Each layer external shell starts out rough.

[wirlybird]

In the pic you can see in the circled area that it looks rough, kind of like a vibration. Each layer starts like this then smooths out and prints nice.

PLA-210,

S3D - FFCP

Thanks for any thoughts.

[MindFuLL]

Is it like that all the way around or just on the side you photographed? If you raise the extruder and manually extrude into the air does it come out straight down or to the side/in a spiral?

[wirlybird]

It pretty much cleans up as it goes past the right side of the circle I drew then is a great print.

I’ll try the manual extrude to see but I have the same thing on another printer with the same part but in ABS.

[MindFuLL]

Have you checked to make sure there is nothing weird with the .stl(have you rotated it to see if the anomaly moves?) and is all your motion lubricated and moving freely?

Assuming “yes” to the above, take a look at my visual aid.
Where there is a red X, an axis is switching directions.
If that is where the anomaly is then you want to check that axis. Is there any play anywhere? Is the belt tight? Is the belt too tight(this can cause it to vibrate like a guitar string on a direction change)? Have you done any mods to that axis that would make the moving parts heavier?
Where there is a blue O, both axis are moving at equal speed.
If the anomaly happens here it’s a little more tricky. When any axis moves it causes vibration. When both are moving at the same speed they can cause resonance and significantly amplify the vibration(this is more common than you might think). You should be able to feel it by lightly laying a hand on the machine. Let me know if this is the case and I can help you troubleshoot further.
Hope that helps!
-Jesse

[npagazani]

In your S3D settings are you printing inside to outside, or outside to inside? Try reversing and report back. This may be very similar to the ringing effect you see on sharp corners. But in this case it could be the print head transitioning from the inside of the shell to the outside for the next layer and the “ringing” after effect as the mass of the print head settles down. You could also try adjusting the S3D setting that indicates a random start point for each layer.

[wirlybird]

Thanks for the suggestions. Right now it is inside-out. The ringing explanation sure seems to make some sense. I can try a random to see what happens but I actually had set a specific point for the seam so it would imitate the real seam on the barrel!

I’ll report back.

[wirlybird]

Motion is good, at least I feel it is. Other prints are not indicating any issue. I have not rotated it but can try. I do have it set for specific start point X=0, Y=300 which places the seam at the rear of the printer so I can’t see what’s going on at that point.

Issue is on a red X and would be at the back of the machine right on a line for the Y axis. i.e it is facing the rear of the platform.

I have not checked the model to any degree so it is suspect.

This issue is similar on two machines, QIDI and FFCP, ABS and PLA so S3D is common and so is the model. I need to try and slow way down to see how that affects it. These just take a long time to print even for the small one. I am over run with green and red barrels!!

[Perry_1]

Classic “ringing”.

I see you have changed your settings since your last post. This is a result of that.

This is backlash, a vibration that occurs in the print after the print head moves. It resonates for a period of time until the print head stops vibrating from a move, and as acceleration begins to take effect.

You did not have this before you changed your print settings, so something that you did in those print settings is causing it.

Most likely, it is a result of making the print head move to a specific point before printing each layer. The print head moves to that spot, then travels to the place where it is going to start the print. The travel feed of your printer is the fastest move, and the print head is still resonating and vibrating after it moves to the layer start position before it begins acceleration.

Since you were not having this issue before you changed your settings, I am going to eliminate mechanical issues as the cause of this “ringing”

If you still want to use inside out and a specific start spot on each layer, you have only two options for resolving this.

1. Print slower. This reduces the ringing and vibration caused by a directional change. This will slow down your overall print time, but will reduce ringing dramatically. The slower you go, the less ringing.

2. Lower the acceleration of your printer. This is a somewhat complicated thing to do, and requires changing the settings in your firmware using replicator G software. If you do this, read the Sailfish Manual first and follow each step exactly, and search the web for forums discussion it.

I would just print slower!

[wirlybird]

Perfect and makes perfect sense. Yes, this is the barrel with the blobs! I reloaded the default profile and the blobs stopped (for now) I don’t know why but it seems like it is remembering settings even when you change them. Anyway, I can print slower, no problem there and actually that was my next test.

Would slowing the non print travel help? I can set that I think in S3D also.

[Perry_1]

Yes, slowing non-print travel specifically might improve it, because that is the fastest speed your printer prints at. (because you dont need to slow it down for the extruder to keep up). I believe the ringing is from the momentum of that. However, I am not sure, so you may have to just print slower.

The printer, unless you change the firmware, or something specifically with the printer’s buttons, does not remember settings. The printer reads one line at a time from the gcode, executes it, does the next, etc. So the printer does not remember much.

HOWEVER, Simplify3d is famous for remembering old settings. If you open an old print, the next time you open it the old print’s settings will be in there, etc. If I recall, you are using S3d. So that is probably what you are experiencing.

I always start a new Slicing Process by opening an S3d file that had the same settings from the past that worked, and then replacing the STL(s). If I cannot do that, I reset S3d to the default settings and begin from there. You can also save a profile, and load it each time, but I have not been sucessful at doing that without finding some wierd thing it remembered from before in there.

[Perry_1]

BTW, I notice you are still printing the whole barrel while testing. This seems unnecessary. Move the barrel low on your virtual build plate so that just the top sticks out, and slice from there. Seems like you are wasting material and time…

Just a recommendation.

[wirlybird]

Yea, pretty much what I do for settings. I have “profiles” set up such as FFCP - ABS FFCP - PLA etc saved based on the supplied profile for that particular printer. Then when one goes nuts I delete it and start a new one from the FFCP default profile.

What I meant on it remembering is it seemed at times you change retraction and it makes no difference. A group of us with the QIDI thought we were seeing the same behavior. Who knows!

[wirlybird]

Yea, I thought of that but I am giving the barrels away as pencil holders. I am in the oil and gas business so barrels are a fun desk trinket! At least it puts the material to use but you are right I should remember to do that for testing.

[MindFuLL]

I don’t use S3d but @Perry_1 knows what he’s talking about. Ringing is probably the most frustrating and difficult to diagnose problem I have dealt with in 3d printing(and that is saying something). I just want to add to what he said about trying different speeds. You are fighting vibration, so you want to not just lower the speed but do so in an imperfect interval. For example, if you double or half the speed(an octave) you can end up just stretching or compressing the ripples, while trying something like 89% or even 107% can SOMETIMES eliminate them all together.
I think @perry_1 is dead on about the momentum from the travel speed since it’s happening in only one spot and you had the seam set at that location. Did you have that seam set like that on both of the settings?
-Jesse

[Perry_1]

@Mindfull has good info here. People always wonder why I tell them to print at 73mm/s!

There is a strong indication that your resonance can match stepper movements, etc. I had this exact situation on some extruded text on a print. I kept getting slower and slower on the print… First 60mm/s, then 30mm/s, then 15mm/s. All that happened was the ringing changed. It actually almost went away at 73mm/s. I have been printing at 73mm/s a lot after that (xy print speed).

[wirlybird]

Yes, and it makes some sense because I can see that it does the inner loop then hits the outer and reverses direction so there is momentum from direction change and lateral position change.

Before changing speeds I am going to try a print (just top part) with random and also with most efficient start-stop and see what I can see. Just for fun.

[wirlybird]

Interesting. I was told recently that a full step on the Z is 40 microns to make layer heights a multiple such as 1.2 instead of 1. Another thing I pick up is this for better resolution prints and save some time is drop to 1.6 layer height and print the infill at 3.2 every other layer. Seemed to work out ok.

[wirlybird]

Ok, test 1, slowed non print X-Y movement down from 4200 to 1000 and no difference.

Now running at reduced print of base 1000mm/min and 50% outer shell. Almost done.

Watching the preview while printing it is the direction change doing it I am convinced. It goes from the inside ring to the outer with a direction change at the seam and then the outer to the inner with a direction change again at the seam and I can see a similar effect on the inside in the opposite direction from the seam.

[wirlybird]

Ok, speed at 1000mm/min results are pretty good. Going to ramp up a bit and see if I can find the break point.

[Perry_1]

This thread is dealing with vertical ringing along the x/y, so I dont want you to come to the wrong conclusions when you apply that to layer height, which has a slightly different effect.

As far as infill at every other layer, this can be good if you are printing under certain circumstances, and at a small enough layer height. When your height to width ratio gets too high, printing every other layer of infill, you can get infill that does not adhere well, making your part weak, or it can become so wispy it does not hold your top layers up well.

But yeah, printing infill at every other layer, and support at every other layer, when it works, is GREAT! (really increases printer time), and I do it for my personal printing sometimes, but not for my professional printing.