We need to make a six bar lift for our robot. We are starting from scratch and dont have much of a clue how to do it. Can anyone help me with making this six bar lift?
http://botsnstuff.com/wiki/N-Bar_Linkage#Six-Bar
The instructional vid a wee bit down is very good.
Do let us know if you need more help 
Thanks a lot guys. I will watch those videos now and see if it helps us.
That link is bad but I believe it’s the same video I posted (it has the same video id)
We are not able to figure out what size bar linkages to use… Can someone please tell me this?
That’s up to you. As long as you follow the required pattern, you can make them as long or short as you want. You’ll just need more torque (ie motor strength) to raise the lift if it’s longer. You need to make the lift so that it works for your particular design. Play with a few sizes and see what works well to raise the intake to your desired height. If this is for toss up, make sure you keep in mind that it needs to be mounted below 12" if you plan on going under the trough.
This thread:
https://vexforum.com/t/scissor-lift/25137/1&highlight=lift
had some solid insight as time went by on it. It started off on scissor lifts but there are a lot of links to other places with six-bar linkages that may help you. If you need, I can send you pictures of ours like I sent them to the OP of that thread. Good luck!
Thanks all of you… I hope it really helps… We saw the video but that one was for gateway so we could not make that one coz he used 40 holed c channel… I need one for toss up
I like the lift in blue in that thread.
FYI, The longest C-Channel there is is 35 holes or 17.5".
Many say that Gateway is very similar to Toss Up, and lifts can be reused for pretty much any challenge. It’s things like intakes that vary from challenge to challenge, but a 6 bar lift is always a 6 bar lift. I don’t see why that one wouldn’t work?
That means that he searched for “lift” to find that thread. The search results lead to a link with the search term highlighted. That’s what the &highlight=lift at the end of the link does. If you remove that, it just goes to the regular link.
In order to build a good six bar link-age you would need to make sure the bars are parallel and also to make sure the bars are almost touching as the lift reaches maximum height, it should be able to reach up to 24"! 
I don’t want to disparage the effort 10D went to in making the video that was linked to earlier, but…
He spends the first minute and a half talking about how to make a 6-bar symmetrical and why that matters. SYMMETRY IS NOT RELEVANT. NEARLY EVERYTHING HE SAYS UP TO 1:40 IS EITHER WRONG OR MISLEADING. After that, the video is correct and has lots of helpful information.
He says that symmetry will make a 6-bar lift higher, which is not true. He says that symmetry will make a 6-bar “lift really well” and “work a whole lot better”. While you might notice a loss of performance if your six-bar is very asymmetrical, for practical purposes this is also not true.
What you do want to make sure of is that your six-bar is parallel, which means the links on opposite sides of each quadrilateral should be of equal length. Intentionally non-parallel 6-bars exist, but they involve either a lot of maths or a lot of trial and error, so they’re a topic for a different thread. Their purpose is to rotate the intake as well as lifting it.
Sorry, I don’t know what is wrong with the link. But if you have the same video I won’t worry about it. I should have checked to see if your video was the same one first.
Oh, that’s cool!
Thanks for the info!
http://www.team323z.com/lift-cad.html
I used the 323z CAD section on lifts extensively when going to build my six-bar for the first time. It helps with the hole placement a lot. Hope it helps 
Thanks a lot guys… I really appreciate it. Today we hope to have both sides of the lift assembled.
I’m not so sure. Can you explain this a bit more?
From what I’ve seen, for a given 6 bar configuration of so many holes up and so many over for a given stage, wouldn’t being a parallelogram configuration give the maximum lift point?
You get “triangles” at the max lift point when one of the lift pieces is not entirely equal so that angle limits the lift a little. Higher or lower angle at the top depending upon which part is left shorter makes the triangle bind at the front or back part of the six bar segment. I am not talking about the vertical spacing distance but the fact they are equal for either the front or back parallelogram of the six bar.
Without the binding into a triangle and making the lift look like a parallelogram, the angle is able to be tighter and in effect, raise you higher.
I could draw some pictures or do the math but am a bit lazy right now. 
There’s a difference between parallel and “symmetrical”. Parallel means each quadrilateral is a parallelogram. You want this to be the case, usually, both to avoid limiting the height you get and to lift without rotating.
“Symmetrical” in the video is used to mean that both quadrilaterals are identical parallelograms. That’s the part that isn’t necessary. It’s true that for a given length of the middle vertical bar the linkage will go higher if the long horizontal bar is mounted halfway up (i.e. if both parallelograms are of equal height). But where on the horizontal bar you attach the vertical bar (or, the relative width of the two parallelograms) really doesn’t matter.
Searching “6 bar linkage” on Google came up with http://www.aura.org.nz/archives/672 near the top of the search results (although it may be based on my history more than anything else).