Due to how FIRST designed their c-channel and angle brackets, it is impossible for the outside frame dimension to be a whole number inch, the length will always have a .25 inch over the length of the c-channel. The rules allow for a square robot 28" by 28", but when we built the robot it ends up 28.25 since the channel is 1.125 inches wide. Will the .25 inch be an issue in inspection so we have to cut it down to 27.25 inches?

See Rule R03 - maximum frame perimeter 112

See Rule R04 In the STARTING CONFIGURATION, no part of the ROBOT may extend outside the vertical projection of the FRAME PERIMETER, with the exception of minor protrusions such as bolt heads, fastener ends, rivets, etc.

It causes your frame perimeter to be over 112", so you’ll be cutting it down. Whether you do it now or at the event is up to you, but I highly suggest doing it now. You could do that by just taking 1/2" off in one direction, instead of 1" in all 4 directions, if being a square isn’t critical.

Ask any team who had to redo their robot after a bolt head didn’t fit into a size box in previous years how rigid the inspectors are… there’s a reason many teams design slightly undersize.

Yes, as noted above you will not pass inspection.

Oh, my mistake, I did my math wrong (thought it was 102 for some reason) and assumed he was concerned about the max dimensions from last year. I’ll delete my post.