Is this a mechanical issue?
I've ruled out pretty much everything software based that i can set in Slic3r, Cura and S3D; from speed, acceleration, jerk, temperature, i've tried it all.
Every overhang gets damaged on the right side, left side is always ok. Belts are tight, nothing is loose or slipping.
Problem is on all 4 Prusa i3 MK2 that i have, even on the 2 that i upgraded with the e3d Titan.
I have used about 5 or 6 different fan shrouds now, and about 3 different fans for the filament. I made my own fan shroud now, which blows a absurdly bonkers amount of air onto the print from the left, the right and the front. Didn't help at all on this problem.
Could this be a idler issue? The Prusas use smooth idlers on X and Y, not the toothed idlers that just about everyone else uses.
Re: Is this a mechanical issue?
Not an idler issue. That would not be preferential per side and it looks like you are extruding okay.
My first guess was the fan shroud, but you have clearly tried to address that.
Those are pretty aggressive overhangs, but the fact that the other side is okay means the right side should be too.
In short, you have tried all the things that come to my mind for this.
The only other thing I can think of is that there is a hysteresis in you X axis, so there is a slight displacement in where the nozzle is relative to where it thinks it is - DEPENDENT on the direction it was coming from. Some people (not me) have put a twist into the X axis belt to remove some of the "twisting" that it is doing (this puts the smooth part of the belt on the idler). And people have looked very carefully at the x-axis idlers how how they are positioned and tried to shim it to keep it in line. If you search this forum for "belt twist" you will see both positive and negative examples.
That is the only thing I can think of that you have not stated in your post that you have looked at.
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Re: Is this a mechanical issue?
Not an idler issue. That would not be preferential per side and it looks like you are extruding okay.
My first guess was the fan shroud, but you have clearly tried to address that.
Those are pretty aggressive overhangs, but the fact that the other side is okay means the right side should be too.
In short, you have tried all the things that come to my mind for this.
The only other thing I can think of is that there is a hysteresis in you X axis, so there is a slight displacement in where the nozzle is relative to where it thinks it is - DEPENDENT on the direction it was coming from. Some people (not me) have put a twist into the X axis belt to remove some of the "twisting" that it is doing (this puts the smooth part of the belt on the idler). And people have looked very carefully at the x-axis idlers how how they are positioned and tried to shim it to keep it in line. If you search this forum for "belt twist" you will see both positive and negative examples.
That is the only thing I can think of that you have not stated in your post that you have looked at.
The way you described it is similar to what i think the problem is, it's somehow of mechanical nature from the right side.
The layer begins in the back, moves along the left side to the front, then to the right side and back again.
I guess it has something to do with the x axis motor being on the left side where the pulling/pushing force is, so there isn't a problem here; but on the left side there is nothing, except a rubber belt tension that wobbles around a smooth idler.
With the y axis it's the same, with a motor way in the back and nothing in the front.
I suspect this problem could go away if i one used two x and two y motors, one on each end to even things out.
I took a file to both x axis plastic parts to increase the holes in it to avoid that the belt and the idler rubs on the plastic parts, and to try to get the right side of the belt perfectly in the middle of the idler at all times. This did not help.
I wonder how they put the twist on the x axis belt, i tried that before but the twist rubs the idler and the x carriage in the wrong places.
Re: Is this a mechanical issue?
I've ruled out pretty much everything software based that i can set in Slic3r, Cura and S3D; from speed, acceleration, jerk, temperature, i've tried it all.
you've tried a lot.... did you get a video? i have no such issues but you didn't post what model it was either so....
i have other printers with smooth idlers... long as they're bigger than the toothed pulley of the motor... but that causes a different problem, not deformed plastic on an overhang. if it was mechanical it would affect more than that.
Re: Is this a mechanical issue?
I've ruled out pretty much everything software based that i can set in Slic3r, Cura and S3D; from speed, acceleration, jerk, temperature, i've tried it all.
you've tried a lot.... did you get a video? i have no such issues but you didn't post what model it was either so....
i have other printers with smooth idlers... long as they're bigger than the toothed pulley of the motor... but that causes a different problem, not deformed plastic on an overhang. if it was mechanical it would affect more than that.
The current print where i have this problem is the Drakkar on thingiverse: https://www.thingiverse.com/thing:475672
I have made this test to figure out my problem: https://www.thingiverse.com/thing:2727180
It has 4 overhangs, in all directions.
When i print this, always at least two overhangs are broken, and one or two are ok. Sometimes the right two are broken, sometimes the ones behind, sometimes both in the front.
You can try this out for yourself, i have yet seen a printer around me that can print all 4 cleanly. Print uses 2 grams of filament.
Re: Is this a mechanical issue?
I have made this test to figure out my problem: https://www.thingiverse.com/thing:2727180
It has 4 overhangs, in all directions.
So I printed two of your tests. One oriented front to back and one left and right. (The model only has overhangs in two directions (?).)
All of the overhangs print perfectly on my printer. MK2 (some S). Hatchbox PLA filament. Slic3r latest with default settings. (A side anecdote - a friend had different overhang performance with a different brand of filament - and good luck with Hatchbox).
Sorry for the bad photos, but all 8 overhangs look perfect.
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Re: Is this a mechanical issue?
Are you using Linear Advance? What K? I am using Linear Advance.
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Re: Is this a mechanical issue?
Thanks for trying it out.
I printed two yesterday as well, but after another.
The first print was perfect, with good and sharp edges, and the second print which i started 2 minutes after the first one was finished, had damaged overhangs on the right and the back sides. Only the front left side was ok.
This was with the same gcode.
I had this problem last week as well, printed 4 benchies one after another, the first one was perfect, and on the second, the third and the fourth the front hull was completely dented in. Same gcode on all 4 benchies.
Is this a issue when the printer is warm from another print?
I am using LA with a K factor of 45 on my Prusa with the e3D Titan (the Titan needs 45), and K30 on the Prusa with the stock Extruder.
Re: Is this a mechanical issue?
...
I have widened the air outlet on the Titan with a wirecutter now to more than double the size.
Previously the air out the the 3 holes (left, front, right) almost blew the filament of the nozzle, now it should cover a wider area and now it isn't as concentrated and strong.
Perhaps a wider airflow helps.
Re: Is this a mechanical issue?
Taken a wirecutter to my air outlet, as seen here:
https://shop.prusa3d.com/forum/improvements-f14/improved-fan-shroud-nozzle-t5263-s100.html#p64953
So far so good, benchies don't seem to have a dented hull anymore, will try some larger parts.
Will try the Drakkar part again, perhaps now both shields will survive.
Re: Is this a mechanical issue?
Glad you are making progress.
This is an excellent test for the printer:
https://www.thingiverse.com/thing:2064029
Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage or loss. If you solve your problem, please post the solution…
Re: Is this a mechanical issue?
Just an update for this issue.
I found the problem, but i never thought i should look into that direction for a fix.
After i changed the nozzle to a new one, the problem was suddenly almost gone.
I could print the most beautiful stuff with the old nozzle that i have a few months in now, just not some overhangs.
New nozzle in, problem almost gone.
Then i took the printer out of the enclosure and printed the problematic prints again, and the overhang problem was completely gone.
Urg.
I searched more than 2 months for this problem now.
It seems the airflow inside the enclose, even with the door open and two fans to blow the warmer air out the back, was not enough.
Lets replicate the problem.
Printer in enclosure, door open, air fans on, slight overhang problem. Old nozzle in, totally broken overhangs.
Printer out, prints a bit better now. New nozzle in again, completely awesome prints.
What the fuuuuuuu..
I'm guessing the enclosure acts a bit like a heat dam, causing the filament fan to create a vortex like airflow where it sucks in the same lukewarm air as before, regardless of enclosure fans or not.
And the nozzle, i can only guess that a lot of printing took it's toll on it, it could print simple stuff well, but more delicate stuff not.
Now i'll exchange nozzles a bit more frequently now, at least, when i see the problem again.