Vex Bridge Battle rule Explanation

Can anyone explain rule G11 from the Bridge Battle Manual

Field tolerances may vary by as much as +/-1”, so teams must design their robots accordingly.


probably means that the fiels elemeants…ie the bridge can vary in dimension slightly along with everything else…

That makes sense, can any IFI robotics engineer confirm this?

Another question,

I am using 6-32 screws from my hardware store that are flathead. I figured since the VEX ones strip a lot, i would rather use the flathead screws. (silver color) Can I use these or will I get disqualified during inspection?

I would suggest not using these, for they are not exactally identical.


The VexLabs screws don’t “strip a lot”. Hundreds of users use dozens of screws in each robot they build and only very, very infrequently do any of these people have a screw head “strip”. If someone told you that they strip a lot when being tightened or loosened by a correct tool during normal/appropriate use, they were mistaken.

PS: Using screws that are not identical to the Vex screws (right down to the hex button head (instead of flat, torx, phillips, etc.)) will be illegal at FIRST competitions.

ok i have NEVER had a screw of any type(black or silver) strip, and i have tightened screws so much my hex key broke!! the screw did still not strip, the paint might rarely possibly come off but i doubt it, this would not really count as stripping though

+/- 1 in means that they aren’t going to hold the person who built the field responsible if it is not exactly perfect.

I seem to have bad luck then, because the 6-32 motor screws have stripped a couple of times (with the right size tool) and have forced me to do some painstaking work to remove them from the motor.

Thanks, I guess I’ll just order some more Vex 6-32’s.


Well I guess I will have to take this into account when I am building my robot.


It has happened to me too; and so far I have been successful by removing (and throwing away) the screw as soon as I notice any that it is getting sloppy.

I have had good luck removing almost-stipped screws by holding the allen wrench at an angle so that it is able to press aganist whatever vestiges of the orginal surface remain.


I have also found that ball head hex wrenches are very effective at removing stripped 6-32s.

This is exactly correct.

It is a good practice for teams to design their robots with a factor of safety anyways. This rule is designed to protect event organizers from complaints about minor field variances.

Will there ever be a goal which is an extra 1" taller? Probably not. Should you design to go 1" taller than the goal height just in case? Absolutely.


Are we allowed to change our robot battery in between matches.



Yes, they wouldn’t make you run the whole thing on one battery.

Is there any rule which says you’re not allowed to do this?

no the only rule on batteries is that you can only use one power pack at a time so only one controller battery and one robot battery


just to clarify…
the rules allow you to use only one battery in the robot per match, but it does not say anything about switching batteries in between matches.

Is this is correct? (I can switch batteries)


I may not be John, but it should be fine if you swich batteries. They won’t require you to last a whole tournoment without a recharge

ok at my comp. i saw teams with 5 power packs at least but they can only use one at a time

i kept my single power pack charged between matches and it was fine, and we had 6 motors and were doing some serious motor usage