Defining Hatch Boundaries

This tech tip explains the different options for defining hatch boundaries.

Select Draw > Hatch from the AllyCAD menu (or click on the hatch icon in the Drawing toolbar). The hatch prompt bar will appear, and will display 6 square buttons which correspond to the 6 boundary methods:

Define circular hatch boundary

Select the Circle boundary method by clicking on the circle icon in the hatch prompt bar. The Draw Hatch Circle option will prompt you to indicate the centre point of the circle and then a point on the radius of the circle.

Use the snap or jump modes to move to the circumference of the circle and click to indicate the position. A hatch will be created inside the circle boundary you have just defined. Right click in the drawing area and select Accept to finish the hatch, or select Add New Boundary to add another boundary to the current hatch.

Define rectangular hatch boundary

Select the Rectangle boundary method by clicking on the rectangle icon in the hatch prompt bar.

The Draw Hatch Rectangle option will prompt you to indicate the two points defining the opposite corners of the rectangle. Use the snap or jump modes to move to the first point and click to indicate the position. A rubberband rectangle will be displayed. Use the snap or jump modes to move to the second point of the rectangle and click to indicate the position. A hatch will be created inside the rectangle you have just defined. Right-click and select Accept to finish the hatch, or select Add New Boundary to add another boundary to the current hatch.

The Draw Hatch Rectangle option also allows you to chamfer or fillet the rectangle corners by selecting a 'Finish' type in the prompt bar, and entering a chamfer length or fillet radius.

Define polygon hatch boundary

Select the Closed Polygon boundary method by clicking on the polygon icon in the hatch prompt bar.

The Draw Hatch Polygon option will prompt you to indicate the points of the polygon. Follow the prompts so as to indicate as many points as required to define the polygon boundary. Right-click to view the pop-up menu:

Select Cancel Last Vertex to undo the last point you indicated.

Select Cancel Current Boundary to remove the entire polygon and start again.

If you select Add New Boundary, you will be prompted to click on the start position of the hatch polyline.

The Finish option will create a hatch inside the polygon you have just defined. Right-click and select Accept to add the hatch to the drawing.

Define hatch boundary by selecting entities

Select the 'hatch boundary from entities' method by clicking on the button in the hatch prompt bar.

This option prompts you to indicate the entities that make up the boundary of the area you want to hatch. The entities must form a closed loop. Click near the entity to be added. The entity is highlighted to indicate it has been selected:

Continue to select the entities to be added to the boundary. If the entities have been grouped or the entity is a drawn with a polyline, the object may be selected by clicking inside the border. The right side of the lock above has been grouped and is selected by clicking inside the border.

Once all the entities have been selected, right click on the drawing area and select Finish Current Boundary from the popup menu. A hatch will be created inside the boundary you have just defined. Right-click and select Accept to add the hatch to the drawing.

Define hatch boundary by intersections

Select the Intersection boundary method by clicking on the intersection icon in the hatch prompt bar.

The Draw Hatch by Intersections option will prompt you to indicate the boundary elements (intersecting entities) which make up the area you want to hatch.

Follow the prompts to indicate the elements in a clockwise or anticlockwise order. Each element must intersect with the previous element that you indicated. If it does not, a warning will be displayed informing you that the indicated entities do not intersect. Once the last intersecting element is selected, a hatch will be created inside the elements you indicated. Right-click and select Accept to add the hatch to the drawing.

Define hatch boundary by automatic tracking

Select the Autotracking boundary method by clicking on the tracking icon in the hatch prompt bar.

The Draw Hatch by Autotracking option will prompt you to click inside an existing perimeter.

The point you indicate must be inside a closed boundary/perimeter for this option to work, otherwise an error message will be displayed.

A hatch will be created inside the perimeter you indicated. You can continue to click inside more perimeters to add to this hatch, or you can right-click and select Accept to add the hatch to the drawing.

The Detect Islands option in the autotracking prompt bar allows you to exclude closed regions inside the perimeter that you are autotracking.

If the Track Selection option is selected, then the autotracking method will create a hatch using only selected entities as the boundary/perimeter (ie: it will ignore non-selected entities).

The Tolerance option allows you to specify a “gap” distance to be ignored when the entity is not closed. This will allow the auto tracking to track around the perimeter entities even though they do not technically form a closed loop. The example above shows a shape that is not closed (even though it may look closed). The gap between the start and end points is 0.5. The autotracking will fail unless an autotracking tolerance of greater than 0.5 is specified