diff --git a/.antigravity.md b/.antigravity.md
index d710b22..cc023e4 100644
--- a/.antigravity.md
+++ b/.antigravity.md
@@ -48,6 +48,6 @@ This generates a zip file in the `release/` directory using Blender's extension
 - **Registration**: All Blender classes (Nodes, Sockets, Operators, Menus) must be decorated with `@register_class` from `registry.py` to ensure they are registered correctly during initialization.
 - **Node Evaluation**: Nodes follow a pull-based evaluation model. Use `resolve_input(self.inputs.get("SocketName"))` within a node's `evaluate_output` method to trigger the evaluation of upstream nodes.
 - **NumPy First**: For any geometry processing, prioritize NumPy vectorized operations over standard Python loops to maintain high performance.
-- **Scaling**: 2D polygon operations via Pyclipper use a `SCALE` factor (defined in `core/slice.py`) to convert floats to integers, as Pyclipper operates in integer space.
+- **Scaling & Integer Math**: 2D polygon and geometric operations use a `SCALE = 1000` factor (defined in `core/slice.py`) representing 1 micron ($1\ \mu\text{m} = 0.001\text{ mm}$) integer math units to eliminate floating-point precision issues.
 - **Type Hinting**: Use exhaustive type hints for all new functions and classes.
 - **Documentation**: Update `doc/NODES.md` when adding new nodes and `doc/MODULES.md` when adding new modules.
diff --git a/AGENTS.md b/AGENTS.md
index 5d34e81..f039bef 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -20,8 +20,8 @@ Nodes follow a pull-based evaluation model. Use `resolve_input(self.inputs.get("
 ### Performance
 For any geometry processing, prioritize NumPy vectorized operations over standard Python loops to maintain high performance.
 
-### Scaling
-2D polygon operations via Pyclipper use a `SCALE` factor (defined in `core/slice.py`) to convert floats to integers, as Pyclipper operates in integer space.
+### Scaling & Integer Math
+2D polygon and geometric operations use a `SCALE = 1000` factor (defined in `core/slice.py`) representing 1 micron ($1\ \mu\text{m} = 0.001\text{ mm}$) integer math units to eliminate floating-point precision issues.
 
 ### Type Hinting
 Use exhaustive type hints for all new functions and classes.
diff --git a/GEMINI.md b/GEMINI.md
index 3b9e9e1..381e15c 100644
--- a/GEMINI.md
+++ b/GEMINI.md
@@ -48,7 +48,7 @@ This generates a zip file in the `release/` directory using Blender's extension
 - **Registration**: All Blender classes (Nodes, Sockets, Operators, Menus) must be decorated with `@register_class` from `registry.py` to ensure they are registered correctly during initialization.
 - **Node Evaluation**: Nodes follow a pull-based evaluation model. Use `resolve_input(self.inputs.get("SocketName"))` within a node's `evaluate_output` method to trigger the evaluation of upstream nodes.
 - **NumPy First**: For any geometry processing, prioritize NumPy vectorized operations over standard Python loops to maintain high performance.
-- **Scaling**: 2D polygon operations via Pyclipper use a `SCALE` factor (defined in `core/slice.py`) to convert floats to integers, as Pyclipper operates in integer space.
+- **Scaling & Integer Math**: 2D polygon and geometric operations use a `SCALE = 1000` factor (defined in `core/slice.py`) representing 1 micron ($1\ \mu\text{m} = 0.001\text{ mm}$) integer math units to eliminate floating-point precision issues.
 - **Type Hinting**: Use exhaustive type hints for all new functions and classes.
 - **Documentation**: Update `doc/NODES.md` when adding new nodes and `doc/MODULES.md` when adding new modules.
 - **Token-Efficient Testing**:
diff --git a/blender_manifest.toml b/blender_manifest.toml
index 57cec05..861811b 100644
--- a/blender_manifest.toml
+++ b/blender_manifest.toml
@@ -59,7 +59,6 @@ wheels = [
 
   "./wheels/python_libnest2d-0.1.3-cp313-cp313-manylinux_2_27_x86_64.manylinux_2_28_x86_64.whl",
   "./wheels/python_libnest2d-0.1.3-cp313-cp313-win_amd64.whl",
-  "./wheels/cudaslicer-1.0.0-cp310-cp310-linux_x86_64.whl",
   "./wheels/shapely_polyskel-0.1.2-py3-none-any.whl",
   "./wheels/euclid3-0.1-py3-none-any.whl",
   "./wheels/pyransac3d-0.6.0-py3-none-any.whl",
diff --git a/core/nodeslicer/nodes/path.py b/core/nodeslicer/nodes/path.py
index 6b162c2..b24c5b8 100644
--- a/core/nodeslicer/nodes/path.py
+++ b/core/nodeslicer/nodes/path.py
@@ -5,7 +5,7 @@ import numpy as np
 from ..bpy_ns_types import NfEnumProperty, NfBoolProperty, NfFloatProperty, notify_tree_changed
 from ....registry import register_class
 from .base import SliceNode, SlicePaths, SlicingObject, SlicingCollection, slice_at_range, SliceNodeJoiner, SlicingGroup
-from ...slice import align_path_seam_sharpest
+from ...slice import align_path_seam_sharpest, is_closed_path
 
 @register_class
 class SLICENODE_GetPaths(SliceNode):
@@ -109,20 +109,26 @@ class SLICENODE_SliceShells(SliceNode):
             merged_object.mesh[:, :3, :] = merged_object.mesh[:, :3, :] @ mat.T
             merged_object.mesh[:, 3:4, :] = merged_object.mesh[:, 3:4, :] @ mat.T
 
-        min_z = merged_object.mesh[:,0:3,2:3].min()
+        min_z = float(merged_object.mesh[:, 0:3, 2:3].min())
         from math import floor
         min_z = floor(min_z / layer_height) * layer_height
-        max_z = merged_object.mesh[:,0:3,2:3].max()
+        max_z = float(merged_object.mesh[:, 0:3, 2:3].max())
 
         h_first = fl_height if fl_height is not None else layer_height
-        z_first = min_z + h_first
-        z_rest_start = min_z + h_first + layer_height
 
-        if z_rest_start < max_z:
-            z_rest = np.arange(z_rest_start, max_z, layer_height)
-            z_values = np.concatenate(([z_first], z_rest))
-        elif z_first < max_z:
-            z_values = np.array([z_first])
+        min_z_um = int(round(min_z * 1000))
+        lh_um = int(round(layer_height * 1000))
+        flh_um = int(round(h_first * 1000))
+        max_z_um = int(round(max_z * 1000))
+
+        z_first_um = min_z_um + flh_um
+        z_rest_start_um = z_first_um + lh_um
+
+        if z_rest_start_um < max_z_um and lh_um > 0:
+            z_um_values = list(range(z_rest_start_um, max_z_um, lh_um))
+            z_values = np.array([z_first_um] + z_um_values, dtype=np.float64) / 1000.0
+        elif z_first_um < max_z_um:
+            z_values = np.array([z_first_um], dtype=np.float64) / 1000.0
         else:
             z_values = np.array([])
 
@@ -156,9 +162,9 @@ class SLICENODE_SliceShells(SliceNode):
 
         if len(z_values) > 0 and fl_height is not None and layer_height > 0:
             mult = fl_height / layer_height
-            z_first = z_values[0]
+            z_first_um = int(round(z_values[0] * 1000))
             for i, p in enumerate(slices):
-                if len(p) > 0 and abs(p[0, 2] - z_first) < 1e-4:
+                if len(p) > 0 and int(round(p[0, 2] * 1000)) == z_first_um:
                     slices.extrusion_rate[i] = slices.extrusion_rate[i] * mult
 
         if rotation and any(rotation):
@@ -326,7 +332,7 @@ class SLICENODE_CudaSliceMesh(SliceNode):
                         if len(cnt) < 2:
                             continue
                         cnt_3d = np.column_stack([cnt, np.full(len(cnt), z)])
-                        if not np.allclose(cnt_3d[0], cnt_3d[-1]):
+                        if not is_closed_path(cnt_3d):
                             cnt_3d = np.vstack([cnt_3d, cnt_3d[0]])
                         cnt_3d = align_path_seam_sharpest(cnt_3d)
                         perim_paths.append(cnt_3d)
@@ -336,7 +342,7 @@ class SLICENODE_CudaSliceMesh(SliceNode):
                     if len(cnt) < 2:
                         continue
                     cnt_3d = np.column_stack([cnt, np.full(len(cnt), z)])
-                    if not np.allclose(cnt_3d[0], cnt_3d[-1]):
+                    if not is_closed_path(cnt_3d):
                         cnt_3d = np.vstack([cnt_3d, cnt_3d[0]])
                     cnt_3d = align_path_seam_sharpest(cnt_3d)
                     infill_paths.append(cnt_3d)
@@ -367,8 +373,9 @@ class SLICENODE_CudaSliceMesh(SliceNode):
 
             if first_layer_z is not None and fl_height is not None and layer_height > 0:
                 mult = fl_height / layer_height
+                first_z_um = int(round(first_layer_z * 1000))
                 for i, p in enumerate(perim_sp):
-                    if len(p) > 0 and abs(p[0, 2] - first_layer_z) < 1e-4:
+                    if len(p) > 0 and int(round(p[0, 2] * 1000)) == first_z_um:
                         perim_sp.extrusion_rate[i] = perim_sp.extrusion_rate[i] * mult
 
             if rotation and any(rotation) and mat_inv is not None:
@@ -387,8 +394,9 @@ class SLICENODE_CudaSliceMesh(SliceNode):
 
             if first_layer_z is not None and fl_height is not None and layer_height > 0:
                 mult = fl_height / layer_height
+                first_z_um = int(round(first_layer_z * 1000))
                 for i, p in enumerate(infill_sp):
-                    if len(p) > 0 and abs(p[0, 2] - first_layer_z) < 1e-4:
+                    if len(p) > 0 and int(round(p[0, 2] * 1000)) == first_z_um:
                         infill_sp.extrusion_rate[i] = infill_sp.extrusion_rate[i] * mult
 
             if rotation and any(rotation) and mat_inv is not None:
diff --git a/core/slice.py b/core/slice.py
index 36411f5..a51343d 100644
--- a/core/slice.py
+++ b/core/slice.py
@@ -12,8 +12,14 @@ from ..infra.blender.blender_mesh_capture import PdfProperties
 
 from .geometry import ndarray_lru_cache
 
-# Scaling factor for pyclipper (it works with integers)
-SCALE = 1_000_000
+# Scaling factor for 1 micron unit integer math (1 mm = 1000 microns)
+SCALE = 1000
+
+def is_closed_path(path: np.ndarray) -> bool:
+    """Checks if a 2D or 3D path forms a closed loop in integer micron space (1 micron unit)."""
+    if len(path) < 3:
+        return False
+    return bool(np.all(np.round(path[0, :2] * SCALE) == np.round(path[-1, :2] * SCALE)))
 
 def _transfer_path_attr(src_attr: np.ndarray, orig_pts: np.ndarray, new_pts: np.ndarray) -> np.ndarray:
     """
@@ -27,7 +33,7 @@ def _transfer_path_attr(src_attr: np.ndarray, orig_pts: np.ndarray, new_pts: np.
         return np.zeros(0, dtype=src_attr.dtype if hasattr(src_attr, 'dtype') else float)
     if N == 0:
         return np.zeros(M, dtype=src_attr.dtype if hasattr(src_attr, 'dtype') else float)
-    if N == M and np.allclose(orig_pts, new_pts):
+    if N == M and is_closed_path(orig_pts) == is_closed_path(new_pts) and np.all(np.round(orig_pts * SCALE) == np.round(new_pts * SCALE)):
         return src_attr.copy()
     if len(src_attr) > 0 and np.all(src_attr == src_attr[0]):
         return np.full(M, src_attr[0], dtype=src_attr.dtype if hasattr(src_attr, 'dtype') else float)
@@ -100,12 +106,12 @@ def align_path_seam_sharpest(path: np.ndarray) -> np.ndarray:
     falls back to the sharpest angle overall.
     
     If path is open or has fewer than 3 distinct vertices, returns path unchanged.
-    Uses vectorized NumPy operations for high performance.
+    Uses exact 1-micron integer arithmetic for orientation and angle selection.
     """
     if len(path) < 4:
         return path
 
-    if not np.allclose(path[0], path[-1]):
+    if not is_closed_path(path):
         return path
 
     pts = path[:-1]
@@ -113,36 +119,39 @@ def align_path_seam_sharpest(path: np.ndarray) -> np.ndarray:
     if M < 3:
         return path
 
-    pts2d = pts[:, :2]
-    x = pts2d[:, 0]
-    y = pts2d[:, 1]
+    pts_um = np.round(pts[:, :2] * SCALE).astype(np.int64)
+    x = pts_um[:, 0]
+    y = pts_um[:, 1]
     x_next = np.roll(x, -1)
     y_next = np.roll(y, -1)
-    signed_area = 0.5 * np.sum(x * y_next - x_next * y)
-    if abs(signed_area) < 1e-9:
+    signed_area_um = np.sum(x * y_next - x_next * y)
+    if signed_area_um == 0:
         return path
 
-    prev_pts = np.roll(pts2d, 1, axis=0)
-    next_pts = np.roll(pts2d, -1, axis=0)
+    prev_pts = np.roll(pts_um, 1, axis=0)
+    next_pts = np.roll(pts_um, -1, axis=0)
 
-    v_in = pts2d - prev_pts
-    v_out = next_pts - pts2d
+    v_in = pts_um - prev_pts
+    v_out = next_pts - pts_um
 
-    l_in = np.linalg.norm(v_in, axis=1)
-    l_out = np.linalg.norm(v_out, axis=1)
+    l2_in = np.sum(v_in**2, axis=1)
+    l2_out = np.sum(v_out**2, axis=1)
 
-    valid = (l_in > 1e-6) & (l_out > 1e-6)
+    valid = (l2_in > 0) & (l2_out > 0)
     if not np.any(valid):
         return path
 
     cross_2d = v_in[:, 0] * v_out[:, 1] - v_in[:, 1] * v_out[:, 0]
-    if signed_area > 0:
-        concave_mask = valid & (cross_2d < -1e-6)
+    if signed_area_um > 0:
+        concave_mask = valid & (cross_2d < 0)
     else:
-        concave_mask = valid & (cross_2d > 1e-6)
+        concave_mask = valid & (cross_2d > 0)
+
+    l_in = np.sqrt(l2_in.astype(np.float64))
+    l_out = np.sqrt(l2_out.astype(np.float64))
 
     cos_angles = np.full(M, 1.0)
-    dot_prods = np.sum(v_in[valid] * v_out[valid], axis=1)
+    dot_prods = np.sum(v_in[valid] * v_out[valid], axis=1).astype(np.float64)
     cos_angles[valid] = dot_prods / (l_in[valid] * l_out[valid])
 
     if np.any(concave_mask):
@@ -436,14 +445,6 @@ class SlicePaths(list[np.ndarray]):
             
         return self.copy_with(new_paths)
 
-        new_paths = []
-        for p in self:
-            # Shift to center, rotate, shift back
-            new_p = (p - center) @ rot_mat.T + center
-            new_paths.append(new_p)
-            
-        return self.copy_with(new_paths)
-
     def get_first_layer_midpoint(self) -> np.ndarray:
         if not self:
             return np.zeros(3)
@@ -515,6 +516,7 @@ class SlicePaths(list[np.ndarray]):
         """
         Aligns the seams (starting point of closed paths) in SlicePaths.
         Supported modes: 'sharpest'.
+        Uses 1-micron integer math.
         """
         if not self or mode != "sharpest":
             return self
@@ -525,7 +527,7 @@ class SlicePaths(list[np.ndarray]):
         new_extra: dict[str, list[np.ndarray]] = {k: [] for k in self.extra_attributes}
 
         for i, p in enumerate(self):
-            if len(p) < 4 or not np.allclose(p[0], p[-1]):
+            if len(p) < 4 or not is_closed_path(p):
                 new_paths.append(p)
                 new_ext.append(self.extrusion_rate[i])
                 new_feed.append(self.feedrate[i])
@@ -543,34 +545,37 @@ class SlicePaths(list[np.ndarray]):
                     new_extra[k].append(self.extra_attributes[k][i])
                 continue
 
-            pts2d = pts[:, :2]
-            x = pts2d[:, 0]
-            y = pts2d[:, 1]
+            pts_um = np.round(pts[:, :2] * SCALE).astype(np.int64)
+            x = pts_um[:, 0]
+            y = pts_um[:, 1]
             x_next = np.roll(x, -1)
             y_next = np.roll(y, -1)
-            signed_area = 0.5 * np.sum(x * y_next - x_next * y)
+            signed_area_um = np.sum(x * y_next - x_next * y)
 
-            prev_pts = np.roll(pts2d, 1, axis=0)
-            next_pts = np.roll(pts2d, -1, axis=0)
+            prev_pts = np.roll(pts_um, 1, axis=0)
+            next_pts = np.roll(pts_um, -1, axis=0)
 
-            v_in = pts2d - prev_pts
-            v_out = next_pts - pts2d
+            v_in = pts_um - prev_pts
+            v_out = next_pts - pts_um
 
-            l_in = np.linalg.norm(v_in, axis=1)
-            l_out = np.linalg.norm(v_out, axis=1)
+            l2_in = np.sum(v_in**2, axis=1)
+            l2_out = np.sum(v_out**2, axis=1)
 
-            valid = (l_in > 1e-6) & (l_out > 1e-6)
-            if not np.any(valid) or abs(signed_area) < 1e-9:
+            valid = (l2_in > 0) & (l2_out > 0)
+            if not np.any(valid) or signed_area_um == 0:
                 best_idx = 0
             else:
                 cross_2d = v_in[:, 0] * v_out[:, 1] - v_in[:, 1] * v_out[:, 0]
-                if signed_area > 0:
-                    concave_mask = valid & (cross_2d < -1e-6)
+                if signed_area_um > 0:
+                    concave_mask = valid & (cross_2d < 0)
                 else:
-                    concave_mask = valid & (cross_2d > 1e-6)
+                    concave_mask = valid & (cross_2d > 0)
+
+                l_in = np.sqrt(l2_in.astype(np.float64))
+                l_out = np.sqrt(l2_out.astype(np.float64))
 
                 cos_angles = np.full(M, 1.0)
-                dot_prods = np.sum(v_in[valid] * v_out[valid], axis=1)
+                dot_prods = np.sum(v_in[valid] * v_out[valid], axis=1).astype(np.float64)
                 cos_angles[valid] = dot_prods / (l_in[valid] * l_out[valid])
 
                 if np.any(concave_mask):
@@ -679,36 +684,41 @@ def slice_at_z(edges, normal_vector=np.array([0,0,1]), tolerance=1e-15):
 
         segment_count = filtered_arr.shape[-2] // 2
         segments = filtered_arr.reshape(segment_count, 2, 3)
-        segments = np.around(segments, 6)
+        # Quantize to micron resolution
+        segments = np.round(segments * SCALE) / SCALE
         all_segments.append(segments)
 
     return all_segments
 
-def link_segments(segments: np.ndarray, tolerance=1e-6) -> list[np.ndarray]:
-    """Links segments (N, 2, 3) into continuous paths."""
+def link_segments(segments: np.ndarray) -> list[np.ndarray]:
+    """Links segments (N, 2, 3) into continuous paths using 1-micron integer grid."""
     if len(segments) == 0: return []
     z = segments[0, 0, 2]
     pts = segments[:, :, :2]
     
-    def to_key(p): return tuple((p / tolerance).round().astype(np.int64))
+    # Quantize to integer micron tuples: (x_um, y_um)
+    pts_um = np.round(pts * SCALE).astype(np.int64)
     
-    adj = {}
+    adj: dict[tuple[int, int], list[tuple[tuple[int, int], int]]] = {}
     for i in range(len(segments)):
-        p1, p2 = pts[i, 0], pts[i, 1]
-        k1, k2 = to_key(p1), to_key(p2)
-        if k1 == k2: continue
+        k1 = (int(pts_um[i, 0, 0]), int(pts_um[i, 0, 1]))
+        k2 = (int(pts_um[i, 1, 0]), int(pts_um[i, 1, 1]))
+        if k1 == k2:
+            continue
         adj.setdefault(k1, []).append((k2, i))
         adj.setdefault(k2, []).append((k1, i))
         
     paths = []
     used = set()
     for i in range(len(segments)):
-        if i in used: continue
-        p1, p2 = pts[i, 0], pts[i, 1]
-        k1, k2 = to_key(p1), to_key(p2)
-        if k1 == k2: continue
+        if i in used:
+            continue
+        k1 = (int(pts_um[i, 0, 0]), int(pts_um[i, 0, 1]))
+        k2 = (int(pts_um[i, 1, 0]), int(pts_um[i, 1, 1]))
+        if k1 == k2:
+            continue
         
-        path_pts = [p1, p2]
+        path_pts = [pts[i, 0], pts[i, 1]]
         used.add(i)
         
         # Forward
@@ -717,14 +727,15 @@ def link_segments(segments: np.ndarray, tolerance=1e-6) -> list[np.ndarray]:
             found = False
             for next_k, idx in adj.get(curr_k, []):
                 if idx not in used:
-                    pk1, pk2 = to_key(pts[idx, 0]), to_key(pts[idx, 1])
+                    pk1 = (int(pts_um[idx, 0, 0]), int(pts_um[idx, 0, 1]))
                     other_pt = pts[idx, 1] if pk1 == curr_k else pts[idx, 0]
                     path_pts.append(other_pt)
                     used.add(idx)
-                    curr_k = to_key(other_pt)
+                    curr_k = next_k
                     found = True
                     break
-            if not found: break
+            if not found:
+                break
             
         # Backward
         curr_k = k1
@@ -732,16 +743,21 @@ def link_segments(segments: np.ndarray, tolerance=1e-6) -> list[np.ndarray]:
             found = False
             for next_k, idx in adj.get(curr_k, []):
                 if idx not in used:
-                    pk1, pk2 = to_key(pts[idx, 0]), to_key(pts[idx, 1])
+                    pk1 = (int(pts_um[idx, 0, 0]), int(pts_um[idx, 0, 1]))
                     other_pt = pts[idx, 1] if pk1 == curr_k else pts[idx, 0]
                     path_pts.insert(0, other_pt)
                     used.add(idx)
-                    curr_k = to_key(other_pt)
+                    curr_k = next_k
                     found = True
                     break
-            if not found: break
+            if not found:
+                break
             
-        res = np.column_stack([np.array(path_pts), np.full(len(path_pts), z)])
+        p_arr = np.array(path_pts)
+        if len(p_arr) > 2 and is_closed_path(p_arr):
+            p_arr[-1] = p_arr[0]
+            
+        res = np.column_stack([p_arr, np.full(len(p_arr), z)])
         paths.append(res)
     return paths
 
@@ -755,7 +771,7 @@ def segments_to_slice(segments: np.ndarray, ignore_holes: bool = False) -> list[
     open_paths = []
     for p in linked:
         path_pts = p[:, :2]
-        if len(path_pts) > 3 and np.allclose(path_pts[0], path_pts[-1]):
+        if len(path_pts) > 3 and is_closed_path(p):
             closed_paths.append(p)
         else:
             open_paths.append(p)
@@ -768,7 +784,7 @@ def segments_to_slice(segments: np.ndarray, ignore_holes: bool = False) -> list[
         for p in closed_paths:
             path_pts = p[:, :2]
             path_pts = path_pts[:-1]
-            scaled = (path_pts * SCALE).astype(np.int64).tolist()
+            scaled = (path_pts * SCALE).round().astype(np.int64).tolist()
             pc.AddPath(scaled, pyclipper.PT_SUBJECT, closed = True) # pyright: ignore[reportAttributeAccessIssue]
         
         if ignore_holes:
@@ -789,7 +805,7 @@ def segments_to_slice(segments: np.ndarray, ignore_holes: bool = False) -> list[
         
         for path in solution:
             if not path: continue
-            fpath = np.array(path) / SCALE
+            fpath = np.array(path, dtype=np.float64) / SCALE
             fpath_3d = np.column_stack([fpath, np.full(len(fpath), z)])
             # Close loop by appending the first point for internal consistency
             fpath_3d = np.vstack([fpath_3d, fpath_3d[0]])
@@ -824,10 +840,9 @@ def get_boundary_path(pt1: np.ndarray, pt2: np.ndarray, loops: list[np.ndarray])
     min_len = float('inf')
     
     for loop in loops:
-        # Pyclipper paths are usually not closed in the array (last != first) if ET_CLOSEDPOLYGON
-        # but NodeSlicer usually keeps them closed. Ensure it's closed for logic.
+        # Ensure it's closed for logic.
         working_loop = loop
-        if not np.allclose(loop[0], loop[-1]):
+        if not is_closed_path(loop):
             working_loop = np.vstack([loop, loop[0]])
             
         idx1, u1 = find_point_on_loop(pt1, working_loop)
@@ -876,12 +891,12 @@ def boolean_slice(subject: SlicePaths, object: SlicePaths, operation: str = 'UNI
     object_dict: dict[int, list[np.ndarray]] = {}
 
     for s in subject:
-        z = int(round(s[0, 2] * 1000))
+        z = int(round(s[0, 2] * SCALE))
         all_z_keys.add(z)
         subject_dict.setdefault(z, []).append(s)
 
     for s in object:
-        z = int(round(s[0, 2] * 1000))
+        z = int(round(s[0, 2] * SCALE))
         all_z_keys.add(z)
         object_dict.setdefault(z, []).append(s)
 
@@ -912,10 +927,10 @@ def boolean_slice(subject: SlicePaths, object: SlicePaths, operation: str = 'UNI
         def add_paths_to_clipper(paths, role):
             for s in paths:
                 path_pts = s[:, :2]
-                is_closed = len(path_pts) > 2 and np.allclose(path_pts[0], path_pts[-1])
+                is_closed = is_closed_path(s)
                 if is_closed:
                     path_pts = path_pts[:-1]
-                scaled = (path_pts * SCALE).astype(np.int64).tolist()
+                scaled = (path_pts * SCALE).round().astype(np.int64).tolist()
                 pc.AddPath(scaled, role, is_closed) # pyright: ignore[reportAttributeAccessIssue]
 
         layer_results = []
@@ -923,26 +938,26 @@ def boolean_slice(subject: SlicePaths, object: SlicePaths, operation: str = 'UNI
         def process_op(subs, clips_scaled, clips_pts, op_type):
             for s in subs:
                 path_pts = s[:, :2]
-                is_closed = len(path_pts) > 2 and np.allclose(path_pts[0], path_pts[-1])
+                is_closed = is_closed_path(s)
                 
                 if not connect_along_boundary or is_closed:
                     pc.Clear()
                     if is_closed: path_pts = path_pts[:-1]
-                    pc.AddPath((path_pts * SCALE).astype(np.int64).tolist(), pyclipper.PT_SUBJECT, is_closed)  # pyright: ignore[reportAttributeAccessIssue]
+                    pc.AddPath((path_pts * SCALE).round().astype(np.int64).tolist(), pyclipper.PT_SUBJECT, is_closed)  # pyright: ignore[reportAttributeAccessIssue]
                     for c in clips_scaled:
                         pc.AddPath(c, pyclipper.PT_CLIP, True) # pyright: ignore[reportAttributeAccessIssue]
                     
                     solution = pc.Execute2(op_type, pyclipper.PFT_EVENODD, pyclipper.PFT_EVENODD) # pyright: ignore[reportAttributeAccessIssue]
                     for path in pyclipper.ClosedPathsFromPolyTree(solution): # pyright: ignore[reportAttributeAccessIssue]
-                        fpath = np.array(path) / SCALE
+                        fpath = np.array(path, dtype=np.float64) / SCALE
                         fpath_3d = np.column_stack([fpath, np.full(len(fpath), z)])
                         layer_results.append(np.vstack([fpath_3d, fpath_3d[0]]))
                     for path in pyclipper.OpenPathsFromPolyTree(solution): # pyright: ignore[reportAttributeAccessIssue]
-                        fpath = np.array(path) / SCALE
+                        fpath = np.array(path, dtype=np.float64) / SCALE
                         layer_results.append(np.column_stack([fpath, np.full(len(fpath), z)]))
                 else:
                     pc.Clear()
-                    pc.AddPath((path_pts * SCALE).astype(np.int64).tolist(), pyclipper.PT_SUBJECT, False) # pyright: ignore[reportAttributeAccessIssue]
+                    pc.AddPath((path_pts * SCALE).round().astype(np.int64).tolist(), pyclipper.PT_SUBJECT, False) # pyright: ignore[reportAttributeAccessIssue]
                     for c in clips_scaled:
                         pc.AddPath(c, pyclipper.PT_CLIP, True) # pyright: ignore[reportAttributeAccessIssue]
                     
@@ -966,7 +981,7 @@ def boolean_slice(subject: SlicePaths, object: SlicePaths, operation: str = 'UNI
 
                     segments = []
                     for path in open_results:
-                        fpath = np.array(path) / SCALE
+                        fpath = np.array(path, dtype=np.float64) / SCALE
                         p_start = get_p(fpath[0])
                         p_end = get_p(fpath[-1])
                         if p_start > p_end:
@@ -997,20 +1012,20 @@ def boolean_slice(subject: SlicePaths, object: SlicePaths, operation: str = 'UNI
                     layer_results.append(np.column_stack([path_to_add, np.full(len(path_to_add), z)]))
 
         if operation == 'INTERSECTION':
-            obj_closed_pts = [s[:, :2] for s in object_slices if len(s) > 2 and np.allclose(s[0], s[-1])]
-            obj_closed_scaled = [(pts[:-1] * SCALE).astype(np.int64).tolist() for pts in obj_closed_pts]
+            obj_closed_pts = [s[:, :2] for s in object_slices if is_closed_path(s)]
+            obj_closed_scaled = [(pts[:-1] * SCALE).round().astype(np.int64).tolist() for pts in obj_closed_pts]
             process_op(subject_slices, obj_closed_scaled, obj_closed_pts, pyclipper.CT_INTERSECTION) # pyright: ignore[reportAttributeAccessIssue]
             
             # Pass 2 for B_open ∩ A_closed
-            b_open = [s for s in object_slices if not (len(s) > 2 and np.allclose(s[0], s[-1]))]
+            b_open = [s for s in object_slices if not is_closed_path(s)]
             if b_open:
-                sub_closed_pts = [s[:, :2] for s in subject_slices if len(s) > 2 and np.allclose(s[0], s[-1])]
-                sub_closed_scaled = [(pts[:-1] * SCALE).astype(np.int64).tolist() for pts in sub_closed_pts]
+                sub_closed_pts = [s[:, :2] for s in subject_slices if is_closed_path(s)]
+                sub_closed_scaled = [(pts[:-1] * SCALE).round().astype(np.int64).tolist() for pts in sub_closed_pts]
                 process_op(b_open, sub_closed_scaled, sub_closed_pts, pyclipper.CT_INTERSECTION) # pyright: ignore[reportAttributeAccessIssue]
         
         elif operation == 'DIFFERENCE':
-            obj_closed_pts = [s[:, :2] for s in object_slices if len(s) > 2 and np.allclose(s[0], s[-1])]
-            obj_closed_scaled = [(pts[:-1] * SCALE).astype(np.int64).tolist() for pts in obj_closed_pts]
+            obj_closed_pts = [s[:, :2] for s in object_slices if is_closed_path(s)]
+            obj_closed_scaled = [(pts[:-1] * SCALE).round().astype(np.int64).tolist() for pts in obj_closed_pts]
             process_op(subject_slices, obj_closed_scaled, obj_closed_pts, pyclipper.CT_DIFFERENCE) # pyright: ignore[reportAttributeAccessIssue]
             # DIFFERENCE is not symmetric for open paths in the same way, usually A - B means A is the main focus.
 
@@ -1020,7 +1035,7 @@ def boolean_slice(subject: SlicePaths, object: SlicePaths, operation: str = 'UNI
             obj_closed = []
             obj_open = []
             for s in object_slices:
-                if len(s) > 2 and np.allclose(s[0], s[-1]): obj_closed.append(s)
+                if is_closed_path(s): obj_closed.append(s)
                 else: obj_open.append(s)
 
             if operation in ['UNION', 'XOR']:
@@ -1028,7 +1043,7 @@ def boolean_slice(subject: SlicePaths, object: SlicePaths, operation: str = 'UNI
             
             for s in obj_closed:
                 path_pts = s[:, :2]
-                scaled = (path_pts[:-1] * SCALE).astype(np.int64).tolist()
+                scaled = (path_pts[:-1] * SCALE).round().astype(np.int64).tolist()
                 pc.AddPath(scaled, pyclipper.PT_CLIP, True) # pyright: ignore[reportAttributeAccessIssue]
             
             op_type = pyclipper.CT_UNION # pyright: ignore[reportAttributeAccessIssue]
@@ -1097,12 +1112,11 @@ def buffer_curve_slice(
 
     from shapely.geometry import LineString
     
-    # Group paths by Z height to avoid flattening the entire model into 2D
+    # Group paths by Z height in integer microns
     groups: dict[int, list[np.ndarray]] = {}
     for p in slice_paths:
         z = p[0, 2]
-        # Use scaled integer for stable dictionary grouping of floats
-        z_key = int(round(z * 1000))
+        z_key = int(round(z * SCALE))
         groups.setdefault(z_key, []).append(p)
 
     paths_list: list[np.ndarray] = []
@@ -1172,11 +1186,11 @@ def offset_curve_slice(
 
     from shapely.geometry import LineString, Polygon, LinearRing
     
-    # Group paths by Z height
+    # Group paths by Z height in integer microns
     groups: dict[int, list[np.ndarray]] = {}
     for p in slice_paths:
         z = p[0, 2]
-        z_key = int(round(z * 1000))
+        z_key = int(round(z * SCALE))
         groups.setdefault(z_key, []).append(p)
 
     paths_list: list[np.ndarray] = []
@@ -1192,9 +1206,7 @@ def offset_curve_slice(
                 continue
 
             pts_2d = p[:, :2]
-            
-            # Check if path is closed
-            is_closed = len(pts_2d) > 2 and np.allclose(pts_2d[0], pts_2d[-1])
+            is_closed = is_closed_path(p)
             
             if is_closed:
                 try:
@@ -1242,7 +1254,7 @@ def offset_curve_slice(
     return paths_list, groups_list
 
 def paths_to_shapely_polygon(paths: list[np.ndarray]) -> BaseGeometry:
-    """Converts a list of paths on a layer to a single Shapely geometry using pyclipper to resolve holes."""
+    """Converts a list of paths on a layer to a single Shapely geometry using pyclipper to resolve holes in 1-micron space."""
     if not paths:
         return Polygon()
         
@@ -1254,9 +1266,9 @@ def paths_to_shapely_polygon(paths: list[np.ndarray]) -> BaseGeometry:
         if len(p) < 3:
             continue
         pts_2d = p[:, :2]
-        if np.allclose(pts_2d[0], pts_2d[-1]):
+        if is_closed_path(p):
             pts_2d = pts_2d[:-1]
-        scaled = (pts_2d * SCALE).astype(np.int64).tolist()
+        scaled = (pts_2d * SCALE).round().astype(np.int64).tolist()
         pc.AddPath(scaled, pyclipper.PT_SUBJECT, True) # pyright: ignore[reportAttributeAccessIssue]
         
     tree = pc.Execute2(pyclipper.CT_UNION, pyclipper.PFT_EVENODD, pyclipper.PFT_EVENODD) # pyright: ignore[reportAttributeAccessIssue]
@@ -1265,13 +1277,13 @@ def paths_to_shapely_polygon(paths: list[np.ndarray]) -> BaseGeometry:
         polygons = []
         if hasattr(node, 'Contour') and node.Contour and not node.IsHole:
             if len(node.Contour) >= 3:
-                exterior = np.array(node.Contour) / SCALE
+                exterior = np.array(node.Contour, dtype=np.float64) / SCALE
                 interiors = []
                 child_islands = []
                 for child in node.Childs:
                     if child.IsHole:
                         if child.Contour and len(child.Contour) >= 3:
-                            interiors.append(np.array(child.Contour) / SCALE)
+                            interiors.append(np.array(child.Contour, dtype=np.float64) / SCALE)
                         for grandchild in child.Childs:
                             child_islands.append(grandchild)
                     else:
@@ -1296,13 +1308,13 @@ def get_infill_mask_slice(slice_paths: list[np.ndarray]) -> tuple[list[np.ndarra
     if not slice_paths:
         return [], []
 
-    # Group paths by their Z height
+    # Group paths by their Z height in integer microns
     groups: dict[int, list[np.ndarray]] = {}
     for p in slice_paths:
         if len(p) == 0:
             continue
         z = p[0, 2]
-        z_key = int(round(z * 1000))
+        z_key = int(round(z * SCALE))
         groups.setdefault(z_key, []).append(p)
 
     paths_list: list[np.ndarray] = []
@@ -1392,12 +1404,11 @@ def buffer_slice(slice_paths: list[np.ndarray], distance: float, miter='round',
 
     if not slice_paths: return [], []
     
-    # Group paths by Z height to avoid flattening the entire model into 2D
+    # Group paths by Z height in integer microns
     groups: dict[int, list[np.ndarray]] = {}
     for p in slice_paths:
         z = p[0, 2]
-        # Use scaled integer for stable dictionary grouping of floats
-        z_key = int(round(z * 1000))
+        z_key = int(round(z * SCALE))
         groups.setdefault(z_key, []).append(p)
     
     join_types = {
@@ -1410,7 +1421,7 @@ def buffer_slice(slice_paths: list[np.ndarray], distance: float, miter='round',
     
     paths_list: list[np.ndarray] = []
     groups_list: list[int] = []
-    pco = pyclipper.PyclipperOffset(arc_tolerance=tolerance * SCALE) # pyright: ignore[reportAttributeAccessIssue]
+    pco = pyclipper.PyclipperOffset(arc_tolerance=int(round(tolerance * SCALE))) # pyright: ignore[reportAttributeAccessIssue]
     
     # Buffer each layer independently
     group_id = 0
@@ -1423,21 +1434,21 @@ def buffer_slice(slice_paths: list[np.ndarray], distance: float, miter='round',
         for p in layer_paths:
             path_pts = p[:, :2]
             # Strip redundant closing points
-            if len(path_pts) > 2 and np.allclose(path_pts[0], path_pts[-1]):
+            if is_closed_path(p):
                 path_pts = path_pts[:-1]
             
             if len(path_pts) < 3: continue
-            scaled_paths.append((path_pts * SCALE).astype(np.int64).tolist())
+            scaled_paths.append((path_pts * SCALE).round().astype(np.int64).tolist())
         
         if not scaled_paths: continue
 
         # Add all paths for this specific Z layer
         pco.AddPaths(scaled_paths, jt, pyclipper.ET_CLOSEDPOLYGON) # pyright: ignore[reportAttributeAccessIssue]
-        solution = pco.Execute(distance * SCALE)
+        solution = pco.Execute(int(round(distance * SCALE)))
         
         for path in solution:
             if not path: continue
-            fpath = np.array(path) / SCALE
+            fpath = np.array(path, dtype=np.float64) / SCALE
             fpath_3d = np.column_stack([fpath, np.full(len(fpath), z)])
             # Re-close loop
             fpath_3d = np.vstack([fpath_3d, fpath_3d[0]])
@@ -1451,7 +1462,7 @@ def buffer_slice(slice_paths: list[np.ndarray], distance: float, miter='round',
 
 @ndarray_lru_cache(maxsize=32)
 def infill_slice(slice_paths: 'SlicePaths', density: float, rotation_deg: float = 0.0, infill_type: str = 'GRID') -> tuple[list[np.ndarray], list[int]]:
-    """Generates a grid or rectilinear infill clipped by the provided paths. Consistent across layers."""
+    """Generates a grid or rectilinear infill clipped by the provided paths. Consistent across layers using 1-micron integer grid."""
     if not slice_paths or density <= 0: return [], []
     
     rotation = np.radians(rotation_deg)
@@ -1478,39 +1489,43 @@ def infill_slice(slice_paths: 'SlicePaths', density: float, rotation_deg: float
     rg_min_x, rg_min_y = rotated_corners[:, 0].min(), rotated_corners[:, 1].min()
     rg_max_x, rg_max_y = rotated_corners[:, 0].max(), rotated_corners[:, 1].max()
 
-    # Generate the global static grid lines in de-rotated space
-    rg_min_x -= density
-    rg_max_x += density
-    rg_min_y -= density
-    rg_max_y += density
+    density_um = int(round(density * SCALE))
+    if density_um <= 0:
+        return [], []
+
+    # Generate the global static grid lines in de-rotated space using integer microns
+    rg_min_x_um = int(np.floor(rg_min_x * SCALE)) - density_um
+    rg_max_x_um = int(np.ceil(rg_max_x * SCALE)) + density_um
+    rg_min_y_um = int(np.floor(rg_min_y * SCALE)) - density_um
+    rg_max_y_um = int(np.ceil(rg_max_y * SCALE)) + density_um
 
     vertical_lines = []
-    x = rg_min_x
-    while x <= rg_max_x:
+    x_um = rg_min_x_um
+    while x_um <= rg_max_x_um:
         vertical_lines.append([
-            (int(x * SCALE), int(rg_min_y * SCALE)),
-            (int(x * SCALE), int(rg_max_y * SCALE))
+            (x_um, rg_min_y_um),
+            (x_um, rg_max_y_um)
         ])
-        x += density
+        x_um += density_um
 
     horizontal_lines = []
-    y = rg_min_y
-    while y <= rg_max_y:
+    y_um = rg_min_y_um
+    while y_um <= rg_max_y_um:
         horizontal_lines.append([
-            (int(rg_min_x * SCALE), int(y * SCALE)),
-            (int(rg_max_x * SCALE), int(y * SCALE))
+            (rg_min_x_um, y_um),
+            (rg_max_x_um, y_um)
         ])
-        y += density
+        y_um += density_um
 
-    # Group by Z
+    # Group by Z in integer microns
     groups: dict[int, list[np.ndarray]] = {}
-    if hasattr(slice_paths, 'groups'):
+    if hasattr(slice_paths, 'groups') and slice_paths.groups:
         for p, g in zip(slice_paths, slice_paths.groups):
             groups.setdefault(g, []).append(p)
     else:
         # Fallback if it's just a list
         for p in slice_paths:
-            z_key = int(round(p[0, 2] * 1000))
+            z_key = int(round(p[0, 2] * SCALE))
             groups.setdefault(z_key, []).append(p)
         
     output_paths: list[np.ndarray] = []
@@ -1539,15 +1554,15 @@ def infill_slice(slice_paths: 'SlicePaths', density: float, rotation_deg: float
         offset_2d = np.array([global_center[0], global_center[1], 0])
         active_paths = [(p - offset_2d) @ rot_mat_inv.T + offset_2d for p in layer_paths]
 
-        # Clip lines with active_paths
+        # Clip lines with active_paths in integer micron space
         pc = pyclipper.Pyclipper() # pyright: ignore[reportAttributeAccessIssue]
         
         for p in active_paths:
             path_pts = p[:, :2]
-            if len(path_pts) > 2 and np.allclose(path_pts[0], path_pts[-1]):
+            if is_closed_path(p):
                 path_pts = path_pts[:-1]
             if len(path_pts) < 3: continue
-            scaled = (path_pts * SCALE).astype(np.int64).tolist()
+            scaled = (path_pts * SCALE).round().astype(np.int64).tolist()
             pc.AddPath(scaled, pyclipper.PT_CLIP, True) # pyright: ignore[reportAttributeAccessIssue]
             
         if current_grid_paths:
@@ -1559,7 +1574,7 @@ def infill_slice(slice_paths: 'SlicePaths', density: float, rotation_deg: float
         # Rotate back
         for path in clipped_lines:
             if not path: continue
-            fpath = np.array(path) / SCALE
+            fpath = np.array(path, dtype=np.float64) / SCALE
             fpath_3d = np.column_stack([fpath, np.full(len(fpath), z)])
             rotated_fpath_3d = (fpath_3d - offset_2d) @ rot_mat.T + offset_2d
             output_paths.append(rotated_fpath_3d)
@@ -1570,7 +1585,7 @@ def infill_slice(slice_paths: 'SlicePaths', density: float, rotation_deg: float
 def group_segments_by_z(segments: np.ndarray) -> dict[int, np.ndarray]:
     z_values: np.ndarray = segments[:, 0, 2]
     unique_z: np.ndarray = np.unique(z_values)
-    groups: dict[int, np.ndarray] = {int(round(z*1000)): segments[z_values == z] for z in unique_z}
+    groups: dict[int, np.ndarray] = {int(round(z * SCALE)): segments[z_values == z] for z in unique_z}
     return groups
 
 ############################################################
diff --git a/tests/test_slice.py b/tests/test_slice.py
index 9d6891c..86315ce 100644
--- a/tests/test_slice.py
+++ b/tests/test_slice.py
@@ -951,6 +951,43 @@ class TestSlice(unittest.TestCase):
         mock_layout_missing = MagicMock()
         node_missing.draw_buttons(None, mock_layout_missing)
 
+    def test_micron_integer_math(self):
+        from NodeSlicer.core.slice import SCALE, is_closed_path, align_path_seam_sharpest, SlicePaths
+        self.assertEqual(SCALE, 1000)
+
+        # A square with tiny float noise (< 0.5 micron) at endpoint
+        sq = np.array([
+            [0.0, 0.0, 1.0],
+            [10.0, 0.0, 1.0],
+            [10.0, 10.0, 1.0],
+            [0.0, 10.0, 1.0],
+            [0.0001, -0.0001, 1.0] # 0.1 micron noise
+        ])
+        self.assertTrue(is_closed_path(sq))
+
+        # Seam alignment with integer math
+        aligned = align_path_seam_sharpest(sq)
+        self.assertEqual(len(aligned), len(sq))
+
+        # Test buffer with 1-micron precision
+        sp = SlicePaths([sq], groups=[0])
+        buffered = sp.buffer(1.0)
+        self.assertGreater(len(buffered), 0)
+
+    def test_micron_segment_linking(self):
+        from NodeSlicer.core.slice import link_segments, is_closed_path
+        # Segments of a triangle with slight float jitter (0.2 micron) at shared vertices
+        z = 2.5
+        segments = np.array([
+            [[0.0002, 0.0, z], [10.0, 0.0001, z]],
+            [[10.0, 0.0, z], [5.0, 8.660254, z]],
+            [[5.0, 8.660254, z], [0.0, 0.0, z]],
+        ])
+        paths = link_segments(segments)
+        self.assertEqual(len(paths), 1)
+        self.assertTrue(is_closed_path(paths[0]))
+        self.assertTrue(np.allclose(paths[0][0], paths[0][-1]))
+
 
 if __name__ == '__main__':
     unittest.main()