jammin is NOT okay, man. (filament regularly jams in heat break)
This is an ongoing problem with my VC 3.1 x 400. Filament gets jammed in the heat break and the only way I can get it to print again is usually to ram a hot metal rod down the filament path.
A recent rebuild of the print head (Eva 3) cleared it up for a few days, but it has now resumed being a PITA.
21 Replies
tagging @Lemcott on request 🙂
jams in the heatbreak are going to be one of two things:
- heatbreak is physically not set correctly and the filament is getting caught on something
- heat is too hot and the heatbreak gets warm enough to start melting plastic up in the break before it even gets to the block.
in a UHF at 210ish running pla I'd hope you were moving 100+mm/s, if not, we could just be moving too slow to allow all that heat to creep up.
filament flowing through the block and nozzle is basically 'water cooling' you are using a liquid running through a system to absorb the heat and move it out, if that water is allowed to sit there on the hot point it will begin to boil
20 (first layer and tiny bits) up to 230 mm/s (infill)
perimeter speed is around 100
I think my slowest overhang is still like 40, maybe 60. and I'm probably printing closer to 195
retraction speeds/lengths?
not sure, offhand. I rarely have to deal with stringing and usually use firmware retraction. And I can't get to my printer right now
60 mm/s sounds right for speed, though, and around 1mm retraction length, give or take
one thing I haven't checked yet but has been on my mind is what the voltage for the cooling fan is actually set to. it's a 24V fan, but I'm not 100% certain the jumpers are set to 24V
supply is 24V for sure, but I can't be sure about any voltage drop or not by the time it reaches the fan without destroying the fan, basically
thoughts about further attempts to fix the issue.
1. I could try replacing the fan. There are other options that should be drop in replacements, though I notice that the higher air flow fans all have PWM control, unlike the one that came in my original kit.
2. I could stick an adapter on the front of the Eva to direct the air into one side of the heat sink, the idea being that the exhaust would blow out through the other side. The lack of exhaust has been a lingering concern to me for a long time, though it may be unfounded.
3. I have a pile of thermistors that I bought a while back so I could add a chamber temp sensor. I could use one of these to monitor the temperature closer to the heat break, though this would be a bit tricky to mount and I would probably have to splice wires as the factory ones are pretty short.
at this point I have replaced every non-printed part of the print head and several of the printed parts as well, and none of these changes seem to have affected the issue
only the fan and shroud are left, really
another possible solution, though it feels like a cop-out, would be to add a filament unload command at the end of the print gcode
just finished a print that involved a bunch of layers that were slowed down due to minimum layer time settings in the slicer. And even though I unloaded the filament right after, it still jammed up.
there seems to be a lot of evidence of heat creep.
when is it jamming up
what you just said does not make sense
I unloaded the filament, and when I loaded the next filament later, it wouldn't feed past the usual heat break clog
presumably when I unloaded the last filament, it left enough in there to form a clog
when you unload first turn off the heat and then extrude 25-50mm while it is still hot, then quickly retract all the way out.
this helps purge the final end of the plastic that is already warm and by retracting immediately afterwards you can ensure the smallest amount of melted filament on the end of the tip
I like... kinda just always have done this? but I've never really seen it anywhere else.
I guess a lot of tip forming macros do this
anyway, still, on a rapido I'll have heat cranked and just rip it out and never really have an issue, so maybe something is up with your heatbreak
how do you unload? just the unload macro or retract a bunch or manually or?
unload macro
pretty sure it does what you describe
here's an example job from superslicer. I haven't actually printed it yet, and I'm reluctant to until I can convince myself that the 10mm/s speeds on the spines is not going to be a problem, or I can make it so they're not printing that slow. I've tweaked the layer time goal settings for the filament and the speed settings for the print and neither had any affect.
I think I can upload the llama gcode, which is the one that the heat break clogged after printing, if anyone wants to take a look
As some context: I recently ran tests trying to get a heat creep jam on a stock VC4. With no hot end fan and fully soaked passively heated chamber, I could not get a jam with pla or petg. Tests included a voronoi egg with low average flow rate and lots of retraction.
That's with rapido 2 plus, which may be significantly improved in this regard over earlier versions.
check if the heatsink grub screws is tightend
also check if you havent lost the heatsink clamp
assuming its a rapido
UHF?
will double check these in a bit, just started a print, but having just rebuilt the print head I can say that the parts were all there and tightened after I rebuilt it. And obviously before.
Yes
at this point i've eliminated just about everything except the fan and maybe the slicer settings. Fan is a 24V gdstime GDA4010 that came with the kit.
@Lemcott what slicer do you use? Would you mind taking this STL and saving it in your slicer with your most commonly used (PLA, preferably, if you use it), filament profile and printing profile and post it? I'd like to make a comparison between your profile and mine and see if there's something obviously amiss.
post the 3mf, i mean, so it contains the profile and I can look at it 🙂
i use SS most of the time, fwiw
these are super basic
thanks!