diff --git a/cadquery/cq.py b/cadquery/cq.py
index 799f8c2f..c987c9b4 100644
--- a/cadquery/cq.py
+++ b/cadquery/cq.py
@@ -2279,14 +2279,15 @@ class Workplane(CQ):
         how long or wide a feature must be to make sure to cut through all of the material
         :return: A value representing the largest dimension of the first solid on the stack
         """
-        # TODO: this implementation is naive and returns the dims of the first solid... most of
-        # TODO: the time this works. but a stronger implementation would be to search all solids.
-        s = self.findSolid()
-        if s:
-            return s.BoundingBox().DiagonalLength * 5.0
-        else:
+        # Get all the solids contained within this CQ object
+        compound = self.findSolid()
+
+        # Protect against this being called on something like a blank workplane
+        if not compound:
             return -1
 
+        return compound.BoundingBox().DiagonalLength
+
     def cutEach(self, fcn, useLocalCoords=False, clean=True):
         """
         Evaluates the provided function at each point on the stack (ie, eachpoint)
diff --git a/cadquery/occ_impl/shapes.py b/cadquery/occ_impl/shapes.py
index b4405dbe..1b81c916 100644
--- a/cadquery/occ_impl/shapes.py
+++ b/cadquery/occ_impl/shapes.py
@@ -242,7 +242,7 @@ class Shape(object):
 
     @classmethod
     def cast(cls, obj, forConstruction=False):
-        "Returns the right type of wrapper, given a FreeCAD object"
+        "Returns the right type of wrapper, given a OCCT object"
 
         tr = None
 
diff --git a/tests/test_cadquery.py b/tests/test_cadquery.py
index b0f844d7..8ddba51b 100644
--- a/tests/test_cadquery.py
+++ b/tests/test_cadquery.py
@@ -1503,7 +1503,12 @@ class TestCadQuery(BaseTest):
         r = Workplane("XY").box(1, 1, 1)
         dim = r.largestDimension()
 
-        self.assertAlmostEqual(8.7, dim, 1)
+        self.assertAlmostEqual(1.76, dim, 1)
+
+        r = Workplane("XY").rect(1, 1).extrude(1)
+        dim = r.largestDimension()
+
+        self.assertAlmostEqual(1.76, dim, 1)
 
         r = Workplane("XY")
         dim = r.largestDimension()
@@ -1728,7 +1733,6 @@ class TestCadQuery(BaseTest):
 
         # Tests the case where the depth of the cboreHole is not specified
         c2 = CQ(makeCube(3.0))
-        pnts = [(-1.0, -1.0), (0.0, 0.0), (1.0, 1.0)]
         c2 = c2.faces(">Z").workplane().pushPoints(pnts).cboreHole(0.1, 0.25, 0.25)
         self.assertEqual(15, c2.faces().size())