Would purchased mecanum wheels work as well if placed in a rectangle instead of a square like they’re supposed to?
I’ve never heard of them having to be in a square. A rectangle should be fine!
omnis are the ones generally put in a square pattern
mechanums work perfectly fine in a rectangle 
I don’t know. I’m assuming that the rollers have to point to the center of the robot, and if they’re oriented at a 45 degree angle, so they would have to be in a square. But we’ve never tried, so we don’t know for sure. None of the reports we’ve read seemed to indicate that this is the case, but many of our team members were pretty certain.
Thanks for the replies. Good to know.
Mecanum wheels work when in a rectangular configuration, although I can see how some people may think they must be in a square if they are told that the wheels must be in an x configuration when viewed from the top.
We’re living proof. We’re running in a recangular configuration with absolutely no issue.
Holonomic drivebases really work best if the rollers touching the ground are all directed right at the same point (usually the center of the robot). With 45-degree mecanum rollers, that does mean a square is optimum. But a rectangle still works fine, with only a tiny bit of power lost due to scrubbing friction.
Omnis don’t even “need” a square either, though they can be really annoying in a rectangle.
Just to be clear, for those unfamiliar:
“Holonomic drivebases really work best if the perpendicular bisectors of the axles of the rollers touching the ground are all directed right at the same point”
Our robot is using mecanums in a rectangular configuration. It works very well.