The Three Trims: TRIM, BTRIM and EXTRIM

So what are the "Three Trims" and what do they do?


This tip will discuss the "Three Tenors Trims" (AutoCAD commands) that allow a user to trim objects within a drawing. Practically every AutoCAD user has used the basic TRIM command but did you know about the other two trim commands......BTRIM and EXTRIM?

If you are wondering who are these guys: CLICK HERE (Wikipedia: The Three Tenors)

The TRIM Command

'José Carreras' aka TRIM allows a user to trim objects that intersect with the edges of other objects.

Enter TRIM on the command line or access the command from the AutoCAD Home Ribbon (as shown below). TRIM can also be accessed from the 'Modify" pulldown menu.


To trim objects, select the boundaries and press Enter, then select the objects that you want to trim. To use all the objects as boundaries, press Enter at the first Select Object prompt (without actually selecting any objects).

In the example above, once the cutting edges have been selected (1 and 2), simply click on the entity that you want to trim (3 and 4).

Additionally, a user can trim object(s) by Fence, Crossing, Project and Edge. Erase and Undo commands are conveniently included in the TRIM sub-command options.

For additional information on these sub-commands, please refer to the Autodesk Knowledge Network page for the TRIM command - CLICK HERE.

The BTRIM Command

'Luciano Pavarotti' aka BTRIM allows a user to trim objects that intersect with the edges of a block. The BTRIM command uses the same sequence of steps as the TRIM command. BTRIM is an express tool within AutoCAD.

Enter BTRIM on the command line or access from the AutoCAD Express Tools Ribbon (as shown below). BTRIM can also be accessed from the Express pulldown menu. 



Note: you can use the standard TRIM command to trim to a block edge (not sure when this functionality was added to the standard TRIM command, however the BTRIM command is still available however it is now obsolete (at least in AutoCAD 2017).

The EXTRIM Command

'Plácido Domingo' aka EXTRIM allows a user to trim all objects on one or the other side of an entity such as a polyline, line, circle, image or text. This command quickly allows for all objects to be trimmed at once, including objects that may be too small to see or large amounts of overhanging entities that would require added effort to individually select using the standard TRIM command.

Enter EXTRIM on the command line (this command not available from the AutoCAD Express Tools Ribbon nor in any pulldown menu, it's a 'hidden' command, likely why so many users are not aware of it).

In the example below, the magenta circle will be used as the 'cutting' edge. 



Autodesk Knowledge Network – Command Reference Links