Cura: Use Infill to transition Filament?

[cfelicio]

Pretty cool idea, not sure how hard it would be to implement:

https://mosaicmanufacturing.zendesk.com/hc/en-us/articles/115002756094-Minimizing-Filament-Waste

Basically, instead of printing a large, solid prime tower when switching filaments, this attempts to purge the filament inside the part (as infill). This means:

1 - Infill needs to be printed first
2 - The object needs to be large enough to provide enough infill
3 - The prime tower need to offer variable infill (100% infill at top / bottom layers, sparse prime tower when printing infill)

Considering dual / multi color are becoming more prevalent, and Cura seems to be implementing a lot of exciting features recently (variable layer height, tree support, etc), wondering if the devs would be willing to take a look at this one? :-)

[BagelOrb]

To me tis feature doesn't make sense. If you want to minimize material then you should only print material where needed.

So you can only reduce material where it's not needed.

The infill material is needed, however.

Rather we should minimize the material for infill by looking at where we don't need as much material, rather than doing it in the uncontrolled fashion you propose.

I think this issue should be a [Won't fix].

[ianpaschal]

If you want to minimize material then you should only print material where needed.
The infill material is needed, however.

But that's kind of his point right? Rather than "waste" material printing a prime tower, use the infill to prime?

[BagelOrb]

If you don't need a prime tower than don't print it!

The whole idea of the prime tower is to make sure we are extruding correctly. If we skip that and print infill instead we know we are printing infill incorrectly, while infill serves a purpose and so it should be printed correctly.

[cfelicio]

Im not proposing to skip the prime tower, just have a dynamic one. Example:

Layer 1 - 4: Prime tower 100% infill (as there is no infill printed yet)
Layer 5 - 20: Prime tower 20% infill (rest goes inside the part as infill)
Layer 20 - 25: Prime tower 30% infill

I understand that the feature might not sound that useful for old style setups, where you have multiple nozzles, but the new gen of printers are all trying to go for the multiple extruders with a single nozzle, and that requires a much larger prime tower, wasting a lot more filament that could be used to infill instead.

The approach mosaic took (as shown on the link) is quite cool, but proprietary. Cura seems to be implementing quite a few innovative features, hence why I thought I'd ask! :-)

[BagelOrb]

I don't agree in your division of printers into old and new style. The Y-splitter has been around for a long time - also for Ultimaker printers. It's a cheap solution for hardware, but causes a rediculous amount of material waste and also a waste of space for the build plate. But that's just semantics ;)

The prime tower in Cura was never meant for Y-splitters and I don't think Ultimaker will spend time on implementing a feature for Y-splitter printers. However we will consider pull requests if somebody writes code for your proposed solution.

[Ghostkeeper]

This ties in with https://github.com/Ultimaker/Cura/issues/3550 and https://github.com/Ultimaker/Cura/issues/3553 to make it possible to have a lower-density prime tower for one of the extruders.

The proposal here is to purge some of the volume of the prime tower inside the infill. Not sure if that will improve things though. If you purge the same material somewhere else it won't really save time. And it might reduce the strength of the infill because the layer bonding is weaker.

[BagelOrb]

No, the proposal here is to just print infill instead of printing a prime tower and purging.

[cfelicio]

Hi Tim,

Sorry if I wasn't clear on the request. I don't think the proposal is to only print infill without the tower, that's not possible as for some areas of the print there is not enough infill to do the transition, so a tower is still required.

The idea is to actually to have a tower with dynamic fill. Example:

Layer 1 - 4: Prime tower 100% infill (as there is no infill printed yet)
Layer 5 - 20: Prime tower 20% infill (rest goes inside the part as infill)
Layer 20 - 25: Prime tower 30% infill

Thanks! :-)

[cfelicio]

This basically takes #3550 one step further.

[sjoerdtimmer]

I like the idea but I foresee the following problem: When you switch from 20% to 30% infill most infill lines will not align with the previous layer. If you do that multiple times all strength will be gone from the structure. Normal infill works because the infill line-line-distance does not change (or only a little with some of the fancy new infill patterns). There are two possible solutions: 1) only halve or double the line-line distance between layers. That way they will align maximally where possible. 2) let infill lines gradually move towards each other and merging when not needed and split (in advance) when they are needed again. This would require a completely new infill type...

[Ghostkeeper]

In 3.5 with the new prime tower strategy it would be feasible to prime less for one of the extruders on some layers. We don't require any more that the inner prime towers are resting on a previous layer since they attach to the side of the tower. We do require that the outer prime tower is sturdy so one of the extruders won't be able to do this.

[sjoerdtimmer]

I was referring to the proposal to change from 20% infill to 30% infill between layers. That would give problems I believe.

[Nerdy314159265]

I would thing something like Rectilinear would already work since it has that alternating pattern to keep a relatively narrow gap and there are no paths that the higher % layers would take that wouldn't have some support under them.

[cptSwing]

I'd love to see this feature in Cura! Just leaving a link to PrusaSlicer here, I haven't used it myself --> https://help.prusa3d.com/en/article/wipe-tower_125010 ("wipe to infill")