High Strength 84-Tooth Gear

My team and I were recently working on our competition bot. We have 2 motors geared from a 12 tooth gear to an 84 tooth gear. We were working on code and our 84 tooth gear broke. It wasn’t a tooth that broke, it was the hole where the shaft wen through. It almost looks like a circle now. I was wondering if there was a high strength version of the 84 tooth gear. If not, how could I reinforce the gear so it doesn’t happen again.

We have one gear on each side of an arm and we stripped both of them. Has anyone used a 12 tooth to a 60 tooth? If so how did it work for you.

A lot of teams will take two 84-tooth gears and screw them together to increase the strength of the gear to prevent breaking.
When the center hole strips and no longer holds the axle, you can screw bar locks to the gear so the axle is held by those, which are in turn attached to the gear via its screw holes. If the gears are next to the arm, you should screw them directly to the arm so the axle is only supporting it and not subjected to torque.

  1. You are applying too much torque to the joints. Once you reinforce the joints between the gears and the axles, there is a good chance the axle will twist.

  2. Convert the new round holes into carefully aligned new holes; and insert the High Strength Gear metal hubs into the new 84-tooth gears.

  3. Use metal Bar Locks to supplement the 84-tooth gear’s connection to your axle instead just using the hub of the 84-too gear.

  4. Double up the 84-tooth gears so that 4 are used to make two pairs. In each pair place the gears back-to-back and bolt them together.

  5. Instead of using gears, use a chain that starts at a motor, is looped over a sprocket or other low-friction, load-bearing point, and is then attached to the pivoting device some place that creates the right mechanical advantage for the motor to be able to do its job (think of lifting a cartoon castle’s drawbridge.

  6. Use a rack and pinion arrangement to raise and lower the pivoting device.

  7. Use springs (elastic) or counterweights on the pivoting item to reduce the torque that must be transferred through the 84-tooth gears’ hubs.

  8. Et cetera, et cetera, et cetera.

Thank you for the feedback. I was thinking about using elastic. What do you think about using a 12 to 60 tooth gearing ratio?

Are you powering the 12 Tooth Gears?

And are you looking for power, or speed.

-If you want power: Power the smallest gear directly from your motor chained to your largest gear which is connected to your lift.

-If you want speed: Power your largest gear directly from your motor chained to your smallest gear which is connected to your lift.

I hope this is what you were talking about.

I was thinking of using gears. Chain would work, but our team doesn’t have much of it.

Well just take off the chain.

Do you want strength or speed?

Like I said before:

-If you want power: Power the smallest gear directly from your motor geared to your largest gear which is connected to your lift.

-If you want speed: Power your largest gear directly from your motor geared to your smallest gear which is connected to your lift.

when you say arm i assume metal is going on the same shaft as the 84 tooth gear if you bolt the metal directly to the gear you will no longer have the problem because the shaft will become simply a pivot point. a similar thing happened to a team at my school in the clean sweep season and when they reinforced the gear the shaft twisted.

I was thinking about mounting the arm directly to the gear. Just the way our robot is built, it would be nice to just switch out gears. I am looking for a powerful arm. It doesn’t need to have alot of speed, but any extra would be helpful.

Do you think 12 tooth to 64 tooth would be enough torque?

It should be fine.

How much torque do you need?

How heavy is your collection mechanism, and how many objects do you plan to carry?

I would agree mounting your bar to the gear would not make it break/slip etc.
We are doing that this year, and we also did that last year and we had NO problems with the gear.

The mechanism isn’t very heavy. It only carries 2-3 objects. The mechanism is a dual conveyor belt system that is just wide enough for the objects. With the 84 tooth gear, if the robot fliped onto its back, it could roll itself back over with its arm.

You should have enough power if you are using 323 motors set on high power which are powering the 12 tooth gears which are geared to the 64 tooth gears.

You should be fine.

We are using the old 3-wire motors.


Well, I still think you should be fine.
(The 3-Wire motors have been discontinued)

It would help if you could use 2 motors on each side.

Is it possible for you to do that?

Can I have a picture/or a drawing of what your robot looks like now?

Actually, we are using 2 motors on each side.

I need a drawing/picture to see what you are doing so I can better help you.

Do you have one?

it may be enough torque but from 4.5 years of robotics experience its way better to do a quick redesign now than to have something go wrong in the 3rd match of the finals

I agree with the complete redesign. We are just so far along and we have such a “solid” design that we are trying to fix this problem first. If we have to redesign, we will but we are trying to fix it now. Here is a picture:http://db.tt/hpKCO2LS

P.S Sorry for the big pic. Its my first time. :stuck_out_tongue:

flip the motors and gears on the c-channel and then add a smaller piece for support of the axles