Finally Printing - Extruder Temp Question
TLDR: Why do I need to use 230C to extrude PLA? That seems too hot, but it fails at lower temps.
Long version:
When I first started calibrating my printer (v2 calibration and the flat 1 layer square from the "life z adjust" thread) I was struggling with what seemed like the ideal live z adjustment in one test would completely fail on the next test. I was moving the adjustment up and down and the results weren't going as expected, and I couldn't get a repeatable outcome even if i changed nothing from one test to the next.
Eventually I realized that maybe the z height wasn't the issue, but perhaps the extrusion wasn't working as well as it should. I then tried the test where you ask the printer to put 100mm of filament through the extuder. The first time I did this I got about 10mm of filament to move. Next, I started messing with the spring tension (default of 14mm without filament was the original setting) and finally determined that my springs need to be just a bit tighter (12mm), but even this would only get about 30-50mms of filament to go through. All of the testing up to this point had been using the default extruder temp of 215C.
I still wasn't thinking the temp was the issue, and I did a bunch of stuff to try to clear any clogs that had perhaps formed in the extruder, but without any improvement. It was only by accident that I tried to extrude after loading filament while the extruder was cooling down from having been heated up to 290C to see if anything would ooze out of the empty extruder and it was still around 240C and a nice stream of filament came out and coiled up on the bed. After that I started experimenting and found that only at 230C was I able to get nice extrusion. I still don't get 100mm if I ask for 100mm (usually about 80mm) but it seems to flow and extrude consistently enough that I can get a good first layer and a good print.
I've mostly put all this detail in, on the off chance that it will help someone who might be stuck with a similar problem. My question after all of this is up at the top.
Re: Finally Printing - Extruder Temp Question
Forgot to mention that it's just a generic filament from a local store (no labels to know what it is) but I had used it many times in my 1st gen I3 and got the best prints between 185C and 195C.
Re: Finally Printing - Extruder Temp Question
Yup, way too hot.
However, old filament (which may have soaked up moisture) requires higher temps to print as does filament produced by a manufacturer when switching from PLA to ABS...
There's probably other reasons as well, which is why I purchase branded filaments (and not from China).
Peter
Please note: I do not have any affiliation with Prusa Research. Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage…
Re: Finally Printing - Extruder Temp Question
old filament (which may have soaked up moisture) requires higher temps to print
I'm thinking all of my filament qualifies as "old," but what would be a typical timeframe that filament might start to fall into the old category?
Also, I live in a place where the average humidity is around 6% and figured that was too low to worry about filament absorbing water from the air, but maybe I was wrong about that.
Re: Finally Printing - Extruder Temp Question
Your climate will be considered dry by filament standards.
I try to do a small test print (very small and quick) when I do a new filament, just to see how it works. Takes very little time, and almost no filament. (and sometimes, I just PLUNGE right on in, if it is a brand I know).
I like this little guy, as it gives me a sense of surface, and stringiness.
https://www.thingiverse.com/thing:22263
Any advices given are offered in good faith. It is your responsibility to ensure that by following my advice you do not suffer or cause injury, damage or loss. If you solve your problem, please post the solution…
Re: Finally Printing - Extruder Temp Question
Update:
I've been having lots of problems with under-extrusion that created voids in prints or just stopped printing altogether. I even went so far as to manually rewind a spool of filament (at least it was 1/2 full) to be sure it wasn't going to catch on itself and cause extrusion problems (which seemed to be happening). 2 hours later, I got 1 good print, or so I thought until it failed at the very top in the same fashion. I'm going to print a cordless drill spool winder attachment as soon as I can!
Unfortunately, I couldn't seem to get reliable extrusion no matter what I tried. This was the same using the supplied g-code files or using manually sliced (Slic3r Prusa Edition).
In the end I think I had changed too many variables... I'd set the extrusion multiplier based on the 100mm test. I'd measured and averaged the filament width and set that, and I'd tried the default spring tension, tighter spring tension and looser spring tension.
I managed to watch a youtube video where the person suggested only changing 1 of the ways to deal with over/under extrusion and for instance leaving the filament width at 1.75. I tried this and I think it's part of the ultimate solution, but even so, i still had issues.
While I was sitting there at my workbench, I happened to look in one of the boxes of various left-over bits from building the kit (upgrade version, many parts from my 1st printer are still hanging around). I noticed a spring that looked like the extruder tension springs but a little beefier. I found the 2nd one that matched it and wondered if perhaps these came with the kit and I re-used my originals. I have no idea. These new ones are chrome, the others were darker (probably black oxide). I switched these into place, and had to go with a much looser tension, and yet they seem to actually be holding the idler much more solidly than the first set. For instance, when the first set was adjusted (seemingly) the idler could be deflected a few mm by hand if you pushed on it. With these new springs, there is no deflecting it by hand when it's at a good tension.
I figured out the good tension by starting at 14mm as suggested, but the motor wouldn't even turn, it just made noise. I then loosened the springs bit by bit until it was turning, then it would occasionally have the same issue where it would make noise and not turn, so i'd loosen a 1/2 turn more, and so on. Once I got to a point (about 20mm) where it was never clicking, it seems to be working very well. I write this several prints later, without issue. Btw, this noise I'm talking about from the motor is like the noise when doing the xyz calibration and having the z-axis all the way up, it's not the noise (that's also a clicking) of when the filament is being eaten by the drive gear.
Not sure if I'm now using the correct springs, but they're working great, so I'm not going to worry about it.
Re: Finally Printing - Extruder Temp Question
After a few days the new springs stopped working and while trying to troubleshoot that, the printer ended up so clogged that I disassembled the extruder and hotend. I found a blob of something stuck in the heat break. I think it might be a piece of ptfe, but with it removed, the extruder seems to be the best it's ever been. The stock springs at the stock adjustment are seeming fine so far.