Almost always one of two things, and neither is a bug:
1. **Wrong rotation axis.** Spin the model around its **longest, most-detailed axis**. The import pop-up now recommends one for you (Vertical for tall shapes, Horizontal for long shapes lying down), but double-check it. The wrong axis means the silhouettes barely change as the model turns, so the hull stays vague. Re-import and try the other axis — it can be night and day.
2. **Too few angles.** More angles = a tighter hull. 12 is a good start; bump to 24 if you still see facets. Past ~24–36 it barely changes for most shapes.
And remember the hard limit: anything the wire can't see from outside in some silhouette (interior pockets, hidden concavities) will fill in. That's the nature of hot-wire cutting, not a fault in the tool. Turn on **Show original (ghost)** (under the viewer) to overlay your model on the result and see exactly what's reproduced vs filled.
1. **Wrong rotation axis.** Spin the model around its **longest, most-detailed axis**. The import pop-up now recommends one for you (Vertical for tall shapes, Horizontal for long shapes lying down), but double-check it. The wrong axis means the silhouettes barely change as the model turns, so the hull stays vague. Re-import and try the other axis — it can be night and day.
2. **Too few angles.** More angles = a tighter hull. 12 is a good start; bump to 24 if you still see facets. Past ~24–36 it barely changes for most shapes.
And remember the hard limit: anything the wire can't see from outside in some silhouette (interior pockets, hidden concavities) will fill in. That's the nature of hot-wire cutting, not a fault in the tool. Turn on **Show original (ghost)** (under the viewer) to overlay your model on the result and see exactly what's reproduced vs filled.