By Printara · Published 25 September 2026 · 10 min read · Written for PrusaSlicer 2.9
How to Split an STL in PrusaSlicer (Cut Tool, Connectors, Dovetail and Cut by Line)
Bambu Studio and OrcaSlicer both grew out of PrusaSlicer, and their cut tools still share its design. The original cuts a model with a plane, adds plug, dowel or snap connectors, can cut a dovetail, and lets you draw the cut straight on screen. This guide covers every part of it in PrusaSlicer 2.9, the current version in September 2026, with the details that matter on Prusa printers: the MINI's 180 mm cube, the MK4S's 250 x 210 mm bed, the Core One's 270 mm height and the XL's 360 mm.
Short version. Select the model, press C, move the plane to the seam, under Cut result tick both objects and pick Place on cut, click Add connectors, choose Dowel with a Size tolerance of 0.2 to 0.3 mm, place two or more on the cut face, Confirm connectors, then Perform cut.
First: will it fit if you turn it?
Prusa beds are not all square. The MK4 and MK4S print 250 mm along X but only 210 mm along Y, and 220 mm high. The Core One is 250 x 220 mm with 270 mm of height, the MINI is 180 mm in every direction and the XL is 360 mm. A part that is 240 mm long does not fit along Y on an MK4S, but it does fit along X. Before you cut, turn the model with the Rotate tool (R) so its longest side runs along X, and check the size in the object manipulation panel on the right. Many oversized models only need that.
If the model is from Printables or another library, also check the files list: designers of large models often upload a pre-split version with their own joints, which will be better than a cut you make blind.
Step by step: cutting a model in PrusaSlicer
1. Open the Cut tool
Select the object and press C, or click the Cut icon in the left toolbar. A cut plane appears through the model and the Cut panel opens.
2. Place the cut
- Keep Mode on Planar.
- Drag the arrow on the plane, or type the height in Cut position.
- Drag the arcs to rotate the plane for an angled cut.
- Hold Shift to draw a cut line instead (next section).
- Flip cut plane swaps the sides, Hide cut plane and grabbers gives you a clear view, and Reset cut resets the plane and removes connectors.
3. Set the cut result
Under Cut result the two halves are called Object A (upper) and Object B (lower). Tick the ones you want to keep, and for each choose Keep orientation, Place on cut or Flip upside down. Place on cut lays the part on its flat cut face, ready to print without support under the seam. Then choose Cut into: Objects or Parts (explained below).
4. Add connectors
Click Add connectors. The view turns to the cut face and the panel shows:
- Type: Plug (peg on one part, hole in the other), Dowel (holes in both parts and a separate pin to print) or Snap (a peg with a bulge that clicks in).
- Style: Prism or Frustum; Shape: Triangle, Square, Hexagon or Circle.
- Depth and Size, each with a Tolerance, and Rotation to turn a non-round connector.
- For snaps, Bulge and Space, proportions of the connector radius.
Left click adds a connector on the cut face, right click removes it, drag moves it. Shift + click and Alt + click add to and remove from the selection, and Ctrl + A selects all connectors. Two or more connectors, spaced apart, keep the parts from rotating. Click Confirm connectors.
5. Perform the cut
Click Perform cut. If PrusaSlicer finds errors in the new parts, it offers to repair them (on Windows it uses the Windows repair algorithm). The parts and any dowels appear in the object list. Press A to arrange, slice and print. For a part that landed on the wrong face, use Place on face (F) and click the cut face.
Cut by line: seams that are not horizontal
Hold Shift and drag across the model. PrusaSlicer turns the line into a cut plane that runs along it and straight into the screen. It is the quickest way to cut along a sloping feature: the hem of a cloak, the brim of a hat, the joint where an arm meets a shoulder pad.
Turn the camera first. The line only defines two directions of the plane; the third is your viewing direction, so a line drawn in a slanted view gives a slanted plane. Side and front views give the most predictable result.
Objects or Parts, and what Parts is good for
Cut into: Objects gives two independent objects. That is what you want when the model is too big: each object can be placed, rotated and printed on its own, even in separate jobs.
Cut into: Parts keeps both halves inside one object as two parts. The object still prints as one piece, but each part can have its own settings and its own filament. Two practical uses:
- Different settings per region. Cut a tall vase at the height where the base ends and give the base part more perimeters or denser infill, while the thin upper part keeps light settings.
- A simple two-colour print. On a printer with several filaments, such as an MMU3 setup or the XL with several toolheads, cut a sign at the height where the lettering starts and assign the top part to a second filament.
Parts is not available once you add connectors, and not in Dovetail mode, because both of those create separate pieces by definition.
Dovetail mode
Set Mode to Dovetail and the cut gets a sliding joint along the seam: a rib on one part, a matching groove on the other. The Groove settings are Depth, Width, Flap Angle (30 to 120 degrees) and Groove Angle (0 to 15 degrees). The joint aligns itself and holds against being pulled apart across the seam, which suits panels, signs and long boxes.
PrusaSlicer makes one groove per cut. For a very long seam, OrcaSlicer can place several dovetails along it; see multiple dovetails in OrcaSlicer. Check the sliced preview of the groove side, where a steep flap angle can create overhangs.
Connector sizes and fit
| Question | Rule of thumb |
|---|---|
| How big? | Size about a third of the smallest width of the cut face, and never closer than a few millimetres to the outside wall. |
| How many? | At least two, as far apart as the face allows. One round connector lets the parts rotate. |
| Size tolerance? | 0.2 to 0.3 mm for PLA or PETG on a 0.4 mm nozzle. Resin needs far less. |
| Depth tolerance? | A little, so the peg does not bottom out and hold the seam open. |
| Plug or dowel? | Dowel if both parts should print on their cut faces. A plug sticks out of one face, so print that part cut face up. |
Test before a long print: cut a 30 mm cube with the same connectors, print it, and adjust the tolerance by 0.05 mm until the fit is right. If holes that sit on the plate come out small, raise Elephant foot compensation in the print settings (Advanced) a little; the first layers bulge outward otherwise.
Troubleshooting
- "Cut plane is placed out of object". The plane misses the model. Use Reset cut or type a Cut position inside the model's height.
- "Cut plane with groove is invalid". The dovetail does not fit this cross-section. Reduce Depth or Width, or cut through a thicker section.
- "Select at least one object to keep after cutting." Tick Object A or Object B.
- "Invalid connectors detected" or "Some connectors are overlapped". A connector leaves the cut face or touches another one. Move it inward or reduce Size.
- "Errors detected after cut operation". Accept the repair. If it keeps happening, the source mesh has holes; repair it first.
- Split to objects did not cut anything. Split to objects and Split to parts only separate shells that are already disconnected in the file. To cut a solid, use the Cut tool.
Need the parts in another program? Right-click a part and choose Export as STL/OBJ.
Beyond a plane: the Printara STL Splitter
PrusaSlicer's own documentation describes the cut as a straight plane, and that is its limit: a plane is right through a column and wrong through a shoulder. The Printara STL Splitter is a free browser tool for the cases where you want the seam to follow the model. It needs a free Printara account to open a file and uses no credits. On a desktop computer with 8 GB of memory or more, models up to 1.5 million triangles are cut in your browser tab and the file stays on your computer; on a phone, a smaller computer or for a larger model the cut runs on Printara servers, still for 0 credits, and the parts go to your library.
- Draw the cut as a stroke on the model, place exact points, or use a straight plane with two tilt angles and a millimetre offset.
- Work out the cuts from your bed: the presets include the Prusa MK4 and MK4S, Core One and XL, and any custom size you type.
- Joints with a proof. Resin pins (the default), dowels, square keys, cone studs or sliding dovetails, 0.2 mm of FDM clearance built in, at least 1.5 mm of wall proved behind every socket, and matching numbers engraved into both faces.
- A ZIP to print from. One STL per part in its assembled position, the dowel STLs and a plain-text assembly guide. In PrusaSlicer, load the parts, use Place on face on each cut face and arrange.
It accepts STL files up to 2,000,000 triangles and works best on a desktop; on a phone the cut runs on Printara servers. The Academy lesson on splitting shows the whole flow in four minutes.
Split along the model, not across it
Free with a free Printara account. No credits, no watermark, no export limit.
Create a free account and split How the splitter works
FAQ
How do I cut a model in PrusaSlicer?
Select the object, press C or click the Cut icon in the left toolbar, move the cut plane to the seam, choose what to keep under Cut result, optionally add connectors, then click Perform cut.
What is the difference between Cut into Objects and Parts?
Objects gives you two independent objects that can be placed and printed separately. Parts keeps both halves inside one object as two parts, which is useful for per-part settings or filaments. Parts is not available with connectors or in Dovetail mode.
How do I cut at an angle in PrusaSlicer?
Drag the rotation arcs of the cut plane, or hold Shift and drag across the model to draw a cut line. The plane runs along your line, perpendicular to the view.
Can PrusaSlicer split a model automatically to fit the bed?
No. You place each cut yourself. Split to objects and Split to parts only separate shells that are already disconnected. The Printara STL Splitter can work out the cuts from your bed size.
What tolerance should I use for PrusaSlicer connectors?
For PLA or PETG on a 0.4 mm nozzle, start with a Size tolerance of 0.2 to 0.3 mm and test with a small coupon. A tolerance of 0 makes the peg and the hole the same size.