. Just please don’t do it only for the reason that it is rare and sexy.

11

I will say that the second alliance on the winning alliance at the competition I recently attended was a scissor lift. I think there is definitely an advantage to being able to lift straight up.

12

Definitely would say that a vertical lift is great for defense if your driver is good enough.

13

Imo, a 2-bar or 4-bar could be just as good at defense as a linear lift

14

I would suggest a dr4b as they are easier to build than scissor lifts, and achieve the same goals. I was one of the tournament champions in the BC season opener using a dr4b, and would presume that a well built dr4b would be more reliable than a scissor lift.

15

You don’t need that kind of height for this game. A 2, 4, or 6-bar is the best bet for this game in my opinion.

16

A scissor may be an effective dumper bot strategy to lift a large hopper over the fence at the last second as well as lift a robot into high hang robot. A single X may be viable versus multiple sections of a scissor. A multi-stage scissor may be overkill. The fence is kind of low.

Scissors are also fairly slow in comparison to other lift types.