Use the Merge page to determine how machining from either end of the port meets.
Merge point — Enter how far (as a percentage) you machine down each end of the port.
Lift start — Enter the distance before the Merge point that the tool starts to lift.
Overlap — Enter the distance centred on the Merge point that the toolpaths overlap. This is an actual value (not a percentage).
Lift height — Enter the distance away from the port walls (into the centre) that the tool lifts at the Merge point. The lift at the end of the toolpath segment will be greater.
- Plunge finishing:
- Spiral finishing:
Lift start and Lift height are needed to minimise the effects of tool springback. When you machine the port from the first end, the tool is plunging into thick material and the resulting forces push the tool away from the side of the port (leaving small amounts of material on the port). Now you machine from the other end. Initially there are similar forces on the tool (causing springback), but when the tool reaches the start of the overlap distance, the forces suddenly change and the tool springback suddenly reduces. This looks like a "dig in" but is actually just machining to the required depth. The Lift start and Lift height values minimise this effect.