How to fix this curve? It should be straight.
There are no excess vertices to be deleted.
Tilt is 0 for all vertices:
did u check whether tilt is 0 for all vertices? if yes, pls provide blend file. thx.
This is a general problem with curves and tilts/rotation in 3D… ( i’m not sure if this is the well known euler axis rotation problem… ) so when you change the spline type to bezier and then select the “upper” handle of that edge and rotate it for exampe 30 degree in the Z-axis…
…your problem might be solved… but as you can see…then you have another problem on the upper edge…
Edit: …and by the way… your profile also isn’t the same width all over the place in the first place… even if radious and weIght are all 1.0… the real problem is the 3D in the curve if you just use 2D then this doesn;t occure…
This might be better solved with some other lofting profile along mesh solution…