Clawbot arm won't move up due to weight (I think)

Hello,
Just bought the IQ kit and been working on building the Clawbot per included instructions.
I noticed that the arm is not able to move up as requested even with provided template code. It is able to move up, but very little - may be like 10 deg.
After some troubleshooting, it appears due to weight of the claw motor.
If I remove the claw motor, it is able to move up smoothly.
Please help.
Thank you in advance.

Welcome to vexforum @agokhale! Hope you enjoy your stay.

Can you please send a video of the problem happening or at least some pictures? That will make it much easier for us to help you.

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The motor should be plenty strong enough. My guess is physical obstruction, like a wire getting in the way somewhere? Or was the claw motor somehow in the wrong spot and blocking the arm from moving? Check your build again, good luck!

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The thing I can think it might be is you didn’t charge the battery once you got it. It might be a reversed gear ratio, though. Can you send pictures and videos?
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did u try turning it off and then on again

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@Noah10851B @Milo409B Please see uploaded video. Thanks in advance.

Unless it’s normal for IQ motors to squeak like that, it’s probably part of the problem. Can you send a picture of where the gears actually mesh?

yes, no difference even after turning off and then on

There’s not enough torque to lift the arm up, so it’s likely because of friction or some discrepancy in the motor itself. I’m pretty sure whatever is causing the squeaking is the issue

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Thanks, appreciate it, will look into

It seems like you have the motor driving the large gear directly. Is that right?

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That’s exactly the problem, the arm motor is mounted incorrectly, it should be driving the small blue gear.

image

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Thank you so much @jpearman and @Noah10851B . That was it! This is my 10 yr old son’s “real” first toy, hopefully he (and I :slightly_smiling_face:) get better at following instructions going fwd.

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The reason that changing the gear setup like what @jpearman said, is because of the:

SCIENCE OF GEAR RATIOS

Before we understand gear ratios, we need to understand:

MECHANICAL ADVANTAGE

So, what is mechanical advantage? Mechanical advantage is the trade-off between torque and speed. High torque = Low speed.
And likewise:
Low torque = High speed.

The same principles are used when you use a jack to lift up your car for repairs, and also the same way the ancient Egyptians built the Great Pyramids of Giza.

For more information on mechanical advantage, I would recommended watching Mark Rober’s video on mousetrap cars or even this video about transmissions by Ford from 1936 (this one is really simple which is way I like it so much).

Now how does this transfer over to gear ratios?
Well, when you drive a smaller gear with a bigger gear, it will produce a speed gear ratio. And vice-versa.

The orange gear is the gear connected to the motor and the green gear is the one connected to the component you want to move.

image

Ok, but where are the ratios?
The ratios come when you want to calculate the torque and speed amount.
The first ratio would be 3:1, because for every 1 time the Driving Gear spins, the Driven Gear spins 3 times. We know this the Driven Gear has 12 teeth and the Driving Gear has 36.
36:12 reduces down to 3:1.

I hope I didn’t over-complicate this. If you have any more questions, PLEASE check out this STEM lab by VEX on gear ratios. Or feel free to private message me,

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