I put a metro in front of the attachment but it seems the right side of the patch is sometimes faster than the left causing the loop to go off the rails.

I've probably already made a mistake here, please let me know.

http://www.pdpatchrepo.info/hurleur/upanddownbox.pd

Make sure to use the [t ] object to ensure that they get executed in the right order.

I think I may have just been an idiot, thanks anyway.