PLA Woes part infinity

[Glacian22]

Hey all, I posted some months ago about how I could not get PLA to print with my E3D for anything, it would always jam about half an hour in every freaking time...eventually I gave up. Now I have my brand new Prometheus, and while it feeds PLA much better, sometimes I get a good print, and sometimes it turns into a filament starved mess.

In trying to figure out what the hell is up, I fed PLA directly into the hotend, and uping the temp to 215c makes it flow through like butter when pushed in directly, but still requires a ton of force via bowden. Is this normal? I've measured the filament, and it clocks in at 1.76, give or take .02, so I don't think it's out of spec. I tore apart the ezstruder and modded it so the bowden passes all the way through (using an E3D pass through push fit), but that didn't seem to help. I also found that the grub screw holding the hobbed gear in place was just slightly scraping against the red arm, so I shaved down the plastic to make sure there's no contact. Still no luck. I've messed with the extruder motor current, both up and down from the 200 it was set at, didn't help.

I do have the hotend fan running off of fan power rather that direct from the power supply, so I'm going to try changing that in a minute, but other than that I'm out of ideas. I can print ABS and nylon no problem, but with PLA the extruder kicks back occasionally, and when it doesn't, sometimes it just grinds the filament instead of pushing it. Guys, all I want is to print in a material that doesn't warp, and smells like pancakes. Please halp. T_T

[McSlappy]

Hmmm. Have you tried another PLA? I know that if I used the translucent PLA it was more prone to jamming the e3d than other solid coloured ones (which all still jammed eventually if I didn't use a drop of oil).

Have you tried a drop of oil?

[DavidF]

try the color fabb filament....well thats all I have to say..LOL

[Glacian22]

I haven't tried oil yet, it did help when I was running my E3D...at least it took longer to jam. XD

Is colorfabb PLA that amazing? It had better be for that price!

[DavidF]

I haven't tried oil yet, it did help when I was running my E3D...at least it took longer to jam. XD

Is colorfabb PLA that amazing? It had better be for that price!

Yes it is expensive. But the results you get make up for the cost. I wouldnt push it to a amazing level though, but it is impressive. I have been finding that cheap filament is just that ""cheap" and that it is well worth it to spend a bit more to get the prints that I am looking for. I have been battleing some cheap stuff lately that has a case of MUMPS. So much in fact that the mumps on the filament get jammed int the bowden tube. Totally un cool!!!
Try contacting Matt at printedsolid.com for some samples. I think I have done enough business with him that if you mention me he will hook you up, but might be limited to what he is allowed to sell it for.

[Glacian22]

Okay, I think I've tracked down the problem. I had the ezstruder feed a few hundred mm of pla through while the bowden tube wasn't attached to the hotend, and then fed some of that filament down into the hotend by hand. After being run through the ezstruder, occasionally a ridge that the hobbed gear made on the filament will catch slightly inside the hotend, right where the bowden is supposed to let out, so maybe this is the source of the problem. ABS and nylon are both a lot softer than PLA, so it makes sense that they aren't carrying as much of an impression from the teeth on the gear, making it a lot less likely for them to get stuck.

This seems like a problem you'd only run into on an all metal hotend, as the stock one has teflon running the whole length, which would be a lot more forgiving. So it seem my options are (if this is actually the problem): switch to a non-all metal, switch to a less bitey hobbed gear, or mod my prometheus by adding a bevel to the top of the barrel/nozzle so it might be more forgiving of chewed up filament.

Thoughts?

*EDIT* looking at the technical drawings of the prometheus, it already has that. W. T. F...how can it possibly still snag?

[Polygonhell]

If your using an all metal Hotend, my money would be on a traditional PLA jam.

I've said before I have 3 E3D hotends and only one of them will reliably print PLA, one will randomly stop extruding mid print then sometimes clear itself, the other jams almost immediately. PLA just behaves differently to other plastics we print with, it was the reason PTFE was originally used in hotends. My solution was to use a JHead for PLA and swap it to the E3D for other filaments.

You can sometimes get into a compound issue where a traditional jam causes the drive gear to eat the filament, which later gets stuck usually at the end of the Bowden tube.

[Glacian22]

Polygonhell, I might just give up and do that. I was just very hopeful about the prometheus given his claims that it'll print PLA jam-free. :/

[McSlappy]

Oh I got my Prometheus today! Perfect timing for my birthday

[Glacian22]

McSlappy, you'll have to tell me how your prometheus works out! Maybe I'm doing something horribly wrong here?

Also happy birthday!

[mhackney]

I have 3 E3Ds (V5 and a 6) and a Kraken hot end and they all print PLA wonderfully after I chased down the gremlins. And I learned something new this weekend.

Firstly, PLEASE read my previous posts on troubleshooting - they might be easier to find on the E3D-Systems forum. I explicitly discuss "deburring" the toothed gear in the ezStruder for exactly the reason you describe - I was experiencing these snags too. But that alone wasn't enough, ultimately it came down to the nozzle bore length. Assuming that is fine, then the debur will help significantly. I've never had to use the "oil treatment" others have described. I don't think it's necessary if you are meticulous and chase down each of the issues I discussed previously. Now for the new discovery...

My son was tuning his new mini kossel this weekend. I had given him a known good E3D with a .5mm bore nozzle to use. Yet, minutes (10-30) into a print he would get clogging and/or filament starving. First I made sure the fan was appropriately placed - if the housing is above the lower fins you can get heat creep and clogging. I checked the filament path looking for snags at the bowden tube and ptc fittings. All ok. I tested by hand pushing the filament from the extruder (by depressing the red filament release lever and pushing the filament) and it flowed evenly with very little pressure. So, I realized the extruder must be the culprit. We checked the current setting and it was ok. So I took the extruder apart... and discovered that the toothed cog was not in exactly the right place. It was about .75mm offset and not exactly aligned with the pressure roller. Also, the screeds that held the top clear section to the motor were not completely tight and that allowed this roller to move side to side by about .5 mm. The net result was that the filament could - and would - roll to the side of the toothed cog and lose traction and stall. Simply repositioning the cog and tightening the screws solved the problem and now it extrudes PLA perfectly.

I am now wondering if many/some of the PLA extrusion issues reported here and there might be related to the ezStruder not being set up correctly. It's an easy thing to miss, especially for the inexperienced, and has a big impact. Interestingly, the negative effect of the offset on ABS is much less, presumably due to the softer ABS filament, it did't seem to have the same tendency to ride to the outside of the toothed cog like the PLA did (as tested after we discovered this).

Hope this helps and happy birthday.

I stand by my experience with these hot ends, they print PLA very reliably. I have logged 1000s of print hours on them on several printers making products I sell with virtually no problems. I'm printing most of these items at 100mm/s also.

cheers,
Michael

[geneb]

If you want to print PLA without worrying about it or tweaking this thing or that, go to hot-ends.com and buy a j-head. Use the fancy all-metal hotend for everything else.

g.

[mhackney]

While I have no problems with j-heads (owning and using several and they are nice units), the "tweaking" has turned out to be primarily not hot-end related. And now with the E3D V6 the nozzle bore length is no longer an issue. The ezStruder adjustment for instance would affect any hot end. I have no problems with PLA so I know it can be done. I print 100s of PLA parts in multiple colors every week with absolutely no issues.

cheers,
Micha

[Glacian22]

Thanks Michael, I will definitely track down your post on deburring. Even after getting your bore modded E3D nozzle, I never had much luck, and somehow I never saw the whole thing about modding the ezstruder, so I'm very hopeful it'll help.


*EDIT* I tracked down your post on the E3D forum about deburring, but could you give me a little more detail on exactly how you did that? I'd rather not ruin the gear by being too aggressive.