Scissor Lifter?
 

Hey all, I was just wondering about experiences that other teams have had regarding scissor lifts??

All comments welcome, I'm just trying to explore all of the possibilities!!

Re: Scissor Lifter?
 

Put it this way, I doubt anyone has ever built a Second scissor lift:)
Seriously though they rarely work very well, they all seem to wobble a lot when they get very high.

Re: Scissor Lifter?
 

No experience, except that I spend a lot of time on man-rated industrial scissor lifts.

If stability is important, scissor lifts of more than one stage should be rated as do not use. I walk from one end of a lift to the other, it sways a bit.

If simplicity is important, scissor lifts in general should be rated as do not use. (See: elevator system, pneumatic lift)

If you can't do much precision work... See the bold text above.

If you are seriously considering doing a scissor lift system, you should do the math. I've heard of engineers getting scared of that math. You need to account for all the stages, the stability, and the precision needed. It's not easy.

Re: Scissor Lifter?
 

Very well put. Scissor lifts are just way more complex than they need to be for FRC application. Most of the Ri3D teams chose to use elevators for a reason. They are simple, can be light weight, and effective.

Re: Scissor Lifter?
 

No. Absolutely not. But I am sure we will see a few teams using them.

Re: Scissor Lifter?
 

We used a scissor lift once on 842 back in Ultimate Ascent. We used it to bring Frisbee to our shooting mechanism because we somehow forgot about gravity. I don't think you could pay us enough to make another scissor lift. Despite it being very small and simple, it was very inconsistent, never landed right, jammed regularly and overall wasted dozens of hours due to having to adjust it. Even if you can get one working quickly compared to an elevator, the time spent fixing and adjusting it is not worth it at all.

Re: Scissor Lifter?
 

At the start of each season, I remind the team of our two absolute rules (born from very bad experiences):

1. No mecanums (yes, even this year)
2. No scissor lifts

My FTC team came to me with a design that included a scissor lift. I asked if that was the best design the could come up with. They said it was. I said you need to try harder! The have a much better design now!

Re: Scissor Lifter?
 

There are only two rules when designing on our team:

1. No turntables
2. No scissorlifts

I haven't had any experience with scissorlifts, but our mentors must have a really good reason for not wanting to ever have one.

Re: Scissor Lifter?
 

The Digital Goats have two rules.

#1 No casters.
#2 No scissor lifts.

Re: Scissor Lifter?
 

I have one rule that applies to FTC more than FRC and it is as follows:

Unless you have to raise an object more than 20ft in the air. A scissor lift is not the answer.

(Bascially unless we play a game like 2011 (bowled over) again you shouldn't need to use a scissor lift.)

Re: Scissor Lifter?
 

Bowled Over was 2011-12. I'll agree that it was probably the only time I've ever seen a scissor lift that was actually effective. Seeing teams shoot those crate 20-30 feet up with elastic powered scissor lifts was both really cool and really scary.

If you want to be successful this year at competitions, a scissor lift is almost certainly not the way to go. Build a nice elevator or something. You only actually need one stage this year.

Re: Scissor Lifter?
 

Out of curiostity, what's if it's single stage? I.E. Two bars that cross with a joint in the middle.
Assume that it's milled accurately and not made on a drill press.

Re: Scissor Lifter?
 

We used a scissor lift in 2013 to score the colored discs while our robot was on the pyramid. We needed a compact mechanism to lift a few frisbees a few feet, and I thought it worked great for us.

Obviously this is very different than lifting totes;however, I think they can work well in specific applications, and to automatically rule them out is a mistake.

Re: Scissor Lifter?
 

Ours are:

1. No Tank Treads
2. No Scissorlifts

We did both in our first year and haven't done either since.

Re: Scissor Lifter?
 

I understand why casters and agree.
but whyscisser lifts