I think you can actually do stacked infill in the software right now, although it is a bit of a hidden feature. Most people only think of adding a new extruder entry into their FFF Settings when they have another physical
extruder, but you can actually add another virtual
extruder to change how the same toolhead will print infills, supports, etc.
There are 2 key pieces of knowledge you need to know to do this.
- If you want to make a new virtual extruder, you just need to click "Add Extruder" and then make sure the extruder toolhead number remains unchanged.
- Once you have a second virtual extruder, the layer height for that extruder will be based on the diameter that you assign to it. For example, if it has twice the diameter of your primary extruder, the layer height will be twice as big as well.
So if you want to do stacked infill, you just need to add a second virtual extruder that the software will use for the infill regions (call it "Virtual Infill Extruder"). Enginwiz, it sounded like you wanted to print 3 outline layers for every 1 infill layer. In this case, just make the Virtual Infill Extruder have 3 times the diameter of the primary extruder. Then go to the Infill tab and choose the infill extruder to be the Virtual Infill Extruder.
If you go make some G-Code at this point, you should be able to see the stacked infill working. But, there's one more change you need to do before printing. In a way, you "tricked" the software into using a different layer height for your virtual extruder by telling it your virtual nozzle had a much larger tip diameter. If you prepare your STL file with automatic extrusion width enabled, you will see this results in a much larger extrusion width. You will probably want to set the extrusion width manually to a more reasonable value and then lower your extrusion multiplier accordingly to make sure you are extruding the right amount of plastic. I don't have a printer in front of me right now to confirm this, but my first guess would be that you need to lower your extrusion multiplier by 1/(n^2), where n is the number of stacked layers you are using (3 in the above example).
So again, this is somewhat hidden but there is a lot you can do about it once you find out. You could change any of your ooze control settings for example and have those apply only to infill regions or to support structures by changing the extruder to the new virtual one you created. Pretty neat stuff.
As always, if you have any ideas about how to streamline this process, we would love to hear it! For example, I know someone suggested just having an explicit layer height override for each extruder so that you don't have to use the fake diameter trick to get your virtual extruder to use a smaller layer height. That's an option, but I would love to hear you guys' feedback if you can think of anything that would be easier and just as versatile.