My team this year is working through the kinks of using multi-Stage linear slides. for our arm. Anyone have any luck and want to share some pics? we are using the new linear slides. we are finding them to be cumbersome and beastly in size.
Help.
Are you interested in linear/ elevator lifts or something else.
1103 currahee had some godly multistage linear lifts
http://www.youtube.com/watch?v=AAKR_UMiZd8
you can also find a lot of information in the thread about him https://vexforum.com/t/team-1103-robot/18347/1&highlight=1103+linear+lift
https://vexforum.com/t/7702-talus-reveal/23318/1&highlight=7702+reveal
this thread has some of the material form our lift. If you want pics or a video let me know and i will see if i gan get them to you. I would personally not do this lift for the game this year, but that is totally up to you. Just my opinion. It gets very thick and heavy very fast.
What would you suggest for this year’s lift?
When in doubt 6 bar.
4 bar will also be solid this year. It’s a little lighter, easier to build, and the extra reach from 6 bar doesn’t seem like too great an advantage. In fact, if you hang with your arm, you might not want it to reach further forward.
We used a multi stage lift for Gateway, here’s a photo (partially disassembled).
and the original concept CAD.
It worked well but was ultimately too slow for the game, it used the older style linear slides.
I don’t see how a 4 bar robot is going to fit under 12" and hang with its arm. We have a full size 6 bar built in a 12" robot and it BARELY reaches high enough to hang. That’s the benefit of a 6 bar this year.
Oh trust me, it’s completely possible. Do some math.
The attachment on the end of the 4 bar for hanging can be longer than 12 inches, or it can be offset so that the mechanism can go completely vertical, or at least higher than it normally could, as 3018 did in round up. It’s probably unfeasible to use a 4 bar on a 12" tower with a 12" attachment at the end of the arm, but it’s certainly possible to hang with a 4 bar with some innovation.
our team is using a six bar lift and we have made it so that it will reach 28" from the bottom of the middle bar and it fit under the 12" when collapsed so we think that when we have an intake attached on we can hang 
Odd, we had a bunch of issues making our chain bar fit within dimension and reach the column goal:confused:. Maybe cause we restrained ourselves to one tower.
Oh man, Now I’m excited to see what you guys are up to! Are you going to be at the Dulaney High School competition on June 15th?
Anyway, back to your question, Is it going to be just one linear lift or 2? Like, will it be one that lifts the (what ever you want to lift) from behind, or 1 on each side, or something else entirely? If 2, then good luck, one of our teams tried to make that effective for 3 years in a row and it still never worked out for them. This configuration tends to get binded while lifting because of one side going faster then the other. This could be fixed if you linked the 2 together with some sort of pulley, but I personally don’t think it’s worth the time and effort. If 1, I may be able to put together a little model or something to show you.
As for 6 bars or 4 bars, you can’t forget about the good old 2 bar! If you think about it, they can go completely vertical. Assuming you mount the arm 11" high and it sits 17" on the ground, from the bottom of the mounting point, you can have about a 20" arm. If you go completely vertical from said 11" mount point, you have a 31" reach. That means you only need a 9" extension to reach the hanging bar. This could easily just ba a hook on your feeder. Just make sure you add some sort of tipping protection on the robot and you’re good.
There is nothing wrong with linear lifts. It is just that the more stages you add and the shorter you make each stage the less feasible it becomes. We ran in to this problem with the 15 in height limit, but if you are ok with not fitting under, then it will be a fine choice for this year. The other problem with linear lifts( at least with ours) they tend to get out of alignment and need adjustment about every 2 competitions. This adjustment takes a long time and has to be done just right or there will be friction problems. You also have to be very carful when shipping them. Ours got messed up on the way to worlds. 
I think that kinda defeats the whole purpose of the lift… If you can’t fit under the barrier, then it’s pretty much just a hanging tool. Linear slide lifts don’t have that much reach, an arm would be far more effective for dumping over the barrier.
didn’t wanna show it this early but heres a teaser 
That looks really good! Where are you putting the sprockets to make the slides move by motor? Or is there even sprockets 
?
it’ll be up soon enough! either chain or nylon rope… it’s my favorite elevator/lift design so far! keep an eye out for it 
I would love to see a rope linear lift system! I actually was planning on doing it in RoundUp. It was my first year in VEX so I really didn’t know how to build 
I winded string through linear slides that were standed(stood?)-off to each other. Toooooooooo much friction so never worked but it was a mini version of the chain lift that became popular after 1103 popularized it.
Imagining the chain system on your lift looks like it would actually work! With the pulley system and minimal friction I think it would work just as good if not better than chain. The only downfall is that you can’t quickly change the size of the string. You would have to untie it and then retie.
Actually if you just have the string winded until the final set of slides and tie it to the final set without actually creating a full circuit of string then that would work as well, gravity would have to pull down the lift though. Attached is a picture of what I mean.