Oozing after Hotend disassembly.  

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Limeray
(@limeray)
Active Member

I had to disassemble my hotend and heatsink after some filament got stuck at the stop of the ptfe tube. 

After reassembly i get extreme oozing. Is there anything i could have done wrong? My printer is a week old and worked perfectly until now.

Posted : 14/10/2019 6:53 pm
Tim
(@tim-m30)
Illustrious Member

These sorts of problems are common after improper disassembly and re-assembly.

Recommend you pull it all apart and rebuild it; but this time use the E3D-V6 Assembly guide so you get the pieces put back together correctly.  And besides getting the nozzle/heat break interface correct, use heat sink grease, too.

It is always wise to get more than one opinion......
Posted : 14/10/2019 6:55 pm
Limeray
(@limeray)
Active Member

Thanks for the advice. I followed they guide step by step but it seems the hotend is extruding some filament without the e axis pushing.

Posted : 14/10/2019 9:43 pm
Tim
(@tim-m30)
Illustrious Member

Yes, and that is one consequence of not following the assembly guide to the letter.  The bits regarding nozzle placement and torque are crucial.

https://wiki.e3d-online.com/E3D-v6_Assembly

 

It is always wise to get more than one opinion......
Posted : 15/10/2019 2:16 am
bobstro
(@bobstro)
Illustrious Member

Be sure you carefully follow the bit about the nozzle not being tightly screwed to the heat block before tightening the heatbreak down to the nozzle. There should be a small gap between the nozzle and heat block. Also be sure to heat to 285C before doing the final tightening. The key is to make sure the nozzle and hotend are tightened to each other with the heatbreak essentially being a nut between them. You don't want a gap between the nozzle and heatbreak.

If you find that the heat block threads are fouled with filament when you take everything apart, heat it up to a high temperature and run the heatbreak through it a few times to clear the molten filament out. You don't want anything coming between the nozzle and heatbreak when you're done with reassembly.

Be prepared for a bit of cleanup. Having  a spare heater cartridge and thermistor on hand might be a good idea.

This post was modified 10 months ago by bobstro
My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 15/10/2019 4:19 am
Limeray
(@limeray)
Active Member

I cleaned the nozzle, block and heat break with a kitchen blow torch and also did all the steps to tighten the nozzle. I get no more leakage from the top and bottom of the block but i noticed that the heatsink is not getting warm at all so i will try replacing the thermal compound.

Posted : 15/10/2019 12:28 pm
david.a66
(@david-a66)
Honorable Member

heat sink should not get very warm - that's it's goal - keep the top part of the heat break near room temp

Posted : 15/10/2019 5:08 pm
Limeray
(@limeray)
Active Member

I'm at loss now. I cleaned all parts of the hotend, reassembled the hotend again and really made sure to follow every step. Still the nozzle is extruding pla while the printer is preheated and idle. See video: https://1drv.ms/v/s!AnDCt-7H4HUPjsMiFErLdkDVumxBZQ

This post was modified 10 months ago 2 times by Limeray
Posted : 16/10/2019 5:53 pm
Tim
(@tim-m30)
Illustrious Member

Contact Prusa support using CHAT ...

It is always wise to get more than one opinion......
Posted : 16/10/2019 8:33 pm
Tim
(@tim-m30)
Illustrious Member

And, CHAT will probably ask for this: take a clean sharp photo of the nozzle and heater block from underneath looking up, and post it here.

It is always wise to get more than one opinion......
Posted : 16/10/2019 11:22 pm
Tim
(@tim-m30)
Illustrious Member

As for the ooze ... the video doesn't show if the extruder motor is spinning, nor does it show how you have the spool and filament feeding to the extruder.  Even certain types of filament guides will cause problems like this.

Very wet filament will cause what you are seeing.  A fresh from the bag new dry spool is a good test. Load the new filament, extrude 100 mm to get the handled/fingerprinted section out of the way, and then watch what happens. 

Seriously - the only thing that causes filament to extrude is pressure: which either comes from the extruder motor, gravity, or steam.  Gravity on a 100 mm length of filament is small; steam is the next source; followed by the extruder gearing.  So if neither of those three are the cause, then there is something we have not seen affecting your printer.  So your filament handling system is the next suspect.

It is always wise to get more than one opinion......
Posted : 16/10/2019 11:32 pm
bobstro
(@bobstro)
Illustrious Member
Posted by: @limeray

I'm at loss now. I cleaned all parts of the hotend, reassembled the hotend again and really made sure to follow every step. Still the nozzle is extruding pla while the printer is preheated and idle. 

That is not an alarming amount of ooze and should not cause the problems you were showing in your earlier pics. It will likely stop after a bit unless your temps are higher than necessary for the filament. The filament is clearly coming out of the nozzle and not leaking from between the nozzle and heater block, or heater block and heatbreak. Small strands like that will usually be pulled off the nozzle when the prime line is printed at the start of your print jobs. If you watch many of Jo Prusa's videos, you'll see him snag a bit of ooze off the nozzle at the start of a print using tweezers.

If you're concerned about oozing at the start of your prints causing problems, use a 2-step extrusion temp warmup where you heat up the nozzle only to a "no ooze" temp (e.g. 160C) before mesh bed leveling and only come up to full printing temp after the bed is ready and leveling completed. I've got a documented example of this in startup gcode here.

This post was modified 10 months ago by bobstro
My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 17/10/2019 4:41 am
bobstro
(@bobstro)
Illustrious Member

One other note: Check the cabling for your thermistor and heater cartridge (the red cable). They look to be dangling a bit low at the back of the heater block, although it may just be the camera angle. If they're too low, they might be lower than nozzle level and snag either on the printer or print. If you removed and reassembled the wrap and tie wraps, be sure they're tightened up.

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 17/10/2019 4:45 am
Limeray
(@limeray)
Active Member

My filament is the default silver/gray one that comes with the MK3S and is only two weeks old. The filamanet is sitting on the default filament arm that is included with the MK3S. 

I've made some new photos showing the nozzle and a video showing that the extruder motor is not moving at all:

Video: https://1drv.ms/v/s!AnDCt-7H4HUPjsMqYaWSIx3vhaf-wQ?e=w1fOWu

I noticed that the extrusion seems to be delayed quite a bit. When the printer starts printing the prime line, half the line is missing i.e. not printed at all.

I will contact the support, thanks for all your help.

This post was modified 10 months ago by Limeray
Posted : 17/10/2019 8:53 am
bobstro
(@bobstro)
Illustrious Member

That cabling DEFINITELY looks to be hanging below the nozzle. That is going to cause problems.

My notes and disclaimers on 3D printing and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan...
Posted : 17/10/2019 3:37 pm
Tim
(@tim-m30)
Illustrious Member

And the nozzle looks to be a bit deep in the heater block.   And why the fear of posting a photo of the entire printer so we can see how it is set up?  You're having an unusual problem, and the standard things that cause it - according to you - aren't present.  Looking for unusual causes is all anyone can do to help; but you insist it isn't anything odd, either.  So I'm out of ideas.

It worked before you disassembled the printer. It didn't work after you put it back together.  That's where you need to look for problems.

It is always wise to get more than one opinion......
Posted : 17/10/2019 4:35 pm
Limeray
(@limeray)
Active Member
Posted by: bobstro

That cabling DEFINITELY looks to be hanging below the nozzle

Here is another photo level with the heatbed. It is lower but not lower than the nozzle. Should be fine right?
Posted by: @tim-m30

And why the fear of posting a photo of the entire printer so we can see how it is set up?

I quickly got these photos and the video this morning, shortly before i head to leave for work. Here is a photo of my current set up.

Posted by: @tim-m30
And the nozzle looks to be a bit deep in the heater block

That's the result i got after initially unscrewing the nozzle 1/4 turn.

I just got a fresh spool of prusa pla and it is still the same.

And yes, to the best of my knowledge i followed the assembly instructions correctly. That of course doesn't mean i didn't made mistakes along the way. I really appreciate all the help you folks have given me so far. Thank you.

This post was modified 10 months ago by Limeray
Posted : 17/10/2019 6:18 pm
Tim
(@tim-m30)
Illustrious Member

Still at the assembly wasn't done right: the nozzle is against the heater block. It shouldn't be.

It should look like this after hot torquing.

The nozzle must tighten against the heat break, not the heater block.  If the nozzle HEX touches the heater block, the heat break is not tight.

This post was modified 10 months ago 2 times by Tim
It is always wise to get more than one opinion......
Posted : 17/10/2019 7:37 pm
Limeray
(@limeray)
Active Member

So i've lowered my temperature to 200 °C and actually get usable results. Could my Thermistor be damaged or somehow isolated from the block?

Posted : 21/10/2019 7:34 pm
Limeray
(@limeray)
Active Member

Never mind. It stopped printing after half an hour.

Posted : 21/10/2019 8:14 pm
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