Vex Toss Up 7793r Reveal

With a competition coming up next week, I thought that I’d show the robot on the forums to get some good ol constructive critisism :D. Leave a thought on robot and as a rookie team, advice is appreciated. Videos, and details below:

Drivetrain: 1X5 Channel, 4 motor internal 1.6 speed, 4 omni wheels on pillow blocks

Lift: 4 motor scissor lift powered by linear sliders vertically, geared 3:1 on rack and pinion , and reaching 40 inches

Intake: 2 NZ rollers for bucky balls, flip down, and 2 large ball intakes connected by chain and the intake is powered by 2 motors

We used all 393s, 2 batteries, 1X5 c channel chassis, but we still managed to high hang at quite some speed. Picks up 3 bucky balls and two large balls at any combination.

Flip down intake:

Picking up balls:

High Hanging(should’ve filmed it with a big ball):

Anti Tip Pegs: [Vex Toss Up Anti Tip Pegs - YouTube

.](Vex Toss Up Anti Tip Pegs - YouTube)

I never thought of doing it that way. I’ll get our X team to look into it. Does it remove the difficulty of getting the first three or four inches started that you get with a horizontally moving Linear Slide? They had to go up an entire gear ratio because getting it started was so difficult. It seems like it moves a bit slower, but that might just be my imagination.

You have a very nice robot. I’m in favor of scissor lifts for this year’s game if people want to high hang. Do you need to push the large balls up against something to pick them up? I saw you do that in both the high-hanging and intake videos.

Also, what was your final weight at? It must be fairly light with only a 3:1 gear ratio for hanging.


I had the EXACT problem with the scissor lift, thats why it I did it like that. Horizantally it has problems, but vertically the problem is eliminatied. The big ball intake does need to have something to push against, it probably needs tuning before i can do it without it.

In the end the robot was super heavy. I used no aluminum(except for stand offs) and with all the weight from the 1X5 c channel and battery, screws, metal etc. it added up to a lot. The lift in a vertical movement of power probably increased the efficiency, thus being able to hang, but it is still slower than a six bar without hanging capabilities.

You, good sir, just turned a robot we were about to take apart into something we can actually use. Can I trouble you for some more pictures of how you got the vertical linear slides to raise the scissor lift? It seems fairly simple, but I’d like to see what you did before I get them taking the entire lift apart.

Sure thing, but I warn you that it is maintenance demanding( to a small extent) the plastic slider will under go a lot of stress, so you need to do a better job than me, I’m not refining it because it is using time I don’t have before the competition. I also only have photos on my camera so its limited. I can send you more tommorow.

We tried doing almost exactly the same lift for last years competition. However, we were never actually able to connect the scissors to the actual sliding bit on the tower well. So, the lift would just warp. We had to scrap that design.

What did you use?

That looks like a solid robot which I bet will do very well! For this early in the season it is a fantastic robot for a rookie team, it looks like something a top tier veteran team would build.

Great job!

I’ll get back to you in a sec, I’m getting more photos close up of the robot.

Thanks! .

A nice and solid robot! It looks very heavy, but it was still able to lift itself and amazing.

We had very solid scissor lift which was built for last year World Competition. It turned out very solid and reliable. We believe scissor lift will be very helpful to hanging this year. We are continuing to built a Toss up robot this year based on Scissor lift. Here are the photos I posted last year.

Our lift mechanism is horizontal and power by gears.](

  • The lift is sort of slow; no doubt because it hangs. If you use surgical tubing to pull the lift down (the robot up) than you might be able to use a faster ratio. Basically, you want the motors to have to work at the same force when hanging and when lifting 3 buckies to the goal.
  • Are the omni wheels chained together? I highly suggest that you chain them together. That way, when your robot is on 2 wheels (e.g. wheelie), you will still have 4 motors of power.
  • Does it stay hanging w/o power? It looks like it starts dropping and then the motors are engaged again by the driver. Remember that the match is scored when all objects come to rest.
  • Does the bot fit under 12" with 3 buckies?
  • The pushing into a wall to get a large ball is not good.
  • Preset lift heights are amazing, and should be implemented.
  • Do you have autonomous routines for all 4 tiles yet? This early in the season, there might be few with autonomous routines, so you might stand out. :smiley:

Good work on a functional scissor. The lifting system makes me a bit worried though. Personally I am not a fan of rack-and-pinion lifts, but if it works for you, then great! A lot of force is needed at the beginning of lifting, and not much toward the end, meaning your gear ratio will need to be slow enough to handle the beginning, and then be overkill the rest of the way up. Some of this is inevitable though, so take this with a grain of salt.

Great job on a functional robot this early in the season!

-The 4 motors are powered to the rear (rear wheel drive only)
-The robot stays hung when on the bar w/o power, it was going down because I pressed the button instinctively when I heard the motors reach extreme position.
-it goes under the stanchion with 3 bucky balls
-i really do need to work on the big ball intake yeah :smiley:
-I have 4 atonomous routines, and I plan on using that LCD

i have the rack and pinion set up vertically, so the problem with extra power needed in the bottom position and not at top is eliminated. The slow factor is from hanging ability, I could actually turn the motors from torque, to HS that would probably have some more speed and still hang.

I was aware of the rubber band assist in goign down, but I am only considering, i can’t decide right now.


Our lift mechanism is horizontal and power by gears.](

I have seen your robot! I must say that the scissor lift was very well designed, with that cut c channel. It really allows you to brace your gears on both sides will maximising intake space!

normally I don’t really like scissor lifts because in the past I have seen so many of them and they never really worked well, but this is pretty cool I have never seen a scissor lift like that before, I really like the rack and pinion style of doing it :slight_smile: my advise is as soon as possible get aluminum bars on instead of steel then you can lift faster and still hang :slight_smile:

My friends robot gets to have tons of alluminium c chanel because they dont sell steel :mad: lol, but yeah, aluminum is always great:p

excellent robot this early in the season!
it can do it all!
the large ball issue will just be fixed with tweaks and testing with time
looks solid!
again, great work! :slight_smile:

Here are some more close up photos of the scissor lift.

Thanks. I’ll talk to my team about it, and see if they’re interested.

Lots of good engineering and design choices to me. I’m going to go in order of the photos you posted. Many of the suggestions are quite minor, so choose what you want to do with your time crunch. unless, im counting wrong, i believe there’s 9

photo 1: It’s risky to have your intake rollers unsupported on the bottom during competition. Screws get loose often. However, I see why you have them like that and it’s benefits for grabbing. I suggest attaching lockplates in place of, or in addition to the collar and connect them to the sprocket. Also, is it possible to squeeze the sides of the drivetrain closer together? I can’t tell completely from the photo, but it looks like the robot’s axles are longer than it needs to be

photo 2: I like what you did with offsetting your top roller with your bottom roller. The chaining for that seems fair enough. I can’t tell whether you’ll need larger sprockets or not though. However, I see that the motors are also chained to your main intake. Because of this, you’ll have power decay. I suggest hard mounting your motors to improve your bucky intake, but using a set of gears or chain to continue to power the large ball intake. You can probably install the gearing between the mounting bar and intake roller and use the axles to your advantage to defend the motor

photo 3: I noticed you have a lot of motor power going on that lift system. 4 motors at 3:1 should give you about 72 pounds of lifting force. You can probably take away 2 motors and use them on your drivetrain. In reaction to this though, I also noticed that you didn’t use rubberbands. They’re cheap, you can find them in common stores, and they give you free power.

photo 4: I think you should place a cross bar across the front of the robot near the front. It should significantly increase your stability and your tolerance against defense.

photo 5: At a competition I went to, I got called out for having a rollguard like that. We were forced to remove it due to “intentional damage”. Plus they weren’t stable enough anyways. I would replace those standoffs for actual channel.

photo 6: More picky stuff. your motors are currently exposed to ramming and the electronics aren’t tied down to metal. A robot has the possibility of tearing out your wires.Zipties ftw.

photo 7: the front of your intake looks connected by only 2 standoffs from the intake to the lift. Try your best to increase it to 4 points of connection

Photo 8: Your scissor lift has a lot of screw heads facing inwards. That will slow down your maintenance during competition. By having screw heads out, your team can easily tighten bolts without getting in each others way. Also, if you move your batteries and/or your scissor lift forward, i think your gravity will be more centered, allowing you to turn quickly. Also, you should add a center wheel, or change your wheels to high traction. Right now, its extremely easy to play defense on your robot from the sides

Photo 9: Did you consider sinking into the foam tiles when making your elevated drivetrain? we had an orientation like that, but we forgot to consider sinking.

EDIT: I haven’t watched the videos, I wrote this in school

Dude, how heavy of a robot did you build? Any “sinking” into the tiles should be so negligible as to mean nothing.