Lot of stringing and blobs on some parts, others print fine
 
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Lot of stringing and blobs on some parts, others print fine  

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akomives
(@akomives)
Eminent Member
Lot of stringing and blobs on some parts, others print fine

Hej good people of Prusa,

 

I have a Mini+ printer, which I have upgraded to a Bondtech IFS Extruder kit, alongside with the updated heatbreak. I have built up the kit out of pieces, have followed the original Prusa manual and when doing the extruder bits have combined Prusa and Bondtech manual steps (since I have never built the original extruder in the first place).

 

I have added the custom G-code for the extruder steps and for the changed PID values in the PrusaSlicer settings. So every model that I convert to G-code have the needed commands for the Bondtech extruder and the heatbreak.

 

I am using alcohol to wipe off the print bed. I have done the first layer calibration according to manual, have a nice first layer. Belt tension is within spec, all the fasteners are tight. No strange noises or other problems, what I can see.

 

I have done some test prints, using Prusament PLA, Prusament PETG and Prusament ASA. XYZ calibration cubes, mainly. I have also done the Prusa bolt and nut out of PLA. Have printed the nut out of TPU, as well. Both the PLA and the TPU nut can be threaded onto the PLA bolt without problem. Calibration cubes look nice, nothing serious. I have done a benchie, looks okay, very little stringing.

 

Recently I have purchased some Sainsmart TPU (TPU-PUR-0.8KG1.75) to print mainly FPV quadcopter installation parts. Like canopy for camera and such.

 

I have also designed some RC accessory parts, that I have printed out of Prusament PETG. I give you Thingiverse examples to refer to my experiences.

 

1. FPV goggles VRX adapter, made of ASA:
https://www.thingiverse.com/thing:5157999

2. RC battery charger fan adapter PETG:
https://www.thingiverse.com/thing:5148064

3. FPV toothpick canopy PETG:
https://www.thingiverse.com/thing:5138773

4. RC transmitter stick guard PETG:
https://www.thingiverse.com/thing:4157895

5. Long range quadcopter frame PETG:
https://www.thingiverse.com/thing:4769576

6. Mini container PET bottle cap size PLA:
https://www.thingiverse.com/thing:4900080

7. FPV toothpick canopy TPU:
https://www.thingiverse.com/thing:4762982

8. Five33 Switchback cam mount (40CamMountFullLengthFoxeer) TPU:
https://www.thingiverse.com/thing:3950022/files

 

Test prints

Posted : 28/12/2021 9:07 pm
akomives
(@akomives)
Eminent Member
Topic starter answered:
RE: Lot of stringing and blobs on some parts, others print fine

My experience is rather mixed.

 

1. Went rather well. Not much problem faced.

2. Lot of stringing, almost “hairy” model.

3. Lot of stringing, “hairy” model, had to work a lot afterwards to “clean” it.

4. Similar as above. Stringing everywhere.

5. Same as above.

6. Beautiful, no problem.

7. Basically a mess. Big blobs and stringing everywhere.

8. Looks like a mess. Extreme stringing everywhere.

 

I haven’t done any tuning of the parameters. Usually use 20 or 30% infill, and use support either everywhere, or just on the build plate.

 

What am I doing wrong, please? Will post pictures, need to gather some “evidence”.

Posted : 28/12/2021 9:09 pm
akomives
(@akomives)
Eminent Member
Topic starter answered:
RE: Lot of stringing and blobs on some parts, others print fine

Some pictures. A totally messed up PETG print and the PLA benchie.

PETG Prusament

 

PLA

PLA

Posted : 28/12/2021 9:15 pm
akomives
(@akomives)
Eminent Member
Topic starter answered:
RE: Lot of stringing and blobs on some parts, others print fine

Prusament PETG, stringing everywhere.

PETG

Posted : 28/12/2021 9:16 pm
akomives
(@akomives)
Eminent Member
Topic starter answered:
RE: Lot of stringing and blobs on some parts, others print fine

I assume that the general extrusion for PLA and ASA is fairly dialed in, since those filaments work nicely.

For PETG I have no idea. It is Prusament PETG, which is stored in a sealed and closed box, which has silica air drier canister in the box. So it shouldn't be wet. All my filaments are stored in this big box with air drier canister added and soft sealing rubber seams tightening the lid to the box.

The extruder steps are adjusted as per the tutorial of Bondtech.

"

M92 E415

M301 P13.54 I0.98 D46.58

; intro line

"

Print settings are 0,05 mm ultradetail

Filament preset is chosen according to material used.

 

For the TPU I have found the matching Sainsmart TPU preset in Prusaslicer, so it should handle the slicing accordingly.

Posted : 28/12/2021 9:21 pm
3Delight
(@3delight)
Moderator
RE:

For people to help you, you need to supply a bit more info:

  • What temperature Hot-end are you using?
  • What temperature Heatbed?
  • Are you sure it's Prusament and not Prusa filament?  (There is a difference.)
  • Did you have problems before upgrading to the Bondtech IFS Extruder?
  • Did you remember to redo your Z-Offset after changing the filament?
  • How much experience of 3D printing do you have?

I've just re-read your earlier posts and think you said that you changed the extruder while assembling the Mini? This will make it harder to diagnose the problem as it could be a problem with the Mini, the Bondtech or both or neither!  It's recommended that you assemble the Mini as-is first, make sure everything is working and then do the swap to Bondtech.

 

Posted : 28/12/2021 9:32 pm
akomives
(@akomives)
Eminent Member
Topic starter answered:
RE: Lot of stringing and blobs on some parts, others print fine

Sorry, I try to provide more information below, please.

Prusament filament

  • For PETG I am using the default setting, what the printer sets. Right now I am printing with the green PETG. Currently it is 250 degrees Celsius hot end and 90 degrees Celsius bed temperature. I just use the preset coming from Prusaslicer, haven't changed anything on cooling or heating.
  • I have added a picture above, there should be Prusament ASA, red PETG (haven't tried yet), green PETG and silver PLA. Have ordered together with the printer. They are stored in a sealed box with air drier canister.
  • I have never used the printer before the Bondtech upgrade. Have purchased the upgrade kit same time and have built the printer from zero to Bondtech upgrade directly. I have followed the Prusa manual exactly until the point where the extruder parts have been covered, there I have "combined" the steps from Bondtech and Prusa manuals until the extruder has been completed. Then I have reverted to Prusa manual to finish the assembly of the remaining steps.
  • I don't redo the Z-offset calibration upon filament change. Just purge the old filament. I remain at the printer when it starts the print and observe the first few layers to be able to react if anything is deviating. Like not sticking or being too flat first layer. According to my experience the calibration remains well defined, first layer seem to work very nicely on this printer. The filament is not "crushed", nor being dragged in the air until it sticks. Looks like the manual states it should look like.
  • I haven't had any experience with 3D-printing prior to this. My first printer.

 

Yes, probably that was a mistake to build immediately with the Bondtech and not performing all the test prints with the default configuration.

Posted : 29/12/2021 8:10 am
akomives
(@akomives)
Eminent Member
Topic starter answered:
RE: Lot of stringing and blobs on some parts, others print fine

I have some add:north clear PETG (article number ANPE17CLR), which I will try directly after this print finishes.

I am printing my fan duct from the green Prusament PETG, then plan to slice the same 3D-model with the add:north PETG in Prusaslicer and print it as a comparison.

Posted : 29/12/2021 8:15 am
BogdanH
(@bogdanh)
Honorable Member
RE: Lot of stringing and blobs on some parts, others print fine

In regard of stringing (which seems to be your main issue), there's one thing you didn't mention: do you properly dry filament before use?

[Mini+] [MK3S+BEAR]

Posted : 29/12/2021 9:29 am
Diem
 Diem
(@diem)
Noble Member

I agree with @bogdanh, that PETG looks damp.  It takes surprisingly little exposure to moist air to affect filament and while silica gel can maintain your filament it isn't enough for initial drying.

Cheerio,

Posted : 29/12/2021 10:41 am
3Delight
(@3delight)
Moderator
RE: Lot of stringing and blobs on some parts, others print fine

The first thing I would try is lowering the hot-end temperature, try 245° and see if it helps, don't assume you need to use the higher temperatures stated.  Start in the middle as you have done then work up or down as needed.  When the temp is too high the filament can ooze out and cause stringing.

There are other settings you can try, retraction being the primary one, have a read of this: https://help.prusa3d.com/en/article/stringing-and-oozing_1805/

As for dampness, try the temp changes and retraction first, if that doesn't work then you can try drying your filament. Air dryer sachets and canisters only absorb moisture from the air they can not draw it out of the filament in general... that requires heat.  For that will need either a heated filament dryer, food dryer or an accurate oven. Here's an example guide: https://all3dp.com/2/how-to-dry-filament-pla-abs-and-nylon/ and here is just one companies guide to drying their filaments: https://www.3dxtech.com/drying-instructions/

 

Posted : 29/12/2021 11:22 am
akomives
(@akomives)
Eminent Member
Topic starter answered:
RE: Lot of stringing and blobs on some parts, others print fine

Thank you for the tip. No, I haven't dried the filament. Need to test this.

The green PETG is the first one, that I have opened and I have put it back to its sealable plastic bag, but it has been out in ambient air during printing. So it has been exposed to some humidity.

 

Posted : 29/12/2021 11:44 am
akomives
(@akomives)
Eminent Member
Topic starter answered:
RE: Lot of stringing and blobs on some parts, others print fine

Thank you for the links, will read and try drying in oven.

Will study settings in PrusaSlicer, how to adjust temperature for PETG profile.

I will do these studies in the coming days and will report back on my findings. Your support is much appreciated!

Posted : 29/12/2021 11:46 am
Diem
 Diem
(@diem)
Noble Member

Sorry @3delight, I disagree.  Try drying before touching the default settings, it's cheap and does no long term damage.  Be sure to work with filament in top condition to be certain you are not being misled into an endless cycle of fruitless tweaking.

Cheerio,

Posted : 29/12/2021 11:52 am
BogdanH liked
akomives
(@akomives)
Eminent Member
Topic starter answered:
RE: Lot of stringing and blobs on some parts, others print fine

The oven has reached stable temperature. I have the PETG spool in it. Starting 18:40, will remove it around 22:40.

58 deg C

 

The oven does not have any well defined marking for these low temperatures, I had to iterate my way to slightly under 60 degrees. Have measured multiple surfaces in to oven, so it is hopefully under 60 degrees. Even if my LIDL laser temperature meter is off by 5 degrees Celsius I should be fine 🙂

 

PETG in da oven

Posted : 29/12/2021 5:42 pm
BogdanH
(@bogdanh)
Honorable Member
RE: Lot of stringing and blobs on some parts, others print fine

It just hurts my brain when I hear about drying filament in oven... Two spools of PETG, which you will melt in a month, is 60€. On the other hand, food dehydrator is only 40-50€, will dry any type of filament properly and will serve you forever.

[Mini+] [MK3S+BEAR]

Posted : 29/12/2021 7:49 pm
akomives
(@akomives)
Eminent Member
Topic starter answered:
RE: Lot of stringing and blobs on some parts, others print fine

I will look around for this type of device. Probably better for drying the filament, but I don't have it available now, so I try the oven first.

Posted : 29/12/2021 7:55 pm
3Delight
(@3delight)
Moderator
RE: Lot of stringing and blobs on some parts, others print fine

 

Posted by: @diem

Sorry @3delight, I disagree.  Try drying before touching the default settings, it's cheap and does no long term damage.  Be sure to work with filament in top condition to be certain you are not being misled into an endless cycle of fruitless tweaking.

Cheerio,

Thant's OK, each to their own.  We can all only go by our own experiences, for me any stringing I've had has been solved by lowering the hot-end temperature a few degrees.  Fingers crossed that this works.

Posted : 29/12/2021 9:47 pm
akomives
(@akomives)
Eminent Member
Topic starter answered:
RE: Lot of stringing and blobs on some parts, others print fine

I have tried to reprint the fan duct. With dried filament.

There is some stringing, but much less then previously. So an improvement.

Dried filament

Will try to purchase a fruit drier, as well.

Next step is to try the VRX module cover, that has been completely messed up previous time. Now with dried filament. Next step afterwards is to lower hot end temp sligthly from default.

It starts at 240 deg C for me as default, then after a couple of layers printed cranks it up to 250 deg C. I will play with these settings. As well as read more about stringing.

Will follow up as soon as I have something to show.

Posted : 29/12/2021 10:54 pm
akomives
(@akomives)
Eminent Member
Topic starter answered:
RE:

I have ordered a fruit dehydrator, will test it. Probably it will not arrive before 2022, though.

Posted : 30/12/2021 9:52 am
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