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Troubleshooting Blobs

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I am getting tons of strings and blobs on my prints (picture attached). Marlin firmware with 2208s. It seems like the tests i print turn out well but the larger prints have problems.

So far I have tried:
Printed a temp tower and adjusted for best temp
Printed a retraction tower and adjusted speed and distance
Calibrated e steps
Opened a new filament

Where should I start adjusting?

HI !

+1 with Dtylerd comment.

What are your values ? (bed, nozzle, e-step, 2208 voltage, retraction dist, retraction speed, etc...)

Which filament ? PETG, PLA, other ?

Z-Hop ? height ?

Do you encounter these issues right after a mod, nozzle changed, or suddenly ?

Which extruder ?

Which nozzle ?

Bowden or direct ?

Etc...

Provide as much information as possible, and pictures of your setup can also help.


The brownish color of some parts (mainly blobs) of your filament is strange, is your nozzle clean ? old ? new ?

You also have a layer shift. What's your travel speed value ? (don't go above 120mm/s to avoid issues)

Hi, soory for the sparse post, I'll try and provide more information here.

Bed: 60C
Nozzle: 201C
2208 vref: .8 on all
Retraction Distance/Speed: 5mm/ 40mm/s
Z Hop Enabled at .075 Height
PLA
Stock Extruder
.4mm Nozzle
Bowden
Speed is 50mm/s Shoud I be able to print much faster than that?

Attaching a picture of my set up, I have filament feeding from a sunlu dryer to the printer.

OK !

1) Based on the picture it seems to me that there is something wrong with the bowden tube (is it bent or not?) and with cables on the head side.
You also forgot the small clips to block the tube on both nuts.
What's the black cable below the head ?
More pictures required to see if there is another issue here or not.

2) VREF at 0.8V seems low, check if motors are hot during a long print (>2h) and rise the voltage by 0.1V until they are too hot.

It must be safe up to 1.1V.

Check this thread : https://www.thingiverse.com/groups/anycubic-i3-mega/forums/general/topic:35708

3)Set Z- Hop to 0.08 or 0.12mm, your printer is not able to achieve a Z step of 0.075mm. (as far as I remember the the 'Magic number' is 0.04mm on stock Mega S for Z axis).
4) Change the bowden tube for a Capricorn (a real one, buy official, lot of fakes)
5) I personally print at 40mm/s as I've time and found this speed to be the top quality on my setup, when I want something quick and dirty I go up to 120mm/s on my setup without any issues.
6) Check the travel speed (Which slicer are you using?) to be not above 120mm/s
7) Clean your extruder if not already done and check if gears are fine or not.
8) Check if the belts are well tensionned, not too much but for sure not loose.
9) Which FW did you use ? (Knutwurst?)
10) TMC 2209 are way better than 2208 on Mega S

There is room for improvement on your printer if DIY is not something you're afraid of.

Check my setup here : https://www.thingiverse.com/make:1060405

FoX Z(X) 50mm Axis - Anycubic I3 Mega or any (custom 3d printer) - X-Gantry system

What hot end and extruder do you have in that set up?

I use the system from https://www.swiss3dc.com and I achieve very good results.

Thank you for all the information! So far, moving the heat block up has fixed the original issue.
The bowden tube is not bent, but i think i will go for a Capricorn. The cable below the head, i replaced the nozzle fan with a noctua which i think the cable fell down when i was messing with it.

I use cura and knutwurst and i had not changed from the suggested z hop. I'll look in to that with your suggestions.
I'll be looking at your set up and doing more upgrades, I've changed a few things but there's room for improvement

With those big clumps of extra plastic I'm wondering if your hotend is maybe put together incorrectly and allowing extra plastic to leak out where it shouldn't. Especially if you've had your nozzle off, make sure it's firmly seated against the heatbreak. The nozzle shouldn't screw all the way down so it's flush with the heater block, it should be out slightly and the heatbreak should be seated against it firmly inside.

You are right, after putting a new nozzle on I can see it leaking from the top slowly. I am confused on what you mean about the heat block. Isn't the heat break above the block? When the nozzle is tight it sits on the heat block.

It looks to me that you also used the wrong type of nozzle...MK8.
This would be more like the right type....V6.
https://3dprinting.stackexchange.com/questions/8665/which-nozzle-should-i-buy-for-anycubic-i3-mega

I was going to bring that up, but if the threads are the same (which they are) and it's pressed against the bottom of the heatbreak, I can't see why it would make a difference. Of course I've never actually tried a nozzle like the one he is using, so I could be wrong.

The MK8 Nozzle has a shorter thread than the V6 one, maybe thats why his hotend leaks....

Could be true, but that can be adjusted. I've also had the proper type that ended up having threads that were a bit shorter (probably because I was ordering cheap knock offs) and I made them work by threading the heater block up a bit, as discussed.

Thank you for all the help. So far, threading the heat block up fixed the leak, but i think i will go get the right nozzle for the future and do it right.

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The heat break is a threaded tube that goes in to the heat block. The threaded part of the nozzle needs to butt up tightly against the end of that tube. You shouldn't be able to thread the nozzle in so far that it's totally flat against the heat block because it should run in to the end of the heatbreak first. There should be a small gap when it is fully tightened.

Here is a picture that might clarify:

https://i.stack.imgur.com/cjuNi.png

Should i be able to thread the heat block farther up then?

Yes, it probably only needs a small adjustment anyhow