bad overhangs on one side of print
So for a while i have been having issues with overhangs on my core one..
its only really noticeable on one side of the print, where they start to "curl" up, which results in very uneven and ugly overhangs.
I always had the latest firmware and prusaslicer installed and used on mutliple files and orientation.
it seems like all overhangs which points to the front left, so away from the cooling fan, are the bad ones.
The problem also only started near summer when i first ntoiced it, but brushed off as the room being too hot. But since its autumn, it cant be that.
Also the firmware and slicer changed version once since this was happening.
I tried checking the cooling fan speed in my slicer but its set to 100% and on my core one to the default 40%
Im also printing polyterra pla, and esun pla and esun pla+.
color doesnt seem to make a difference
they start to "curl" up, which results in very uneven and ugly overhangs.
It is in he nature of additive overhangs to curl, the thermal contraction during cooling is the underlying cause. This may also cause head-crashes and consequent layer shifts.
With some parts just rotating the part on the print sheet is enough to move susceptible areas into a better orientation.
If this doesn't help save your project as a .3mf file
Files > Save Project as
Zip the .3mf and post it here. It will contain both your part and your settings for us to diagnose.
Cheerio,
RE:
yeah, that makes sense. I just dont understand why it didnt do that for 3 months or so..
I know saying it didnt do this before it did is kinda stupid but eh..
Anyway, i was thinking about a custom cooling fanduct. The only real problem is the clearance on the toolhead.
i know that valve released a model of the index's controller and headset and marked zones in which they could be modified ( https://github.com/ValveSoftware/IndexHardware/tree/master )
Maybe im going a wrong path here but if prusa has something similar to the core ones printhead, maybe a circular fanduct would help a bit...
I just dont understand why it didnt do that for 3 months or so..
We're at a change of season and consequent change of heating/AC - it's surprising how many printing problems are seasonal.
Cheerio,
RE: bad overhangs on one side of print
how hot is too hot though?
id say 16-20°C in the room the printer is in should be decently cooled right?
RE: bad overhangs on one side of print
The asymmetry in overhang performance is a known fact in many printers, I think. My Core One also prints overhangs best when they are oriented towards the back, where the fan and the wide, uninterrupted fan shroud are. I have read that in the Mk4s, where the fan is sitting in front, it's the other way round.
Regarding the question why performance is worse now than it was a couple of months ago: Any chance that other parameters besides the room temperature have changed -- printing speed or other slicer settings, material etc.? Ideally you still have the Gcode and the resulting printed object that worked well back then, so you can do a direct comparison vs. a print (with the same material) today. Also, it might be worth a try to dry the filament -- maybe absorbed humidity deteriorates the print quality?
@jurgen-7 is right, the biggest seasonal difference is the humidity level when the outside air is either heated, cooled or allowed direct access. Direct sunlight can also pre-heat filament and affect the heatbreak efficiency.
Cheerio,
RE:
i actually just tried to dry my filament a tiny bit by setting buildplate temperature to 55°C and chamber to 60!C.
according to my scale, it lost abt 2g of weight and when i tried the voron cube again, the overhands actually seemed to be worse with similar temperature.
The one thing that i did notice though, is that my nozzle and heating block seem to be able to rotate semi freely. could that maybe be a problem? maybe its not tight enough or not far enough up so the fan struggles to cool? I tried tensioning the thumbsscrews as far as i could but it didnt really change anything.
i still have the gcode for older prints where things seemed to be good enough and the "bad" ones now. are they still relevant?
i also added a picture of the new voron cube i did with green being a good overhang and red the bad one
RE: bad overhangs on one side of print
i actually just tried to dry my filament a tiny bit by setting buildplate temperature to 55°C and chamber to 60!C.
How long did you dry it like that? And what was the actual chamber temperature -- it can't have reached 60°C with the build plate at 55°C?
RE: bad overhangs on one side of print
yeah, chamber was at around 33 with printhead on printing temperature for a bit more heating and it took 2 hours with occasional venting
RE: bad overhangs on one side of print
yeah, chamber was at around 33 with printhead on printing temperature for a bit more heating and it took 2 hours with occasional venting
I'm afraid that will not have done much in terms of drying. Prusa recommends 6 hours at 45°C for PLA; some other sources are a bit more aggressive and go to 50°C or even 55°C. Depending on the weather conditions where you live, and the place where your printer and filaments live in your house, a dedicated filament dryer may be a worthwhile investment.
RE: bad overhangs on one side of print
i saw a video from cnc kitchen about drying in the microwave or oven.. do you by any chance know if those methods are valid?
RE: bad overhangs on one side of print
Sorry, I don't have any personal experience with that approach and have not looked into published reports on it either. It seems plausible in principle -- exciting and heating the water molecules to make them diffuse out of the filament, while only heating the filament itself very little. But I have no idea how long it would take.
I'm sure some other users here can chime in based on actual experience !
The problem with microwaves is that they manage their lower rate settings by adjusting the ratio of full power bursts to off time; it can be done but it's very easy to overcook and melt the filament even on low power.
I use a cheap domestic food dehydrator, lightly modified, it has worked well for five years now.
As long as the heatblock is not actually flapping around it doesn't need to be tight.
Cheerio,
RE: bad overhangs on one side of print
Well, ive got an update.
i tried drying filament and everything and it ended up being clogged paths in the brass CHT after someone tried printing abs with pla settings.
I got a new nozzle after realising i couldnt get the cooked pla out with the needle and coldpulls
RE: bad overhangs on one side of print
Yes, microwave is a bad idea. Besides the already mentioned typical 10 second PWM cycle, the field distribution inside the chamber is very uneven. There will be a hotspot near the waveguide when the turntable passes it.