No solids on intersect with helix

Hi, I have a problem when executing this code:

```
height = 35
radius = 19.8
pitch = 10
teethDepth = 3
wall = 0.8

wire = cq.Wire.makeHelix(pitch=pitch, height=height*2, radius=radius)
helix = cq.Workplane(obj=wire)

result = (
cq.Workplane("XZ")
.center(radius, 0)
.polyline((
(0, 0),
(wall, 0),
(wall+teethDepth, pitch/2),
(wall, pitch),
(0, pitch),
(teethDepth, pitch/2)
))
.close()
.sweep(helix, isFrenet=True)
)
result = result.intersect(
cq.Workplane("XY")
.workplane(offset=pitch * 1.75)
.circle(radius*2)
.extrude(height),
clean=False
)
```

The `result` is empty. When I change radius to `19.0` it works and I get a thread with clean straight cuts on the top and bottom. but not with `19.8`. Same behaviour with other values.

What goes wrong? And there is no Exception thrown.

## Environment:
Linux, Python 3.9, cadquery 2.2.0