FlashForge Finder problem, malformed layers

Hey all.
I have a problem related to 3D printing that I am hoping for some ideas, perspectives and possibly a fix for. After a week of experimentation I am no closer to a solution, so hence I come here in search of answers. Below is a somewhat detailed description on what I am observing.

Problem:
It appears as though specific layers in a model I am printing are deformed for some unknown reason. I have tried several things (see below) to figure out what is causing this issue. It should be noted that I have printed about 50 different models, both toy models (e.g. cats and dogs) but also robotic parts with requirements on dimensions, structural integrity, etc. So far, the machine has performed well.
Attachment 10527
Fig 1: Side view. Note how the layers are malformed. It could be that only one layer is malformed, and the following is deformed because they miss support.
Attachment 10528
Fig 2: Note also in the inside corners that the melted filament is dragged across as a spider-web almost.

I am not trying to print a somewhat complex model. I have previously printed an almost identical model on a different machine (a Cube 3D), but now I am using a FlashForge Finer. Its not the exact same model, but the complexity is similar.

Model details:
The thinnest wall is 3mm, with a lot of holes and some over-hanging parts, some of which requires support. I’m using auto generated trees, with some unnecessary trees cut away. I am happy to post-process the part with sharp knife and a drill-bit to get the dimensions correct. Looks/esthetics is not significant here (it’s a robot part)
Model is 100x100x120mm. Maximum for machine is 140x140x140


Specifics:
Printer: FlashForge Finder
Slicer software: FlashPrint 3.17.0 32 bit (was using 3.16 before and had same problem)
Firmware: 1.5.20170419 (was using older FW before and had same problem)
Material: PLA 1.75mm Temp range 190C - 220C

Significant settings (a lot can be configured on the Finder, but these are the settings I think is most relevant)
Speed: 60/80 mm/s
Infil: Hexagon 15%
Temprature: 220C (225 for the raft)
Layer height 0.18mm (nozzle diameter is 0.4 far as I can work out)
Perimiter shell count 2
Combine infill layers: 2 ( combines two layers on the inside of the model. I tested with this set to 1 but that didn’t help)
Extrusion: Speed 109% (default for this machine, worked well in the past)

What I have done so far:
I have tried printing 5-6 times with different tweaks to the settings. I lowered speed to 40/40 (print/travel) but that didn’t help. I stepped temperature up to 230 (thinking that this could be kind of delamination), but that did not help. I tried modifying the model, actually redrawing it fro scratch, exporting a new stl and then slicing this anew, but that gave the same results.

Next I suspect that it is the vertical z direction that has some kind of mis-step, since the malformed layers are at somewhat regular intervals, and at the exact same location on each try.
Attachment 10529
Fig 3: To check z direction I printed a 120mm tall 30mm cube. The result is a perfect print. Next, I made a similar structure but hollow with 3mm walls (worst case from the model I have problems with). Additionally I made gaps in the sides, as shown above. This model also comes out perfect. Finally, I put a lot of holes in the thin parts of the object as shown above. Still the model is printing perfectly.


The next thing I tried was lowering the temperature, suspecting that the filament is dragged around because its not solidifying fast enough. I previously tried with a large external desktop fan for cooling (another recommendation from web serachinges), but the fan did not help at all. So then I tried lowering extruder temp to 200C (from 220C which is default).
Attachment 10530
Fig 4a: The result of lowering to 200C is a disaster. The problem is significantly worse, and in fact the model structure collapsed on the printer. Previous attempts at least held together until I touched them.
Attachment 10531
Fig 4b: Closeup of the stringing from my 200C temp try.





PLA material:
One potential (again from various web searching) source could be non-uniformnes of the filament. Hence I took measurments from one roll of filament (Ive used 4 different roles on this experimentation so far), using a micrometer at 10cm intervals.
I found an average filament width of 1.749 with a standard deviation of only 5 um (micrometer). It seems that the filament dimension should be well within spec.



Discussions and thoughts:
1.) The bottom of the model prints without fault. Its only at specific layers this problem happens. It looks to me, and my admittedly somewhat untrained eye when it comes to 3D printing, as though the problem is related to large changed in surface area between adjacent layers. From a control engineering perspective its somewhat reasonable to equate surface area to cooling load on the extruder heating element, thus step changes in the surface area could be expected to cause temperature control problems. Could this be what I am seeing?

2.) Could this be a problem with the slicer software? I have not found any other software that can slice for FlashForge Finder, without setting it up as a “custom device”. This requires more knowledge of the inner workings of 3D printers and the various gcode formats then I currently possess.

3.) Could it be a low temperature problem? Since dropping temperature made it substantially worse, perhaps increasing temperature is the right thing to do? If so I would need to go above the recommended range for the PLA filament. I already tried 230 without any noticeable improvement, but that was also running a fan. Perhaps running 230-240 without a fan? This is PLA so such temp ranges seems extreme... Could it be a fault with temperature sensor on the extruder, thus controlling the temperature at a to low setpoint?

Conclusion:
I have tried every test model I can think of as relevant to the problem I am seeing. I tested changing both printing speed, extruder temperature and adding external cooling from a powerful desktop fan (which I then ran at different settings to experiment with cooling pressure). I even re-draw the model with some differences in structure to see if the problem is in the design. The model I am printing is part of a robot so the room for experimentation in design is limited. It may be that both my designs therefore has the same problem, hence I can not rule out model as the source of the problem, however unlikely this seems. I have not been able to try other slicers.

Any ideas? What more could I try here? Any settings to check (and/or post here to further describe the problem).

Any help would be greatly appreciated. After 7 days of testing I am no closer to a solution...
Best regards,
Ole

given that you are using pla and printing really hot for pla.
I'd suspect that your extruder thermistor has either moved or is just not reading correctly.

That said you have some good prints.

So could it be the model itself ?
what are you designing it in ?

Hey

Just now I am actualy printing a model very similar to the one which was giving me trouble, and now this also prints just fine.

I suspect that the problem is in the slicer. I was using FlashPrint 3.17.
I dont know why this software suddenly is giving me broken gcode for this particular model.
Everything else I have sliced and printed has worked just fine.
As you noted, the printed models, except the one giving me trouble, looks excelent. There are sometimes minor imperfections, but those I can easly tune away by adjusting apropriate settings.

For completnes of this thread my current hypothesis is, somewhat un-substaantiated but lets say its at this point an educated guess:
I think the FlashPrint slicer is making misstakes when _deleting_ supports. I was adding alot of supports automatically, and then deleting most of them, leaving only a large amount of supports in one espesialy troublesome part of the model. In the revised version, the one which now prints perfectly, there are no supports. Previously, I have never first added, then deleted, supports. Hence I suspect that is the problem. The broken layers where always in connection with holes throguh the sidewalls of the model, so it makes sense that the supports are to blame. Also, the print results where perfectly fine until reaching the layers where supports where first added, then deleted. The fact that dropping to 200C on extruder made the problem so much worse is likley a secondary effect, as 220C seems to work just fine on the new revised model.


Despite the problem being solved satisfactory atm, I would be very interested to hear any thoughts more experienced 3d printerer aficionados may have :)

Also, advice for other slicer software compatible with FlashForge Finder would be apritiated.

Cheers,
Ole

Really interesting. I know this Thread is a year old, but right now i have exactly the same Problem.
Flashforge Finder, using the Flashforge Software and PLA.

I have also tried a lot and found that when printing complex structures the print misses out complete slices, so my models looking the same as yours on the Pictures.
The Fails are always in the same height, so i was quite sure that this is not a Problem with the PLA or the temperature.
Simple forms like a pillar work fine with no Problems. So what you suggest is that the Support may be the Problem. That would make sense as the pillar is so simple that it does not have any Support.

I will try in this direction and give an update.

Hello again

So an update from me as promised. Referring to printing Problems with the Flashforge Finder, Flashforge SW and PLA.

At the Moment i am printing the model of a WH40k Titan. For those of you, who do not know what that means, it is basically a big Robot. It has legs, arms, head, weapons, that Kind of stuff.
When printing the various parts then the prints fail as several layers seem to be "left out" and the parts look exactly like the Pictures of prints posted by ombrastein.
On the other hand my Printer prints simple forms like a pillar without any Problems. The "missing layers" seem always to be at the same height when printing complex forms.
Any changes to Printer Settings like Temperature, Speed, infill or usage of different Versions of the flashforge SW did not change anything.

As ombrastein suggested, i experimented with the supports. So i rotated the head of the Titan in a way that it now sits with the flat side on the printbed. As a result it needs no Support.
Usually i do not like printing like that as it is always difficult to remove the part from the printbed this way. But i did it for a test and it worked. Exactly the same head in the same size and it printed without any Problem when i used no supports.

So thanks to ombrastein for this hint as i now know where the Problem is located. On the other Hand it does not really help me much as there are many pieces which can only be printed with usage of the supports. So i am wondering if anyone has an idea how i can proceed now that i know the source of the Problem.

Maybe anyone knows of an alternative SW which is free an can use the Flashforge Finder?

One last update from me, i hope it will help future Flashforge-Finder-Users with similar Problems.

Even after some longer Research i didnt find any free Software which supports the Flashforge Finder.
As SimplyFy3d allows you to test the function of ist SW on your 3dprinter for 2 weeks with a complete refund if it doesnt work, i did try that one.
To make it short, it worked. SimplyFy3D does not Support WiFi to the Finder, but USB is good enough for me.
All those models, where i had the above described Problems using the Flashprint SW, now print perfect with the new SW.
So yes, it was a SW Problem within Flashprint when trying to print some complex structures with lots of Support.

The Investment of 150 Dollar solved the Problem. Not nice, but i see it as an invest in the future as SimplyFy3D seems to be a big Player in 3dPrinter-SW and will probably also work with future Printers.