Sizing tool variance

I bought one of the new-style (e.g. the one that can expand to 36inches) official-from-Vex sizing tools. In spite of my best efforts (and re-efforts) at assembling it, the tool is off by 1/8 inch both vertically and horizontally (it is too large). Has anyone else had similar issues? Any ideas on how to resolve?


Yes, I have the exact same issue.


I could be wrong, but it seems as if the sizing tools have always given slightly more room than 18inches in every direction. (Or it might just be that 35 hole c-channels are by default slightly less than 18 inches long; I have never actually measured the sizing tool to see if it was actually 18 inches.) I’m not sure, but this could just be VEX’s “grace” when it comes to sizing. Again, I could be wrong, but I think this is normal for a sizing tool.

35 holed c-channel is 17.5 inches


Yes, but it always feels like there’s more than half an inch of extra space in the sizer when I put a full length c channel in it. (I may be wrong; feel free, someone, to correct me with the facts)

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The new ones are definitely slightly large than 18 inches. My school uses the really old one (the one that uses a steel plate on the bottom), and measurements during competitions seem more lenient than at school . I imagine this is to make measuring easier for inspectors. With a properly sized tool, it is very difficult to make sure everything is lined up when checking the size of a robot.


I contacted my regional manager. The size variance is known and intentional.
My questions:
Depending on which sizing tool is used for inspection, can a team pass at one event, then fail at the next event with the exact same robot?
Seems appropriate that some decision and accompanying language about sizing would alleviate some headaches.


What does this mean - that Vex has intentionally made the 2 different models of Sizing Tool (e.g. the old steel one and the newer aluminum one) that don’t measure the same dimensions? Or is it known that there is simply variance from one sizing tool to another, due to manufacturing, assembly, etc.?

I’m concerned with handling situations where a robot passes inspection under one sizing tool but fails a field sizing check under a different one.