From 4ec9f7e281ddd0b901dfedb818ac5d6f18f245e9 Mon Sep 17 00:00:00 2001
From: Markus Lampert <markus@bibi.ca>
Date: Fri, 6 Sep 2019 21:44:23 -0700
Subject: [PATCH] Prevent endless loop through negative step down values in
 engraver.

---
 src/Mod/Path/PathScripts/PathEngraveBase.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/Mod/Path/PathScripts/PathEngraveBase.py b/src/Mod/Path/PathScripts/PathEngraveBase.py
index 8a88107e57..9b9239ea6d 100644
--- a/src/Mod/Path/PathScripts/PathEngraveBase.py
+++ b/src/Mod/Path/PathScripts/PathEngraveBase.py
@@ -53,10 +53,14 @@ class ObjectOp(PathOp.ObjectOp):
         zValues = []
         if obj.StepDown.Value != 0:
             z = obj.StartDepth.Value - obj.StepDown.Value
+            stepdown = obj.StepDown.Value
+            if stepdown < 0:
+                stepdown = -stepdown
 
             while z > obj.FinalDepth.Value:
                 zValues.append(z)
-                z -= obj.StepDown.Value
+                z -= stepdown
+
         zValues.append(obj.FinalDepth.Value)
         return zValues