[Variable layer height on a print]

Let me clarify a few things on this matter for you guys. Cura (15.X or 2.X) has no actual variable layer height. There's a few things that can sorta do layer heights for different parts though:

• The initial layer height can be separate from the rest.
  
• The infill layer height can be increased. This is actually a trick; Cura will combine multiple layers of infill together, and so it only works on multiples of the normal layer height. And only if there are enough layers of infill on top of each other so that they can be combined. Something similar is in the works for support in the 2.7 release (planning of this issue is not set in stone though).
  
• The raft air gap is also not dependent on the layer heights and can be set to anything you like.
  

There's two major problems we are facing for variable layer height.

For one, if you use variable layer heights then all of the built-in profiles in Cura become moot. Layer height is such an influential setting that if you change the layer height there's typically some 20-ish settings that should change alongside it. This can be seen when you switch profiles from Normal Quality to Draft Print or something, there's typically 20 or so settings that will change then. Ideally these settings would change automatically if the user changes the layer height (or is that ideal?) but we haven't figured out all the intricate connections and interplay between settings, so if the user changes the layer height right now, the quality will surely be less than optimal. That means that we can't enable Variable Layer Height by default. S3D solves this problem by... not having this requirement that we must guarantee good print quality for the Ultimaker printers.

The second major problem is collision checking. Currently Cura will avoid going through walls as much as possible so as not to create scars on the surface of the print and reduce clogging. This is a 2D problem because we know that all parts that we can collide with are on the current layer. The rest is on lower layers. With variable layer heights, the layers become separate and so there might be some already-printed part that is 0.001mm lower than the current layer. You can collide with it if that layer is too close, so you have to consider some other layers to avoid collisions. This is a technical problem in our current architecture, which S3D did set up properly to account for this feature. It can be overcome with some refactoring, but before we think of a solution for the first problem we won't be trying to refactor the architecture to solve the second.

With the formulas, would it be possible to reset the profile at a certain height?, choose a layer height change at 400 layers out of 600 layers, which would just reset the profile you would have to set again yourself, this option will only be available in "custom settings"? Or as a "experimental app add on"

Maybe if a gradual z step into layer change may help with that?

Its having the option to print a simple block at 200micron layer height, but change to 60micron on the last 20 layers for a emboss or such...

Or 200micron up to an overhang, change layer height for a overhang to 60micron, layer change again after the over hang, back too 200micron height.

Just curious, with the tweakatz add on app, if i had my speed @ 80mm/s, and change to 50mm/s in app, do i have to change flow rate to bring the flow rate from 80mm/s to match a flow of 50mm/s or does the app do that itself (as a profile standard @ 50mm/s)?

2 legs touching buildplate at different heights!!

What about 3 ? (lol!) .