Fillet Guide
Inspect & Print

Check a part and export it for printing

Fillet checks your part against your printer while you model: does it fit the bed, does it need supports, is it safe to slice. When it passes, export a 3MF and open it in your slicer.

Choose your printer

Fillet checks your part against one printer’s build volume. Pick yours first. New designs start on the Bambu Lab A1 mini.

  1. Tap the printer button in the toolbar, at the top right.
  2. Choose your printer. Each one is listed with its build volume in mm.

The bed in the viewport changes to the new size and is labelled with the printer’s name. The printer is saved with the design, and Undo takes the change back.

Printer Build volume (mm)
Bambu Lab A1 mini 180 × 180 × 180
Bambu Lab A1, P1P, P1S, X1 Carbon, X1E 256 × 256 × 256
Bambu Lab H2D 325 × 320 × 325
Prusa MK4 250 × 210 × 220
Prusa Core One 250 × 220 × 270
The H2D’s bed is 350 mm wide, but one nozzle reaches only 325 mm of it. Fillet uses 325 mm, so a part that fits can be printed with either nozzle.

Read the Print check

When nothing is selected, the inspector on the right shows the Print check. It updates after every change, so you can keep an eye on it while you model.

To see it, tap an empty part of the view, or tap Clear selection in the inspector.

A shelf bracket seen from below, with the underside of its shelf tinted red. The bed is labelled Bambu Lab A1 mini. The Print check in the inspector reads Fits the bed, 50 × 30 × 60 mm; Overhangs, 1200 mm² past 45°, with Show; Watertight, Safe to slice; and Material: Volume 30 cm³, PLA, solid 37.2 g, Bodies 1.
A shelf bracket, printed upright. The shelf's flat underside would need supports.
  1. Fits the bedThe part's size, checked against your printer.
  2. OverhangsHow much area hangs over thin air. Show tints it red.
  3. WatertightThe surface is closed, so the slicer can fill it.
  4. MaterialVolume and the weight of a solid PLA print.
  5. OverhangFaces that need supports turn red.

A green tick means the check passed. An amber triangle is a warning: the part prints, but not as well as it could. A red cross is a problem to fix before you export.

Check What it tells you
Fits the bed The size of everything you can see, in mm. If the part only fits turned 90° on the bed, it says Rotate 90° in the slicer in place of the size. If it doesn’t fit either way, the size is followed by is too big.
Overhangs The area that tilts past the overhang angle, such as 1200 mm² past 45°. With none, it says No overhangs, which means it prints without supports.
Watertight Safe to slice when every surface is closed. Otherwise it says Not watertight and counts the open or non-manifold edges. This mostly happens with imported STEP files.
Steps failed Only shown when a step on the timeline failed. Tap Show to open it.
Material The volume, the weight in PLA if printed solid, and the number of bodies.
The weight assumes a solid print at 1.24 g/cm³. Your slicer’s estimate will be lower, because it uses infill. Hidden bodies are left out of the size, overhang, watertight, volume and weight checks, but Bodies counts them too.
Change your design with the timelineA failed step is left out of the model. Fix it before you export.

Find overhangs

An overhang is a face that points down and leans out further than your printer can bridge. Turn on Overhangs to see them on the model.

  1. Tap Overhangs in the tool strip, or press ⇧Shift⌘CmdO. You can also tap Show in the Print check.
  2. Turn the view so you can see the part from below. Overhangs are tinted red.
  3. Tap Overhangs again to turn the tint off.

Faces that rest on the bed never count. Walls never count either, however tall they are.

On the Mac, Design › Show Overhangs and Design › Lay Flat on Face are in the menu bar too.

Change the overhang angle

A face counts as an overhang when it leans more than the overhang angle away from vertical. A wall is 0°, and a flat ceiling is 90°. The default is 45°, which most printers manage without supports.

  1. Tap the printer button in the toolbar.
  2. Scroll down to the angles, below Show overhangs.
  3. Choose an angle from 35° to 60°. Pick a lower angle to be stricter.
The printer menu scrolled down: Bambu Lab X1E, H2D, Prusa MK4 and Prusa Core One with their bed sizes, then Show overhangs with a tick, then the angles 35° to 60° with 45° ticked.
Show overhangs and the overhang angle sit below the printers.
The overhang angle and the red tint aren’t saved with the design. When you open it again, both start over: tint off, 45°.

Lay the part flat

The side that touches the bed decides what needs supports. The bracket above has a shelf that hangs out in mid-air. Laid on its side, every face is a wall or rests on the bed, and it prints without supports.

  1. Select the flat face that should touch the bed.
  2. Tap Lay flat on the bed in the inspector, or tap Lay flat in the tool strip.
The side face of the shelf bracket selected in blue. The inspector names it Flat face, Area 1000 mm², and lists Next actions: Sketch on this face, Drill holes in this face, Lay flat on the bed, Press Pull these faces, and Shell, removing these faces.
Select a face, then pick Lay flat on the bed from the Next list.

The part turns over and lands on the bed. To try another side, tap a different flat face. When it’s right, tap Done.

The shelf bracket lying on its side on the bed, with no red faces. The Print check reads Fits the bed, 50 × 60 × 30 mm; No overhangs, Prints without supports; and Watertight, Safe to slice. The timeline at the bottom shows Profile, Bracket and Lay Flat 1.
On its side, the bracket prints without supports. Lay Flat 1 is now a step on the timeline.

Lay flat is a step on the timeline, like any other. Tap its station to choose another face, or delete it to stand the part back up. Only a flat face can go on the bed.

Select edges, faces and bodiesTap a face to select it. The Next list shows what you can do with it.

Export for your slicer

When the Print check looks good, export the part. Tap the Export button in the toolbar, next to the printer button, and choose a format.

The Export menu open with three choices: 3MF (Bambu Studio, PrusaSlicer…), STL, and STEP (other CAD apps).
Choose 3MF for your slicer.
Format Use it for
3MF Bambu Studio, PrusaSlicer, OrcaSlicer and most other slicers. The file is in mm and the part sits in the middle of your printer’s bed. Several bodies arrive as one object with a part per body, just as you modelled them.
STL Older slicers and tools that don’t read 3MF. Every body goes into one mesh, in mm.
STEP Other CAD apps. It keeps the exact shapes, not a mesh.
  1. Tap the Export button and choose a format.
  2. In the save sheet, pick a folder in On My iPad or iCloud Drive, then tap Save.
  3. Open the file in your slicer from the Files app. Save it to iCloud Drive to pick it up in Bambu Studio on your computer.
  1. Click the Export button and choose Open in Bambu Studio. Fillet makes a 3MF and opens it in Bambu Studio. Without Bambu Studio, the file opens in your Mac’s usual app for 3MF files. The Export button shows no spinner for this, so a large part can take a moment to appear.
  2. To keep a file instead, choose a format and pick where to save it.

Only bodies you can see are exported. To export one part on its own, hide the others in the browser first.

Curves are exported finely, to within 0.01 mm, so holes and fillets come out smooth. A large part can take a moment. After you choose a format, the Export button shows a spinner until you can pick where to save the file.

Work with bodies: primitives, combine, move and mirrorHide a body with its eye in the browser to leave it out of the export.

Tips for a clean print

Round, bevel and hollow: Fillet, Chamfer and ShellRound edges, bevel corners and hollow out a part.See inside with Section viewCut the part open to check wall thickness inside.

Questions and answers

Why does the Print check say Rotate 90° in the slicer?
The part is longer than the bed in one direction but fits the other way round. Turn it 90° on the bed in your slicer.
Why is my slicer's weight lower than Fillet's?
Fillet weighs the part as if it were printed solid. Your slicer prints the inside as infill, which uses less filament.
Why don't I see the Print check?
Something is selected, or a step is open. Tap Done or Cancel, then tap an empty part of the view.
Why is a body missing from my export?
It’s hidden. Show it with its eye in the browser, then export again.
Does the printer I choose change the export?
Only where the part lands. A 3MF puts the part in the middle of that printer’s bed. The part’s size never changes.
Why is my part Not watertight?
Its surface has gaps, which mostly happens with imported STEP files. Most slicers can repair small gaps. If yours can’t, fix the file in the app that made it.
Round, bevel and hollow: Fillet, Chamfer and ShellSee inside with Section viewFiles, iCloud and importing STEPMeasure

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