For my (almost) first print attempt with my new X2D, I need support on my model. I have a simple setup: the AMS feeding various colours of PLA to the primary nozzle and the side spool feeding Support for PLA to the Aux nazzel. The model uses only one colour of PLA, so no switching.
Yet Bambu Studio insists on building a Prime tower when I tell it to add its own suppirt. Why? What am I missing? How can I get it to understand that there are two nozzles, each feeding its own material, and as such, there is no value in the tower (except to Bambu Labs in wasting filament, which I then have to pay for)?
Is the only solution to design my own support and indicate the material differences, thus avoiding the tower? (Which I probably need to do anyway as BS is infilling a lip on the bottom of the model, instead of putting in a support layer.) If so, is there any optimisation guidance on designing support structures to minimise waste?
The reason why there is a prime tower is because every time a nozzle switches, the nozzle which takes over must be primed and needs to build up pressure inside of it. Without doing that, you would get issues with extrusion in the first few lines after the switching.
You can play with it, however, and test out slicer options like: purge into objects’ infill, purge into objects’ support, purging volumes, etc. You can even turn off the prime tower completely, but I wouldn’t do that.
Thanks @lookalek. That makes some sense. But what doesn’t here is that when printing a simple item without support, the pre-print nozzel prep is a double line about 4cm long (not accounted in BS), then it happily gets to the real printing. But with a design requiring support, the tower is purging more filament than it is using for the actual print, coming to about 42cm of tower printing per layer when it’s hollow and 160cm when it decides to fill it! Over the 227 layers of the tower, that’s about 150m of 0.2mm print, which – if my calculation isn’t too hacky – in the region of 2m of fillament. (Half of that is it putting in 50-odd mostly-solid but useless layers.)
It also doesn’t ever put any Support fillament into the tower; indeed, there appears to be no purging of that nozzle on a switch. And purge into objects’ infill does nothing.
Thanks @Gerrit. I was thinking along those multi-part lines as well. Though I may have an even better solution: the support structure being built for the overhang is probably larger than the tower, so as long as I can ensire it gets built before the model it is supporting… I think it was doing that anyway, but is thers a way to enforce it?
Of course, that becomes a risky proposition on the first run, where BS has put a support tree ring directly atop part of the real model, without even a support interface layer between…
I did a bit of that as prep; the default tower is 3x3 cm, with an additional shell (the shell can be easily removed). At 1.5cm wide, it’s maybe 4cm long; after that, it gets overly long again. And it’s triple-walling what ends up being the longer side. From an eyeball-it perspective, that seems to be near optimal.