✓ Accepted answer
You have made one error in your script, C0 is already a CFrame value so you don't have to do...
armweld.C0.CFrame
Also another thing you should have done is just added from the current CFrame that you had to work with so it should've be something like this...
armweld.C0 = armweld.C0 * CFrame.fromEulerAnglesXYZ(0, 0, 90)
armweld.C0 = armweld.C0 * CFrame.fromEulerAnglesXYZ(0, 0, 90) * CFrame.new(0,0,0)
Yet another thing!!!!!!
When using CFrame Angles, the Angles work in some other different kind of rotation system so you should make it so it does it in radians, this will make it so you can use the normal rotation system. This is how it should be done
armweld.C0 = armweld.C0 * CFrame.fromEulerAnglesXYZ(math.rad(0), math.rad(0), math.rad(90)) * CFrame.new(0,0,0)
If this helped please accept my answer! ~tantec
2 comments
Don't repost problems. To properly format your code, click the blue Lua icon which will insert two lines of "~~~~". Then place your code in between these two lines.
I only reposted because I couldn't find my first post even when I clicked "mine"