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How to assemble a keychain tag and its inlay in the slicer

· 4 min read

The Keychain Tag Designer exports a tag as several STL files: one for the tag and one for each inlay. An inlay is a border, logo or text in another color. The tag has a groove and the inlay fills it exactly, so in the slicer the parts have to sit inside each other. This post explains how to get there, and why the parts drift apart when you load them one at a time.

The easy way: 3MF

The Export 3MF button gives one file with the tag and every inlay already assembled into one object, each part in its own color. Open it in the slicer and the parts are in place. All that is left is assigning the filaments (see below). If you use the STL files instead, read on.

What the STL export gives you

For a rectangular tag with a single-color border, the export gives two files:

  • keychain_tag_rectangle_tag.stl – the tag with its groove,
  • keychain_tag_rectangle_inlay.stl – the inlay that fills the groove.

If the logo has several colors, you get one file per inlay, e.g. …_inlay1_ff0000.stl and …_inlay2_0000ff.stl. The number is the inlay, followed by its color from the preview. STL files carry no color, so the name is the only place it is recorded.

All files share one coordinate system: the inlay already sits in the groove, at the right height.

Why the parts drift apart

When you load each file separately, the slicer treats each one as its own object:

  • it centers it on the bed by its bounding box,
  • it drops it onto the bed, so its bottom is at z = 0.

The tag’s bounding box includes the loop, while the inlay’s often does not (for example when the inlay is just text). The two centers differ, so the inlay ends up shifted. It also falls onto the bed instead of staying in the groove, which on a 2 mm tag with a 0.6 mm deep inlay starts at 1.4 mm.

Moving the parts by hand is not recommended, because tenths of a millimeter are hard to hit. It is easier to load them the right way.

Loading them as one object with several parts

This works in PrusaSlicer, OrcaSlicer and Bambu Studio:

  1. In the import dialog (or in the folder with the downloads), select all the tag’s files at once: the tag and every inlay.
  2. Load them together, with the import button or by dragging them into the slicer.
  3. The slicer asks whether the files should be one object with several parts. Answer yes.

The parts then keep their positions from the files. The object list shows a single object, with the tag and the inlays as its parts.

Assigning filaments

Give each part its filament:

  • in PrusaSlicer, right-click the part in the list and pick the extruder,
  • in OrcaSlicer and Bambu Studio, select the part in the list and set its filament (the number next to the part).

The tag gets the base color and each inlay its own. The color in the file name helps you get it right.

What the printer needs

A flush inlay takes up the top few layers, just like the tag around it, so both colors are in the same layer. That means you need a multi-material printer: an AMS, an MMU, several heads or a tool changer.

A plain filament change at a given height (pause / M600) does not work here. Everything from that height up would be in the new color, including the tag around the inlay.

Printing tips

  • Match the inlay depth to the layer height. A 0.6 mm depth with 0.2 mm layers gives exactly three inlay layers and a clean color change. With 0.12 mm layers, 0.6 or 0.72 mm works well.
  • Keep the prime/wipe tower the slicer adds when an object uses several filaments. Without it, the colors mix in the first moves after each change.
  • Check the layer preview before printing: the inlay color should appear only at thickness minus depth (1.4 mm in the example) and fill the groove to the top.
  • Thin border lines narrower than the nozzle (below about 0.4 mm with a 0.4 mm nozzle) may be dropped by the slicer. If the border disappears in the preview, increase the line width in the designer.

In short

The files are already aligned. Load them together as one object with several parts, assign the filaments and check the layers. The same goes for the Coaster Designer, except that the base part is called body instead of tag.