Switching between nozzles and purging behaviour is not working well enough at all.
See this video:
So on this layer, blue prints, then this video shows it moves to the purge tower and adds quite a lot to the tower (EDIT: I now know this is called “ramming” and I had it set to 20 where 5 seems better), then switches to red which only purges a tiny amount.
The first few seconds after this creates under-extrusion on the print until it can sort the pressure out.
Are we looking at a bug, or something I can fix with a setting?
The issue is only on this eye as this is the first point of contact after the “purge”.
Also worth noting that I’m using identical filament for both colours (same brand and type), so they have the same profiles. When it’s time for the red to switch to blue the exact reverse happens.
The tower is combined of 2 elements: ramming length and prime volume.
The default settings mean the overall tower is very heavy and wastes a lot of filament. The mistake is reducing the prime volume. Instead, finding a balance is the way to go.
Personally, I’m finding this to be a good balance without wasting too much filament:
Filament ramming length: 5 (no harm in higher, but I’m not seeing much benefit)
Filament prime volume: 30 (I would say no less than 20)
The H2D will be my first printer and this is unsettling, as I was hoping spending this kind of money would save me from having to fuss with things like this.
Do I need to start a log to keep track of things like this so that I know what to do when it happens to me, or is this the kind of thing that finds its way back to profile updates?
The defaults would work fine, but the problem is they are too excessive where you could have a 70g prime tower on a print that is 100g. So of course you adjust the setting down to an appropriate setting which then causes issues.
I had never heard of “ramming” until now either, so I’m not sure how people are meant to immediately understand this setting (which again is way too high and wastes so much filament unnecessarily).
That completely kills the purpose of saving filament with 2 nozzles.
There are other issues too like extra walls are being added into the middle of a print where colours change. For example, a coloured eye would have 2 walls that follow that colour into the model. For some reason anything I slice in Bambu Studio is adding up to 8 walls making the model so much heavier (should be areas of infill instead of solid walls).
I sliced the exact model in Bambu Slicer and Orca and Orca doesn’t do this and there is zero setting difference.
Just little things like this are taking away a lot of the potential of the H2D. If I could use Orca then I don’t think these would be issues.
Calibration tools are another example where I like to finely tune every filament, but the tools aren’t available in Bambu Studio. The H2D is targeted at a slightly more advanced user than previous models (mainly due to the price), but the slicer limitations of Bambu Studio hurts.
You don’t even need a prime tower if your filament is dry.
The H2d definitely needs a tower. Due to the nozzle switch, there is almost always a bit of oozing and bits of filament will end up on your model instead.
Also, as proven in my original post, since the nozzle is fully loaded and waiting, the pressures are all out of whack and if you don’t prime it, you will get 5-10 seconds of printing with either no flow or inconsistent flow causing pretty bad defects on the print.
I asked the same question in Reddit but it seems to fit better here.
so you even „need“ a prime tower if you use the same material / color in both nozzles to make use of the whole build plate even when each nozzle will only be not in use shortly?
If that’s the case it would mean i have to choose between being able to use the whole build area but most likely will have imperfections (since no prime tower) or I can’t use the whole build area but with a nicer look (since there is a prime tower).
I believe, in the absence of a prime tower, the slicer will try to prime to infill. I can’t remember where I read that. It said something like, imperfections may occur on layers that do not have any infill.
