I’m kind of new to 3D printing (X1C is my first printer, yay!). I’ve been having issues in general with overhangs/bridging with all filaments, but I’ve got a need to get PC working for a print I’m needing to complete so I’m kind of forced to face my demons.
Before getting into the problem I do want to state that since this is my first printer, I’m concerned that my expectations might be too high and there might not really be an issue so please tell me if this is the case! Now onto the problem/setup…
I’ve performed calibration and believe I’ve selected the best values for my particular machine. Items I’ve tried to fix the problem thus far:
Slowing print speed (as low as sub 10mm/s for all line types)
Enforcing constant flow rate for all exterior surfaces
Part cooling
Flow rate
Extrusion Rate Smoothing
Number of walls
Wall order (outer/inner, inner/outer, inner/outer/inner).
Infill type (maybe pushing or distorting exterior walls on overhang? bit of a stretch)
The roll of PC was dried ~ 6 months ago (12h @ 90C) and placed into the AMS with an abundant amount of silica gel and the AMS is reporting a ‘1’ for the humidity level and my hydrometer is reporting <10% humidity.
Attached is the 3mf that has the settings used for the prints in the photos.
The issue seen, despite many changes being made/tested, are nearly identical when viewing in person which makes me believe this is a setting issue as the printer is faithfully reproducing copies, but again I could be woefully ignorant here.
What you have there is a very bad test for overhangs so I assume they are shown upside down.
Overhangs work only if there is enough for the new line to bond to.
You test print comes with rounded shapes which make overhangs even more complicated.
It is an advanced test model.
Let me try to explain the overhang issue:
You have a certain layer height and a certain angle.
With that you get steps per layer.
If the overlap on the previous layer is less 20% for the new layer’s outer wall you have not much to stick it to.
That is where supports come for the rescue.
Check the preview in the slicer to see how those layer lines overlap and how this overlap changes towards to the top of the model.
The extrusion width does not change but with a lower layer height the steps are smaller.
This results in having more overlap.
The temp and speed are also vital factors to consider.
You want the nozzle temp just high enough to allow for PROPER bonding at the highest speed the model allows for.
At any lower speed the bond will be no issue.
Speed is a bit of a hit and miss thing.
Slowing down for overhangs and increasing the fan speed does help.
But you need to factor in the overall layer time!
In you pics the model grows with the overhang, increasing the layer time to provide better results.
For a larger model the overhangs might come out much better already as the plastic had more time to cool down.
I have not much use for PC in terms of filament, only use PC the solvent.
But I used ABS a lot in the old days and overhangs were a total pain.
Here’s my five cents to get you in the ballpark:
If this test model is rather small then please try again with three of them on the plate and some distance between them.
Don’t worry about blobs or drooling, we want to see the overhangs…
If that provides a MUCH better result for the individual models:
Do a temp test to find the LOWEST nozzle temp your PC provides proper results with - then increase it by 3 to 5 degrees.
Print one of those sloped overhang test models where the angles and on the steps.
This gives you a proper indication of the failure angle.
You might get away support free to around 35/40 degrees but above that not so much.
Anything below this threshold should come out acceptable enough.
In order to get it you need to play with the overhang speed reduction and add more cooling.
It DOES help if the overhang(s) are close to the side fan that blows over the model
For ABS I often went as low as 20% of the overall print speed in order to prevent things from curling up or the outer wall falling apart.
Welcome to the world of 3D printing. If this is your first foray, you’ve made very good progress. I’d like to highlight your statement above: I can confirm that you are expecting too much. But don’t be concerned, it’s not you, it’s just that gravity sucks!
The samples you printed are exactly what one would expect from steep overhangs. In fact, you should be commended on how well they turned out. You’re on the right trajectory.
As you’re discovering, there’s no magic bullet in this craft—it’s both art and science. Changing the vertical orientation 180 degrees can solve overhang issues but may weaken the part due to altered filament layers. It often comes down to trial and error.
Your approach is logical and incremental, which is great. Many expect 3D printers to work like office printers, but it’s more like cooking—you need to figure out the right settings for the best results. That’s part of the fun, unless you’re not a tinkerer, then it can be frustrating.
