Scissor lift?
 

My team was considering making a scissor lift as a scoring mechanism. We had some concerns though. Has any team made a sucessful scissor lift before? We have limited resources does anyone know the price of what it might cost to make one? What is the level of engineering this would take?

Thank you for any advice you have.

Amanda Cullen

Re: Scissor lift?
 

It's generally very difficult to make scissor lifts "work", and when they do work they have many poor mechanical/kinematic qualities. They need to be light-weight to work decently, but it takes a lot of added weight to make them robust enough to actually work. It also takes a tremendous amount of force to start lifting them, as there is a very poor transmission angle.

Regular arms, four-bar arms, and forklift/telescoping elevators are all mechanically preferable to scissor lifts.

Re: Scissor lift?
 

our team hasn't built one that i know of, but looking at schematics and pictures of scissor lifts, it might be a complex device to build. you would most likely need a lot of pneumatic parts, which can be large and heavy. if you can afford to leave that much space and add that much weight to your robot, then a scissor lift could work. you would have to make sure it is stable enough and that it can operate smoothly.

Re: Scissor lift?
 

My team has three Design "Rules":
1. No Jaguars
2. No Suction Cups
3. No Scissor Lifts

In all seriousness, scissor lifts are pretty difficult to get working, especially at a reasonable weight compared to elevators or arms.

Re: Scissor lift?
 

i get #2 and #3, but what do you have against Jaguars? :confused:

Re: Scissor lift?
 

Team 1208 built one in 2007. The lift materials cost about $300, it worked quickly and went to a height of 11 feet. We won an engineering award due to its design. That said, we are not building one this year despite the similarity of the game. Other designs were superior.

Re: Scissor lift?
 

Mostly superstition and bad luck. We got a bad batch in 2009 and have generally had a bad time with them since. We like Victors a lot more due to their smaller footprint, lack of automatic overcurrent disablement, and general reliability.

The list, like any absolute in a design discussion, is a joke.

Re: Scissor lift?
 

ah gotcha. we actually prefer the jaguars over victors. probably because we blew up a few victors last year ::ouch::

Re: Scissor lift?
 

Team 841 made one in 07. I was the one that did most of the building for it and was copilot that year so I was operating the lift during the games.

From what I remember, it ended up being expensive and rather heavy. It takes a lot of material to make one. During those games, we wanted to be able to score on the top goal pieces.

Re: Scissor lift?
 

My high school team 616 (no longer competes) created a successful scissor lift in 2005. It was powered by two Fisher-Prices motors that drove a lead screw. The amount of power needed to lift from starting position was so much that we propped each level of the lift up about an inch. And it was heavy, we were about 0.5lb under the weight limit. Picture attached below.

Chris, just for you I've also attached a picture of our suction cups from 2004 in action...

Re: Scissor lift?
 

Our team made one in '08 (overdrive). Long story short, our team won't likely make one again. There were many issues in making it function well.
It did, however, make one of our team's best-looking robots.

Re: Scissor lift?
 

Thank you so much for the information guys. We will not be building a scissor lift (My team now believes me) Thank you!

Re: Scissor lift?
 

Good call. For most teams, scissor lift CONS far outweigh the PROS.

-Brando

Re: Scissor lift?
 

There is only one use I can ever see for a scissor lift in FRC, and that's a horizontal scissor lift with a cuckoo bird on the end that pops out when a Minibot hits the trigger. Sadly, the 12" cube means we'll probably never see this.

Re: Scissor lift?
 

Haha, quite true!

Re: Scissor lift?
 

Why no jaguars?

Re: Scissor lift?
 

My team has a running joke with scissor lifts.
"Everyone tries a scissor lift once, nobody tries it again."

This is one of the more common rookie design errors in games like this. Scissor lifts look promising, but are just no good in FRC for reasons unapparent at first glance.

Just the other day:

New Mentor: Couldn't we just use a scissor lift?
Other Mentors and Older Students: *Laugh*
Older Mentor: "Everyone tries a scissor lift once, nobody tries it again. We are NOT doing a scissor lift."

Basically, don't use a scissor lift.

Re: Scissor lift?
 

Well as long as it pops out after the match is over.........:yikes:

Re: Scissor lift?
 

I think it's doable. What reasons have others seen not to do a scissor lift? If it's made right I think that it could work.

Re: Scissor lift?
 

It is absolutely doable. The issue is that several other designs (single bar arms, 4 bar arms, elevators) can do the same things but win out on simplicity, mechanical advantage, etc.

Re: Scissor lift?
 

See post #7