3-yr aniv. sale no bargain,0.2mm nozzle clogged after 2 yrs clog-free

Bambu Lab P1 Series Troubleshooting
1

I don’t know the last time I posted an article for myself in the troubleshooting section, but I’ll gladly take any feedback on clogs regarding the 2mm nozzle.

I searched and wasn’t able to spot any solutions, so if I’ve overlooked a post that answers my question, please, by all means, point me to it.

In the meantime, I decided to take up Bambu’s 3rd anniversary sale and picked up the 4-nozzle 30% off special. It looked like a good deal - until it wasn’t… at least for me.

image
image600×600 87.4 KB

I ordered all four nozzle sizes for the P1/X1, 3 bare nozzles, and 1 full assembly (8mm), along with a 3-pack thermistor with clips and an extra fan. I needed those extra parts to get the free shipping, and I figured it wouldn’t hurt to have them on hand. This is yet another reason Bambu gets very little of my accessory business - not only is the customer service lousy, but it just feels like there are always strings attached.

____________________________________________

My first nozzle clog​:bangbang::astonished:

The 8mm worked fine and I can see where it has its utility. The 6mm is still in the box - the only reason I got it and the 4mm was to get the promo discount. However, it was the 2mm I was really interested in.

For the record, I’ve never had a nozzle clog. Ever!!! In the 2+ years I’ve had my P1P (upgraded to hardened steel), I’ve never experienced a clog - which is maybe why I was never able to help others on this forum who have. This time was different.

The nozzle tested fine. I did some filament calibration, a couple of basic geometry test prints, and even a Benchy, etc… But the nozzle clogs after about six hours of use.

I thought about heat soak or some other temperature-over-time problem. I printed with both the door open and closed. Neither had any effect. What’s odd is that I can heat up the filament manually and reverse-extrude it, but not force it reliably into the nozzle. The issue isn’t that I’m stuck - it’s that the setup is unreliable. It’s a pity, because I can see the utility for certain precision prints I was unable to do in the past.

Thoughts, anyone❓

2

Have you always used the same filament type or have you changed from I don’t know, PETG to ABS to PLA? If that’s the case, I found with my limited experience with 0.2 nozzles that purging temperature might not be high enough, purge longer at higher temperature to make sure the nozzle is clear from previous higher temp filament. 0.2 nozzles can be tricky.

3

Hi @Olias ,

If have had plenty of clogs for a whole bunch of reasons. But they were almost always with the .4 rather than the .2.

Since you describe the clog occuring around 6h into a print, heat creep does sound like a reasonable diagnosis.

With PLA, I usually target a chamber temp of 35-39°C to eliminate warping while avoiding heat creep. However, with many retracts, ironing and low flow (.2 nozzle!), I usually try to stay below 35°C. I expect that similar chamber temp windows exist for other materials (I think you mainly print PC?) which may be quite narrow in low flow conditions.

Speaking of flow, with a given chamber temp, cold end cooling options are rather limited. To counter the heat creep, using a smooth timelapse may give the option to get rid of some of the cold end heat build up in the prime tower. It is wasteful but can be checked in the flow preview.

Another thing which can counter heat creep in the borderline region is related to the filament thermal conductivity. High conductivity filaments are much more prone to heat creep than low conductivity filament with low flow. So if the problem occured with black filament, where a common pigment is carbon black, you may already be able to improve by going for a different color.

Or something really weird which was discussed a while ago in the forum: Blowing air down the PTFE using a small fan and a y-splitter. As I do not have an H2D, I am not sure if that is implemented there. I have not tried it myself so I can not comment on its effectiveness or detrimental side effects.
Edit: Link to post: Extruder cooling strategies? - #5 by RocketSled

Besides all of this, there are of course other major causes for clogs. A lot of stuff following the PTFE paths (which you are well aware of), and of course: plain bad luck, i.e. filament ovality, dust, dirt, etc…

Another point of note is the unclogging procedure. A successful reverse extrusion passes possible contaminants back through the extruder where they may get dislodged and sit there like little monsters biding their time… Took me ages to understand that travelling clog the first time I had that. It is also the reason why I only do hex key cold pulls these days, despite the hassle.

Best wishes, :crossed_fingers: & :four_leaf_clover: ,
Yours,
Eno

1 Like
4

It’s just a another cunning trick to upsale more.

For 0.2mm nozzle, I use TZ 3.0 from aliexpress from the getgo, and luckily haven’t gotten any clog, not yet.

image
image405×397 36.9 KB

It came with CHT brass nozzle but I guess 0.2mm doesn’t really need ‘high flow’ though.

My guess is, the filament you are using contaminated with particle(s) about 0.2mm, which wouldn’t be an issue for 0.4mm. But yeah…

5

Thanks, my friend. That Rocketsled post was a good one - I missed it, probably because I hadn’t run into this issue until now.

BTW, the filament I’m using is a high-flow PLA which in addition to using it in the past, was on a lightning deal for $12/kg. I was able to calibrate to 26 mm³/s, but I guess I overlooked the obvious: try another PLA? :man_facepalming:

I do have one other theory I haven’t chased down yet. I’ve been using my own thermal grease instead of Bambu’s paste - which, as anyone who’s had to salvage a nozzle knows, turns into something more like plaster after a few weeks. Makes servicing a pain later. So along with swapping filament, I’m going to reseat the thermistor using Bambu’s paste. Can’t hurt, at least short term.

7

That high-flow PLA could indeed have an increased thermal conductivity in order to enable the increased flow.

Similarly, when I looked into thermal grease when I had to assemble my first nozzle, I was surprised that it was easy to spot greases with a higher conductivity. Unfortunately, electronics are not my forte, so I can not dive into that. But it does sound like a worthwhile endeavour to explore what happens if the heater is more efficiently transfering its heat into the hot end. The thermocouple should of course keep the temp, but it is at the far end from the cold end…

Best wishes, :crossed_fingers: & :four_leaf_clover:,
Yours,
Eno

8

Did you ever figure out your issue? I all the sudden can not print at all with a .2mm nozzle. I have hundreds of hours printing with it with no problem and all the sudden I can’t get past layer 3 without a clog.

9

I was able to recover the nozzle and as near as I can tell, it was definitely heat creep. I say that because when I took apart the extruder, at the top of the feed was the telltale bulge of softening filament backing up into the extruder. It was easy enough to fix, I just did subsequent prints with the glass cover open and monitored the chamber temps to keep them below 35c. Since then I’ve take the 0.2mm nozzle out of service and switched back to the 0.4mm which is fine for most of my needs.

1 Like
10

The problem is the 0.2mm profiles have very low flow rates, they are set at 2mm³/s or lower for most filaments. When I use my 0.2mm nozzles I bump the speed to 8-12mm³/s for PLA Basic and ABS/ASA. When its at 2mm³/s the filament sits in the extruder for a very long time and has time to soften from the hot gears. And yes you need to have good ventilation to prevent heat creep.

Also if you have aftermarket extruder gears that have metal arm that will cause premature heat creep issues. I would suggest to sticking to stock bambu gears.

I would do a max flow test and set the volumetric flow rate between 8-12mm³/s to avoid this issue.

11

Thanks for the tip. I am trying this tonight. Hopefully it helps.