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Troubleshooting frequent hotend clogs or extruder skipping

bythorsthunder

Member
Staff member
Moderator
Voron Owner
1. Hotend Fan- This is the lower fan on MiniAB, Afterburner, Stealthburner. Is it a good fan and running at full speed? Is airflow directed inwards towards the hotend?
2. Retractions- Cura default Voron profile is 6.5mm @ 80mm/s and other slicers may also have high values in their stock profiles. Start with 0.75mm @30mm/s.
3. Toolhead PTFE- There should be a small length of PTFE or Capricorn tubing (not FEP) between the extruder and hotend. This should be 1.9-2.0mm ID. It needs to be snug so cut it long, test fit and trim as required during installation.
4. Reverse Bowden- This is the tubing between the top of the toolhead and runs to the spool. This must be PTFE (not FEP) and should be 3mm ID.
5. Nozzle- Nozzle should be hot tightened to the specs provided by manufacturer of the hotend. Make sure you have the right style of nozzle so it is bottoming out against the heatbreak and not the heater block. Make sure nozzle is not clogged. Replace to test.
6. PLA- If printing PLA avoid the Dragon High Flow Hotend. Make sure door is open and remove panels if necessary.
7. Print Speed- Ensure you are not exceeding the max volumetric flow rate for your hotend/material/temp combo. Ellis' tuning guide has an excellent max volumetric flow test.
8. Extruder Stepper Current- High motor current will create excessive heat which can warp the printed extruder parts. Post the motor part number and ask if unsure.
9. Tension- Ensure you have filament tension spring sufficiently compressed. With CW2 ensure flathead gear mesh screw is not screwed out too far.
10. Extruder- Check bearings for smooth motion and inspect for broken wires/bad crimps. This can result in the extruder stopping for brief periods and skipping whole sections of layers.
11. Temperature- ABS nozzle temps are typically 240-255. Ensure correct thermistor in config.
 

mallcop

Member
Staff member
Voron Owner
Point #4 is very important. FEP is "slippery enough" initially, but it will get incredibly sticky over time. If you are running on clear FEP/PFA tubing, you are on borrowed time, and should replace it ASAP!
 

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raymond

New member
Point #4 is very important. FEP is "slippery enough" initially, but it will get incredibly sticky over time. If you are running on clear FEP/PFA tubing, you are on borrowed time, and should replace it ASAP!
Man, my LDO kit came with the clear one.

I've noticed that it works perfect for ABS, but it absolutely won't work for PLA/PETG
 

bearthababe

New member
Looking at my reverse Bowden from a LDO V0.1 kit, and it definitely looks like the right one. I guess I've got another thing to order. Great info BTW!
 

snympi

Member
#6 will absolutely happen even with the doors open on a V2.4. If you print with PLA mostly, use the normal Dragon.
 

Al_Capwn

New member
Double check the grub screw in your extruder is tight. I had the exact same issues as you and did way too much troubleshooting before thinking to check it out.
 

Al555

New member
Does the reverse Bowden run all the way from the toolhead to the spool? I have seen some builds where there is a short piece of tubing at the tool head and the filament is then bare until close to the exhaust vent where it enters another piece of tubing.
 

mallcop

Member
Staff member
Voron Owner
Man, my LDO kit came with the clear one.

I've noticed that it works perfect for ABS, but it absolutely won't work for PLA/PETG
It's not going to work for ABS very long. My LDO FEP got sticky enough that I could drag the printer across a table with just the friction in the tube. That, needless to say, caused a lot of troubleshooting issues.
 
Does the reverse Bowden run all the way from the toolhead to the spool? I have seen some builds where there is a short piece of tubing at the tool head and the filament is then bare until close to the exhaust vent where it enters another piece of tubing.
Yes it is supposed to run all the way to the toolhead. Any folks you see with just a small piece of bowden tube out the toolhead will be asking questions at some point why their extruder is "clogging' or "stops extruding" which goes back to the OP's number 4 again.
 

LoadMaster7

Well-known member
Yes it is supposed to run all the way to the toolhead. Any folks you see with just a small piece of bowden tube out the toolhead will be asking questions at some point why their extruder is "clogging' or "stops extruding" which goes back to the OP's number 4 again.
Hmm, I guess I'm doing it wrong. I have one tube to guide it from spool to heat chamber and a short one on the toolhead. My printer doesn't seem to mind. I hope no one tell my printer. :unsure:
 
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