Tutorial: a Guided Loft and a Sheet Metal Tray

This tutorial builds a small duct and a tray with tools added in the 0.17 versions: the closed control-point spline, a plane placed with Placement, a loft that follows a guide curve, a variable fillet with a point along its edge, and edge flanges that meet corner to corner. The finished part is in File ▸ Open Example Part (Tutorial) (also on the start window): open it to look round, or follow the steps in a new part.

The bottom profile

1. Select the Top Plane and click Sketch.
2. Click Control-Point Spline on the Sketch tab and click eight control points round the origin, roughly at (50, 0), (40, 25), (0, 30), (−40, 25), (−50, 0), (−40, −25), (0, −30) and (40, −25). Click the first point again to close it: the curve runs round smoothly, near the points rather than through them.
3. Select the spline: its panel shows the Degree (3) and the Closed box. Select a control point to see its Weight; leave it at 1 for now. Drag a control point and the curve follows.
4. Exit the sketch.

A plane, moved and turned

1. Click Reference Plane, pick the Top Plane and set the offset to 100.
2. Under Placement, set Turn its axes in the plane to 30°: the plane's axes turn in the plane, so whatever is sketched on it turns with them.
3. Sketch a circle of radius 20 at the origin on this plane and exit the sketch.

The guide curve

1. Sketch on the Front Plane. With Control-Point Spline, click three points: the first where the bottom profile crosses the X axis (about 46.67, 0), one out to the side (about 62, 45) and the last on the circle (20, 100). Finish with a double-click or Enter.
2. A guide curve has to touch every profile. The first point lies on the bottom profile's curve, not on a control point: with these control points the curve crosses the axis at 140/3 = 46.6667 mm (select the point and type 46.6667 for its X in the panel).

The guided loft

1. Click Loft, pick the bottom sketch and then the circle's sketch as the profiles.
2. Under Guide Curves, pick the guide sketch. The loft's side follows the guide between the two profiles, and the profiles stay exactly as drawn. The note reads "2 profiles, 1 guide curve".

A fillet with a point along its edge

1. Click Fillet, set the type to Variable size and Radius to At vertices and points along edges, and click the loft's bottom edge where the guide starts.
2. Set the radius to 3: that is the radius at the edge's vertices.
3. Under Points along the edges, click Add Point: half way along the edge (50 %) with a radius of 8. The point is marked on the edge; the fillet swells smoothly from 3 at the vertices to 8 there.

The tray

1. Sketch an 80 × 60 rectangle on the Top Plane, beside the duct, and click Base Flange on the Sheet Metal tab with a thickness of 1.5 mm.
2. Click Edge Flange and pick the four top edges, with a length of 20. Under Corners, Corner to corner is the default: where two flanges meet, each runs on up to the other's inside face and ends square, the gap apart, and the bends end in a small V cutout. Mitred would close them on the diagonal, and Overlap would run one flange past the other's end.
3. Click Flatten to see the tray laid out, with its bend lines.