Cut a model with Prusa Slicer and put it back together with dovetail joints

The Prusa Slicer supports a couple different patterns for cutting a model into pieces and then joining it back together after the print. I wanted to print a sword that was too large for my printer.  It needed to be in 4 pieces.  The Prusa Slicer supports cutting a model using an infinite plane and joining those back together after the print with plugs, snaps, dowels, or dovetail joints.   The dovetails work great but need different reinforcement and printing settings than the plugs or snaps.

The standard planar cut

The standard cut is "planar" or a flat cut across the piece.  This is a pretty common way of cutting a figure to split printing or for some other need.

The slicer "Add Connectors" button brings you to another screen that lets you size the connectors that will join the two pieces.

You can place a connector anywhere on the cut line by clicking on it.  The geometry of the connector is specified in the panel.

Dovetail Cut

You can instead try a dovetail cut that removes the need for connectors.  The cut is more complicated so it can't or shouldn't be used in many situations based on the amount of material.

Dovetail Cuts in practice - good and bad

The sword was printed with standard perimeter and infill settings. That was not a good idea.  The material around the joint was not strong enough when using the default settings.

This picture shows two pieces of a sword joined by the dovetail cut.  I thought this technique would create a super stable and strong joint when glued because of the complexity of the join and the amount of surface area.

Here is the sword broken down into 4 pieces, every joint was a Dovetail cut.   I used a Silk filament here that is super hygroscopic and needs to be dried every time it is used. 

I tried changing the angle of the dovetail joint from 60 to 65 degrees to have more material on the piece with the two outer edges.  Increasing the angle made the joint base a little wider still did not provide enough material for this joint.  The base was too small and the settings didn't provide any infill to strengthen the pieces.  These broke off with a minimum amount of pressure.
The large side of the joint didn't have enough material either and was easily snapped off. It is pretty obvious that we need to strengthen the connector area if we're planning on putting any pressure on dovetail joints.

Reinforcing the dovetail

Prusa Slicer lets you change the slicing behavior at different layers on a per-part/component basis.  This lets you change the infill density and style for specific layers or height ranges.  The picture at the right specifies infill density changes on all the joints.

  • Highlight the part
  • Right mouse --> Add height range modifier
  • Highlight the Range
  • Right mouse --> Infill
  • Change the infill

You can click on the picture at the right to see the popup menu choices or do the same in your Prusa session

Plug, dowel, snap

The insertion areas of the planar cuts also need to be reinforced if you intend for them to have any load. They should work fine if you are just making a piece of art or figure that isn't going to operate under any stress


The first video demonstrates the dovetail joints with failure.

A followup video that shows how to change the infill at different heights to reinforce the joint.

Revision History

Created 2024 05


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