Anyone else printing with HTPLA with the XL?  

RE: Anyone else printing with HTPLA with the XL?

I print at 225.  I printed a PLA temp tower. I would suggest you do the same.   

RE: Anyone else printing with HTPLA with the XL?

Do you mind sharing which brand specifically? I've done temp towers before but I found it didn't really help me determine which of those temperatures might be more suspectable to jamming (and what kind - the infamous nozzle plug or the heat creep). I'm finding if I unload and reload the Nextruders between prints it seems to do better, but 240C, 225C and 215C all seem to be giving me grief on this machine unfortunately.

My nickel/copper nozzle didn't save the day either alas. I ended up getting filament stuck in the adapter too which is a bit frustrating.

RE: Anyone else printing with HTPLA with the XL?

This sounds more like an issue with retraction settings than temperature. See if it blocks if you reduce or disable retraction, then use stringing test prints to work your way back. You should not need much retraction at all, but for some filaments I found it can be a bit sensitive to retraction speed (if you go too fast, filament can rip and stick above the meltzone).

RE: Anyone else printing with HTPLA with the XL?

Jayo

Posted by: @m00dawg

Do you mind sharing which brand specifically? I've done temp towers before but I found it didn't really help me determine which of those temperatures might be more suspectable to jamming (and what kind - the infamous nozzle plug or the heat creep). I'm finding if I unload and reload the Nextruders between prints it seems to do better, but 240C, 225C and 215C all seem to be giving me grief on this machine unfortunately.

My nickel/copper nozzle didn't save the day either alas. I ended up getting filament stuck in the adapter too which is a bit frustrating.

RE: Anyone else printing with HTPLA with the XL?

Yep I thought about retraction too since I recall reading that minimizing retraction is known to help with HTPLA. The defaults for the XL look similar to my Voron settings (length 0.8mm). My MK3s are 1.7mm. Feels like there's some differences in the extruder designs causing it but for a lot of my models I think I can probably get away without retraction or at least minimizing it.

RE: Anyone else printing with HTPLA with the XL?

I use no retraction for most PLA/ABS/ASA (some exceptions with around 0.5mm, mainly matte stuff), around 1-1.5mm for various PETG, and max 3.5 for flex.
It's good to start with a temp tower, and I do so myself. But people think it can help with stringing, blobs and nozzle blockage. This is incorrect. Temp towers are supposed to help determine the best temperature for layer adhesion, detail resolution, overhangs and bridging, and to some extend how you want the wall finish to look. You check if the print breaks too easily, how the surfaces look, the undersides of the bridging areas and whether the edges curl up. If there are small cone-like structures in the tower, you also check if the tips are well resolved.
I ignore stringing in temp towers completely and before I print them I reduce retraction or switch it off. Once temperature is dialed in, I then dial in retraction with a stringing test (basically just two slim columns or cones on a common base and spaced a couple cm apart). Ironically, the better your nozzle/hotend combination, the worse it tends to handle long/fast retractions. Ideally you would never need it, so they're not designed for it anymore.

With the Prusa XL I found that the difference between many hours of printing with no issues and extruder skipping after 10 minutes can be as little as +0.5mm retraction length. I have some nasty flax-filled PLA which prints everything fine, but with minor stringing, at 3.5mm and 100% always clogs at 3.8mm.

Regarding your question, in my opinion it's almost always some form of heat creep. Either the filament is still too soft when it's in the extruder gear and then gets eaten up or jams in the path above or below the gear, or it sticks in the upper part of the nozzle (what I would consider the OG heat creep because it means the heatbreak is hotter than it should be). Theoretically the XL should monitor the heatbreak temp, but I haven't seen an error yet so I don't know what it actually does when it gets too hot. Maybe it does nothing and just ramps the fan up to max. When I had clogged nozzles it was always contaminated filament or poor quality filament, or special filament with some kind of filler (wood, metal, etc.), or my mistake by not flushing high temp filament enough when switching back to PLA.

RE: Anyone else printing with HTPLA with the XL?

Yep these are all good points. Alas I tried printing without retraction and got a failure. What's worse, when the nozzle does clog, the rounded extruder gear design seems to promote the filament breaking at that point as well requiring me to take the extruder apart to pull it out from the heatbreak. Rather frustrating operation to have to keep doing.

In this case, I don't think it's heat creep all the way up through the shaft though. It looks like the infamous HTPLA plug near the nozzle. It looks strikingly similar to the same problem the MK3s had when using the stock heatbreak which makes me worried I might just be screwed from using this filament, which is super unfortunate because it meets all my requirements very very well and works great on my other printers. It limits what I'll be able to print on the (very expensive) XL. But is what it is. I'll try maybe one more run and also see what Prusa support says before I start looking around for suitable compatible filament that also meets my requires which I can use just for the XL.

RE: Anyone else printing with HTPLA with the XL?

Quick update, talked to Prusa support and they pointed me to Proto Pasta's datasheets which indicate that my problem might be the high print speeds. While I seem to be able to get away with that on my mK3s and Vorons by the datasheet, the max recommended volumetric speed is 2-3mm/s for opaque HTPLA. That's quite a massive difference from the 15 I have been using. So I may give this a go though in the meantime I want to enjoy making prints rather than working on it, so I'm gonna try some normal PLA fun prints. Maybe see if I can find a multicolor vase or some such.

I also reached out to Push Plastic and they mentioned someone there has an XL and has had lots of success with printing their PLAs so I'm hopeful and eager to hear what they suggest.

RE: Anyone else printing with HTPLA with the XL?

I think I managed to sort things out. Basically I was thinking with HTPLA (or more specifically PushPlastic's PLA), I had to print fast. But I was out-running the ability for the plastic to melt and at high temps was causing some heat creep. PushPlastic suggested I turn down the temps and speed based on their own XL testing and that's what I did. Running at the non-IS speeds at 220/215 has worked for several prints now so I think I found my solution!