heatbreak jammed  

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christoph.d2
(@christoph-d2)
New Member

Hi, my name is Christoph form Germany!
Im a new owner of the mk2 and after some struggles with First Laser, sticking issues..etc i made my experiences and im pretty happy with the product!
I build an enclosure and so i had to plugged of the wires and rewired again. Unfortunaly the Fans werent rewired correctly at first so they dosnt spin and i had a Jam in the hotend...

I reassembled the extruder, unscrewed the nozzle, figured out that the nozzle is ok!
The jam is definitely in the heartbreak!
Unfortunately I didn't manage to unscrew the heartbreak and the ptfe tube..
I'm worrying to break the parts and I don't know what do..so I'm pretty frustrated ...do I have to buy a new hotend now?
Please help me, it was so much fun to print and now I struggle two weeks with no solution in sight...
Thanks chris

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Posted : 19/01/2017 2:54 pm
christoph.d2
(@christoph-d2)
New Member

By the way, I printed just with the prusa pla winch came with the printer!
The jam starts just shortly after the PTFE Tube.

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Posted : 19/01/2017 3:02 pm
JeffJordan
(@jeffjordan)
Member Moderator

i don't know if this is a recommended procedure, but i would try the following (advise without guarantee and risk insurance):
:mrgreen:

mount the hotend back into the printer, and heat it up to about 230°C.
move the x-carriage to the middle of the x-axis and the max. possible z-height.
now use an E or A string for electric guitars (the fat ones: 0.42w or 0.52w, not the tiny e-string), push it (like filament) into the heatbreak and pull it out again repetitive.
normally parts of the pla remainders will stick at the windings of the E-string. repeat the procedure until you get through to the nozzle.
maybe it's necessary to cut off the messy end of the guitar string during the process because you won't feed back the dirt into the hotend.

😳 but take care, it's going to be very hot in there (would be a good idea to use some kind of gloves, or at least some pincers). 😳

💡 i had a clogged heatbreak a few weeks ago after swapping from PET-G, BDP and ABS+ back to PLA and i used an E-string (diameter 0.52 mil = 1.32mm) this way to get the baked remainders out of the hotend successfully.

dem inscheniör is' nix zu schwör......
Posted : 19/01/2017 3:53 pm
david.b14
(@david-b14)
Honorable Member

I am just throwing out some ideas.

-Boil hot water in a large pot / tea kettle.
-Use ziplock bags / plastic / tape to cover all parts and openings except the heat break
-Slowly pour the hot water over only the heat break
-once the heat break is nice and hot, see if you can pull out the filament using some tweezers

It seems like if you could just remove the heat break only, then getting out the filament would be a much easier task.

As a data point, my other 3D printer came with piano wire that is used to push out filament that get stuck.

Warning. On my other printer i had a jam. I did not realize that the PTFE liner will deform easy once it has been heated. Luckily I had spare PFTE because I bent the original with pliers.

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Posted : 19/01/2017 3:59 pm
JeffJordan
(@jeffjordan)
Member Moderator

I am just throwing out some ideas.

-Boil hot water in a large pot / tea kettle.
-Use ziplock bags / plastic / tape to cover all parts and openings except the heat break
-Slowly pour the hot water over only the heat break....

don't think that'll do the trick. usually hot water only reaches 100°C and pla melts at about 190°C.

dem inscheniör is' nix zu schwör......
Posted : 19/01/2017 11:21 pm
david.b14
(@david-b14)
Honorable Member

I was thinking that when I heat my pla models for annealing, the PLA gets soft and stretchy which may be enough to pull some out but a heat gun or hair dryer may be a better way to apply heat.

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Posted : 20/01/2017 12:56 am
JeffJordan
(@jeffjordan)
Member Moderator

yeah, heat gun would be a good idea !

dem inscheniör is' nix zu schwör......
Posted : 20/01/2017 12:56 pm
james.s9
(@james-s9)
New Member

I have also had exactly the same problem, Only had the printer for a few weeks with only a dozen prints. I damaged the ptfe tube in attempting to unblock. Was very disappointed to see I couldn't order replacement parts from Prusa, I believe i've identified the right bits to buy from E3D so I'll let you know those details once they have arrived and I've confirmed they are correct.

No idea what caused the original block, I've only printed with the PLA that came with the printer and the block happened halfway thru a print. The first part of the print looked fine, unfortunately I had left the print after confirming the start was ok (Who actually watches their printer like a hawk for 2 hours?) so It was dry printing for an hour. I suspect a minor blockage turned into something more severe in that time.

I'm now planning mods to the print assembly to make the hot end more accessible 🙂

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Posted : 21/01/2017 2:36 pm
david.b14
(@david-b14)
Honorable Member

I was think how to avoid this with some circuits.

Filament run out sensor is a start but it will not account for other failures.

I am thinking it is better to detect if the filament spool stops feeding / spinning which would automatically kill or pause the print.

This could be done by taping a small magnet to the spool and using a hall sensor.

This would account for if the jams no matter what the point of failure is (fan goes out, nozzle clog, filament runs out).

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Posted : 21/01/2017 10:39 pm
mavu
 mavu
(@mavu)
Estimable Member

Well, no experience with that exact problem here, but I guess you managed to melt the PLA in there because of not running the hotend fan.

You could do the same again.

Disconnect hotend fan.
set hotend temperature to 80c.
use fresh filament to push the clog out.
then, turn of the heat, and keep pushing until it gets too cold.

Maybe?

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Posted : 21/01/2017 10:58 pm
Multigrain
(@multigrain)
New Member

Well, no experience with that exact problem here, but I guess you managed to melt the PLA in there because of not running the hotend fan.

You could do the same again.

Disconnect hotend fan.
set hotend temperature to 80c.
use fresh filament to push the clog out.
then, turn of the heat, and keep pushing until it gets too cold.

Maybe?

I had a nasty jam in the heatbreak myself earlier. I did something similar to this and it worked well for me, thanks.

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Posted : 20/05/2017 11:46 am
rob.c7
(@rob-c7)
New Member

I had a very similar problem, and in my case none of the suggestions in this thread helped.  I finally realized that, after taking the heatbreak out of the heat block, I had forgotten the key thing - thermal paste on BOTH sides of the heatbreak!  The nozzle and heatblock were getting up to temp, but the heatbreak was too cold to melt filament on the way in.  

One last disassemble/reassemble (with thermal paste this time) and I'm running like new again

 

Hope this helps the next one to google "feed stops at heat break" 🙂

Posted : 20/04/2020 1:58 pm
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