AutoCAD Tip: Fast Precision Edits with Fillet, Chamfer, and Trim

Speed up cleanup and finishing geometry by mastering Fillet, Chamfer, and Trim for precision edits with minimal clicks.

• Know your persistent settings
  • FILLET remembers Radius. Check or reset with R during the command or set FILLETRAD.
  • CHAMFER remembers Distances and Angle. Use D (two distances) or A (distance + angle). Variables: CHAMFERDIST1, CHAMFERDIST2, CHAMFERA.
  • Set TRIMEXTENDMODE to 0 for modern “Quick” Trim/Extend (AutoCAD 2021+), 1 for legacy “select cutting edges first.”
  • Use EDGEMODE = 1 to allow Trim/Extend to implied intersections beyond endpoints.
• Essential behaviors
  • FILLET with Radius = 0 is a rapid “square-and-join” tool that trims/extends two objects to a crisp corner.
  • SHIFT while in TRIM temporarily toggles to EXTEND (and vice versa), eliminating command swaps.
  • Use Multiple option in FILLET and CHAMFER to repeat without relaunching.
  • Polyline options (P) in FILLET/CHAMFER apply to all corners of a selected polyline at once.

Fast workflows you can apply today

• Close gaps and clean corners
  • Set FILLET R = 0 and click the two objects. Great for tidying imported linework and ensuring watertight corners.
  • If endpoints don’t physically meet, turn on EDGEMODE=1 and use TRIM/EXTEND with a quick drag selection.
• Batch roundovers
  • Set FILLET R to your value, choose P (Polyline), select the polyline to fillet every vertex in one pass.
  • For selective corners only, use FILLET M (Multiple) and click the pairs you want.
• Consistent bevels
  • In CHAMFER, set D then enter Distance1 and Distance2 (or use A for distance + angle) and apply with P for polylines or M for repeated corners.
  • Use Trim = No Trim inside FILLET/CHAMFER when you need bevel/round geometry without altering the original lengths.
• Smart trimming
  • With modern TRIM (quick mode), click unwanted segments directly; drag-crossing to remove multiple at once.
  • Tap SHIFT to extend edges to boundaries on the fly, then release to return to trimming.
  • Use Fence during TRIM/EXTEND to process complex clusters rapidly.

Power-user tips

• Create ribbon macros or aliases that set radius/distances and launch the command, e.g., “R0FILLET”: ^C^C_fillet;R;0;.
• After heavy edits, run OVERKILL to remove duplicates and collinear fragments; it keeps filleted/chamfered geometry clean.
• For 3D solids, switch to FILLETEDGE and CHAMFEREDGE to modify model edges instead of 2D curves.

Avoid these pitfalls

• Unintended arcs/bevels caused by leftover FILLETRAD or chamfer settings—verify before applying.
• Mixed object types: convert splines or ensure polylines are joined (PEDIT > Join) for predictable results.
• Annotation layers: make sure you’re editing on the correct layer; lock non-target layers to prevent stray trims.

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