Hello there,
I’m pretty new to the 3D printing community and bought a A1 couple of weeks ago.
Yet I’m facing a problem that seems quite advanced to me and I can barely find informations about this specific behaviour.
The challange is to construct the most small and compact (cylindrical) rolling bearing possible to print with a A1.
I’ve got some inspiration from available bearings on thingverse and makerworld but want to add some of my own constructive ideas - as well as more oriented like real bearings.
My current approach looks like this:
These most important dimensions should give you a impression about how minimalistic I’m thinking of.
Dimensions are
mm.
The sliced part looks something like this:
I’m facing a problem at the first layers of the 45° overhang at the inner cage-holder-axis part for the cylinder rollers.
The problem:
For a unknown reason there comes a quite strong force on the small inner bolt, that ripps it completely off the plate.
Sometimes earlier, sometimes later, sometimes it even breaks off neighbour parts as well.
Once it even kicked the (single, inner) part meters away from the printer.
Green part was printed fine, at the red marked layer this part somehow explodes.
Those flying bolts got a diameter of 2mm and are about 3mm long
Question is what force causes this, where it comes from and how it can be reduced?
Since the print itself looks quite fine, I still hope to get this done somehow without increasing its overall dimension.
Hypothesis: - to be confirmed
The overhang of increasing diameter causes the topmost printed layer to STICK OUT!? (partially, especially at the seam)
So the next printed layer may collide with standing off material of the previous layer?
If so, then…
- Slower print speed gets worse, because the previous layer will be colder, so harder?
- Faster print speed gets better, because the previous layer will be hotter, so softer, so the collision force will be weaker?
- Thinner layer height gets worse, because with a nozzle of 0,4mm the filament must be pressed down more
- Thicker layer height gets better, because collission of upstanding sections of the previous layer is potentially smaller
I’ve done 8 failed print attempts now with different settings, those assumptions are hard to confirm.
That’s why I’m asking here what are your experiences related to this scenario?
However that’s my current impression of the most likely cause.
As seen in pictures above, the layer surface actually looks quite fine - so I doubt my own hypothesis.
But thats the only possible cause I can think of where the breaking force comes from.
Conditions:
- BambuLab A1
- 0,4mm nozzle
- Basic PLA, gray, freshly out of the oven for 8h at 50°C
- Heatbed temperature default, I think it was 65°C
- Speed default as well as throttled to 50%
- Default PEI print plate, adhesion should be fine, used newly, never-printed spaces of the plate
- Full calibration 2 weeks ago
- Tries with and without dynamic flow calibration on each print
- Fast heatbed calibration on each print enabled
- Bamu studio settings - all default EXCEPT:
- Tried 0,2mm layer height (default), as well as reducing to 0,16 and 0,12 also fails
- Top & bottom surface pattern concentric
- Prime tower disabled
- Also tried seam position random, also fails
- Mostly printing by object (single object on the plate, but I want the slicer to not calculate moving aside after each layer), some tries default by layer
Looking forward for your experiences and ideas!
Hoping for other replies than the depressing solution of:
Design the thing bigger to get stronger adhesion
I’m aware of this possible solution, but as the title says I’m searching for most minimalistic design.
Is it simply NOT possible to print overhangs on this small cylindric objects?
If not - I most likely need to decide for a constructive design with a bearing cage on the outer side of the rolling cylinders instead of the inner side.
Kind regards