Lofted Cut
Lofted Cut takes material away in the shape of a loft. Two or more closed profiles, each in its own sketch on its own plane, are blended in the order listed, and the blended shape is cut out of the part. Up to eight guide curves, each in a sketch of its own, steer the sides of the cut between the profiles, for a pocket that bows, bends or swells. It is the cut side of Loft: the same panel, set to Cut material.
When to Use It
- Cut a pocket or a hole whose shape changes with depth, such as round at the top and square at the bottom
- Cut a curved or bowed hole with one guide curve, or a barrel shaped pocket with two
- Cut a tapered opening that passes through three or more different shapes in turn
Step by Step
- Start with a part to cut. Lofted Cut needs a solid already there.
- Draw the first closed profile in a sketch, often on a face of the part, and click Exit Sketch (see Exit Sketch).
- Draw each further profile on a plane of its own: type a distance in the Offset box of the Sketch on panel before you pick the plane (see Reference Planes). Click Exit Sketch after each.
- For guided sides, draw each guide curve (optional, see Guide Curves below) in a sketch of its own, and click Exit Sketch after each.
- Click Advanced on the Features tab, then Lofted Cut. The panel opens as Lofted Cut with Cut material lit.
- Check the Profiles list: the up and down arrows reorder, × removes one, and the picker with Add puts another waiting sketch at the end. Clicking a sketch in the Model tree adds it too.
- Add guide curves under Guide Curves: pick a guide sketch and click Add, or click it in the Model tree.
- On a part with more than one body, choose which bodies to cut under Bodies to cut in the Cut panel (see Extrude and Cut).
- Watch the red preview, then click Lofted Cut.
Guide Curves
A guide curve for a lofted cut is the same as for a loft: an open run of lines and arcs, in a sketch of its own, from the outline of the first profile to the outline of the last, passing through the outline of every profile between. With guides, the profiles must be on parallel planes, listed in order along them.
- One guide: each section moves sideways to keep touching it, so the hole bends but keeps its size.
- Two guides: each section moves, turns and stretches along the line between them.
- Three or more: each section takes the closest even stretch that touches them all.
The Loft page has every rule for guide curves; they are the same for the cut.
Options
- Add material or Cut material: the panel heading reads Lofted Boss/Base or Lofted Cut. The Lofted Cut button opens it as a cut, and after it the Loft and Boundary buttons open as an added solid again. The two buttons in the panel switch it either way, and a choice made there stays; the lit button on the toolbar follows.
- Profiles: the numbered list in blend order. The button needs at least two.
- Guide Curves: the numbered list of guide sketches, up to 8, each with × to remove it. Leave it empty for a plain lofted cut.
- Bodies to cut: set in the Cut panel when the part has more than one body.
- Start and end constraints are None: the profiles blend smoothly in the order listed.
Edit It Later
Right-click the step in the Model tree and choose Edit Feature. You can reorder the profiles with the arrows, and a guided lofted cut lists its Guide curves, each with a × that removes it. With none left, the step is the plain lofted cut. Click Apply to rebuild. To change a profile or a guide, right-click its sketch under the step and choose Edit Sketch. To add a guide, delete the step and cut again. Undo puts a removed guide back.
Tips and What to Expect
- The cut is exact. A 4 mm circle on the top of a 20 mm cube lofted to a 4 mm circle 10 mm below it, with one arc guide that bows out 1 mm at the middle, cuts a bent hole of the same 4 mm size all the way: pi x 2 x 2 x 10 = 125.664 mm3, the same as a straight hole.
- The order of the profiles matters: reordering changes the shape of the cut.
- The red preview shows the shape that will be cut away, before you click.
Common Problems
- "The cut removed no material." followed by "The lofted shape does not pass through the part." Move the profiles or the guide curves so the loft runs into the part.
- "A loft needs two or more profiles, each a closed shape in its own sketch." Add a second profile.
- "A loft takes at most 8 guide curves; this one has 9." Remove a guide.
- "Guide 1 misses the outline of profile 2 by 0.500 mm." Edit the guide sketch so the guide passes through that outline.
- "With guide curves, every profile must be on a plane parallel to the first." Put every profile on a plane offset from one plane, or remove the guides.
- "There is nothing to cut yet." Make a solid first, for example with Extrude.
- "Tick at least one body under Bodies to cut (Cut panel), or tick Cut every body it touches."