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Dress-up: Lead In/Out

In one sentence: Add tangential arc entries and exits to a profile pass to avoid dwell marks and over-cuts at the start and end points.

Overview

Workbench: CAM
Menu: CAM → Dress-up → Lead In/Out
Command: CAM_DressupLeadInOut
Shortcut: none

Adds a lead-in arc at the start of a profile pass and a lead-out arc at the end. The arcs approach and depart the profile tangentially, so the tool gradually engages the cut rather than plunging perpendicular to the surface.

Intuition

If a profile starts by plunging straight into the material, the tool dwells momentarily at full engagement — which leaves a dwell mark or small gouge. A lead-in arc brings the tool into the cut from the side, distributing the entry load and avoiding the mark. The lead-out arc prevents the tool from dwelling as it exits.

When to use it

  • Finishing passes where surface quality matters.
  • Profile operations on materials sensitive to dwell marks (aluminium, brass).
  • Any profile where the start/end point would otherwise be visible.

When NOT to use it

  • Rough passes where surface finish is not important.
  • Operations where space is too tight for a lead arc (small pockets).

Key parameters

Parameter Description
Lead In Length Length of the lead-in arc (mm)
Lead Out Length Length of the lead-out arc (mm)
Lead In Arc Sweep angle of the lead-in arc (degrees)
Lead Out Arc Sweep angle of the lead-out arc (degrees)
Start Radius Radius of the lead-in arc
End Radius Radius of the lead-out arc
Use Lead In / Use Lead Out Enable or disable each arc individually

Common mistakes and pitfalls

Lead-in arc cuts outside the stock

Reduce Lead In Length, or apply a Boundary dress-up to clip the lead arc to the stock boundary.

See also