TEGNEMASKIN

The problem

Merge by Distance is all or nothing

A low merge distance leaves gaps unwelded. A higher one catches the gaps, but also vertices that just sit close together: points along a tight edge loop, or an eyeball resting in its socket.

TM Select Doubles shows you every candidate first, sorts out the ones that look like neighbours rather than doubles, and lets you decide.

  • Blender 5.0+
  • Edit Mode
  • N-panel → TM Model
  • Version 1.8
The Select Doubles panel with a distance slider, a Live toggle, a list of two clusters, Add Selected and Exclude Selected, and the Select Checked, Merge Checked and Explode Parts buttons

See before you merge

Doubles as a list you can check

Find Clusters groups the doubles into clusters. A whole split seam shares one row, such as 64 verts (32×2), so a long seam is one decision, not thirty-two.

Each row has a check box. Clusters that look safe start checked; anything suspicious is flagged and left for you to decide. Click a row to select those vertices in the viewport.

Features

Built for models with many parts

A large model joined from dozens of mesh islands, with split seams and parts that only touch, is where blind merging goes wrong.

Dots in the viewport

Every cluster gets a dot where the merged vertex will end up, coloured by what Merge Checked will do with it.

Seams as one row

Pairs that follow each other along open edges are grouped, so a split seam is listed and checked as a whole.

Neighbours left out

Vertices one or two edges apart, or in the same face, are neighbours, not doubles, and are skipped.

Parts kept apart

Vertices from separate mesh islands that only touch, like an eye in a face, are flagged instead of welded.

Live distance

A log slider from 0.01 mm to 10 cm. With Live on, the clusters and the selection follow as you drag.

Merge to the centre

Each checked cluster merges to its own centre point. Nothing else in the mesh is touched.

Explode to inspect

See a copy of the mesh with its parts pulled apart, so you can tell which pieces a cluster joins. Apply merges in the original.

Fine-tune any row

Take single pairs out of a seam with Exclude Selected, or turn a gap the distance missed into a cluster with Add Selected.

A joined robot mesh in Edit Mode with green dots along split seams on the chest, red dots where separate parts touch, and the cluster list in the sidebar
A joined character mesh at 1 mm. The green seams on the chest are ready to weld. The red points are where separate parts clip into each other, so a few of their vertices end up very close together. Those are held back. Blender's own Merge by Distance would weld all of them, without showing you which.

Workflow

Four steps

Most of the work is finding the right distance. The rest is a quick look.

  1. Distance

    Turn on Live and drag the slider until the gaps you want to close show up.

  2. Look

    Check the dots in the viewport and the list. Red rows are worth a closer look.

  3. Decide

    Check or uncheck rows, or use All, None or Safe. Exclude or add single pairs where a row isn't quite right. Live turns off so your choices stay.

  4. Merge

    Merge Checked welds each checked cluster into its centre.

A split sphere with green dots along the seam and a red dot where a small joined sphere touches it
Green dots along a split seam, where the two sides are 0.3 mm apart. The red dot marks a joined part with a vertex very close to one on another mesh island. Blender's own Merge by Distance would weld that one too, without telling you.

Explode Parts

Pull it apart to see what touches

On a joined model it can be hard to see where one part ends and the next begins. Explode Parts makes a copy of the mesh and pulls its parts out from the centre, with a slider for how far.

Parts that a checked row would weld stay together, so what comes apart is exactly what Merge Checked would leave apart. Check a red row and that part slides back in. Rows, dots and selection work on the copy as usual, and Apply merges the checked clusters in the original, with its modifiers, shape keys and vertex groups untouched.

The joined robot mesh exploded: green seams on the chest stay together, while a neck ring and an arm joint have moved out, with red lines to the points where they only touched
The same character, exploded. The green seams on the chest hold together, because they will be welded. The spine ring and the arm joint only touch their neighbours, so they move out, with red lines to the points where they touched.

Reference

What the colours mean

GreenChecked. Will be merged.
GreyUnchecked. Left as it is.
RedFlagged: large, neighbours or between parts. Left unless you check it.
YellowFlagged, but checked by you. Will be merged.
The Options section: Skip Mesh Neighbours, Open Edges Only, Keep Parts Apart, Flag Above, Frame Selection and Show Dots

Options

Tune what counts as a double

Skip Mesh NeighboursLeave out vertices one or two edges apart or in the same face. Pairs under 0.1 mm still count.
Open Edges OnlyOnly look at vertices on open edges, where parts should have been welded.
Keep Parts ApartFind doubles inside each mesh island, and flag everything between islands.
Flag AboveFlag clusters with more vertices than this (4 by default).
Frame SelectionZoom the view to a cluster when you click its row.
Show DotsShow or hide the dots in the viewport.
The Quick Select & Merge section with Select Doubles and Merge Selected Doubles

For simple jobs

Quick Select & Merge

When you just need the classic approach: Select Doubles selects all vertices within the specified distance of another vertex, letting you inspect them before hitting Merge Selected Doubles.

Both are also in the Select menu in Edit Mode.

Good to know

The details

UVs stay where they are. Merging moves vertices, not UV coordinates. Each face keeps its own UVs, the same as Blender's Merge by Distance.

A seam has to line up. Pairs between two mesh islands only count as a seam when open edges on both sides lie on top of each other. Parts that just touch or cross are flagged.

Edit the mesh, find again. If the mesh changes after Find Clusters, the add-on asks you to run it again instead of merging the wrong vertices.

Several objects at once. Works on every mesh in Edit Mode. Explode Parts works on one object at a time.

The exploded copy is only for looking. It is shown without modifiers, and it is deleted again when you apply or cancel. If you add or delete geometry on it, Apply asks you to start over.

Interested?

Ask about the add-on

Blender5.0 or newer
TypeExtension (.zip, install from disk)
Where3D View → N-panel → TM Model, and Edit Mode → Select
Version1.8
Get in touch → All add-ons