Problem ceating flat pattern from sheet metal

Hi Guys,

I am new to solidworks so please bare with me.

I am building a chassis for my hotrod. The chassis rails taper in the side elevation from front to rear and have bends/curves in two planes.

I have a 3d solid model of the rails, 2d side and top elevations and have managed to produce each face as a piece of sheet metal.

I did this by sketching one elevation on the top plane, the other elevation on the front plane. I then used one edge of one sketch to create a sheet metal base flange/ tab. I then used the sketch on the other plane to perform an extruded cut through the sheet.

I have all four sides of the chassis rail generated like this and they all fit together to make a box section. Now I need to flattern these pieces in order to generate the true 2d geometry to send out to the laser cutters. I have managed to do this with the top face inside face and outside face but for some reason I can't get the bottom face to work.

Any help would be very much appreciated.

lbottombent.SLDPRT

You are missing two tangents in Sketch1.

Also, I would not use Extrude Cut to trim sides across bends - the resulting flat does not have sides perpendicular to the flat (you can check this in wireframe).

A better way it to Thicken a trimmed surface body. This ensures the part is uniform thickness and that the sides are perpendicular to the flat.