[BUG] Delayed extrusion after travel when using 0.6 mm nozzle (and 0.4 mm as well)

[rasssta]

Printer type - [MINI] Mini

Printer firmware version - [e.g. 4.0.5, ...] 4.4.1+4194

Original or Custom firmware - [Original/Custom] Original

Optional upgrades - [e.g. Filament Runout Sensor] Filament runout sensor 0.6 mm nozzle WiFi

USB drive or USB/Octoprint Octoprint. But I have the same issue when printing from USB.

Describe the bug I have an issue with scars and holes in perimeters, that I believe started to show when I switched to 0.6 mm nozzle. I'm not actually 100% sure it's related to the nozzle since the issue only shows in certain prints, so it's not really clear when it begun. But the problem also seem to appear with 0.6 mm nozzle for the MK*, see https://github.com/prusa3d/Prusa-Firmware/issues/2760. Prusa support has been involved in that ticket and referred me to create a new one in this repo.

The issue is that extrusion is delayed after certain travel moves by the print head, which causes scars and holes in the print. I've tried to slice with PrusaSlicer, SuperSlicer and Cura and I get the same problem with all of them. I've also tested to remove the filament sensor but the problem persists. PTFE tubes have been replaced to new ones.

It seems to be mainly related to extrusions that are made after the print head is moved from the left hand side to the right hand side of the sheet.

In the print example (picture attached) I placed 4 towers, one in each corner of the sheet. The tower on the right was on the bottom right, the top tower was on the top right, the left one on the top left and the lower one on the bottom left.

But if I move the right hand towers close to the middle I still get the same issue with them, whereas if I move the left hand towers to the middle they print just fine. So it's not just about the actual placement of the object on the sheet, but rather the combination of placements and the print moves it creates.

The problem also occurs with single objects where the same type of movement is performed, in the print, from left to right on the sheet.

I have made some videos where I've filmed the print head and extrusion wheel and the extrusion wheel starts moving at the exact same frame as the print head is lowered (after z-hop), for the parts of the print where I get the holes/scars. I haven't compared it to the non-hole objects but I would assume that the extrusion should start when the print head is lowered?

How to reproduce Swap to 0.6 mm nozzle. Put an object in each corner of the sheet which has only 1 perimeter.

Expected behavior No holes or scars in the print.

G-code See next post.

Crash dump file None

Video None. But phots will be attached.

NOTE: If you are affected by this issue, please print the test gcode that Prusa Support has uploaded further down in this issue https://github.com/prusa3d/Prusa-Firmware-Buddy/issues/2997#issuecomment-1454763541 and post your result(s) in this issue, please include filament name as well.

[rasssta]

[rasssta]

Gcodes:

Cura: OPM_rettest_2.txt

PrusaSlicer: rettest_0.6n_0.2mm_PLA_MINI_15m.txt

[rasssta]

I just changed back to a 0.4 mm nozzle and I get the same error so it's not related to the nozzle size

[rasssta]

I have created two demo/test STLs where each tower is marked with I/II/III/IIII or none (which is center tower, I will call it number 5) in the 5 tower STL.

STLs (rename to .stl): Rettest_4tow_0.4mm.txt Rettest_5tow_0.4mm.txt

4 tower test: Print order: Tower 3, 4, 2, 1 Tower 4 has a lot of gaps A lot of stringing for tower 2 All other towers are overall okay.

5 tower test: Print order: Tower 1, 3, 5, 2, 4 A lot of stringing for tower 4 Gaps are now on tower 5 instead

[rasssta]

Reverted to FW 4.3.4+2835. Same issue.

[art-0]

Your problem is related to retraction length. Each type (PLA, PETG) of filament needs a different one. Change the retraction length e.g. to 1

also read about linear advance e.g: https://forum.prusa3d.com/forum/hardware-firmware-and-software-help/linear-advance-for-the-mini/#post-618399

[rasssta]

I'm well aware of both retraction length and linear advance. Both have been extensively tested and tuned without any difference in regards to this problem.

[rasssta]

Adding another STL with 2 towers that is faster to print: Rettest_2tow_0.4mm.txt

[Prusa-Support]

Thanks for testing and reporting.

For clarity, it seems that the print in the first picture doesn't match the .gcode file prepared in Prusa Slicer. The Prusa Slicer G-code was not using pre-settings. The retraction is a bit exaggerated and LA is 0.04 (I would expect it to be around 0.12 or so for PLA + 0.6 nozzle). I don't want such little things to make the problem look even worse.

I could reproduce the problem in similar print scenarios though.

I recommend focusing on reducing the print complexity so that more users can easily reproduce the same print scenario without worries.

For example:

1. Use Prusa Slicer genuine pre-sets, stock 0.4 mm nozzle printer, Generic PLA filament, 0.2 QUALITY print profile.
2. Use rounded shapes to reduce speed and flow alteration around the corners.
3. 0% infill and 1x perimeter for better visibility of the issue
4. Painted seam line towards the center, so that the nozzle won't cross the perimeters during the travels.

test.zip notes

• objects and perimeters printed counterclockwise, starting with the front-right corner

result

• all objects are affected
• the first object (front-right) is most affected (after travel from-left-to-right)

1st in the sequence

2nd in the sequence

3rd in the sequence

4th in the sequence

If more users can reproduce and confirm the issue, that would be appreciated.

A shaking or deformed hotend PTFE tube could be a concern! It would create more artifacts like this. Consider cleaning the hotend and reseating the hotend PTFE tube if your results are noticeably worse with the same settings. Before my test in the pictures I did that, just to be on the safe side. 🙂

Michele Moramarco Prusa Research

[posen4u]

Thanks for testing and reporting.

1. Use Prusa Slicer genuine pre-sets, stock 0.4 mm nozzle printer, Generic PLA filament, 0.2 QUALITY print profile.
2. Use rounded shapes to reduce speed and flow alteration around the corners.
3. 0% infill and 1x perimeter for better visibility of the issue
4. Painted seam line towards the center, so that the nozzle won't cross the perimeters during the travels.

test.zip notes ... If more users can reproduce and confirm the issue, that would be appreciated.

A shaking or deformed hotend PTFE tube could be a concern! It would create more artifacts like this. Consider cleaning the hotend and reseating the hotend PTFE tube if your results are noticeably worse with the same settings. Before my test in the pictures I did that, just to be on the safe side. 🙂

Michele Moramarco Prusa Research

I sliced your provided test file on my MK3s, using the Prusament PLA, 0.2 QUALITY and Prusa Slicer default 0.4 printer profile printing with Prusament PLA Blend My Silverness. Note, my printer is running in stealth mode. I tested this twice, first having the model centered on the bed and then move each tower to the corner of my larger printbed.

• Test 1, towers centered on bed with the same distances as on the mini bed.

• Test 1, All 4 towers (placed in their representative corners)

• Test 2, towers moved further out the corners for MK3 size.

• Test 2, All 4 towers (placed in their representative corners)

• Comparison bewteen test 1 and 2

Print files

• nocrossing_mk3s.zip

[rasssta]

For clarity, it seems that the print in the first picture doesn't match the .gcode file prepared in Prusa Slicer. The Prusa Slicer G-code was not using pre-settings. The retraction is a bit exaggerated and LA is 0.04 (I would expect it to be around 0.12 or so for PLA + 0.6 nozzle). I don't want such little things to make the problem look even worse.

Regarding the retraction I don't actually recall which settings I used back then as I've tested so much stuff back and forth by now.

But I was actually a bit surprised that 0.12 is the default LA setting when I started to look into LA, and did the linear tuning test print found here https://marlinfw.org/tools/lin_advance/k-factor.html and got the following result:

0.04-0.05 seems to be the best according to the test.

EDIT: My bad! I was under the impression that the printed values were multiplied x10 for some reason. Will try with 0.40 instead of 0.04.

[rasssta]

1. Use Prusa Slicer genuine pre-sets, stock `0.4 mm nozzle` printer, `Generic PLA` filament, `0.2 QUALITY` print profile.

2. Use rounded shapes to reduce speed and flow alteration around the corners.

3. `0% infill` and `1x perimeter` for better visibility of the issue

4. Painted `seam line` towards the center, so that the nozzle won't cross the perimeters during the travels.

test.zip notes

I printed the test1nocrossing.gcode found in the zip and got the following result with Prusa Mini, 0.4mm nozzle, FW 4.3.4+2835, AddNorth PLA Economy White:

1st:

2nd:

3rd:

4th:

[rasssta]

Another test print, this time with my normal settings (still K0.04 for this one). 99% sure of the print order:

Prusa Mini, 0.4mm nozzle, FW 4.3.4+2835, AddNorth PLA Economy White.

1st (bottom left):

2nd (top left):

3rd (top right):

4th: (bottom right):

[rasssta]

Another test, this time with my usual settings (as in the previous post) but this time with K-value of 0.42 instead of 0.04.

Prusa Mini, 0.4mm nozzle, FW 4.3.4+2835, AddNorth PLA Economy White, M900 K0.42.

1st:

2nd:

3rd:

4th:

[rasssta]

I have confirmed that the same problem exist in FW 4.2.0+2067 and 4.3.0+2756.

[posen4u]

... MK3s tests...

Adding that I am using firmware 3.12.1-5686 on my MK3s. I did another test using a reverse bowden setup as I had it available, and that made no real difference in print quality. However I swapped the filament out for "Clas Ohlson PLA" and ran the same gcode, no issues. So for the MK3 maybe this is only a case of fine tuning the default Prusament PLA profile.

Reverse bowden setup

Reverse bowden result

Clas Ohlson PLA result (not reverse bowden)

[elHatchling]

I Tried the test.zip on a Prusa Mini+, FW 4.3.4. Bought it March 2021. The only mod is that I am using the "BondTech Heatbreak Prusa Mini".

Prusaslicer 2.5.0, Used 0.20 QUALITY, Prusament PLA profile, 0% infill. More or less everything fromm the .3mf file in the zip.

All cylinders printed fine, with no gaps, but with some stringing.

[Prusa-Support]

Thanks for your feedback.

@posen4u It seems safe to rule out the MK3-series from this issue.

@elHatchling Isn't it that BondTech Heatbreak requires a few firmware parameters and print settings tweakings?

Retraction and Linea Advance setting can make a difference but apparently that wouldn't be all.

In two cases, it seems that the object/elements printed after a "large" travel from-left-to-right is subject to noticiable gaps while the nozzle resumes extruding. It may be useful to collect more examples of prints made with other Prusa MINI printers in order to confirm the issue and assess its diffusion.

New reports of the test made with other MINI printers, are welcome. Please include pictures and relevant information about hardware, firmware, print settings and filament.

Michele Moramarco Prusa Research

[elHatchling]

Regarding the Bondtech Heatbreak. Only thing I did was to use a shorter PTFE tube, according to the instructions from Bondtech. Nothing else have changed. No firmware parameters or print settings tweaked. Using stock Mini Firmwares when updating and using stock Prusaslicer settings for printing.

[krcm0209]

New reports of the test made with other MINI printers, are welcome. Please include pictures and relevant information about hardware, firmware, print settings and filament.

I printed the test1nocrossing.gcode supplied by @Prusa-Support on my Mini.

Modifications from a stock machine

1. Swapped to SuperPINDA
2. Swapped to Revo Micro hotend

Versions

Firmware: 4.4.1+4194 Bootloader: 2.0.2 Buddy Board 1.0.0 (1120X017XC0434)

Stats

• X axis: 5.4 km
• Y axis: 4.9 km
• Z axis: 37.1 m
• Filament: 271.6 m
• Print time: 3d 5h

Filament

Prusament PLA Blend Lime Green

Nozzle

0.4mm

Photos

[krcm0209]

I can't really back this up with science or evidence (partly because I don't have the time right now to deep dive on this subject), but I have a feeling this behavior is in large part due to:

1. the internal tolerance of the stock bowden tube on the Mini
2. the transition from a very gentle bend radius at the left-most position to a relatively extreme bend radius at the right-most position causing a pulling effect on the filament due to a changing path length

Potentially relevant or enlightening article for those unawares: https://e3d-online.com/blogs/news/battling-bowden-tube-physics

[ryanklafuric]

Following up on this thread via a reddit post in r/prusa3d.

I printed the test gcode provided and had some fairly gnarly results. As expected, results were worst in the front right. The best result was the front left. I also suspect that this issue is related to the bowden tube, like @krcm0209 mentioned.

I'm going to try changing filaments, and using a different spool holder to see if that has any positive impact.

Photos of all four:

Front right (worst):

Rear right:

Rear left:

Front left (best):

Asides from this test, I've observed this gap affecting prints like this Gridfinity cube:

[rasssta]

I can't really back this up with science or evidence (partly because I don't have the time right now to deep dive on this subject), but I have a feeling this behavior is in large part due to:

1. the internal tolerance of the stock bowden tube on the Mini

2. the transition from a very gentle bend radius at the left-most position to a relatively extreme bend radius at the right-most position causing a pulling effect on the filament due to a changing path length

I'm in the same position, can't back it up with science but I have been thinking about just the same two points. I don't know if there actually is a proper solution to this issue (but only workarounds) as it seems to be related to hardware and concept (bowden).

However, I can see 3 possible directions (feel free to comment!):

1. A function in the slicer which compensates for the movement of a bowden printer (can be for Mini or Universal). Let's say you specify where the bowden tube is located on the printer (right, top, top right, etc.) and then the slicer will build some form of compensation mesh for how much of extra restart length or deretraction to use after each travel depending of position A and position B for the travel (as the problem only occurs after left -> right movements).
2. Pretty much the same as 1, but implementing this in the Prusa Mini firmware instead of the slicer. Will probably have the same end result, but only solve this issue with the Mini and not for other printers using PrusaSlicer.
3. Redesigned bowden concept for the Mini. Instead of having the tube exit the extruder upwards it might be an idea to move the extruder and redirect the exit direction 0-45 degrees downwards, hence being able to use a shorter tube and more direct angle for the tube towards the printer head. Note that this is just my average Joe brainstorming so take it with a grain of salt :-)

Also, thanks to the "newcomers" in the thread for your contribution with test prints! The Reddit thread highlights that this is an actual problem for people so its nice to have more people giving input here in the issue.

[rancor1223]

New reports of the test made with other MINI printers, are welcome. Please include pictures and relevant information about hardware, firmware, print settings and filament.

Michele Moramarco Prusa Research

Here is my result with basically stock Mini+, only with a 0.6mm nozzle. I will repeat this test with 0.4mm in next few days.

Printer type - [MINI] Mini+ (purchased in 2021/10; 29 print days logged; the PTFE tube was never replaced)

Printer firmware version - [e.g. 4.0.5, ...] 4.4.1+4194

Original or Custom firmware - [Original/Custom] Original

Optional upgrades - [e.g. Filament Runout Sensor] Filament runout sensor 0.6 mm nozzle levendig silicone sock on the heatblock

To generate the Gcode I used stock settings (for 0.6mm nozzle) with the few changes from the provided 3mf file in PrusaSlicer 2.5 for "Generic PLA" (I used eSUN PLA+).

(prints are ordered clock-wise starting with bottom right corner of the bed) First two on the left might appear connected, but there is a gap, just filled in with stringing.

---

I'm glad this is finally being looked into, I've struggled with it for a good while (although I don't remember this being a problem back when my printer was new).

[xarvh]

Coming from Reddit, I seem to be having similar issues.

Original Mini+, replaced heatblock and using a 0.6mm tungsten carbide nozzle, everything else is original.

• 0.20mm Quality @Mini (modified), the modifications are from the .3mf
• Generic PLA
• Original Prusa Mini & Mini+, but changed Nozzle Size to 0.6mm

[d-sko]

Hi, I've printed the 3mf file in the test zip as is on a Prusa Mini without any modifications running firmware 4.4.1, here are the pictures:

[minameismud]

New Prusa Mini+, received Feb 27, 2023. No mechanical modifications other than the filament sensor relocation for the Mini Base. I have had to disassemble & reassemble the extruder twice to clean it, and the filament got stuck unloading after this test run, so #3 is going to happen soon.

Printed the test .gcode with the sample Prusament PLA Galaxy Silver that came with the printer.

Firmware version: 4.4.1+4194 Bootloader Version: 2.0.6 Buddy Board: 1.0.8 Total filament: 634.9m Print time: 7d7h

FWIW, I was trying to combat this with the Extra length on restart setting. At 0.15, it seemed to help.

[vintagepc]

Here are my test results. Mini has had a nozzle change and the base modification but the extrusion system remains stock. It's interesting to note there is also underextrusion on the base layers of the circle that is most affected by the gap.

Using Toner Plastics Silver City PLA (Ingeo)

[rasssta]

It's interesting to note there is also underextrusion on the base layers of the circle that is most affected by the gap.

Good catch! Haven't noticed that myself before.

[ScreennameTaken]

Ok so i've run the test gcode on my mini from the first post (4.4.1, with a Revo and a Bondtech extruder. nozzle used was the 0.4) The problem only appeared on the last cylinder that the mini comes from left to right.

https://user-images.githubusercontent.com/24358412/229854349-cdc9fe89-8a8b-47f1-8181-75b9ecbd03fc.mp4

[LegsLucas]

Prusa Mini+ (1 year old, 7d print time)

Firmware: 4.4.1 +4194

Mods: Bondtech IFS extruder E3D Revo 'Prusa Mini Edition' Capricorn XS PTFE tubing Revised X End

File: test1nocrossing.gcode Filament: Atomic 'Perfect Orange' PLA Nozzle: Brass 0.4mm

Results:

[ryanklafuric]

What I find fascinating is that users with the upgraded Bowden extruder are also experiencing this “under extrusion after travel” issue (apparently).

I’d be curious if people with a direct drive conversion experience this issue as well.

[lemonnfresh]

Stock Mini+ .04mm nozzle 4.3.4 Purchased March 2022

Issue: Printer appears to under extrude after travel. I've masked the symptoms by upping the extrusion multiplier to 1.05. Symptom often appears on walls/perimeters on lower right of prints especially those that run directly across the x axis.

All Four, Front View. Front Closeup

Rear Closeup

All Four Matte, Front View

Front Closeup Matte

Rear Closeup Matte

[Lagersuufer]

Stock Mini+ 0.4 mm Nozzle Purchased 2020 FW: 4.4.1 SUNLU PETG, Gray

Exact same issue. Results of printing the test file are identical to those already posted, under-extrusion in on the cylinders on the right size after a large X-axis move.

[aab010799]

Completely stock Prusa Mini+ Purchased February 2023 Inland PLA+

[antp123]

I also have the same problem, firstly noticed it when I switched to 0.6 mm nozzle and printed big part, where seams were set to Random (it left holes in some places)

Printer Type - Prusa Mini+, everything is stock Printer firmware - 4.4.0 Filament - Prusament PLA Galaxy Silver

Ran the provided test print with: 0.6 nozzle (default PrusaSlicer settings for 0.6mm nozzle) 0.4 nozzle (default PrusaSlicer settings for 0.4mm nozzle) Then tried to change Bowden tube to a new one (from extruder to hotend) and performed the test print again, but it didn't make much of a difference. Results are here:

Also there is difference in wall thickness even at Front Left cylinder:

[aab010799]

I should also note that my Mini generally prints the seams randomly regardless of which settings I have. It's quite frustrating. Many of my prints have zits all over despite using the "aligned" settings in Prusaslicer.

[slurpdenon]

Just wanted to throw in that I've had these issues since I got my Mini+ at the beginning of the year. Talked to support at the time, and they recommended cleaning and reseating the PTFE in the hotend, but that didn't fix anything. Then we assumed it was moist filament that was causing oozing between retractions, but that also didn't resolve my issues. Support seemed out of ideas, so I've just assumed I was doing something wrong, so I'm glad I stumbled across this and now know I'm not crazy. Unfortunately I've wasted a lot of filament after a supports failed because of this on a big print :(. Hope there's a fix for this soon, It's quite frustrating to deal with, and I notice it slightly in nearly every print I've done since I first got the printer.

[ncdc]

Here are my results with a 0.6 nozzle. Retraction length 2.1mm as that's what I normally run to avoid underextrusion-after-retraction issues.

First

Second

Third

Fourth

[Matto5577]

Here is my test results. I have stock mini+, only 0.6 mm brass nozzle. Ran the provided test print with: 0.6 nozzle (default PrusaSlicer settings for 0.6mm nozzle) Printer firmware - 4.4.1 Filament - Azurefilm PLA Black

[blsmit5728]

FYI, I had this problem exactly. I fixed it by replacing the hotend PTFE and the Extruder to Hotend PTFE.

[ScreennameTaken]

FYI, I had this problem exactly. I fixed it by replacing the hotend PTFE and the Extruder to Hotend PTFE.

There are people though with the same issue that use an all metal hotend and different extruders. Personally i'm using a Revo unit, a Bondtech extruder and a capricorn bowden tube.

[ryanklafuric]

Strongly agree that this issue is not at all related to the hotend. I ran the test before with a perfectly stock Mini (see above) then I ran the test again with a brand new Slice hotend Copperhead upgrade kit and a SuperPINDA sensor installed and got the exact same results in some very high-quality Atomic PETG (see below).

Print order: Front left > rear left > rear right > front right

Front left:

Rear left:

Rear right:

Note that the tearing at the seam appears worst here and this is the only cylinder printed after a left/right printhead travel.

Front right:

Upgrades since last test:

• Better filament pathing
• Higher quality filament (Atomic PETG)
• Slice Engineering all metal Copperhead hotend installed
• SuperPINDA sensor installed to replace the old PINDA sensor

Notes: I intentionally chose a pretty high quality hotend and roll of filament (brand new, no moisture) to isolate those variables. Given that results are the same (albeit with less stringing) it seems like they aren't factors in the problem.

[ryanklafuric]

I've got a direct drive kit that I'm going to try installing. Will run this test afterwards to see if that fixes the issue. If that's the case, it would appear that this is related to the bowden tube extruder placement and/or pathing.

[rancor1223]

After testing my stock Mini+ with 0.6mm (test results posted before) I switched it back to 0.4mm. I used the example 3mf file as given. Resulting models are ordered clock-wise starting from bottom right corner of the heat bed.

I will be switching to Revo soon so I will run the rest again with that.

[ryanklafuric]

Alright, I just finished the direct-drive conversion and re-ran the test.

Print order: Front left > Rear left > Rear right > Front right

Front left:

Rear left:

Rear right:

Front right:

Notes:

• All cylinders are basically flawless irrespective of print head travel distance and direction
• The direct drive extruder i'm using is a Bondtech LGX Lite with the settings specified by them (0.6a motor current, 35% retraction speed, etc)
• Same filament as before (Atomic PETG Marble Gray)
• Same hotend as before (Slice Copperhead Upgrade for the Mini)

As far as I'm concerned, this basically confirms that the issue we're seeing in this bug is caused by the bowden extruder and the bowden tube pathing. An upgraded hotend alone didn't fix the issue for me or others, and adding an upgraded bowden extruder didn't fix the issue for others either.

The only thing that fixed this issue for me was the direct drive extruder upgrade.

[ScreennameTaken]

Here is a different image to add to my previous ones. Take a look at the feet, the left and the right one. As well as the perimeters. Thing is, there are no gaps, unless its going from left to right.

[irrational314]

Figured I'd contribute.

Prusa Mini+ original hotend, Bondtech IFS extruder, firmware 4.40. Fairly recent hotend PTFE replacement. I don't have any Prusament PLA but this is Inland white PLA.

All references to corner will be done from the perspective looking at the printer. Front right:

Right Rear:

Left Rear:

Front Left:

[abrancat]

Alright, I just finished the direct-drive conversion and re-ran the test.

Print order: Front left > Rear left > Rear right > Front right

Front left:

Rear left:

Rear right:

Front right:

Notes:

• All cylinders are basically flawless irrespective of print head travel distance and direction
• The direct drive extruder i'm using is a Bondtech LGX Lite with the settings specified by them (0.6a motor current, 35% retraction speed, etc)
• Same filament as before (Atomic PETG Marble Gray)
• Same hotend as before (Slice Copperhead Upgrade for the Mini)

As far as I'm concerned, this basically confirms that the issue we're seeing in this bug is caused by the bowden extruder and the bowden tube pathing. An upgraded hotend alone didn't fix the issue for me or others, and adding an upgraded bowden extruder didn't fix the issue for others either.

The only thing that fixed this issue for me was the direct drive extruder upgrade.

Hi all, new to this thread, first time posting on Github.

After 2 failed prints due to a similar underextrusion problems on support structures, I found this thread. I have been experimenting with the files shared by Prusa support as well, and I also believe this has something to do with the X-axis moving left to right with the bowden setup. When it flexes and becomes a sharper angle (left to right) I would bet that it is pulling up some of the filament out of the hotend, which is causing the delayed extrusion after this move. I ran 5 tests with this, only changing the "extra length after restart" in increments - setup and photos below:

Printer type - [MINI] Mini

Printer firmware version - [e.g. 4.0.5, ...] 4.4.1

Original or Custom firmware - [Original/Custom] Original

Optional upgrades - [e.g. Filament Runout Sensor] Filament runout sensor E3D micro prusa mini edition (but had the same issues with stock hotend) 0.6 mm nozzle

USB drive or USB/Octoprint Octoprint. But I have the same issue when printing from USB.

Jessie Soul Black Glitter PETG

All images shown in this order: front left, back left, back right, front right

Test 1: Stock Jessie PETG settings in PrusaSlicer 2.6 - 2 issues, back left and back right of print bed

Test 2: same settings, plus .3mm extra length on restart - issue only with back right

Test 3: same, plus .5mm extra length on restart - better, only issue with back right

Test 4: same, plus .8mm extra length on restart - better yet

Test 5: This is where I am leaving it for now, I feel it is a good compromise between too much extrusion in most circumstances, but enough to fill the gap in the L>R bowden issue

Thanks for all the help everyone! Outside of updating the firmware in the printer to account for this, not sure what else can really be done at this point.

ETA - I will not be sticking with the 1mm extra length on restart for most prints, I believe this will give me far too may globs of filament - but I believe that using the extra length on restart option can be tuned for specific prints to get a consistent compromise.

[ryanklafuric]

Hi Michele (@Prusa-Support),

Just wanted to check-in. What's needed from the Prusa side to help fix the under-extrusion issue affecting the Mini?

Happy to help out some more if needed. Others are too, I'm sure. Just need to know what's needed from our end.