One common method of adding realism to a model created in Autocad's 3D interface is to add a chamfer or a fillet to the edges of the object. A chamfer is generally a machined-angled surface added to the straight edges of an object, most commonly at thirty or forty-five degree angles to the flat planes of the object. A fillet is a rounded edge machined in a similar fashion, and described by a radius. The purpose of both fillets and chamfers is to reduce any imperfections caused by the cutting and tooling of metal machine parts. When we see these artifacts on an object created in a 3D modeling program like Autocad, our eye interprets them as belonging to a real objects, and subconsciously lends an air or realism to the model.
In the example shown here we have a metal bracket with notches, grooves and holes cut into the various surfaces and planes. We have added fillets and chamfers to the edges to lend this air of realism. The bracket itself was initially created using the standard Box tool and punching in the values for width, height and depth. Then a variety of Boolean operations, such as Union, Subtraction and Intersection were applied. The three boxes are joined together using the Union command. Then more boxes representing the grooves were added to the initial bracket shape, then cut out using the Subtract command.
The hole in the bracket's base was created by adding a cylinder and projecting it through the base. The Subtract command was also used to cut out the hole. And finally we wish to chamfer and fillet the edges. To do so we first select the Chamfer tool from the Modify tab at the top Ribbon panel. Next the user selects the individual lines which make up the edges to be chamfered, completing the selection by clicking the Enter key on the keyboard. Autocad then asks for a distance or angle - here we could type in 2, for example, and hit Enter twice. This means that the distance along each of the two perpendicular surfaces adjacent to the edge will be 2mm. We then click the line or lines again and again hit the Enter key. The chamfer of 2mm on each side of the edge should appear, cutting away the original edge.
The Fillet tool operates in a similar manner; the tool being found stacked behind the Chamfer tool in the Modify tab. In our example shown here the top edge of the overhanging lip was filleted using a radius of 2mm. The edge or edges are first selected, and the Radius value is entered.
In this way a sense of realism can be employed with smaller 3D models, especially after highlights are picked out when realistic lighting and materials are added to the scene. For larger models, however, like architectural or interior design models, adding too many chamfers and fillets is not recommended since this increases the file's size and rendering time. In such cases often the edges closest to the camera only are filleted and chamfered, leaving the further details alone since those edges are blurred anyway by distance.
Tom Gillan has been a consistent trainer for AutoCAD-3D to corporate clients in Sydney for the past seven years. Please visit our website for additional information: http://www.designworkshopsydney.com.au/autocad-3d-courses/.