I am in the process of figuring this out, this post is an attempt to save me time in the hope that I am missing something obvious.
I’ll be brief. I have 2 x J1s machines, both print TPU exclusively all day. The new Hardened 0.4mm Hotends have been great, but only 2 days ago, the left extruder on one of my machines has started clicking and eventually jamming causing the machine to stop, which then I am prompted by the screen to check the nozzle.
It doesn’t happen on the first few layers, but to be fair, there is a lot more detail as the print gets higher, a lot more retraction. Keep in mind the machine has been running flawlessly for months, and is one of 2 J1s units doing the same thing every day…only the left extruder that is using the same gcode as the others is starting to clap out.
what I have done so far
Lowered the retraction from 1.4 - 1.2mm
lowered the retraction speed from 25 - 18mm/2
recalibrated bed levelling
ran PID autotune
test print a large rectangle at single layer height to fine tune the Z height
A temp tower in TPU is next to useless, I considered it in case I have a faulty thermistor.
After these quick attempts to rectify, It’s still doing it. Any suggestions for solving this over the slicer would be great (Using Orca), in addition any mechanical suggestions. I have had other issues solved on my other machine by replacing the extruder ribbon cable, but that cable had signs of wear, this one doesn’t. When nothing has changed and the other extruders are running the same gcode, it’s got me thinking this could be mechanical.
I’m thinking the same thing. With the hotends now having the fixed nozzle, I am wondering how I am going to get that sorted.
I see eSun make a cleaning filament… I’ve seen it around for years, but have always just chosen to swap out nozzles, or remove then and heat them up with a blow torch.
Any ideas other than the cleaning filament ?
It doesn’t appear to be, it also appears to be aligned well. this particular machine is only a couple of months old and only uses TPU, you would think that if there was wear it would be premature, but it was actually a consideration I had not mentioned above.
On a whim, I bought a small amount of cleaning filament for my Original. There wasn’t really anything wrong with it, but I was switching from black to white and back again, so I mostly wanted to make sure I got all the old color out.
I was surprised at how much smoother my prints were after using it. I hadn’t noticed that the surface was a bit uneven until after the cleaning. I replaced this print head maybe 4 years ago, but print infrequently. If you print all day every day, you likely have more hours on your head than I have on mine.
The first clean, I just manually pushed a bunch of cleaning filament through while the head was hot (the Original doesn’t have auto load). I loaded white, and still had a few streaks of black during the prime. I didn’t really care, and let it print. After the print finished, I repeated the cleaning, let it cool down, and did a cold pull with the cleaning filament. That got a bit more color than just pushing it through. I’ve only done it twice, so I’m still experimenting.
It would be a a good deduction other than with my print farm, all the spools ( I have about 12 going at once across various machines) are in dry boxes at 18% on the hygrometer, and easily exchangeable which is how I know it happens on various spools that are now currently working on other machines as well as the remaining extruders on the J1S, I also had the same idea about purging the hotend at a high temp. I got it up to 280 and purged teh hotend… sadly, the problem still exists. Thanks for the suggestion
I understand that it might be a bit much… I have 8 machines here with DD extruders all running between 1.2 and 1.4mm retraction with no issues at all… as mentioned in the original post, this has been running for a lot of hours like this. I am not convinced the retraction is the problem, although it seems to be highlighting the problem. I am leaning towards a hardened partial clog for that reason.
How did you change the nozzle on the new hot ends ?
I have an Artisan with non-hardened hot ends, but it looks like the J1 brass hot ends use the same MK8 nozzles as the Artisan/2.0. The Diamondback MK8 nozzles are a little larger diameter, but they still fit through the hole on the silicone covers.
The old hotends did have a replaceable nozzle… The new ones with the hardened nozzles have pressed in nozzles that are not replaceable. If I could remove this nozzle, that would be an easy solution. The old hotends clogged with TPU very quickly, but that was a heat creep issue.
I don’t have a J1 so only brainstorming here.
Maybe purging with a harder filament like any other than tpu like pla, petg, etc could help? A cold pull after this would clean definitely all out of the filament.
If you have a look at the cleaned nozzle and compare the problematic with a normal nozzle do you see any differences in the hole size or scratches?
I appreciate that… and this is definitely what I am chasing in this discussion. I have tried running a harder filament through, I use PLA to both purge, and cold pull ( at 120 degrees)… but unfortunately, the problem is still happening. Currently, the machine is printing fine with the right hand side extruder, but sadly the left hand side is still clogging when the retractions kick in. The right hand side is using the same filament and same gcode.
I have ordered a new hot end and the cleaning filament… a small hone that could be drill powered would be excellent for cleaning and polishing the hotend all the way down to the nozzle… but short of that, I can’t think of any other way to clean a stubborn partial clog.
With a torch and magnifying glasses, I cannot see any damage or deforming to the hot end
Well… the cleaning filament didn’t work. A couple of cold pulls, and running about a foot of cleaning filament through at 280 degrees… Still clogging. 3 other J1S extruders havent stopped.
I will fit the new hotend when it arrives in a couple of days and report back.
