Scissor Lifter?

[yara92]

Originally Posted by IndySam

The Digital Goats have two rules.

#1 No casters.
#2 No scissor lifts.

I understand why casters and agree.
but whyscisser lifts

[waialua359]

Nothing wrong with scissor lifts!

[asid61]

Originally Posted by waialua359

Nothing wrong with scissor lifts!

Why and how? This seems to be a very contradictory veiwpoint here, and I'd like to hear your thoughts. What is your experience?

[waialua359]

Originally Posted by asid61

Why and how? This seems to be a very contradictory veiwpoint here, and I'd like to hear your thoughts. What is your experience?

We built one in 2003 stack attack and it stacked bins very nicely. The scissors lift only had to go 2 bins high max.

[Al Skierkiewicz]

We built one in our rookie year (1996), we never even thought to replicate that experience since. I use a scissor type man lift here at work on a regular basis. In order for it to work well, a rigid precision frame and bearings in the joints are essential. The problem with most is the non-precision with which they are built. This leads to instability while moving and therefore intermittent loads that exceed the ability of the drive to overcome.
We have a do not use list too...
No casters/shopping cart wheels for obvious reasons.
No omni wheels on ramps.
Anything else that does not fit the game.

[sviridovt]

Let me just repeat every one here: NO SCISSOR LIFTS unless you want to know what hell feels like. The only time one should even consider a scissor lift is when you have to lift for small distances, with only one layer. Anything more will be waaaaay unstable.

[waialua359]

Originally Posted by sviridovt

Let me just repeat every one here: NO SCISSOR LIFTS unless you want to know what hell feels like. The only time one should even consider a scissor lift is when you have to lift for small distances, with only one layer. Anything more will be waaaaay unstable.

While our team probably won't be making one, I'd bet that it's still possible to create an effective one for specific purposes.
How ironic that the best VEX robots this year all use scissor lifts, where the game requires precision and going really high.

[InFlight]

A scissor lift to raise totes is probably an overly complex and likely too slow in operation compared to the alternatives.

Ideally you should want to raise the totes in an about a second or two at most.

[IronicDeadBird]

I remember doing a scissor lift and once you get all the kinks worked out its fine, but the amount of moving parts makes it more likely that things will go wrong the taller you get with it. There is a niche that scissor lifts fill and if this niche needs to be filled go for it.

[JamesCH95]

I am quite frustrated by the "we'll never do X because we tried it once and it didn't work" attitude. I find it very narrow-minded and a bad precedent for our students. Technology, collective experience, and requirements all change, and we should be willing to reconsider past decisions and be able to admit to ourselves that we could have done something better.

95's name-sake robot, Grace Hopper, used a scissor lift with great success. The compact storage profile of the lift allowed the robot to be completely mobile on the field and still reliably, and quickly, score in the high goals. Also, Grace's scissor lift was fabricated with a lathe, drill press, and belt sander. Precision machining equipment is not required.



Here is an old match video to show what the field was like: https://www.youtube.com/watch?v=YCcBXMrR8DY

Scissor lifts have a very specific application: they allow a mechanism to reach very far while being stored in a very small space. With the lack of height-restricting obstacles and lack of size constraints this year I don't think a scissor lift is appropriate. But I would consider it in the future.