I am planning on making a scissor lift. I could use and pointers that you all could give
Thanks 7862D
I don’t want to put a damper on your ideas at all but have you considered a six bar lift instead? This may not work for your design but for most, it seems to work quite well. It is very simple, gets good height, and can fit well into a robot. The problems I have seen with scissor lifts with both my fellow teams and others are that they are very hard to build and can sometimes be quite heavy. If they are not built well, they often will not extend and contract well and from seeing other teams mess with them, they take a lot of fine tuning to get them working well. I can’t help much with scissor lifts but if you need, I can help with six bar lifts if you care to consider those. Good luck!
I started the year with a scissor lift. From my experience I’d say it’s doable. My robot was very inefficient but still worked from match to match ( not hanging) https://vexforum.com/t/1115a-pre-warren-reveal/24852/1
What I suggest doing would be a system similar to:
http://m.youtube.com/watch?v=cmqX0q0FbRE&desktop_uri=%2Fwatch%3Fv%3DcmqX0q0FbRE. Or:
[- YouTube
a team in my school has a scissor lift using vertical rack and pinion gears. The problem with this is that nearly every match they would literally destroy their rack gears.
I have seen versions of what I did on my robot be successful but with a lot of tuning and a slightly different mechanism.
All in all if you’re determined to have a scissor lift, I advise you that it will take a lot of work before you get it right but in the end it may be exactly what you are expecting.](- YouTube)
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Scissor lifts are one of the more difficult lifts to pull off. You have to minimize friction, perhaps by using shoulder screws. Scissor lifts also require a relatively large amount of force to lift at the beginning when compared to the “top” of the scissor lift. I would recommend going for a different lift this late in the season, it would probably take an entire summer of hard work to get a really good scissor lift.
I agree 100%! We started on our scissor lift 2 weeks after getting home from worlds and spent the summer on it. We had it to where it was dependable, and could even hang, but we were continually getting beat by fast lightweight efficiency robots. We built a 6 bar in 1 week, and it would slaughter our scissor lift in a match. 9090C has an amazing scissor lift, but they also have a lot of experience from dealing with a scissor lift in seasons past.
If you have never made scissor lift before, go and make other type of lifts. An efficient scissor lift need lots of time to tune. If you really want to make it, here are some photos we made last year. We built a same lift this year and work well.
https://vexforum.com/gallery/showimage.php?i=6017&catid=member&imageuser=161725
https://vexforum.com/gallery/showimage.php?i=6018&catid=member&imageuser=161725
https://vexforum.com/gallery/showimage.php?i=6022&catid=member&imageuser=161725
One of the hardest things to deal with when building a scissor lift is getting the two sides to rise and fall in unison. I’d recommend using encoders to automatically regulate their speeds and make sure they move in a synchronized motion (i haven’t done this with a scissor, but I did this for my team’s drive in 2012 to get it to constantly go straight during auto. I figured it’d still apply).
I would love to make a six bar lift I just do not even know where to start. any pointers on that one?
Here is a great video that Exothermic did. It provides some simple pointers that will get you going. Once you have the lift built you can move things up or down or front/back a hole to change the lift geometry. For sack attack we had a modified 4 bar that tilted the intake forward as it went up to make the sacks easier to unload. Building a 6 bar was the best move we have made so far this year. Our scissor lift was dependable, but our 6 bar runs circles around it!
Also, there are some good cad pictures on 323Z’s website.
http://www.team323z.com/lift-cad.html
Well a 6 bar is an extremely simple and is just a modification on the original 4 bar linkage system
For a guide and some examples you can check out
http://botsnstuff.com/wiki/N-Bar_Linkage
N-Bar is referring to any bar linkage based off of a 4 bar. Could be 4, 6, 8, 10, or 12 bar. (or really any even number bigger than 2)
A nice picture to understand the basic concept is
As all of these guys said, all of those are great resources for building the lift. One pointer as you are building though, make sure you have as little friction between the bars on the lift as possible while still making them tight. Also, make sure there is no way for the bars to move back and forth.
We achieved this through bearings on each side of each connection on the lift. We also had a small spacer in between the two pieces of metal. Basically, what each joint ended up being (from interior outwards) was nylock nut, bearing, c-channel one, small spacer, c-channel two, bearing 2, then the end of the screw. So it would look something like ]- for each joint. The - would be the small spacer and the brackets would be our c-channels. It has held up well for us so far.
This bit of advice is just a thing we as a team picked up from our experience though. You can listen or do your own thing. VEX is all about learning from others while doing it yourself so… ya :). I can send you pictures of all of our lift and how we attached it though if you want. We had a hard time figuring out how to attach it all sturdily at the beginning of the season so let me know if you are having a hard time with that. Also, if you have any specific questions, PM me.
That would be wonderful if you could show me some of the images. Im havin slight issues putting it all together
-team 7862D
Certainly. We do have pictures on our Instagram page but I can either PM you or post some to the gallery on here. Which would you prefer?
on here please. our school blocks instagram, message me or put them on gallery, either or. Thanks a million
-team 7862D
I am having a hard time posting images on here because the files from my iPad are too large. Would you like me to email them to you?
That would be just fine. if you would send them to [email protected] the one on here isnt mine
thank you again team7862D