kc, jebba,
Thanks. I am using KISSlicer, and there terminology is a little different, but I have also gotten excellent prints from KISSlicer as well. I think my next step (as you both suggest) is to do a slice from Cura and try that from the Lulzbot TAZ Cura Profiles.
Well…
I have a job that I needed to get printed and all was going perfect.
The first four pieces came out great:
These were all sliced in KISSlicer ahead of time, so I haven’t gotten to trying Cura yet, but that’s next on the list.
Any thoughts as to what could cause this in the middle of a print like this?
Looks to be a partial nozzle blockage. Try some cold pulls.
I’ve had problems like that on both my printers… Slight overhangs often come out with clumps on the surface. Reducing the print speed, tweaking extrusion temps, increasing cooiing amd finalky lowering extrusion rates should help those prints.
Finding the right extrusion temps can be an “art”. Ideally you want to print at the lowest temps to help lock the extruded plastic in place as soon as it comes out of the nozzle. Of course, the temp needs to be high enough to keep up with the print. Too low a temp could cause delamination or weak bonding with the previous layer. See how it can be an “art”? 
. Sometimes in a quiet room, you can hear the filament become molten as the nozzle preheats… Its like a subtle crackling/bubbling sound… which signifies the lower end of the temp range (printing at this temp is probably too low). Oozing indicates a slightly high temp, which can be good for initial layer adhesion and promotes good bonding to adjacent filament… resulting in strong parts. Oozing gives your filament a mind of its own in which could lead to clumping and other weird things.
Increasing fan cooling during overhangs will also help to lock the filament in place. With ABS, I like to reduce fan cooling to 20-30%… the material seems to like cooling at its own leisure. I havent printed PLA in a while, so havent experimented as much.
Use the extrusion multiplier to lower he amount of filament being deposited. Keep in mind too low and you could starve the nozzle. Too little filament can also weaken a part. Alternative to adjusting flow, sample the diameter of your filament with calipers to get a better average diameter of the filament for your slicing software. If the nozzle scrapes the top of the print (sometimes can be heard as a rumbling sound), that’s a good indication of over extrusion.
Anyway sorry for the book… hope some of the insight helps.
KC, Discojon Thanks!
OK, I’m sure that there something I’m doing wrong but I am extremely frustrated.
I have tried to print this model multiple times, ALWAYS with a failure.
The latest:
Failed with cura (with PLA settings from Lulzbot) very early, very beginning of first infill.
Back to KISSlicer, but tweaked the first layer settings for slightly wider (.4 up from .35) and much slower first layer speed (15mm/s). After that I’m printing at 20mm/s for loops and 35mm/s for solid.
First layer, perfect! Second layer FAIL, as you can plainly see.
I feel like I’m grasping at straws, but I’m really frustrated. 
Hmm… that looks like a clogged nozzle. The cold pull is Lulzbot recommended method to help dislodge clogs. It doesn’t look like it worked for you. I believe Lulzbot doesn’t recommend removing the nozzle to clean, give them a call or e-mail for suggestions.
If you raise the nozzle up to 100mm and perform a manual extrude, does the filament come out in a nice straight line? Or does it curl? This can help identify if there is a partial clog… The line of filament should come out straight.
Is it possible that the little blower has gone bad?
kc,
Yes, the filament comes out in a nice straight line.
This is from a 100mm extrude:
WHAT?I just checked the small herringbone gear to be sure it wasn’t slipping on the shaft, but it was tight, so that’s not it.
I can’t imagine that the steps are that far off.
That could be compounding on your problem. Make sure to clean the teeth of the hobbed gear and check that the filament isn’t binding on the spool. Make the changes to account for the extrusion difference and report back.
kc,
Thanks, I think I’m in the process of solving my issue. I tried to calibrate the extruder using the 100mm @ 100mm/m in pronterface, and found that not only was my esteps # way off, I inadvertently overtightened the hobbed bolt when I first took it apart for cleaning. 
I’ve loosed that and the extruder seems to moving a lot more freely (Yeah, DUH).
Anyway, I’ll try another part and see what happens. My next call is to Lulzbot.
Thank you for your help.
Hmm… that’s one to file into the notebook. Overtightening the hob gear bolt sounds like something I would do also. Guess the test is to make sure it rotates freely when the motors are off.
Hope you figure it out… to get good prints you’ll need to get very intimate with your printer. Hang in there, these machines print great.
OK, just tried another print. On the second or third layer there was a point where there was very sparse material being extruded (spider Webs), but because it was running unattended, it pushed itself though and started to extrude again.
I hope that makes sense.
So I let it go and then this.
Hmm… I do see where the infill looks a bit different. Not sure whats going on there. How does the perimeter walls look there? If they look okay, then I wouldn’t worry much about infill layers… unless it starts to affect rigidity of the part. For that part infill looks to be 50-60% which should be fine as long as the top/bottom and perimeter shells are decent.
Personally that looks like under extrusion, the 2 perimeters are not bonded. Did you fully recalibrate the steps per/mm after your last round of fixes? I believe they should be in the 800 - 850 range.
kc,
The perimeters are about the same more rounded and not bonded together.
wantmys2000,
It does definitely look like under extrution and probably is at this point, but NOT at first, until it starts “acting up” everything seems fine and then wham!, It’ll start under extruding and then not extruding at all.
Yes, I did do quite a few extruder calibrations. I finally settled on 870, which seems like a lot to me, but what do I know!
Looking at the Lulzbot info that came with my TAZ 5, says they set it at 842.
As I was typing, I got this response from Lulzbot:
“This looks like a good print. You must just be at the tipping point between back-pressure and feed-pressure if it is starting to get those points where it stops feeding. Please tighten your idlers to 4mm spring compression, make sure that your hobbed bolt is nice and clean, increase your temperatures about 5 degrees at a time until you get good feeding, and give it another shot.”
This sounds like good advice. I’ll try the same print right now.
Got some email advise from Lulzbot which basically said to tighten the idler screws slightly and add 5 degrees until I got things printing right.
Well I’m very happy to say that last night I did a 10+ hour print that is PERFECT!
So, in KISSlicer I was able to set the first layer at 205 degrees and 215 degrees for all other layers, and that was MONEY!
Thank you all for your help in solving this issue, but going to the source really helped.
Awesome! Glad you got it sorted out. I typically like higher early layer temps with slightly lower temps for the rest of the project to aid in cooling (I run the fan at really low percentages). But your prints look perfect, don’t change unless you have problems with warping…
OK, so after 4 or 5 prints that were absolutly perfect, I got this:
I’m at a loss. Everything was going fine. What would cause this behavior?
Well that’s not good.
I removed my nozzle last night for a cleaning. And I think there is something binding the filament on its path past the hobbed bolt. There’s also been talk about heat creep which would affect PLA more sos than ABS. And lastly, I just read something about “seasoning” metal hot end with olive or canola oil.
Seasoning seems to reduce any sticking of the PLA to the hotend… There’s a youtube video of the process on the E3D hotend. Hard to link on my tablet. But basically it seem to be a dab of olive oil and manually feeding the filament through by hand while the hotend is at temp.
