so i need the edge of a side but it needs to always be the right side and the side might be any side i have already got the side i can't get the edge also the part might be rotated 90 degrees 180 or 270 is there anyway way to get the right edge?
You can use CFrame.Angles and Orientation to decide the CFrame rotation of the part.
PartCFrameRotation = Part.CFrame * CFrame.Angles(-math.rad(Part.Orientation.X), 0, 0) -- I don't know the exact axes
If you know the size of the part you can multiply this value with CFrame.new() to get to the edge.