Embedding Devices

Prev: Extra 3: Stitching Devices

Embedding lets you place a complete device (its own labels, shapes, and layers) inside another device. This is useful for printing a high‑resolution section inside a larger low‑resolution device.

Key ideas:

  • Embedded devices are sliced separately, then injected into the parent device’s print layers.
  • Offsets are computed relative to the parent device’s center.
  • Z translations are preserved (child layers are shifted up/down in microns).
  • Embedded devices can be emitted at different resolutions than the parent.
  • By default, subcomponents subtract their bounding box from the parent (often desirable, but not always when embedding).

Step 1 — Build a parent device

Create a normal device with labels and a bulk shape.

from pymfcad import Device, Cube, Color

parent = Device(
    name="Parent",
    position=(0, 0, 0),
    layers=200,
    layer_size=0.015,
    px_count=(2560, 1600),
    px_size=0.0152,
)

parent.add_label("bulk", Color.from_name("gray", 127))
parent.add_label("void", Color.from_name("aqua", 127))

parent.add_bulk("bulk", Cube(parent._size, center=False), label="bulk")

Step 2 — Build an embedded device

The embedded device can use a different pixel size or layer size. Its position is relative to the parent.

from pymfcad import Device, Cube

child = Device(
    name="Inset",
    position=(0, 0, 0),  # parent pixels/layers
    layers=120,
    layer_size=0.0015,          # finer Z resolution
    px_count=(1920, 1080),
    px_size=0.00075,            # finer XY resolution
)

child.add_label("bulk", Color.from_name("gray", 127))
child.add_label("void", Color.from_name("aqua", 127))

child.add_bulk("bulk", Cube(child._size, center=False), label="bulk")
child.add_void(
    "channel",
    Cube((600, 40, 20)).translate((100, 280, 20)),
    label="void",
)

Step 3 — Add the embedded device

parent.add_subcomponent("inset", child.translate((100,100,100)))

You can also choose to disable bounding‑box subtraction for embedded devices (see below).

When slicing:

  • The child’s center is aligned relative to the parent’s center.
  • Any child translation (x/y/z) compounds through the hierarchy.
  • Z offsets are applied in microns to the child’s layers.

Slicing

  • When slicing embedded devices, make sure:

1) Your printer has each light engine properly defined 2) The light engine's names match the expected names for the printer (i.e. visitech, wintech) 3) Your printer definition has the xy_stage_available parameter set properly. 4) Your device sizes match the resolutions of the defined light engines.

Bounding‑box subtraction (important)

By default, add_subcomponent() subtracts the subcomponent’s bounding box from the parent’s shapes. This is often critical for normal subcomponents (prevents double‑solid regions), but it can be wrong for embedded devices in two common cases:

1) Overlap margins — you may want a few pixels of overlap between the low‑res parent and the high‑res inset to ensure a strong connection. 2) Inset smaller than the light engine — if the high‑res device doesn’t fill the light engine’s full resolution, the automatic subtraction can create unexposed gaps around the embedded device.

In these cases, disable the default subtraction and define a custom subtraction void in the parent so you control exactly what gets removed:

parent.add_subcomponent(
    "inset",
    child.translate((100, 100, 100)),
    subtract_bounding_box=False,
)

# Example: carve a custom void with overlap margin
overlap = 20  # pixels to keep overlapping between parent and child
void_size = (child._size[0] - 2 * overlap, child._size[1] - 2 * overlap, child._size[2])
void_pos = (child._position[0] + overlap, child._position[1] + overlap, child._position[2])
parent.add_void(
    "inset_clearance",
    Cube(void_size, center=False).translate(void_pos),
    label="void",
)

Guidelines:

  • Keep subtraction on if the embedded device should carve out a full cavity the same size as the child.
  • Turn it off + add a custom void if you need overlap margins or the child doesn’t span the full light engine.
  • If results look hollowed unexpectedly or you see gaps around the inset, this is the first thing to check.

Notes and limitations

  • Top‑level translation only applies to image offsets if the printer has an XY stage.
  • Embedded devices can be nested multiple levels deep; offsets are compounded through the hierarchy.
  • If the embedded device has different resolution, it will be emitted at its native resolution with its own image offsets.

Troubleshooting

  • Child Z not shifting → make sure the child has a non‑zero Z position and non‑zero layer_size.
  • Offsets not applied → check if the top‑level device has a translation and the printer lacks XY stage support.

Next: Extra 5: Advanced TPMS Structures