From a819a89ede332bd2f79e135563e15ef463b84e65 Mon Sep 17 00:00:00 2001
From: David Osterberg <davost@gmail.com>
Date: Fri, 5 Feb 2021 20:42:11 +0100
Subject: [PATCH] PartDesign: fix regression in Helix

---
 src/Mod/PartDesign/App/FeatureHelix.cpp | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/Mod/PartDesign/App/FeatureHelix.cpp b/src/Mod/PartDesign/App/FeatureHelix.cpp
index 695c02dde7..b571df9a78 100644
--- a/src/Mod/PartDesign/App/FeatureHelix.cpp
+++ b/src/Mod/PartDesign/App/FeatureHelix.cpp
@@ -397,6 +397,14 @@ TopoDS_Shape Helix::generateHelixPath(void)
     double radius = std::fabs(axisOffset);
     bool turned = axisOffset < 0;
 
+    if (radius <  Precision::Confusion()) {
+        // in this case ensure that axis is not in the sketch plane
+        if (v*normal < Precision::Confusion())
+            throw Base::ValueError("Error: Result is self intersecting");
+        radius = 1.0; //fallback to radius 1
+        startOffset = 0.0;
+    }
+
     //build the helix path
     TopoShape helix = TopoShape().makeLongHelix(pitch, height, radius, angle, leftHanded);
     TopoDS_Shape path = helix.getShape();