Robotics Education & Competition Foundation
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Official Q&A: VRC 2022-2023: Spin Up

Usage Guidelines All Questions

String/Rope That Chages Diameter Under Tension


Nathan Rossi (Event Partner)
13-Nov-2022

<R7>

R7e states: An unlimited amount of rope / string, with a thickness / diameter between 1/8” (3.175mm) and 1/4” (6.35mm).

Some types of string (i.e. yarn) when measured under no tension on the original spool of string are within the specified tolerance of R7e. However, when the string is placed under a small amount of tension when used on a robot mechanism, the string becomes smaller than a diameter of 1/8”.

Under what circumstances should string/rope be measured to ensure it falls within the tolerance of R7e? Does string/rope need to be rigid enough such that it does not deform below tolerance at all points on the string?

Thank you for your time!

R7  
Answered by committee

Under what circumstances should string/rope be measured to ensure it falls within the tolerance of R7e? Does string/rope need to be rigid enough such that it does not deform below tolerance at all points on the string?

Thank you for your question! String should be measured on the Robot under no load. There is no requirement that string be rigid enough that it does not deform under load; however, elastic cord/string/etc. is not permitted. Latex tubing (VEX part number 275-1262) is the only exception to this limitation on elastic string.

String must measure at least 1/8"/3mm (at its narrowest point) while on the Robot, should remain highly visible on the Field during Match scoring, and should be easy to untangle from Field elements and other Robots after a Match.

Inspectors are encouraged to use a measuring tool of their choice to inspect string that appears to be close to or below the minimum or maximum sizes. At the VEX World Championship, Inspectors will have tools to measure the diameter of string. The details of these tools will be announced later so that teams can be prepared going into VEX Worlds.