Team 3921B end season reveal

First of all, sorry everybody for including our team reveal in the third page of the Georgia State Championship discussion thread, causing many people unable to see it. Here is our full detailed reveal:
Here are the pictures and videos of our robot 3921B:
The images are in the third page of this thread: These images are taken during Christmas at my home. No major changes are made since it is finished, except for we geared up intake motors, added more belt inserts and put the name plate on.
We have not yet uploaded our video, so I will just post some of the videos taken by team 4495 that involve us:
First qualification match, 3921B, 7878T vs. 675E, 4495C
I really love this match. We almost lost hope when we saw blue balls filled one goal at a lightning speed and our partner kept having stashing issue. But our final moment scoring and descoring helped us a lot and we won by 4 pts. Mind how we gave up the battle in the goal zone at the last 20 seconds and fetched 3 buckies in the hanging zone, and dumped them into the goal zone. That is a match turner. Heard the cheering at the last moment? Usually people do not cheer when buckies are scored in the end zone or large balls are descored.
Quarterfinal 1:
In this match we are the blue robot in the hanging zone that went all the way to stash the two. Actually we can score solid 15 pts starting in the middle zone. But we chose the more risky way, however still lost autonomous. Our captain chose the defense strategy.
Quarterfinal 2:
Both of our robots had issue in the match. We had absolutely no idea why it stopped at the most important moment of the whole tournament… That has never ever happened before. But unexpected things always happen and pretty sure we are going to do better next year.

We planned about things including catapult, hanging/pneumatic assist, gearing up base, changing roller design and so on, but none of these actually went into place. We had so little time that had to be distributed for programming and driver practicing. In general, we spent too much time learning this year. The intake mounting design looks familiar right? Yep that is 599D’s gateway pneumatic lift programming skills world champion’s design. Not necessarily the best design but helped us a lot. Here are some more pictures:
And by the way, I’m Martin, the programmer/designer of team 3921, the tall Asian guy in blue with a backpack throughout the tournament…

I have to say that this year we are already lucky enough to be here. A lot of disadvantages are caused by our inexperience: our drive base is 1:1, which is so slow in toss up. We thought multiple times what about gearing up the base to 160 rpm, but every time we are convinced that 160 rpm is too risky, until we saw 1103 titan’s round up robot is much heavier than ours but has a successful 4 motor 160 rpm drive. But that is after the last tournament for us. The roller is the same. Every time we think about changing to a more efficient design, we fear that things would mess up so we never did get better. But for me, a first year builder who has never heard of VEX less than an year ago, this is monumental. I wanna thank everybody who has helped and inspired me, especially team 599D. And of course we will see you next season, hopefully on the national championship arena. Thanks VEX forum.

The ability to not change something can sometimes be very important. If it isn’t broken, don’t fix it. If you aren’t sure whether a change is a good one, it is always best to build a duplicate of the system and leave the current one intact.

Interesting… I haven’t seen many 8 bars this year. Especially not with angle change.

Hi 3921B, thanks for showing us your robot! I do have one question: What is your logic for using an 8 bar, over the more common six bar this season?

Thanks, Matt

Pretty good robot…! :slight_smile:

Nice robot!

How much of this is steel? Do you know how much it weighs?

Is that all steel?

It looks like a really nice bot, how heavy is it exactly though?

Thanks everybody. Yes this is all steel. That is one of our main issues this year. We have absolutely no aluminum pieces so this is something we have to deal with. We are buying some in june for next year and hopefully it will improve our team. Basically this disadvantage killed our hope for hanging. We do not know the weight, but as you can see we tried to use the simplist structure as possible.

Thanks for your attention! Well the eight bar design was not the best design for this year, I would say. This is our design process: we started out with a scissors lift robot with the same base. Sadly that robot did not work out, therefore we restarted, only keeping the suspended base. The base is 17.5 * 17.5 and that is never changed. We did try to build a six bar, but when the lift is at its highest position, we find that our base is too long and it does get into the way of stashing. At that time I was at home with the robot, so I thought why not just make an eight bar and make the lift reach higher at a smaller angle? So that is how we ended up adding a section on the lift and using four motor 1:5 with rubber band assist to create an absolutely fast and balanced lift. The lift is tuned to be very stable like scissors lift at its hignest position. And yes, the angle is made to assist the stashing, making the ball holder to tilt more when the lift is raised. So this is how we made the eight bar. Note that all the bars are standard sized because I am a first year builder and our instructor does not allow me to cut stuff…

Yessss! This is exactly what my team captain said. I think next season I will do a lot more research, and make sure that the design is the closest to the best before we start to build. And also, our lab needs to support over 70 students and three teams, so it is really not quite possible to make a duplicate. But yes you are right.

Same, I have seen 1 8 bar

Great job building a steel 8 bar!

Pretty sure you can see how much elastic assist was placed to assist 4 torque 393s… yes I have not seen a faster lift than my 8 bar in the tournaments I went to. At the same time basically all the robots have a faster base than this one, so.

Except for my robot I have seen one in houston state videos. How do you think about the videos I posted?