Extrusion problem

miszun
Posts: 18
Joined: Tue Oct 30, 2018 5:09 pm
Location: Poland

Extrusion problem

Postby miszun » Fri May 07, 2021 1:17 pm

Hi,
we have a problem printing small polycarbonate parts with complicated features. It runs quite ok (not perfect but acceptable) where the walls are smooth and simple. If there are small features, supports etc, then it looks like heavy underextrusion. It is not about settings because we printed hundreds of these parts perfectly, and now we get faulty prints using the same gcode files.
extrusion problem.jpg

There are no jams, no noises, everything looks ok besides these holes. Extruder gears are ok, bearings rotate smoothly, there are no obstacles in filaments way. I've swapped extruder motors. Motion controller board receives stable 24V. IMHO, mechanically the whole printer is OK.
The only thing comes to my mind is the extruder's stepper driver. As it is integrated into motion controller (what a pity), there is no way to swap it (with second extruder's stepper driver). Is there a simple way to verify that the stepper driver is faulty or not?
Or maybe there could be another issue causing such an extrusion inconsistency?
Please help.

Jetguy
Posts: 3226
Joined: Tue Mar 22, 2016 1:40 am
Location: In a van, down by the river

Re: Extrusion problem

Postby Jetguy » Sat May 08, 2021 1:25 am

It's not your stepper driver. A bad stepper driver results in a motor that never spins. If it spins- it's not the stepper driver.

Or maybe there could be another issue causing such an extrusion inconsistency?
YES- far more likely slipping in the filament drive grip of the drive gear to the filament, or the fact that your hotend and extruder has back pressure or possible mini jams from retraction that the feeder system slips or skips steps trying to refeed the filament after a retraction.
Last edited by Jetguy on Sat May 08, 2021 2:47 am, edited 1 time in total.

Jetguy
Posts: 3226
Joined: Tue Mar 22, 2016 1:40 am
Location: In a van, down by the river

Re: Extrusion problem

Postby Jetguy » Sat May 08, 2021 1:28 am

we have a problem printing small polycarbonate parts with complicated features. It runs quite ok (not perfect but acceptable) where the walls are smooth and simple. If there are small features, supports etc, then it looks like heavy underextrusion. It is not about settings because we printed hundreds of these parts perfectly, and now we get faulty prints using the same gcode files.


Again, I'd be looking at your hotend and nozzle system, as well as cooling fans cooling the cold section of the hotend as this massively affects retraction and problems with restarts after a retraction. Those items (hotend system, fans) age and wear and easily would account for the problem.

Also keep in mind, nozzle wear is a factor and some filaments (doesn't have to be abrasive) can cause nozzle wear.
That affects flow and control of the filament causing what looks like under extrusion. This isn't the first time I've seen that exact pattern or flaw in printing and it was related to the hotend or nozzle.

Jetguy
Posts: 3226
Joined: Tue Mar 22, 2016 1:40 am
Location: In a van, down by the river

Re: Extrusion problem

Postby Jetguy » Sat May 08, 2021 1:36 am

we printed hundreds of these parts perfectly, and now we get faulty prints using the same gcode files.


Yep, sounding more and more like nozzle wear the more I analyze this.

Jetguy
Posts: 3226
Joined: Tue Mar 22, 2016 1:40 am
Location: In a van, down by the river

Re: Extrusion problem

Postby Jetguy » Sat May 08, 2021 1:51 am

Actually now looking back, I remember the local Makerspace having this issue with polycarbonate that literally kept blowing out entire nozzle tips on a different printer. There might have been a chemical reaction at high temp or some other detail but whatever they were doing, they were eating nozzles like I had never seen before. I blamed it on the specifics of the brass nozzle and not all nozzles are made as well or from correct alloys. But I do now remember that it was polycarbonate they just started printing with and began jus absolutely wearing out nozzles at a rate that seemed odd.

Both the shape of the tip wears as well as the bore.
drWLD.png


https://www.youtube.com/watch?v=uvlMeTnjriQ&t=1s

miszun
Posts: 18
Joined: Tue Oct 30, 2018 5:09 pm
Location: Poland

Re: Extrusion problem

Postby miszun » Sun May 09, 2021 10:44 pm

Jetguy,
thank you for your help. I've replaced the extruder's fan some time ago for Sunon Maglev and I believe it will last longer than the printer itself. The nozzle looks quite good and it's not old, but I'm going to replace it anyway. I have not noticed any accelerated wear so far when printing polycarbonate (and I printed a lot of it), but maybe this time I got weaker or even defective nozzle, or maybe another filament I tried recently caused the damage. Anyway worth of trying. And I will take a closer look at the hotend by the way.
OK, thanks again, Jetguy.

Saperusa
Posts: 28
Joined: Mon Mar 29, 2021 8:45 pm

Re: Extrusion problem

Postby Saperusa » Mon May 10, 2021 12:34 pm

Hi,
Sometimes when You change material, the nozzle inside has some residual on the wall, and this is the reason which is why You have that problem.
When I change material, I have a filament to clean the nozzle and whit this, I don't have the problem of extrusion with a longer life of the nozzle.
It's not expensive, 10 meters are about 8 euro and with 10 meters You have about 50 clean nozzle.

miszun
Posts: 18
Joined: Tue Oct 30, 2018 5:09 pm
Location: Poland

Re: Extrusion problem

Postby miszun » Mon May 10, 2021 12:55 pm

Hi Saperusa,
you are right, cleaning the nozzle after change of material is important. I use flush filament from Sun, and DynaPurge 3d Clean. The strongest I tried was The Flush from Rigid-ink, but it is no longer available. I never have clogs or jams. Sometimes cold pull with nylon filament is needed (rarely), but I hate to do it and avoid it most of the time.
In my case lack of cleaning was not an issue I think.
I've just replaced the nozzle with the new one, and preparing a test run of it.

Saperusa
Posts: 28
Joined: Mon Mar 29, 2021 8:45 pm

Re: Extrusion problem

Postby Saperusa » Mon May 10, 2021 5:26 pm

Hi, miszun,
Dynapurge is the filament I use to clean the nozzle for my PRO2.
In Italy, it's not a problem to buy and it's very good.

Sandro

miszun
Posts: 18
Joined: Tue Oct 30, 2018 5:09 pm
Location: Poland

Re: Extrusion problem

Postby miszun » Mon May 10, 2021 6:15 pm

Hi, Jetguy!
YES you were right! The nozzle was the cause. The new one solved problem.
The old one looks good, it is barely shortened (has a fairly low mileage), but apparently it is worn from inside. I've never seen something like that and what's more, defects in printed parts were so strange, so I would never associate this problem with the nozzle. But you did and I thank you so much!

Saperusa
Posts: 28
Joined: Mon Mar 29, 2021 8:45 pm

Re: Extrusion problem

Postby Saperusa » Mon May 10, 2021 7:54 pm

Hi Miszun,
what brand of polycarbonate You are using with Your PRO2?

S.

miszun
Posts: 18
Joined: Tue Oct 30, 2018 5:09 pm
Location: Poland

Re: Extrusion problem

Postby miszun » Tue May 11, 2021 8:52 am

PolyMax PC from Polymaker. The best of the best (IMHO).


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