Warning to Those Making a Wooden Scale

FIRST General Forum
1

Just a word of caution to teams who are following the official team drawings for the field. The structure on top that includes the rung will not support the weight of a robot. My Ri3D team built it as per official team drawings and it clearly was not able to hold 120lbs. We ended up welding steel (aluminum should also work) to build that section of the scale. It was easily able to support ~330lbs. I reckon it can hold much more than that.

For clarification, I am regarding to the assembly consisting of parts 1, 9 and 11 on page 51 of the team drawings:

2

The wood scale that we had held our robot without issue. I’m 6’ 7" 230 lbs and I was doing pullups on our rung. Not sure if 3026 did anything special when they built our field elements, but it looked stock to me.

3

Interesting. Perhaps we were the ones who built it wrong :D. I would still suggest to make a metal version of it for teams wanting to lift 450lbs.

4

When we built the scale for the Minneapolis kickoff one of the new builders was convinced that it couldn’t be a climbing challenge because they wouldn’t have specified a pine dowel for that. I told him that I’ve seen FIRST make far more suspect choices with the field drawings.

5

The wood scale that we had held our robot without issue. I’m 6’ 7" 230 lbs and I was doing pullups on our rung. Not sure if 3026 did anything special when they built our field elements, but it looked stock to me.

No modifications were made to our scale. We built is as the team drawing specifies. We were able to hang 2 people on the same rung (about 380 LBS). More then safe enough for 1 robot to climb. 3 might be okay but probably pushing its limits.

6

The current drawings also don’t allow you to climb using the sides of the rung. I don’t believe it will be strong enough nor is it the correct width (2.75" on the team drawings vs 2" actual).

7

The rules state you can’t really use the sides holding the rung to climb anyway, so hopefully it doesn’t affect much for those testing on it.

8

Look at the Q and A question 6: FIRST FRC Q&A System

Yes, the box tubing is part of the RUNG as highlighted in 3.3.2. G19 specifies how ROBOTS are permitted to interact with the RUNGS

9

Can you cite the rule that says this? The Rung is defined as both the round and square portions of the tubing.

10

My fault, work blocks the QA site and didn’t realize the confirmed the rung’s definition in that way. ::ouch::

11

Another thing of note is that the wooden drawings use a 1.5" dowel. The 1-1/4" sch40 pipe being used for the real field has an actual diameter of 1.66". It’s a small difference, but still a difference. Also consider the difference in surface properties between wood and aluminum…

Do you have pictures or can you give a description of how you attached the steel structure to the wood scale?

12

I don’t have any pictures of it at the moment. Basically, it was just bolted (with 1/4-20 bolts) on to the 2x4 that the wooden version of the rung would have attached to.