Repeated clogs, maybe due to loose heater block?
I've had 5 clogs in the last two days, all after a couple of hours of printing. Printing quality seems fine up until the clog. When it happens, none of the recommended methods of clearing the clog help. Attempting to unload the filament results in a snap of the filament at the top of the PTFE tube. I have to disassemble the extruder block until I can pull out the PTFE tube, then dislodge the stuck chunk directly.
I've done just about everything I can think of. Recalibrated, checked the gear alignment, replaced the PTFE tube, cleaned everything thoroughly, switching filaments (using prusament PLA, multiple spools have same issue) and every time, clog about 90-120 mins in.
The only thing that seems out of place is that after the first disassembly, the heater block no longer locks into position under the extruder, it pivots pretty freely. I'm not sure if that would impact this or not, but I thought I should call it out.
I've had the printer for all of 2 weeks and its been fine until this happened. I'm just about out of things to try, I'd appreciate any recommendations anyone has.
Re: Repeated clogs, maybe due to loose heater block?
Wow, looks like I'm lucky today. The 3D printing nerd just released this video today:
https://www.youtube.com/watch?time_continue=1483&v=dSPPrb0J8CY
Short version, it sounds like the widening in the default prusa heat break can cause problems in prints with lots of retraction, because the expanded section can cool and get jammed. I've ordered a straight-through heat break and a silicone sock to see if that will eliminate the issue. I'll reply here when I know more.
Re: Repeated clogs, maybe due to loose heater block?
Yes, me like a lot of other people are having this f.... jams. I've watched this video earlier and that just drives me mad to think how Prusa could let this pass through their QA tests? I'm not even capable of print the standard bench gcode from SD card with their standard silver filament! WTF?
Re: Repeated clogs, maybe due to loose heater block?
If your heat block is loose that means something is not seated and there is a gap for filament that is melted to ooze and get stuck. That *will* cause clogs - so start there before you throw money and parts at the problem only to be disappointed.
Re: Repeated clogs, maybe due to loose heater block?
If your heat block is loose that means something is not seated and there is a gap for filament that is melted to ooze and get stuck. That *will* cause clogs - so start there before you throw money and parts at the problem only to be disappointed.
I wondered about this as it seemed like the likely issue to me, but I cant tell what I must be doing wrong. I havent found any instructions for how to put the hot end assembly together properly, as it comes assembled in the kit. I'm making sure the unthreaded portion of the heat break is still visible and the ptfe tube is seated as well as possible. Beyond that I dont know what to do. I assume I must be doing something wrong there. I'd appreciate any guidance or suggestions.
Re: Repeated clogs, maybe due to loose heater block?
This looks like it should fit the bill. I already have the new heat break coming, so I'll make sure to follow thid when I swap it out, see if I can get the heat block to snug correctly. After having the whole thing apart 5+ times though, I'm still not sure where the tension to hold the heat block in place is supposed to come from. just looking at the parts and the enclosure, it seems like should always be able to rotate pretty freely. What's supposed to lock it down?
Re: Repeated clogs, maybe due to loose heater block?
That guide looks good.
When correctly assembled, the bottom of the heat break will tension against the top of the nozzle, visualize it like it trying to push outwards from the middle of the inside of the heat block. Because the threads push in opposite directions, they will jam slightly and keep the heat block in place. (think of it like a "jam nut" where you use two nuts on a bolt to keep one from spinning freely, but inside out (i.e. two bolts into one wider nut)
Be very observant the nozzle is a) not flush against the heat block, and b) given a final tighten AT temperature. Both of those are common assembly mistakes that will cause what you are experiencing.
Re: Repeated clogs, maybe due to loose heater block?
had another jam this afternoon so I had the opportunity to pull the hot end apart and make sure in went back together correctly. I'm confident it's correct now, but I'm still able to twist the hot end assembly within its housing pretty easily. The stiffness of the thermistor wires is the only thing keeping it oriented correctly. This is what I mean by a loose block, is this still problematic?
In any case, the situation has improved, I'm able to successfully print some things that were giving me issues, but the real offender (a wizard miniature with lots of retractions) still causes problems. I'm more confident now that I'm having the issue as described in the video.
Re: Repeated clogs, maybe due to loose heater block?
Update: I've installed the new heat break and all appears to be well with the world. Prints that would reliably fail within two hours before are completing with no issues.
Re: Repeated clogs, maybe due to loose heater block?
Just had my first clog, and now I cant load filament, it seems that there is some PLA filament still in the ptfe tube, (but not enough for me to grip), how do I get it out,? tried running the temp at 255, but its still there, shoved the acu needle in about 3cm ok, but think the clog is too high to melt?