So I'm working on a project where I need to convert A LOT of curved surfaces into 16 Gauge aluminum.  I've been given a 3D model with these parts modelled as surfaces. 

-I thicken the surface and insert into part. (I thicken it a lot to help split the sheetmetal later on.)

-I create a plane relative to the flat side of the curved thickened surface

-I sketch a series of lines, or curves, on the plane, approximating the shape of the curve.

-I create a base flange using the sketch.

-I split the base flange using the surface of the inserted thickened surface, and consume the cutoff part.

-Unsuppressing the sheetmetal pattern _USUALLY_ works.  But then sometimes it doesn't. 

What crucial part am I missing? Bend radius? The part will flatten before the split, but sometimes won't after.  Is the split along the thickened surface creating edges that can't be unbent? I've played with the sketches using just radii, tangent/non tangent, just straight lines, etc. Sometimes it works, sometimes it doesn't.  Ideas?

**I need to work through A LOT of these, so finding a quick/easier approach/solution would be good.  I know there are some 3rd party add-ins, but for now I'm trying to use Solidworks capabilities.**

Thanks!

This one works, "sw convert surface to sm" attached. ("Thickened Surface" body shown for reference)

The version of the part (with curves) will flatten before the split, but not after? Bend lines, at the right heights, show up. "sw convert surface to sm failed" attached.

  I can suppress a failing bend, but then there's usually another that fails, or the flat is a bit off.