Hot end nozzle jam (I think)

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twicx
Posts: 105
Joined: Fri Jan 11, 2013 1:26 pm

Hot end nozzle jam (I think)

Post by twicx »

Hey folks,

I'm having major problems with my hot end recently. I think the problem lies with the nozzle, but i REALLY need to get this sorted. Nothing's feeding at all, it just won't go through the nozzle, so I figure the jam is there.

I first noticed a problem when that error came up in repeteir host that basically means the thermistor is gone. I also noticed that the temperature curve in repeteir host was fluctuating every minute or so by +/- 5 degrees. So I replaced it, and it was reading idle temperatures EXACTLY the same as the print bed, and with no temperature fluctuations.

Next, I tried heating the hot end to 210-215 and manually feed some filament through, but it wouldn't feed. When i took apart the hot end and cleaned out the nozzle with a small drillbit, as suggested, still it wouldn't feed. I also checked that the hot end was heating up, by touching some fillament off the outside of the hot end, but not at the nozzle tip, and it melts just fine. So I figure the nozzle must be clogged pretty badly.

The two problems I now face is that I need to get this sorted fairly quickly, within a week or two, and I don't have the money to replace the hot end as I'm still in uni. I'll definitely be upgrading a lot on the printer once I get working again!

Anyone able to help?

killejano
Posts: 92
Joined: Mon Apr 01, 2013 7:23 pm

Post by killejano »

Did you clean both the .35 hole and the 2mm hole? Might be that you pushed the clog out but it just went back in. Sometimes it take a lot of poking with both 0.35 an 2.0 drills. Also you might try to push filament by hand when the hot end is not in the carriage

twicx
Posts: 105
Joined: Fri Jan 11, 2013 1:26 pm

Post by twicx »

Eh.... I think so. For convenience, I've included a rough sectional diagram to help explain things:

Image

Ok, so there's 3 labeled sections; from top to bottom - Upper section, PEEK section and Nozzle section. I think they're fairly self explanitory.

So when I heat it up, and it's removed from the cartridge, here's how thing's stand. The upper section is completely clear of any blockage, so I'm ruling that out. The peek section is also fine, but it's where the peek section meets the nozzle that things get tricky. When I take it apart, there's always a little bit of fillament just where the peek meets the nozzle. Even with this removed, it wont feed. When I try to push fillament through the nozzle, it just splodges back into the peek section. Somewhere in the nozzle, the hole obviously goes from being the width of the fillament to the tiny pinhole at the exit of the nozzle, ie. the nozzle section of my diagram. That's where the jam is.

hvdd
Posts: 71
Joined: Tue Jul 24, 2012 11:43 pm

Post by hvdd »

hi,
i had exactly the same problem yesterday.
and for safety ordered a spare head :)
but disassembled the nozzle.
a small part of filament is blocking the nozzle just where the peek meets the nozzle.
heating the nozzle part ( 245° - for ABS) and pushed the remaining filament out with a 'pianocord' of 2 mm
then with a small steel wire from downide to upside and catching the remaing filament.
this problem is comming back easely and the only manner for me to avoid is in repetier - dimensions - retraction set 1mm
after slicing at the end you see E-10 change to E-1 and the problem is solved ...... or avoided.
i think if you retract to much the filament it is coming into the 'cold' peek , cool down and is glued on the sides of the alu hole of 2mm.

hvdd
Posts: 71
Joined: Tue Jul 24, 2012 11:43 pm

Post by hvdd »

prevous post was with the second head ( new one)
the temp of the head in cold condition was 12°, bed 26° temp sensor replaced last week and was ok 25.8 and 26
heating up for PLA 200° while slicing a small part ( 5 minutes)
when i came back - after 10 minutes - the nozzle part was pending on his wires and on the bed ....
the tread in the peek part bottom side was melted.
temperatures say 198° nozzle and bed 55°.
appearently the temp sensor was again reading errors and the nozzle was over the max. temp.
again the temp sensor is the reason that the head broke.
immediatly replaced with my last spare :(

twicx
Posts: 105
Joined: Fri Jan 11, 2013 1:26 pm

Post by twicx »

Unfortunately, I don't have the money at the moment to get a new head or a new nozzle, so I'm trying everything i can to fix it. I've seen 4 interesting ideas on other sites. One is to use a caustic soda solution on the nozzle (caustic soda will melt pla). The second is to heat the end to 210, then melt some pla onto the nozzle tip, let it cool, then pull it off with a pliers (doesn't seem wise). Third, the torch method (not really an option for me). And fourth, superlight guitar string when heated. I might have a spare guitar string which would be worth a try, but I have to work out what the thinnest guage I have is. It has to be <0.35mm, right? Would that mean it would fit up the nozzle, like from the opposite end of where the fillament is fed into the hot end? Like where it actually comes out of?

twicx
Posts: 105
Joined: Fri Jan 11, 2013 1:26 pm

Post by twicx »

Image

this is probably a pretty good representation of the cross-section in question. So from my evaluation, it's that tiny little hole at the very bottom that's jammed. all things considered, I figure I've 2 options I could try on my heavily restricted budget.

1. Guitar string - lightest gauge I can get.
2. drill bits. There's a local hardware where I can get 0.2mm and 0.35mm for €4 a piece.

better option?

hvdd
Posts: 71
Joined: Tue Jul 24, 2012 11:43 pm

Post by hvdd »

hoi,

i use one wire from a steel brush , it just fits and is very strong.
push it in the heated nozzle and pull it out on the top side. it works great !
( for 4 € i have 5000 of them )

superhornet59
Posts: 60
Joined: Wed Apr 03, 2013 1:58 am

Post by superhornet59 »

I had success with 0.34mm (they didn't have 0.35 at the time) guitar string from the bottom up. "Flossed" it a few times to be thorough and I was good to go.

twicx
Posts: 105
Joined: Fri Jan 11, 2013 1:26 pm

Post by twicx »

superhornet59 wrote:I had success with 0.34mm (they didn't have 0.35 at the time) guitar string from the bottom up. "Flossed" it a few times to be thorough and I was good to go.
This. I tried 0.28, that went through, then up to 0.30 (i think) then finally to 0.34, and it's feeding again.

The new problem I think is with something around the motor/m6 nut that tightens it at the point where the fillament is fed.

Quick question regarding that, in Repeteir, feedrate and flowrate. One controls how fast the printer moves, and one controls how fast the fillament is fed. Which one is which?

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