AutoCAD Tip – Reverting Trim and Extend mode to same behaviour as previous versions

By Dennis Collin

I recently had a conversation with a user who had been using AutoCAD for many years but didn’t like the way AutoCAD’s Trim and Extend command worked with the latest version and asked the question whether they could set it back, so it behaved like it used to! The answer of course is yes, AutoCAD has always catered for users who like their classic interfaces and behaviours. Indeed, this is a common question on our range of AutoCAD training courses.

With respect to Trim and Extend, the commands’ behaviour is controlled by the system variable TRIMEXTENDMODE.

Setting it to ‘1’ or (One, the default and new behaviour) provides an automatic Trim or Extend function. Setting the variable to Off or ‘0’ (Zero) behaviour reverts AutoCAD back to its classic manual edge selection mode.

A follow-on question was how to disable AutoCAD’s ability to consider the extension of all lines as infinite as possible edges? This setting is also controlled the variable EDGEMODE. Set to on (1), considers lines as infinite lengths. Off (0, Zero) consider lines as finite lengths.

Once set these variables will be saved to the user profile and be remembered for subsequent AutoCAD drawing sessions.