Many of us are thinking about how to reach those insane heights this year and there seems to be only 2 “conventional” lifts capable of reaching 60" : the scissor lift and the elevator lift. I personally am a big fan of experimenting things on my own but since we only have a limited amount of parts I can’t just buy parts to build both a scissor lift and an elevator lift and see for myself which one is the best. This is why I am asking people who have already built either one of these lifts to list the pros and cons of each lift so that we can decide what to buy before we can test anything out. Also, list what parts you would use to build a lift that could reach 60" as that could be useful to help teams know what they need to buy. Obviously, you would need lots of C-Channels for a scissor lift and linear slides for an elevator lift but I don’t know if I should attach linear slides to 1x5x1 C-Channels or if it will be too heavy, if I should use 2 linear slides per stage for extra stability or if this will add too much friction, is lubricant really necessary etc.
Thank you all for your help as our team and probably many others have to make tough calls without being able to test anything.
For an elevator, plan on two slides per stage because you need the stability. A 4 stage linear lift at 18" tall can reach the top of the skyrise. You need grease for sure- buy lithium grease from a Home Depot. 1x5 c channel is not totally necessary but is one way to do it, the way I prefer at this time at least. I built an elevator out of it last night and it was 6.5 feet tall… D:
I don’t understand your next question. You can build elevators with either the old style slides or the new style. If you use the new style you will want to use the 18" slides for your elevator.
Well, to use the 18" slides you would need to cut them a bit since they would need to fit in the 18^3in so my question was how do we use them if we can’t cut them but apparently we can
Now on to the topic of scissor lifts.
We built one of the three scissor lifts that I saw at the world competition, so as you can imagine we have a strong bias towards the scissor lift design. From what I know of the linear lift this is a list of pros, and cons to the two designs
Pros:
Scissor:
low friction
less jamming
simpler to build (in my opinion)
easier to power with elastics
a little less weighty
Linear:
much more stable
easier to balance raising speed
easier to fit into the robot
Cons:
Scissor:
horizontal instability
difficult to balance raising speed
Linear:
heavy
high amounts of friction
thick
heavy
These are all my opinions, and speculations on the linear lift as I have never built one before, but these are from the other posts on the forum.
We built a scissor lift for toss up and used it successfully at Worlds. It was a two motor lift, and could lift 3 buckies AND 2 large balls to stash height in less than 2 seconds.
I spent a lot of time working on it, and have learned a lot about building a good scissor lift. When I have the time (probably in June, after exams), I will put together a post with tips and tricks for a scissor lift, and why to and not to build one.
I respectfully disagree the horizontal instability issue for scissors lift. Yes that occurs a lot for most teams who don’t mind it a lot, but it can be solved perfectly.
To increase stability/how level it is, couldn’t you use shaft encoders (or IMES) to balance? It’s the same concept as using them to drive in a straight line.
We just used some optical shaft encoders on our scissor lift ( sorry if that’s what was in the video im on my school labtop and youtubes blocked) and played with the motor speeds and never had any problem.
I didn’t watch the whole video right now, but did before, but I can’t see what you mean by cheating?
We tried to use a PID control on our scissor lift at first, but it wasn’t as good as just full power both sides. When raised, we always applied a trim to the motors, which also made it much more stiff.
they reached in and righted the robot that tipped over like 3 times. Must have been a practice match or scrimmage as otherwise this would obviously not be okay.
EDIT: My bad, didn’t see that it said practice match in the video name. Still tips an awful lot though.
Well lets start of with this… Scissors can be very well created. Unlike this year that all scissor lifts where slow so that they could hang and lift their heavy robots this year what we need is speed. I have a prototype of a scissor that can get to more than 50" in under 12" so yea… i have a pretty neat design on my scissor lift. Im pretty sure it can go up to the 56 inches in just 3 seconds plus you can help it with rubber bands to make to faster. This scissor lift has a 1:5 gear ratio which makes it really fast and since we don’t have to hang this year it would be the most effective for me right now. I wish to see you all soon
I think we’ll go with an elevator lift because of the tipping problem involved with scissor lifts.
If I were to build an elevator lift, that would mean only using the 18" linear slides, what would we do with the 12" ones ? And also, is it better to use the inner or the outer green delrin blocks ?
