# A Note On Rung Dimensions

Note that the text in the rules is slightly misleading:

MID, HIGH, and TRAVERSAL RUNGS are spaced such that their centers are
2 ft. (~61 cm) apart.

What this means is that the horizontal distance between centers is 2’, not the actual center-to-center distance. The drawing (fig. 5-17) and the official field CAD are in agreement on this point. The C-C distance between rungs is approximately 28 1/2".

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Isn’t the distance from the low rung to the mid rung 3’ 6"? The complex model may have an error.

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The 2 foot number is handy, though, in that it immediately makes it obvious that any design where the robot hangs with its base parallel to the floor and reaches out to grasp the rung may violate the 16" extension rule (depending on robot size/shape). We’re probably going to need to get that base up at an angle, through some combination of clever mechanism, shifting center of gravity, and/or swinging.

It’s going to be fascinating to see the designs teams come up with!

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Keep in mind that your grasp of another rung does not need to be on the forward-most edge of your frame perimeter.

Or it does, but instead of reaching straight out past your frame, you instead reach in the opposite direction over your chassis first, and then past the far side edge of your chassis…

But that still has lots of COG issues to deal with

Excited to see other teams solutions to these rungs, I’m sure hoping my team decides not to go for the traverse…

Also, the complex model puts the top of the 2nd bar 60.61 inches off the ground instead of 60.25in.

The complex version of the wooden field is not the full size of what is seen on the competition field. Since the mid, high, and traversal rung spacing is consistent with what is seen on the real field (the rungs are just not as wide as on the real field), and since all of the heights are true to life, I think they just shortened the distance between the low and mid rungs for convenience sake. The thinking would be that since you can reach to 5’6" when you’re in the Hangar zone, you would climb directly onto the mid rung and then do a monkey bar-type maneuver to get onto the high and/or traversal rungs. There isn’t really a point in climbing onto the low rung first and doing the extra in-air movement when you could just reach it from the ground, so I guess the people at FIRST decided it would be better to move those bars closer together for easier assembly. There isn’t any real necessity for those bars to be spaced 3’6" in the wooden model.

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In the manual it said that in the Hangar zone, an extra layer of hardboard and carpet is placed over the normal field carpet, adding another ~3/8" above the normal field carpet. Maybe that difference you found is to account for the extra floor thickness so that the overall height of the bar compared to the rest of the field is the same without teams needing to get hardboard and extra carpet?

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Shouldn’t it be lower rather than higher then?

Edit: I see what happened, they are actually expecting you to add hardboard and carpet as well to the team element.

That totally makes sense. We are going to move it out to the distance specified in the manual. The only reason we discovered the discrepancy was when we were lining up the rungs on the field. We were confuse when the rung distances were either too short, or too far away from the driver station. I just wanted to make sure I wasn’t going crazy yesterday.

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I believe the plywood and bar height placement are to avoid the necessity of adding hardboard to the carpet. You should be able to just place the field element on your normal field carpet and it will be at the same height.

The manual says it’s 60.25 from the floor protection carpet to the top of the rung, the team element measures 60.61 from the lowest piece of wood to the top rung. So it seems you actually are expected to add hardboard and carpet to reduce that distance by 3/8.

If anyone is interested, we did extend out the low rung to match the manual dimensions.

We still have to set up the safe zones under that rung.

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