G-code Load Mesh Model

Everything in the G-code lane that isn't a pure generator (a vase, a heightmap plate) needs an actual 3D model to work on. That's what this node is for: it loads an .stl or .obj from disk, applies placement transforms, and hands you a ready-to-use MKR_GCODE_MESH plus a rendered preview so you can see what you loaded without leaving ComfyUI.

What it does

The whole config lives in one settings_json string (the pack's style - every G-code node talks JSON). The two defaults that matter for a first load:

• center_xy: true - recenters the model on the XY plane. Almost always what you want, because STLs come in at arbitrary coordinates.
• bed_align: true - drops the mesh down so the lowest point sits at Z=0, i.e. on the virtual bed. Turn this off only if your model is already pre-positioned.

From there you get the usual transform toolbox: scale, rotate_x/y/z_deg, translate_x/y/z_mm, and a neat one, target_longest_mm, which rescales the model so its longest axis is exactly that size - handy when you need "fits in a 100 mm box" without doing the math yourself. preview_view picks isometric or top for the rendered preview, and preview_size sets the preview resolution.

What's inside

The node parses the mesh file into a triangle payload - vertices, faces, bounds, and a triangle count - wrapped as the MKR_GCODE_MESH type. That's what MKRGCodeExternalSlicer slices and what MKRGCodePreview can render as a wireframe. The bounds are also what MKRGCodePlanAnalyzer uses to judge bed usage, so a properly bed-aligned mesh makes the whole downstream analysis honest.

Outputs

• mesh (MKR_GCODE_MESH) - the triangle payload, the star of the show.
• preview (IMAGE) - a rendered look at the mesh so you can confirm orientation before you slice.
• mesh_info_json - source path, triangle count, bounds, metadata, warnings.
• summary - one line: filename, triangles, and height in mm.

Wiring it up

The classic pipeline:

MKRGCodeLoadMeshModel → MKRGCodeExternalSlicer → MKRGCodePreview → MKRGCodeExport

Load the model, slice it with a real slicer, preview the resulting toolpath, and export the .gcode. You can also skip the slicer entirely and just send the mesh straight to MKRGCodePreview for a wireframe check.

Installing it

Part of the pack, so it installs with everything else:

# ComfyUI Manager: search "MKRShift Nodes", install, restart.
# or:
cd ComfyUI/custom_nodes
git clone https://github.com/criskb/MKRShift_Nodes
# restart ComfyUI

No extra dependencies. The mesh parsing is pure Python; no numpy-stl, no trimesh, no model downloads.

Where people get burned

The one thing that trips everyone up: model_path is a server-side filesystem path, not an upload. ComfyUI is a web UI but runs a local server, and this node reads the file from that machine's disk. If you're running ComfyUI on a remote box or in Docker, the file has to live there (or be in a mounted volume). A missing or mistyped path doesn't crash - the node returns a warning and an empty mesh, and anything downstream quietly does nothing or errors on the missing triangles. So check summary and mesh_info_json after a load; a nonzero triangle count is your confirmation the file actually parsed.

Also note the file-based nature means STL/OBJ only - no STEP, no 3MF. For CAD formats you'd convert first. For what it covers (the two classic FDM mesh formats), it's solid.