Reference Section > Shape Library > Lifting Lugs

The Right-Angle Lifting Eye is a flat lifting lug with a straight base, a vertical back edge at right angles to the base, and a round eye with a hole for a shackle or hook. The outline is one closed profile: the base, the vertical back edge, an arc over the top of the eye, and a straight sloping edge that runs from the eye back down to the insert point, tangent to the arc. The eye hole is a separate circle. The lug has one sloping edge. For a lug with two sloping sides, use the Symmetric Lifting Eye.

The shape has no alias names. It appears in the shapes library under Lifting Lugs, Triangles and Tools.

Insert point and direction

The insert point (Base X, Base Y) is the left end of the base, where the sloping edge meets it. The shape is built to the right and upward from there:

•The base runs along +X from the insert point for the Base Width.

•The back edge runs straight up (+Y) from the right-hand end of the base for the Eye Height.

•The centre of the eye is at X = Base Width – Eye Thickness – Eye Diameter / 2 and Y = Eye Height from the insert point. The outer arc of the eye has radius Eye Diameter / 2 + Eye Thickness. It starts at the top of the back edge, and the back edge is tangent to the arc there.

•The outer arc runs over the top of the eye to the point where a straight line from the insert point just touches it. The sloping edge runs from that point back down to the insert point.

The overall height of the lug is Eye Height + Eye Diameter / 2 + Eye Thickness. With the defaults the lug is 125 mm wide and 125 mm high, with a 50 mm hole whose centre is 75 mm above the base and 75 mm to the right of the insert point.

The Base Width dimension is drawn along the base. The Eye Height dimension is drawn vertically, from the right-hand end of the base up to the height of the eye centre. The Eye Thickness dimension is drawn across the material to the right of the hole, at the height of the eye centre. The Eye Diameter dimension is drawn on the hole. The Transform properties (Rotation, Mirroring X) change the orientation of the whole shape.

Properties

Property	Description	Default
Base Width	Length of the base, measured along +X from the insert point to the foot of the back edge (mm or inch). Keep it greater than Eye Thickness + Eye Diameter / 2, so the eye centre is to the right of the insert point.	125 mm (5 in)
Eye Height	Height of the eye centre above the base (mm or inch). This is also the length of the straight back edge.	75 mm (3 in)
Eye Diameter	Diameter of the hole in the eye (mm or inch). 0 gives a single point at the eye centre instead of a hole.	50 mm (2 in)
Eye Thickness	Width of material round the hole, from the edge of the hole to the outer arc of the eye (mm or inch). It is also the material left between the hole and the back edge.	25 mm (1 in)

Limits

•The property page rejects negative values. Zero is accepted, but the lug is only meaningful with positive values. The code does not check the four values against each other.

•An Eye Thickness of 0 leaves no material round the hole. The outer arc then coincides with the edge of the hole, and the back edge touches the hole.

•If Base Width is less than Eye Thickness + Eye Diameter / 2, the eye centre lies to the left of the insert point and the eye hole extends past the insert point. The code does not check for this. Keep Base Width greater than Eye Thickness + Eye Diameter / 2.

When the shape cannot be built

The outline includes a straight edge from the insert point that touches the outer arc of the eye (radius Eye Diameter / 2 + Eye Thickness, centred on the hole). That touch point exists only if the insert point lies outside the outer arc, that is, if its distance to the eye centre is greater than Eye Diameter / 2 + Eye Thickness. The code does not check this. If the insert point is inside or on the outer arc, one of the following happens, and which one depends on the values:

•The build does not find exactly one touch point between the tangent arc and the outer arc of the eye. It then stops without an error: the outline is not drawn and only the eye hole is drawn. There is no warning and no broken-shape marker, so check the drawing for the outline.

•An error is raised during the build. The program shows the broken-shape marker at the insert point and Warning: Cannot build shape from these parameters on the property page. The dimensions are not rebuilt and keep their previous values.

Increase Base Width or Eye Height, or reduce Eye Diameter or Eye Thickness, until the outline is drawn with no warning.

Every 2D shape also has the Transform properties (Base X, Base Y, Rotation, Scale, Mirroring X) and the Polar Array properties, listed after the shape's own properties.