[Testers Needed] Inconsistent Extrusion  

Re: [Testers Needed] Inconsistent Extrusion

My upgraded mK2 to MK2.5 has it now, like first print off it... there's no TMC drivers here. it didn't just prior, cause i printed the parts for it and it has none of the artifacts.... there's even moire now... so i think the moire in mk3 is probably from the same problem.... not the drivers.

That's very interesting. If true (not doubting you) then this exonerates the trinamic drivers. It would narrow it down to the Bondtech gears (which have been mostly cleared in other experiments), the filament sensor, or firmware (which I assume you updated). The last two are related since there are firmware changes to support reading the sensor. That could also fit the theory of CPU overload from extra firmware code and sensor interrupts. What firmware version were you on with MK2 before you upgraded? We should diff that with current.

Re: [Testers Needed] Inconsistent Extrusion

similar issues:

http://www.soliforum.com/topic/10108/extruder-pulse-moire-at-132-microstepping-causing-diagonal-lines/
http://www.soliforum.com/topic/4759/newly-installed-e3d-problems/
http://www.soliforum.com/topic/9347/solidoodle-press-print-quality-and-how-to-fix-it/

if it's not voltage or misconfigured software drivers then it's probably an enisy board issue/stepper motor mismatched for trinamic or they're not up to spec from factory and impedance wasn't checked in QA? so some are ok, others not.

Good work Eric. Very nice find. That first link is an especially interesting case.

The E3D specific stuff is also interesting. Will be following along closely with how this changes things.

Wow, I didn't expect to find a 4 year old post of mine here! (first soliforum link above) I've been thinking about maybe getting an mk3 when I heard about this issue and was reading more about it.

The combination of "Optimal Layer Height for Z axis" on the Prusa calculator page ( https://www.prusaprinters.org/calculator/#optimallayer ) and getting stepper driver current correct are what really helped me get nearly perfect prints in that case. It sounds like linear advance and the driver current being set electronically may be part of the issue these days.

I'd love to help but I'd need an mk3 to do that 😉

Does the trinamic driver current stay the same over a print or is it constantly autotuning?

Ok, I'll be back in 4 years to see if anyone answered! /s

edit: shoutout to Joseph for having that awesome calculator page 4 years ago!

Re: [Testers Needed] Inconsistent Extrusion

THIS JUST IN

Image with light from above.

Image with light from side

Video with motion

Cube on left is normal.
Cube on right has hacked gcode.

Vertical banding also solved. Click the images and zoom in. Seriously. Zoom. In. Look at that. It don't even look FDM in the video!!!

Re: [Testers Needed] Inconsistent Extrusion

THIS JUST IN
Cube on left is normal.
Cube on right has hacked gcode.

Vertical banding also solved. Click the images and zoom in. Seriously. Zoom. In. Look at that. It don't even look FDM in the video!!!

The post is kind of useless without any kind of information.

You may as well have posted 'cancer cured' and left it at that, no instructions to patients as to what to do, no information about what this new cure might be, no links as to where further information can be found (etc etc).

I'm going to assume you've either solved this yourself, or you've read the solution elsewhere, but don't want to share it for some reason ?

Re: [Testers Needed] Inconsistent Extrusion

Cube on right has hacked gcode.

I'm going to assume you've either solved this yourself, or you've read the solution elsewhere, but don't want to share it for some reason ?

I posted.

Literally. The cube on the right has hacked gcode.
Brigandier wrong the script after my concept.

It's 100% useless, and does not fix this problem.

All it does is prove the problem lies in low level marlin.

EDIT:
Here is a new cube I just printed. At the 8 second mark when I tilt the cube, you will notice the "inconsistent" lines, go ALL THE WAY AROUND.
This is I believe the filament causing this issue. I am unsure.
This is Prusa Silver PLA.
(The stuff you can see this effect from across the room with normally)

As far as I am concerned, This 100% fixes the issue, for printing a test cube. (on the down side, this will never print more than a test cube, so it's by no means a fix, a solution, or anything like that)

Re: [Testers Needed] Inconsistent Extrusion

"It's 100% useless, and does not fix this problem."

"This 100% fixes the issue"

I'm glad to hear that this issue has been fixed / has not been fixed

Re: [Testers Needed] Inconsistent Extrusion

"It's 100% useless, and does not fix this problem."

"This 100% fixes the issue"

I'm glad to hear that this issue has been fixed / has not been fixed

Hey, My quote is "This 100% fixes the issue for printing a test cube."

Basically, if you are like me, and a few others, and 2/3 of the prints off your printer are test cubes... this fixes those 2/3. Sadly, the other 1/3rd of the prints, it wont.
And for those of you who don't print test cubes, 99% of the time... it won't help you 99% of the time. And unless you want to learn to generate your own gcode. Chances are it won't help you the other 1% of the time either. 😛

Re: [Testers Needed] Inconsistent Extrusion

This also means mk2s was just a stroke of luck that it printed well..... prusa had no clue why, they just rolled with it until they started adding more features and switching to bondtech in mk3 without really checking quality. it's probably also contributes to MMU v1 print quality outside bowden tuning... Seems like they care about printers but not necessarily anal about the quality of the prints. it would of been immediately noticeable if this were me.

it would probably be slightly better to go back to the old extruder gear since its a bit more steps per mm to mask the issue. i might do that on mk2.5 unless there's a firmware fix soon or i can run something else like klipper on it. but bondtech isn't much use without it being geared.... i've never had filament slip before the extruder skipped steps anyway.... no clue the rational or what issues they had for changing it in the farm.... they're also pricey.

Re: [Testers Needed] Inconsistent Extrusion

Is it known whether this unfixed issue has an impact on precision? I read that this issue is not a big deal when you print functional parts but nobody talks about the effect of this issue on functional parts.

Re: [Testers Needed] Inconsistent Extrusion

Is it known whether this unfixed issue has an impact on precision? I read that this issue is not a big deal when you print functional parts but nobody talks about the effect of this issue on functional parts.

I'm not sure what kind of precision you expect from FDM. This issue generates a slight variance in nanometer area. So it's only visible under certain light sources. in general most people are really happy if they achieve +/- 1 mm precision for the build part. That's why nobody connects this issue with functional parts.

Re: [Testers Needed] Inconsistent Extrusion

Is it known whether this unfixed issue has an impact on precision? I read that this issue is not a big deal when you print functional parts but nobody talks about the effect of this issue on functional parts.

Not 1 person has cared about this when printing for functional parts... or even models. I still have 100% 5-star feedback on all places I print on, and this is definitely my go-to printer over my MK2 (convenience, 24-v quick heat up times, flex bed, all winners for me). I just purchased the MK2.5 kit so I can love both printers almost equally (24-v is pretty awesome).

Re: [Testers Needed] Inconsistent Extrusion

Hey Guys,
while having the incosistent extrusion issue as well there's another thing I noticed and wonder if its related to the same issue:
The solid bottom of prints is less inconsistent than the rest but is clearly visible from the outer surface.

any Ideas what is causing this issue?
The floor seems to be a little smaller than the rest of the print...

Re: [Testers Needed] Inconsistent Extrusion

I suggest the OP post his cube, so that we're all printing the same thing.

Re: [Testers Needed] Inconsistent Extrusion

I think user pbrgle1's github post suggesting bed expansion and contraction may be a fault should be considered. I have seen two problems in most of these posts - moire and layer height inconsistency. The moire can be helped pretty easily but the lay height issues are a little more troublesome imho. Can anyone comment on the possibility of bed expansion and contraction and what heating method is in use? Any history of z-screw backlash? Thanks

Re: [Testers Needed] Inconsistent Extrusion

I have a MK2S (or MK2.25?) where I have only installed heatbed/spring sheet from the MK2.5 kit. I was waiting for the issue to be resolved before doing the whole upgrade. Since my printer was XYZ calibrated, I was able to upgrade just the bed without any issues - just had to recalibrate Z and tweak Live-Z.

I haven't noticed any decrease in quality, but I also haven't printed much yet. I can print a test cube later today and see if the issue happens with just the MK3 bed.

Edit: Added pictures. The filament is Prusa PLA and layer height is 0.2mm. The first one is a 30x30x30 (mm) cube printed in vase mode. The second one is the standard XYZ 20x20x20 calibration cube printed "normally". Both are printed using an MK2S with the MK2.5 upgrade heatbed/spring sheet, but not using the MK2.5 extruder or firmware (no BondTech or PINDA2).

The files were sliced with Slic3r Prusa Edition 1.37.1 using the stock Prusa PLA profiles and the printer firmware is 3.0.12. Both of those are quite old but they work for me. The only issue I've ever had with my MK2S was the original bed was quite warped. Also, I'm really hesitant to change anything related to software or firmware until this issue is resolved. Having said that, it does look like my prints are showing the issue, and unfortunately I did not perform this same test before I changed the bed.

I can take additional pictures if needed.

Re: [Testers Needed] Inconsistent Extrusion

I’m just wondering (I have to admit to just reading the first ten pages of this topic, so excuse me if I’m being redundant): it seems like everyone* is having issues in the XZ plane? I often calibrate Live Z by printing a single layer, 75x75mm square; the mostly come out like this:

It seems to be the same issue, am I right? Ignore the fringes, too high nozzle. 🙂

*see above

Re: [Testers Needed] Inconsistent Extrusion

Is this the same issue or something different?

Re: [Testers Needed] Inconsistent Extrusion

Could the inconsistent extrusion be caused by the PINDA temperature fluctuating?

Re: [Testers Needed] Inconsistent Extrusion

Hi MK3BetaTester,
in normal printing, the pinda is only involved in homing and 9 point bed levelling,

So I would say, no it's not going to cause fluctuations...

but this is an unresolved issue, which could be due to faulty logic, so although it's unlikely, we can't rule the possibility out...

regards Joan

Re: [Testers Needed] Inconsistent Extrusion

I've been getting this on my mk2s!!

Everyone seems to be attributing this issue specifically to the mk3 but I've been having this same exact inconsistent extrusion from my mk2s kit bought on Black Friday last year. I've only seen a few others mention this about their mk2s but the problem exists across models and most on this thread and the GitHub are speaking as if this is mk3 specific.

I don't know much about the build differences and I have the latest firmware for the mk2s from November 2017, but if this post helps rule out some mk3 exclusive possibilities I'm here to lend whatever information/testing I can.