Adding Weight to the Kitbot

Has this always been there? I always find nice little surprises on the Armabot site.

Several years. Armabot product release 2018! - #2 by Andrew_Duerner

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We like to use scuba weights when we need to add weights to our drivetrains. They mount easy, and are pretty inexpensive.

This was the kind of solution I was looking for seems very reasonable!

You just have to make sure that the ones you get are rubber coated or completely sealed because they are usually lead.

The only time we thought we might want to add weight to the robot, we just bought some iron bar and drilled holes for bolts. We would have bolted them to the lower flanges of the inside sheets of the kitbot. In that case, we made them and put them in the bag with the robot.
As Billfred said, lighter is better unless you have a tipping problem and put the ballast as low as possible.

When I need weights professionally, I go with plasma cut steel plates. Make a pile of them with burnt in holes. Frac pump fluid ends work nicely too, if you need about 5,000 pounds :wink:

There are at least 2 main reasons to add weight:

  1. As you said, to avoid tipping.
  2. For extra traction for pushing (or to avoid being pushed). I’ve seen this reason for adding weight more often than to avoid tipping. When we added the 70 lbs to our 2019 off-season bot (discussed above), it was so that we would have sufficient traction to push around other robots. It was very effective. We coined the term Pushing Power Cube ™ for our power cube filled with CIM motors. Our 2018 alliance partner 2655 added weight to their robot for better defensive traction. It was very effective for them as well.

There may be other reasons to want to add ballast. but those are the 2 that come to mind.

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Did you set a record for most CIMs on a robot?


Probably. I can’t remember the exact count but I think it was 20-25 motors.

“CIM Motors - the only ballast you will ever need!”


Number 2 is the biggest one and like I said in this post I think there is a happy medium.

So if you have just a kitbot and can control its weight how heavy do you make it?

Have you played around with any of the driveline simulators (JVN, ILITE, etc)? If your acceleration is traction limited (which can easily be the case at light weight) you may find that your acceleration gets better by adding weight (to a point).

If you are planning to play a lot of defense and want to either be able to push others around or at least stand your ground in a defensive position, then you probably want to be as close as possible to the maximum weight.

If you are concerned about battery life then there may be a happy medium somewhere less than maximum weight.

I can tell you from experience that the 2019 chairbot at full 125 lbs with NEO swerve drive was not only able to push around every robot that we played defense against, but we were also the fastest robot on the field. I have no scientific proof that we were able to out accelerate other robots in a pure side by side off the line scenario, but we were never out-juked by someone trying to get around our defense. We were always able to zip into a blocking position before the other robot could get there. So, I don’t think we sacrificed any speed or acceleration by being at full weight. And when we flew off the Hab 2 starting platform to zoom down the field to play defense the first time there were a lot of startled looks on the faces of the people in the audience (including my own) with the sheer speed.


(587 drive team here)
That bot was an absolute menace on the field, DJ is the master of swerve driving.

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The one downside with scuba weights is that they need to be coated per the rules, and most are not. We solved that with a heavy coat of paint.

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