Why do we use :Inverse() when Applying CFrames to Welds

[nicemike40]

Here, I have answered a similar question before. It may be useful to you:

Why do we inverse cframes after welding?

Inverse() is like the negative version of a CFrame. So you can use it to compute offsets: local a = PartA.CFrame local b = PartB.CFrame local aToB = b:Inverse() * a -- b:ToObjectSpace(a) does this same thing So in this example, a * aToB == b This is useful for welds because welds only know about offsets. So if you were welding PartA to PartB you would just need to set the C0 of the weld to aToB, because C0 literally means “the offset from Part0 to Part1” (if C1 is CFrame.new()). local w …

Also see this post for more details about what C0/C1 actually mean:

Can someone tell me what C0 and C1 properties are?

A Weld is really a point in space. C0 is the position of that point, relative to Part0. C1 is the position of that point, relative to Part1. So if C0 = CFrame.new(1, 0, 0), and C1 = CFrame.new(-2, 0, 0), the weld’s position is 1 stud to the right of Part0, and 2 studs to the left of Part1. Meaning that Part1 is 3 studs to the right of Part0.