Dovetail Joint

How it works

A trapezoidal tongue slides into a matching groove. The angled sides prevent separation perpendicular to the slide direction while allowing free movement along the rail. Used for sliding connections, rails, and alignable joints.

Cross section:

  Tongue:           Groove:
     ╱──╲              ┌──────────┐
    ╱    ╲             │ ╲      ╱ │
   ╱      ╲            │  ╲    ╱  │
  ╱        ╲           │   ╲  ╱   │
                       └──────────┘

Key design parameters

Parameter	Guideline
Dovetail angle	45-60° (steeper = stronger lock, harder to slide)
Clearance (FDM)	0.2-0.3mm per side
Depth	At least equal to the tongue width for strength
Length	As needed — longer = more bearing surface

Design tips

• 45° angle is a good default — holds well, slides smoothly, easy to model.
• Chamfer the entry of both tongue and groove for easy alignment during insertion.
• Clearance is critical — too tight and it won’t slide, too loose and it wobbles. Start with 0.2mm per side and adjust.
• Add a stop at the end of the groove if you don’t want full slide-through.

FDM considerations

• Print orientation — the dovetail cross-section should be on the XY plane (horizontal). Printing the angled faces as overhangs works well at 45°, which is right at the typical FDM overhang limit.
• Elephant’s foot — the first layer squish can make the groove too tight at the bottom. Add a small chamfer at the groove entrance.
• Sand or file the mating surfaces if the fit is too tight — easier than reprinting with adjusted clearances.

When to use

• Sliding rail systems
• Panel-to-panel connections (the bowtie connector in the storage system is a variation)
• Drawer slides
• Removable mounting brackets
• Tool holders that slide onto a rail

Common failures

• Binding — dovetail jams partway. Cause: insufficient clearance, warping, or debris in the groove.
• Wobble — too much clearance. Solution: reduce clearance or add a friction element (thin TPU strip).
• Overhang quality — angled faces print rough on FDM. Solution: keep angle at 45° and use good cooling.