Official Q&A: VRC 2020-2021: Change Up

Question

638: Where do we Measure the Bottom 2 Rings on the Side Goals?

41091A

16-Aug-2020

Further clarification is needed regarding the previously-asked question "G19 Goal Height Tolerance” from the Q&A. Although the game manual has been updated, there has been some debate and confusion about how to properly set up the side goals - e.g. see (https://www.vexforum.com/t/goals-clamping-down-on-change-up-balls/83688/16).

Some teams take the May 25 update to mean that NO part of the goal could be lower than 6.13” and any part of it could be up to 6.63”, other are interpreting this differently; some interpret it to mean the back of the goal have these tolerances, while others think it is the front of the goal. The Game Manual, Appendix A, and the Field Assembly instructions don’t make this clear and don’t appear to represent the actual physical realities of the side goals.

Teams will benefit from a clear understanding of how the field will be set up at competitions and will be better prepared with clarity. Please provide more clarity.

The Game manual at <G19> states, in the 6/25/2020 update: “The bottom opening of Goals between the lowest two rings has a dimensional tolerance of -0.0 / +0.5”.

Appendix A at “Wall Goal Specs” (sheet 7) in the 5/15/2020 update: Shows ALL RINGS PHYSICALLY LEVEL with the distance between the two bottom rings MEASURED HALFWAY FROM THE FRONT TO THE BACK at 6.13” (+0.50/0.00).

Field Assembly Instructions on Page 7 (276-6499-750): Shows the cardboard measuring tool measuring the distance between the bottom two rings AGAINST THE BACK TUBE.

There are several issues that are causing confusion:

 a. Appendix A and the Field Assembly Instructions show a side goal that is level, when in fact, nobody’s is actually level; they are all drooping forward. See point b. below for why that is an issue.

    b. Appendix A and the Field Assembly instructions measure 6.13" from different locations – from the middle and from the back, respectively. With a goal that droops, when measuring from the middle of the bottom two rings (Appendix A), the goal will be higher than a set up that measures 6.13” and its tolerance from the back tube (Field Assembly Instructions). Both setups can result in the very front of the goal (the part of the ring toward the middle of the field) being below 6.13”, even with the stated tolerance; these goals are drooping quite significantly after having little play on them.

   c. It is not apparent whether 6.13” and its tolerance means that NO Part of the ring (whether front or back of the drooping ring) can be below 6.13” and/or whether NO Part of the bottom two rings can be above 6.63”. Consider the case where the front of the ring is at 6.13”, but to get it to that height, the back side connected to the long tubes needs to be higher than 6.63”. Conversely, consider a goal that sets the back side to 6.13”-6.63”, but had a more significant droop than other goals, resulting in the front of the goal being very low.

To eliminate the confusion, it would be helpful to have clear guidance for the following:

What is the shortest vertical distance between ANY PART of the lowest two rings?
If the droop results in the tolerances being outside of the stated +0.5/-0 what should be done?
From where should the vertical 6.13” and its tolerance be measured?

G19

Answer 1

Answered by Game Design Committee

What is the shortest vertical distance between ANY PART of the lowest two rings?

6.13" (155.7mm).

If the droop results in the tolerances being outside of the stated +0.5/-0 what should be done?

It is the responsibility of the Event Partner, in conjunction with their Head Referee, to ensure that fields are assembled according to the specifications listed in Appendix A. If a field is found to be assembled incorrectly, it should be fixed as soon as possible (i.e. prior to any upcoming Matches). It is generally good practice for Head Referees / Event Partners to check key field dimensions regularly throughout a tournament, and adjust as needed.

From where should the vertical 6.13” and its tolerance be measured?

Any location on the top surface of the bottom ring, perpendicular to that ring, vertically towards its associated point on the bottom surface of the second ring.

In a perfect world ("it works in CAD"), the two surfaces would be parallel to each other, and it would not matter where they were measured. This is why it is presented that way in Appendix A - no angle dimension is specified.

In reality, we acknowledge that perfectly parallel surfaces are not a feasible expectation. Therefore, the tolerance was written as (-0.0 / +0.5”) to provide guidance that "if it's going to err, err on the plus side".

Consider the case where the front of the ring is at 6.13”, but to get it to that height, the back side connected to the long tubes needs to be higher than 6.63”.

With the above answers in mind, this is a good example of a goal that has been assembled out of tolerance, and should be rectified as soon as possible.