Fillet Guide
Sketch & Model

Round, bevel and hollow: Fillet, Chamfer and Shell

Fillet rounds edges, Chamfer bevels them and Shell hollows a part out. One tap picks a whole outline, and you can change the size at any time.

Round or bevel edges

Fillet rounds an edge and Chamfer cuts it off at an angle. Both work the same way.

  1. Tap Fillet in the tool strip, or press F. For a bevel, tap Chamfer.
  2. Tap an edge. The edges that run on smoothly from it light up too.
  3. Type a size in Radius, or Distance for a chamfer.
  4. Tap Done.
  1. Click Fillet in the tool strip, or press F. For a bevel, click Chamfer.
  2. Click an edge. The edges that run on smoothly from it light up too.
  3. Type a size in Radius, or Distance for a chamfer.
  4. Press ↩Return, or click Done.
One tap on the front edge picks all 8 edges of the top outline. At 3 mm the round shows before you tap Done.

The part shows the round as you type, so you see the size before you commit. A new fillet starts at 1 mm and a new chamfer at 0.5 mm.

Edges already selected? Tap Fillet edges or Chamfer edges under Next in the inspector, and the step opens with them picked.

One step rounds edges on one body. For a second body, make a second step.

Pick the edges you want

Each tap adds an edge, and a tap on a picked edge drops it. The blue card counts what you have.

  1. Tap one edge of an outline. The whole smooth run lights up: “8 edges picked, In 1 tangent chain”.
  2. Tap Box select, or press W.
  3. Drag from right to left across more edges. Everything the box touches is added.
  1. Click one edge of an outline. The whole smooth run lights up: “8 edges picked, In 1 tangent chain”.
  2. Hold ⇧Shift and drag from right to left across more edges. Everything the box touches is added.
One tap picks the top outline. Then a box dragged right to left touches one bottom edge, and Tangent chain adds the rest of that outline: 16 edges in 2 chains.

A few more ways to pick:

  • One edge out of a run: turn Tangent chain off, then tap the edge to drop it. The other edges stay picked.
  • Every edge around a face: double-tap an edge, on the side of that face.
  • Only what’s inside the box: drag from left to right instead.
  • Without Box select: draw the box with Apple Pencil.
  • Start over: tap Clear in the blue card.
Select edges, faces and bodiesPick exactly the edges, faces and bodies you need.

Choose the size

Radius and Distance take a number in millimetres, or an expression such as wall / 2. With a parameter in the field, the round follows when the parameter changes.

To change the size later, tap the step in the timeline, type the new size and tap Done.

Use parameters and expressionsName your sizes and change the whole design from one place.

Hollow a part with Shell

Shell turns a solid into walls of one thickness. The faces you pick are taken away and leave the part open there.

  1. Tap the face you want open, such as the top.
  2. Under Next in the inspector, tap Shell, removing these faces.
  3. Type the wall thickness in Thickness.
  4. Tap Done.
  1. Click the face you want open, such as the top.
  2. Under Next in the inspector, click Shell, removing these faces.
  3. Type the wall thickness in Thickness.
  4. Press ↩Return, or click Done.
Tap the top face, then Shell, removing these faces. The top becomes the opening, with 2 mm walls.

The walls grow inward, so the outside keeps its size.

  • Open another side: tap the outside of that face. This works on a box with sharp corners. On a part with rounded corners, like this plate, an open side makes the step fail, so open only the top.
  • Close an opening: an opening is a hole now, so there’s nothing there to tap. Tap Clear in the blue card. That closes every opening, so tap the faces you still want open again.
  • No opening at all: tap Shell in the tool strip with nothing selected, and pick no faces. You get a closed box with a hollow inside.

When a step fails

A size can be too big for the part. A round can’t be bigger than the faces beside its edge, and a wall can’t be thicker than the part.

Fillet with Radius 14 mm on the top outline of a plate 12 mm tall. A red card in the inspector reads Fillet radius too large for the selected edges, and the plate keeps its sharp top edges.
A 14 mm round can't fit on a plate 12 mm tall, so the edges stay sharp.

When that happens, the part stays as it was and a red card at the top of the inspector says why. The step also turns red in the timeline, with a red dot on its corner.

The timeline: Outline, Plate, Corners, and Fillet 1 with a red label and a red dot.

To fix it:

  1. Make the size smaller until the red card goes away.
  2. If one edge is the trouble, drop it and round it in a step of its own with a smaller size.
  3. If Shell says the wall is too thick and a thinner wall doesn’t help, an open side runs into a rounded corner. Tap Clear and pick only the top.

You can tap Done with the error still there. The step stays red in the timeline until you open it and fix it.

Change your design with the timelineEdit, reorder, suppress or roll back any step.

Questions and answers

Why did one tap pick so many edges?
Tangent chain is on. It picks every edge joined smoothly to the one you tapped. Turn it off to drop single edges.
Fillet or chamfer on the bottom of a part?
A chamfer. The lowest part of a fillet on a bottom edge faces almost straight down, so it prints as an overhang. A small 45° chamfer prints cleanly. Keep fillets for the top and the upright edges.
Can I round edges on two parts in one step?
No. A Fillet or Chamfer step works on one body. Make a second step for the other one.
How do I close a Shell opening again?
Open the Shell step from the timeline and tap Clear in the blue card. Every opening closes, and you can tap the faces you still want open again. The opening itself can’t be tapped, because that face is gone.
How do I make a closed box with no opening?
Start Shell from the tool strip with nothing selected, and don’t pick a face. You get walls on every side and an empty space inside.
Select edges, faces and bodiesCheck a part and export it for printingExtrude, revolve and Press PullChange your design with the timeline

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