Hello,
I purchased the U1 primarily to solve two problems I had with my previous printer:
Avoiding a huge amount of waste filament during multi-color printing! Check
Avoiding weak points when using PLA as the interface filament!
My experience has been that after switching from PLA, the interface covering the support is good because I can easily peel it off from PETG. However, printing the first layer with PETG on the PLA interface is too cold. I initially assumed the U1 would have no problem with this, as it has a heated build chamber with an upper cover, and the filament change happens relatively quickly, so the interface shouldn’t cool down significantly.
Unfortunately, this hasn’t worked properly so far. I still encounter weak points at the level of the interface filament. When printing with a PLA interface using standard settings, the first layer consists entirely of individual threads (stringing).
Currently, I am using Kingroon PETG filament.
In Orca Slicer, I have set the upper Z-value to 0 and enabled the support connection under multimaterial settings. I would also like to try smoothing the support structure.
Increasing the temperature in the G-code after the interface has led to adhesion issues.
Does anyone have experience with this and can offer advice on which settings allow for homogeneous prints with the U1?
I just printed a part for my granddaughter’s frig in PETG using PLA for supports. This was the 1st time I tried this. I used the Generic PETG settings. The only change I made was to set the supports to use PLA. Don’t know if this had a bearing but there was a brim. The U1 started with the PETG then the PLA. My only minor issue was getting the PLA to release, careful scraping released it.
The U1 does not have a heated chamber, it relies on retaining heat from the build plate. For this to be effective, you need to put a lid over the open top – and currently only DIY and third party lids are available. Other printers have actively-heated chambers, which might become an add-on but it will be necessary to limit the temperature to protect the electronics and mechanics.
Chamber temperature is available in the system monitoring.
I’m going to highly recommend Support for materials! They are more expensive per spool but if used as an interface layer only the cost savings in beautiful, non post processing support removal is absolutely worth it
If you print 2 layers of PLA as an interface layer even at Z-offset = 0, there is a risk that the PETG filament will not adhere to the PLA grid (especially on small areas), and this remains true even at 270°C. Unfortunately, this is exactly what you want to achieve, but only after cooling down.
Smoothing the interface helps enormously and looks better anyway, but it costs time, and significantly so for supported overhangs.
Once you are familiar with the trouble (especially with very hot-printed PET) of removing PET objects from supports without residue, you will only use smoothed PLA interfaces.
With unsmoothed interfaces, I had approximately 15% failure rate on an object with small areas; with smoothed interfaces, 0%.
P.S.: It would be nice if one could paint the areas to be smoothed, similar to supports.
You mean the breakaway PLA ? I bought a spool of that from Bambu, but not yet really happy with that. Are there any special settings to be observed ? I have set the interface to 4 layers…
When you load the Support for PLA into the U1 I believe you need to select Generic Support for PLA, unless there is a Bambu option for Support.
Then, the same in SnOrca. I’ve attached my custom filament settings for Bambu Support for PLA-PETG. I think they released a version for just PLA after I bought this one: Bambu Support For PLA-PETG @base.zip (1.1 KB)
SnOrca will tell you that you have selected Support material and ask to make recommended slicer changes, accept those!
Very important, select your Support material for Support/raft interface only! You don’t want to waste the Support material on anything other than the interface layer…
Test done. Albeit with a simple support test file only for the moment. But it does work well. But, I have changed the z.offset (top z distance) to 0.1 mm. Does work nicer with the breakaway PLA.
I’m facing a bonding issue with very small areas (3 perimeters, approx. 7mm long, as the first layer on the interface) and high speeds (16mm³/s).
Unfortunately, there’s no way to set a separate speed for lower layers (or better yet, for supported layers), similar to how it’s done for the 1st layer or upper surfaces. And slowing down the speed for the entire object or all perimeters goes against my desire to reduce print time.
My workaround: I’ve colored this area (not just the lower surface but also a bit of the edge) so that these 3 perimeters are printed in a (fictional) different color, and assigned this color to a PETG profile with 280°C (intended to bond into the PLA, ) and 4mm³/s. It works quite well, though an extrusion depth of, say, 3 layers would be even better. I’m still looking for that.
Downside: You lose one print head, which I’d actually need for automatic spool changing: PETG due to material consumption, and PLA due to using filament remnants.
I’ve not got into Orca yet, but on Cura you can create a cutting mesh to modify the settings just where the mesh intersects the model. So you would add a cube primitive, make it big enough to enclose the model and 3 layers high, and set modification to 280ºC 4mm³/s.
) and 4mm³/s. It works quite well, though an extrusion depth of, say, 3 layers would be even better. I’m still looking for that.