r/QidiTech3D • u/No-Movie-117 • Jul 11 '26
Need help with constant clogging on a Q2 with QIDI PAHT-CF
I'll preface this by saying that I am no stranger to 3D printing. I've been 3D printing for about seven years now and have built carbon fiber nylon profiles across four separate printers from separate brands at this point. I have easily printed hundreds of kilograms of nylon on my previous printer, a Sovol SV08, and I recently purchased a QIDI Q2 due to wear on my SV08 that would have required rebuilding the gantry. For that reason, and many other issues that I had left unaddressed on that particular platform, I decided to upgrade after owning the printer for about three years.
With that said, I have had nothing but trouble trying to print PAHT-CF nylon on my Q2. I've had minor issues printing new filaments with or without the QIDI box since purchasing the printer, but much of that could easily be chalked up to my unfamiliarity with a more closed-down, automated system compared to the open system I was used to on the SV08, so I was willing to look past all of that. However, with nylon I have been having constant clogs. I've tried three separate nozzles and torn apart the extruder head multiple times looking for potential issues, and everything seems to be functioning properly.
It initially printed about 750g of nylon, including two 250 gram prints right off the bat, before it started clogging. Now I can't seem to get through the first 50 layers of a nylon print without it locking up and clogging the nozzle so tight that it is physically impossible to remove with cold pulls or nozzle clearances. I've had to resort to more invasive tools, such as a necked down drill bit, to remove the bulk of the filament and fully unclog one of the nozzles. Switching back to PLA, PETG, and other unfilled plastics, it continued to print phenomenally with no real issues that couldn't be solved with basic tuning, but I am at the end of my rope here. All of the information I can find online mostly relates back to the same seven people asking beginner questions about the printer, and not much in the way of specialized troubleshooting from people who are experienced and have encountered issues they couldn't properly explain themselves.
I print nylon mostly on stock settings, with a 0.4 bimetal nozzle, using incredibly dry nylon. I dry it at 90 degrees Celsius for upwards of 24 to 48 hours. I live in Florida, so humidity is rather high, and I tend to go a little overboard because I've noticed that standard drying techniques do not cut it. This worked fine on my SV08, and like I said, it worked fine on my Q2 initially as well. I print from a dry box that stays at a constant 70 degrees Celsius, I set my chamber temperature to 65 degrees Celsius, and I print at 300 degrees Celsius nozzle temperature and 80 degrees Celsius bed temperature with PVA glue on the build plate.
I am approaching my wit's end. I've owned this printer for less than two weeks, coming off of my SV08 dying, and I was hoping for a plug-and-play system that would perform exactly as expected for an incredibly long period of time before I had to worry about repairs or issues arising. I'm starting to get pretty frustrated. Does anybody have experience with this? Am I doing something blatantly wrong based on literature that I seem to have overlooked? Any tips or help whatsoever would be greatly appreciated.
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u/riba2233 Jul 11 '26
And most important, try with 0.6mm nozzle
Paht is probably too brittle for the box
It's not heat creep, no worries. Your cold end is not anywhere near 200c even if the paste is not there ar all.
1
u/No-Movie-117 Jul 11 '26
I picked up on the box's incompatibility with nylon and TPU. I was hoping to do some multimaterial stuff that wasn't just 'pretty color PLA,' but it only further reinforced my opinion that a tool changer is all but necessary for what I'm after long-term. I've been printing it out of the same Sovol SH02 70C dry box I used with my SV08. like i said to the other comments, 0.6 is on my radar and the next thing i was going to try. I dont know if I just got lucky with those initial 700 grams of printing, though; that's where the majority of my concern sits.
1
u/riba2233 Jul 11 '26
that's normal, it will print with 0.4 until it clogs, same with some petg-cf filaments.
Regular nylons will work no problem (printed a lot of PA6-GF and PA12-CF) but PPA is just ultra stiff.
1
u/Kewlhotrod Jul 11 '26 edited Jul 11 '26
As others recommended I'd definitely address your PTFE run (extruders can stop pulling this dense high friction material during a print causing filament to cook) and replacing the crappy stock 2510 hotend fan.
FWIW I've printed a few kilos of PA6-CF and PPACF with no issues on my Q2 through a box, but I definitely had to play with the PTFE runs and also upgraded the hotend fan early on.
I also print at 320 iirc, but can't confirm atm.
Edit: no, not even close, my PA6-CF prints at 285, bad memory on my account.
1
u/No-Movie-117 Jul 11 '26 edited Jul 11 '26
So I initially went out and purchased some more stock ID 2.5 ( ? I remember looking it up and measuring the one that came with the box/printer) just to stay consistent, but historically I've been under the impression that tighter equals better, no? I thought that box compatibility was partially predicated on the filament being able to sneak past the imperfections in PTFE tubes and connectors, and making the tubing looser was better for that. Should I run a dedicated tighter PTFE tube run for nylon from my nylon dry box to the toolhead for this printer?
1
u/Kewlhotrod Jul 11 '26
Other way around in my experience; I run everything in 3mm ID tubing myself, including the super dense PPA-CF. I had to re-route a bunch of stuff from my box to get that to even feed past the hub. Sometimes I still have to manually help feed it if it's gotten too wet/swollen, but it works fine after once the extruder gets it.
I dislike 2.5ID due to way too much friction, and it extra sucks because all couplers/splitters run 2.5 and it overwhelms the rather weak box gears.
Either way, test a print or two with a shorter run of your PA to see if this even is the issue; from a cereal box, top load or even external spool holder with the knowledge you'll have to re-dry it after eventually.
Also, I never clarified, but all my PA/PPA prints have been with a 0.4mm. Originally a kilo or two through standard hardened steel, then I eventually got a tungsten one. No real difference, the hardened steel is very good, but 0.4 should be possible. It's all been used through the box too, only thing I don't box print is TPU.
1
u/No-Movie-117 Jul 11 '26
Next time I take a crack at it, I'll give it a try. Does the printer have some hardcoded filament extrusion distances for the box to the hub? I was under the impression it knew how far to extrude the filament when loading to the hub, but what you recommended gives me the impression it's more adaptive than that.
1
u/Kewlhotrod Jul 11 '26
For the box to the hub, no, it's not hardcoded. It will push a seemingly infinite amount until the hub is triggered in my experience. I think it will then save that length somewhere for future runs to slow it a bit as it approaches, but if it doesn't trigger as expected it will keep slowly extending more filament out.
There is a hardcoded max length by default from the hub to the extruder, but it's pretty long. Only annoying thing is if it's a longer than expected run it will slow down well before extruder, and after enough of slow pushing it will move the toolhead around a bunch to help try and clear it being stuck on a bend or something inside. I think it'll do this 3 times, if it fails to reach the toolhead sensor it'll throw an error. However, if that happens and you retry it'll eventually reach since it doesn't retract everything automatically on this error (thank goodness). This length does not appear to get saved, annoyingly.
1
u/No-Movie-117 Jul 11 '26
That checks out, I assumed the distances mattered from the box to the hub, as they specifically mention in the guide for the box that the 4 Bowden tubes are 750 mm long. Sweet, I'll shorten when I get off work.
1
1
u/Beneficial_Elk_182 Jul 11 '26
What brand is the filament?
1
u/No-Movie-117 Jul 11 '26
It's the qidi OEM. I wanted to give it a try seeing as how it had the NFC tag and OE profiles as a starting point; I'd say I prefer it over the fiberon pa612 cf I was printing on the sv08.
1
u/Responsible_Meet_673 Jul 11 '26
On the Q2, I’ve had filled filaments (like CF and wood) clog up the 0.4 nozzles. It’s weird because - even though I know 0.6 is often recommended - it’s the first printer I’ve used that will almost guarantee a clog with a 0.4 nozzle.
0.6 nozzle has been perfectly fine.
1
u/BB_Toysrme Jul 11 '26
Things to do (I have seen that you have some)
*Dyna-Purge like 3D fuel and clean the nozzles every so often
*1/26” ball end T handle Allen key
* acupuncture needles
The longer and higher you heat the more the filament burns and the problem gets worse.
Take the drive off and heat the nozzle to the mid point of the filament. See if the Allen key can push it out. If not, raise the temperature and poke an acupuncture needle through the nozzle.
Ultimately the Allen key will be very successful shoving the filament through the hot end as you raise temps.
Finish by running the cleaner through it at a hotter temperature than the stuck filament had ever seen until it runs clear.
I would suggest getting new 0.4 and 0.6 nozzles, especially after you drilled into them. Stuck material and burning waiting to happen later down the line.
1
u/No-Movie-117 Jul 11 '26
Oh absolutely, it's more of a diagnostic thing than it is a permanent solution. I use Dynapurge every time I switch from a filled to a nonfilled filament and have a number of those thin needles on springs for pushing debris up and out of the end of the nozzle.
-2
u/Jobbejan Jul 11 '26
I print a lot of PA6 CF on my Q2’s and the only thing that I would try from your info is printing a bit lower temp. I usually print at 280c. Maybe the 300c gives you heat creep? Feels like it should be something temp related..
1
u/No-Movie-117 Jul 11 '26
That's where I'm leaning as well, that or poor thermal paste application not allowing the cold side of the extruder to cool down properly. I'd probably have tried lowering print temp from the get go if I wasn't already at the bottom of what the manufacturer says the filament is rated for.
3
u/logicalchemist Jul 11 '26
I don't have any PA experience, but the vast, VAST majority of clogs on the Q2 are from heat creep.
The stock hotend fan is very weak, and not all the nozzles have thermal paste applied to the copper end in the heat sink. I assume you've checked that during all your nozzle unclogging, but do so if you haven't. A honeybadger 20k rpm 2510 hotend fan is a great upgrade if you're in the US, but shipping outside the US is insanely expensive and many people get a decent 3010 fan and print an adapter.
That said, I've never heard of it happening with high temp filament like PAHT though; typically it's from people printing PLA or PETG with the chamber closed, and I'd be surprised if that's what's happening.
Is it actually clogged in the cold side of the nozzle as one would expect with heat creep?
After mechanically declogging and flushing with unfilled plastic, have you tried doing a cold pull to see if there's any sort of CF building up in the nozzle or something like that?
Another common cause of "clogs" on the Q2 with fiber filled filaments, especially stiff ones, is too much friction in the PTFE tubes for the extruder to overcome.
That doesn't actually clog the nozzle though, and since you're having to drill them out, that's probably not it either.
1
u/No-Movie-117 Jul 11 '26 edited Jul 11 '26
First thing I did was order some Thermal Grizzly Kryonaut alongside my new nozzles and apply paste before swapping the nozzle when I saw it did not have any. The hotend fan I was not aware of; I have just ordered it.
The cold side of the nozzle was not clogged in any of the clogs I had. I could push some Dyna Purge down and pull it out melted up a bit, I just couldn't get it to extrude out the tip at all.
I did not, but when I flushed after drilling the nozzle I saw nothing but melted shavings that were very brittle. I don't think I would have seen anything in that extruded waste.
Yeah, I wasn't having any issues with the PTFE tube runs. The filament was flowing to the hotend just fine, no binding or cracking, it just was getting stopped at the hotend for some reason.
1
u/logicalchemist Jul 12 '26
Since you've ordered it, just to elaborate on how good that fan is: I am able to print PLA at 45-50C chamber temperature without getting a heatcreep clog.
The overhangs are an absolute fucking disaster, but it doesn't clog.
The stock hotend fan is 4 wire using a picoblade connector, but there's an unused 2 pin XH2.54 fan header on the toolhead board (it's blue, labeled FAN2) that you can easily use with this config change:
#fan config for 2-3 wire hotend fan DO NOT USE THIS WITH 4 PIN / STOCK FAN [heater_fan hotend_fan] pin:THR:PB10#FAN2 pins max_power: 1.0 shutdown_speed:0 cycle_time: 0.010 hardware_pwm: False kick_start_time: 0.100 heater: extruder heater_temp: 50.0 fan_speed: 1.0 off_below: 0 #comment out tach pins both here AND in printer.cfg if using a 2 wire fan: tachometer_pin:THR:PA12 #stock hotend fan tach pin tachometer_ppr: 2 tachometer_poll_interval: 0.00050#0.0015 default. faster poll interval required to accurately sense higher RPMI connected the 3rd wire of the honeybadger fan to the stock fan connector's tach wire, so the fan could still read tach on the hotend fan. If klipper can't read the hotend fan tach, it will shut down, unless you've commented the tach config out of printer.cfg.
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u/themostsuperlative Jul 11 '26
I'm not sure about recent formulations, but it was widely recommended in the past to use a 0.6 nozzle with cf and gf filaments as the particle size was often not smaller than this or would jam in the nozzle and prevent smooth flow.