why is layer height omitted from per a model settings

[billplate 0]

I'm glad that Cura now has per a model settings.  It is something it has lacked for a long time.

 

But i'm surprised to see we still can't have different layer heights (when printing one at a time) as this would surely be one of the most used setting.

dose any one know why its been omitted?

[nallath 1,117]

Cura has had per model settings for quite some time (since 2.1), but we've never supported multiple layer heights. This is an intentional "omission". Having multiple layer heights makes the slicing process orders of magnitude harder. It's doable if you only use magnitudes of a layer (eg; one object with 0.1 and the other with 0.2), but even that would require large parts of our architecture to be re-written and a load of extra features to be added.

[billplate 0]

Thanks for the reply nallath.

I'm not familiar with the structure of gcode so i only get jist of what your saying. 

Forgive me if this is a stupid question, but could problems u mention not be bypassed by treating the per-model-layer-height setting almost like separate prints in a queue? so it would effectively be loading  a new gcode for each object? A compound-gcode as it were 

Edited April 19, 2018 by billplate

[yellowshark 153]

Well I suspect that is how it works, i.e. if you are printing 4 copies one at a time then there will be 4 copies of almost the same code, to print a copy, following each other except that the x/y axis positions will be different but the extrusion amount will be the same for each line of code. But apart from having to do work on the user interface, in the background you then have to deal with issue of different copies having different heights and avoiding collisions during printing etc.

[billplate 0]

@ yellowshark

what u describe is, as i understand it, how the slicer works, not the gcode,  which is simpler and dost have a  concept of objects or copies.

What I'm saying is, if having multiple layer heights is an issue for the printer.  

Crate a "compound_gcode" which contains multiple objects (each with their own gcode)  which automatically load in sequence, without resetting the nozzle position. Collisions wouldn't be an issue as it would be calculated the same way as a normal one-at-a-time print. the only difference is that each object is treated like a separate gcode before being packaged as this  "compound_gcode".

 

Edited April 19, 2018 by billplate

[ahoeben 1,851]

Note that layer height is available as a Per Model Setting if the Print Sequence is set to One at a Time.

[billplate 0]

30 minutes ago, ahoeben said:

Note that layer height is available as a Per Model Setting if the Print Sequence is set to One at a Time.

 

No its not!

And according to nallath, who sounds like he knows his stuff, it never has been available.

[ahoeben 1,851]

I stand corrected. I agree though that it should be possible in One at a Time printing to do this (and I also know my stuff).

[nallath 1,117]

Theoretically it could be possible to have layer height available if you're printing multiple models in one at a time, but we also have some legacy issues, which make some things harder to build than they actually should be. As we always have more features than we have people to build them, the stuff that isn't used that much tends to not get picked up.

 

Compounding the g-code is theoretically possible, but it does create quite a few issues with avoidance paths.