In other words, in the case of wrapped rotary machining, the preview does not necessarily show what is actually being cut.
Is this all terrible and should we send a delegation to HQ to demand redress? Nah, because this feature is correctly listed as WRAPPED rotary machining.
I believe I can provide a bit of background on this as a whiny user who pushed Vectric into adding wrapping in the first place. I provide this by way of background.
When I purchased my first CNC machine back in 2005 I bought the indexer rather than getting a larger table, mostly because I thought items done on the indexer were cool and it took me back to my days in shop class where the turning lathe was my favorite tool. The problem was that there was no affordable (under $5K) CAD/CAM software for creating indexer files, so the indexer sat unused save for some experimentation with trying programs to do index swapping. There was no way to preview so you had to cut the item to see what it looked like. In retrospect I would have made more money with a larger table than I did with the indexer.
I admit to being a vocal, whiny user who cajoled Vectric into adding a wrapper. There initial support for wrapping in Aspire 2.0 still exceeded my expectations because it showed the toolpath in rotary. This was a huge step forward for indexer owners.
The developers at Vectric know that wrapping isn't a full solution for rotary machining, and that the preview breaks down in certain edge cases. The reason you have to switch to flat view to calculate toolpaths is to serve as a constant reminder that the software is doing wrapping, not true 4-axis CAM.
There has been some discussion of Vectric doing indexer CAM the "right" way but it is a bit of a chicken-and-egg problem. There aren't that many indexers out there so there isn't much software. And there isn't much software because there aren't that many indexers. Vectric also wants to ensure the software is as easy to use as possible.
I've been experimenting with a 5-axis CAD/CAM package that sells for over $10K and I am amazed how incredibly difficult it is to use. But if I need to machine an impeller with undercuts that is the tool I would have to use. I wouldn't even try this with wrapping - wrong tool for the job, wrong job for the tool.
In the mean time I can create unique "artsy" profitable
items on the indexer using wrapping features with ease.