OK, i’ve done some (well, a little) research on some scissor lifts, and I think these two are the best ones out there, if you don’t have pnuematics. There is the chinese way: ( i couldn’t find the pic, but it is where a motor with a gear attached to it revolves around a bigger gear)
and then the american way (I dubbed it that ;)) http://t3.gstatic.com/images?q=tbn:ANd9GcQRx5erl5mmbk-RIHjvmjFs7ZOT07fBR9DCPsDws9up1Aa_6UhZ
Which one is faster, and which one has more power?
I like how you name the scissor lifts thats how my team does it also. I feel that the Chinese one is way faster because it is like a gear ratio. (I know so because my team has been testing it for 5-6 weeks now.) While the American one has more torque.
A con I have found with the Chinese Scissor Lift is that when starting off it has a hard time. To solve this were currently testing some ideas we have. I will surely post them once we finish today. BTW When I mean it has a hard time, the scissor lift can’t go up until raised 3-5 inches.
I will probably post pictures also of our lift soon.
I think maybe using rubber bands could help
just my $0.02
I personally enjoy surgical tubing a little bit more 
You guys read my mind. Thats what we have been testing right now, and the lift is getting better.
Looking at some pictures I had of the Chinese scissor lifts at worlds (also used by the Malaysians) they have some slightly different characteristics. Our kids got beat by both these guys. These were impressive robots.
Lateral stability seems to be an issue for these guys and they solved it in two different ways.
The Shanghai team (8192C although it seemed A and B were darn close copies) used straight bars and sandoffs to create two channels on each side for a two level scissor lift. How much extra stability did this give them? I can not remember if they had a bar going across or not but I think they did. Rubber bands connected right at the bend point of the two X’s using rubber bands (looked like strong ones too). They used a claw style for scoring. This lift seemed impressively fast. Not sure if it was aluminum or steel but aluminum may be good to use. And oh yeah, they could drive really really well.
The other kids from Shanghai (4865) had used C channel metal and cross bracing across in their 2 X scissor configuration. Lots of metal and a snorkel style robot. These guys rubber bands connected a few holes away from the bend point just beyond the black holders. But lost of connectors between left and right side here using a lot more weight.
So there are a few different ways to tackle this problem it seems. Just getting the scissor working is probably the first 20%. The channels at top and bottom are not sliders I think. So connection to top and bottom is problem #2.
Have fun trying to make a good scissor!
Rubber bands or latex tubing could definitely remedy that problem with the first 20%, the assist you at the beginning of the lift then provide little effect as you raise it higher. They can also cushion the return (lowering the lift) for an all around smoother lift.
For the bars, i would definitely go with aluminum. Using the 1x25 or any angle metals (with or without stand offs) gets heavy very quickly, especially since you’re trying to make it as stable as possible. Scissor lifts that reach 30" are going to be crazy tall, make sure your base is also large.
My team has quite a bit of experience with building VEX scissor lifts. One recommendation I have is that if you choose either a rack and pinion type lift on the bottom of your scissor, or a gear rotating around another at the center of the X, then the latex/rubber bands that you use should follow the other format.
To clarify:
If you have a gear rotating around another at the center of the X in the scissors, then the latex/rubber bands should be on the bottom pulling the two ends of the scissors together.
If you have a rack and pinion pulling the ends of the flattened X together, then you should have latex/rubber bands wrapped around a drum in the center of the X.
Combining a motor and a spring force like this causes the two to compliment each other nicely. Each gives the most help at the point where the other provides the least power.
thank you all! now, here is a really cool design that I just thought of for a scissor lift, and I’m gonna share it with you all…
introducing, The Techno Lift!!!
Ok, this lift isn’t that technical, it’s actually quite simple. I don’t have a prototype of it yet, but when I do I’ll post some pics. So basicly, there is a motor powering a small HS gear, which is connected to another bigger gear. That bigger gear has attached to it a 2 1x25 bar that are connected together via standoffs. when the motor turns the smaller gear, then the bigger gear will int turn turn, which will make the 2 1x25 bars go up (or down) now, these two bars are connected to another 2 1x25 bars that can move in the horizontal direction ONLY. Now, when the motor lifts the bar, it will raise the scissor lift!
what do you all think?
Hello,
I was wondering what you are meaning by “any angled metal (with standoffs)” Does this mean you will use the angle slotted metal with standoffs the structure the lift if so How?
And can you send a picture of what it might look like.
Please and thanks:)
Angled metal is much harder to bend and often times torquing the bars on scissor lifts results in warping the lift out of shape, usually at the base. You probably wouldn’t need standoffs if you were using the angled metal (the slotted metal could be an option to use although it gets really heavy) but i would highly suggest it if you were planning on using the 1x25 bar.
I wouldn’t suggest using the angled slotted metal (unless you cut it down to shave weight or used aluminum somehow) because our scissor lift got heavy (minus the two speed transmission it was about 15lb without a claw). However it was extremely strong and pretty stable.
Attached is an example (sorry about all the crummy quality pictures) of our scissor lift robot that could extend 36" (it could go further than the yardstick in the picture)
Curious to see what actuators teams use this year. I can think of three main ones,
4bar (or arms that serve the same purpose)
scissor lift
multi stage chain lift
Hey,
I cant really see alot of the picture because my monitor is small and its hard so I have a couple of questions
Please Thanks:)
Sorry about that. I did repost more images in the gallery so i hope that helps.
1: The metal is slotted angle http://www.vexrobotics.com/products/accessories/structure/segmented-angle.html
2: The red part is i think cut slotted angle, we used a part of the rail slot on it. Its just spray painted red (which I would not recommend doing)
3: I wouldn’t recommend this method, I would stick to earlier posts about the Chinese scissor lift robots. But basically its like corpralchee’s scissor lift (i believe). You use a rack and pinion method to drive the end of the scissor lift laterally. I’ll try and post a picture in the gallery. Might work alright with lower loads, but lifting a whole robot doesn’t work out for too long lol.
Scissor lifts suck. Don’t use them. They break easily, are slow, and are much MUCH worse than just using a Rack and Pinion.
if you connect the “piston” at the bottom right and top left of the bottom x you will ultimately fail trust me we broke high strength gears like that. just thought i would state it in case anyone got innovative