AutoCAD - Using Fillet with Polylines

By Martin Phelps

When the “Fillet” command is used with “Polylines”, there can be several outcomes. A sample closed “Polyline” with dimensions is shown in Figure 1.

Once a “Fillet” radius has been set, in this case the radius has been set to a value of 20, two adjoining lines that comprise the “Polyline” can be selected. Just as if they were standard lines this will place a “Fillet” between the two “Polylines” as shown in Figure 2.

This does mean that using this method, “Fillets” of various values could be applied to the “Polyline”, as shown in Figure 3.

The alternative option would be to use the “Polyline” Sub command, this can be accessed from the “Command Line”, “Right Click Menu” or typing “P + Enter”. This will add the specified “Fillet” to all sections of the “Polyline” as shown in Figure 4.

The “Fillets” are now part of the “Polyline”. If the “Fillet Radius” is changed, for example to 10 and the “Polyline” is re-selected, it will update all the predefined “Fillets” with the new “Radius” value as shown in Figure 5.

When the “Polyline” segment is too short for the set “Radius” the “Fillet” will not added, as shown in Figure 6.

With the “No Trim” option set in the “Fillet” command, the “Fillets” will become separate “Arcs”, and the “Polyline” remains one object as shown in Figure 7.