Gearing for a claw

Someone shared this video here before but I just want to bring it up again because teams from my school just couldn’t figure out a good gear ratio strong enough to hang on to object(s) (I have no clue why but they all decided to make fork bots just for that reason, seriously). The image below is prototype that I came up with, I haven’t tested it yet but I will today. I just want to know if this gearing doesn’t work what are some other suggestions? The one in that video is a complete mystery (I can only tell it uses 2 motors :P).

(I plan to put motors on the centre 2 smaller gears)

It really doesn’t matter, the only ratio that matters is the for the lift

I believe the one in that video is a 1:5, with 2 36 tooth idler gears in the middle. We tried that ratio and it works very well, albeit a little slow. Make sure to add a lot of rubber bands to close the claw. The key is to not keep the motors running at full power when the claw is closed, otherwise they will stall.

we have one: one with torque motors with 60 tooth connecting them it worked well and is really fast

Actually, it does matter. If it’s not strong enough bring the stars in and hold them there, that’s an issue. Also, if it’s super slow with very high torque and it takes you five seconds to close, you will loose every time.

So yeah, gear ratios matter.

Gearing anything in vex matters, i think yo should try internal torque motors with 4 60 tooth connecting them we had that, it worked fine, it was strong enough to hole the cubes and fast enough to pick up stars easily

I know they matter but almost any torque ratio is fine unless it’s like in the extremes.

No. You are wrong. The gearing for the claw matters. These claws need the torque to keep the stars and cubes from falling out. According to your suggestion, you are saying that a 1:1 claw will have enough torque?

As you can see above I explained that any torque ratio would work unless it was in the extremes. I corrected it by saying that. Did you even read the post above yours? A 1:1 can work but it will be really crappy.

I would suggest 1:5 1:3 or 1:7 for a claw ratio

I use 1:5 with 2 torque motors and PID (to apply just enough power to hold the claws in position), and that works very well. I would be hesitant to go too much lower in torque because without PID or if you are grabbing a lot of cubes I could definitely see you stalling them. But i would guess in most cases 1:3 with 2 torque motors would work.

I have a two motor 84 tooth to 36 tooth (high strength, repeated)… It works super good!

Side note: make sure that the claw gearbox is sturdy, we had some problems when our’s was less sturdy.

I don’t really know… I saw a whole bunch of teams in the competition that had a 12/60 ratio, then I see some with 36/60. They both are able to do the same things, just one is faster, so maybe I would suggest 36/60. If you are doing 36/60, you are risking a chance of the motors frying fairly fast. If you are doing 36/60, maybe add a potentiometer to be able to make the motors only do the needed force, and also adding rubber bands closing the claw when no power is active will help.

personally, i use pneumatic, because of their ability to open and close immediately

This is what we have currently on our main bot. We geared the claw to 1:5 and added 2 #64 rubber bands. We use a potentiometer to stop the motors from stalling. Speed when opening and closing has never been an issue. We can score cubes every 7 seconds with our current claw setup.

I recommend that you use two joysticks, giving the claw operation to a different person than the one operating the drive. This will greatly increase speed.

On the contrary, I would argue that, unless the two drivers are really good at communicating with one another, timing would be much better synced if you have one driver controlling both, as long as they have a little practice. Just my opinion… Changes depending on the team and robot itself.

I will never, never, recommend partner joysticks(with the exception of a few edge cases)
The legendary 1103 had it right- the computer is your partner. These robots are not significantly complicated, but I understand that in the middle of a match it may get difficult. A computer will always be there to practice with, and always be consistent, and all the communication is with your hands. For this exact reason I have a button, that, once I have my hang hook inserted into the pole, the robot will automatically hang and lock itself. A good coder + a good driver will always beat 2 of the best drivers with identical bots.

How do the robots with claws in the video contract their claws so that they fit within the size limit before matches?

hinges are your friend, just like the passive forks, u can use hinges and a lock

What kind of a locking mechanism? @vex2.0