Severe issues With PLA and PETG, + questions

I had sever issues with PLA, went back to ABS, and nozzle broke. Replaced Nozzle by preheating the extruder, printed a lot with ABS, worked great aside from some pretty significant warp, which was expected, and a few lousy layers slightly off in the x and y, which happened to before and is expected because I haven’t gotten what I would consider an excellent print. Switched to PETG, had some stingy prints (what its known for) but then the print failed after about 15 layers of the print because the filament jammed (same issue I had with PLA.) Another print, much better, but made it to only an inch, part had a lower infil. All pats have had some shaky exteriors even at low speeds (50mm) meaning some layers aren’t perfectly on top of each other. Also, having done some machinery, and having done the paper trick for zeroing mills I know it works but it drives me nuts. I would like to first level the bed with a dial indicator then use a feeler gauge for the extruder. Side note I have an 18 dollar ceramic heater in a closet on high during all prints (printer is in the closet) also where I store the filament. Not a true enclosure, but it’s also probably 88-95 degrees in there.

What settings are you all using for PETG?
How do I stop the jamming? I was at 255deg and 100 bed temp, and I cleaned the knurled thing, and the tensioner is at 5mm.
Is it worth it to stop using Cura and start using Slicer?
What is the firm height number the Z is supposed to be off the bed?
Has anyone hit the bed with an IR or Laser Thermometer or FLIR to see where the hot/cool spots are?
What’s the best chemical to use to clean the bed? Alcohol or Acetone?
I read about calibrating Z-Step, is there a guide on that? Or a guide for adjusting any of the other preset factory settings to try and get this thing purring?

On the mini, I use these settings for eSun PETG.

245 extruder
60 bed
45 part removal
2mm retraction

I didn’t get good layer adhesion at 225. You might try increasing the extruder temp to see if that helps with the jamming. You could have a blocked nozzle as well, but you replaced it recently. Did you tighten up all the screws? That could help with x/y issues.

I’m getting the best results with a 0.4mm first layer height, 0.1mm normal layers, at about 68% flow rate. Even after calibrating the extruder e-steps, I get significant over-extrusion. I’m working on getting taller normal layers, but I’m getting over-extrusion making vertical walls look crappy still with blobs/zits. There’s a guide from lulzbot about calibrating the e-steps. It might be worth a try to see if it’s off.

I’m using Simplify3D for most of my printing, with Cura mixed in a little here and there. I’ve never used Slicer, so I can’t say how well it works, but I would think it would be fine.

The other questions don’t really apply on the Mini, so I can’t say much there. Unless you have the PEI bed as well. For cleaning I usually just softly wipe with a scotch brite pad. Once in a while I use rubbing alcohol to clean any residues from plastics, hands, etc…

I don’t use PETG (primarily ABS), but I’ll try to fill in some of the answers to your questions:

  • You’re on the right track with the dial gauges and feelers. Quantifying the nozzle / bed height takes a lot of the guess work out of leveling the bed. I’d suggest simultaneously using two dial gauges on either side of the toolhead… with just one you’ll be chasing each corner a number of times since adjusting one affects at least the other corner if not all three.

  • From my experience, Cura is superior to Slic3r. I struggled through Slic3r before buying Simplify3D for my prior printer. It was night and day. So I continued with S3D exclusively for the TAZ. My honest opinion is that I believe Cura can be tweaked to as good or better than S3D.

  • The “firm height the Z is supposed to be off the bed” is 18.5mm for my printer. I’m guessing it will vary depending on the printed X-carrier and printed toolhead variations. Best to find your own, using the feelers… I use a business card which measures .35mm

  • Yes, a member has taken some thermal images of the bed in comparison of the glass to aluminum. I think the thread is here:
    https://forum.lulzbot.com/t/fun-with-infrared-cameras/2192/5

  • Consensus isn’t out on whether IPA or Acetone is good for the PEI. I use both sparingly, but IPA more so than Acetone… Forum members report that the chemicals don’t affect the PEI, but LB has some posts (could be deprecated) warning against the use.

  • Calibration of the extruders can be found here… specifically you’re looking for the step to calculate e-steps:
    https://ohai.lulzbot.com/group/calibration/
    The basic process is to put a mark on the filament, then manaully extrude 10mm, measure how far the mark advanced. If its not amount you requested, use the formula to calculate the proper e-steps. Use the LCD to store the new setting.

As for the jamming…

  • Don’t overtighten the idler. The hobbed bolt doesn’t need to dig into the filament. It should leave some marks to indicate that there’s enough pressure from the idler, but they should be superficial and not really deep. Teeth marks can possibly get caught in the transition from extruder, hotend plate and hotend… if things are misaligned.
  • Check the recommended extursion temps for the PETG, go a little hot with the hotend to ensure the heat is keeping up with the filament. This introduces other things like ooze which you may need to tweak retraction settings.
  • If you’ve had your TAZ for a while, you may want to check the extruder to hotend alignment… over time the screws may loosen and cause a 1-2 mm misaligment which could increase friction in the filament path.
  • Also check that the heatsink blower is functioning, make sure its blowing on the heasink. I like to pivot mine .5 - 1mm down so that it hits the heatsink end block(not the heater block). This will ensure the areas of the heatsink are kept cool to best mitigate any heat creep issues.

What settings are you all using for PETG?

Same as PLA, except: 240° for nozzle, 75° bed. Most important: No fan! Or only on parts that realy needs it. Your blocked nozzle might be due to high nozzle temp. If it gets too liquid and you print fast (high nozzle pressure), it might be squished up the thermal barrier…

How do I stop the jamming? I was at 255deg and 100 bed temp, and I cleaned the knurled thing, and the tensioner is at 5mm.

100° for bed should be far too much for PETG, it starts to soften around 80°! For jamming, see above.

Is it worth it to stop using Cura and start using Slicer?

If you have enough experience to use the advanced features, definitly yes!

What is the firm height number the Z is supposed to be off the bed?

Exactly the height of your first layer. Measure your first layer height und compare to the entered value.

What’s the best chemical to use to clean the bed? Alcohol or Acetone?

I use a spectacle cloth, I don’t know with liquid they are with but they are friendly to plastic and work realy well.

I read about calibrating Z-Step, is there a guide on that? Or a guide for adjusting any of the other preset factory settings to try and get this thing purring?

Readme

So Cura’s first layer height is supposed to be the distance you set home from the bed? Makes sense why you would use say a .005 feeler gauge, then add that to the beginning of GCode for first layer height.

Lots of good help here, recalibrated everything and went to 8mm on tensioner. It is printing much better. After some current parts print I’m going to go thru and re-tighten everything. Also I didn’t know about the fan - I’ll turn that off for the next print as well.

Y’all rock!

I think you got me wrong. You can set your nozzle height (by turning the set screw) basicaly to whatever value you want, as long as your bed is leveled. The only thing that is important is that your measured first layer height is exactly the height for the first layer you entered in your slicer. If your 1st layer height is 0.2 in Cura or whatever, your should measure around 0.18-0.22 with a caliper (near the center of the print bed). You can achieve that by turning the set screw by try and error, or you adjust it simply to something where the nozzle stops a tiny little bit above the print bed (always remeber, we are talking about bed center, not the “home all” point) and compensate with gcode Z-Offset. This version is much more precise or at last a lot quicker at same precision.

There is only one thing to remember when using Z-offset: The stock firmware limits you to positive Z-values. That means if your z-offset is -0.15mm, you can’t print first layer heights lower than 0.15mm. Why? Because if you want to print at 0.1mm for example, the first layer would start at 0.1mm - 0.15mm = -0.05mm. Marlin limits that to 0mm, which means your 1st layer has massive under extrusion.

So I had it with green PETG, white I fiddle with settings and it gets shorter prints fine. However this taller print, at 115% flow, 3.01mm dia, 238 degrees and 65 degree bed, fan off, this happened… Why would it work so well for the first few inches then screw up on everything after? The top part (it’s not supposed to be two parts) broke off it was so weak while trying to remove the bottom from the base. Still learning the signs of this just like learning the chatter on a mill…

No it can’t do base layers either - it’s eSun White PETG, my green from them I got dialed in but used the spool I’ve tried above and below 100% flow, changed to all kinds of temperatures, releveled bed, adjusted tension plus and minus, changed layer height…

Very strange, it looks like it’ fine on some spots, then the lines become thinner until the extrusion stops completely…
Whats’s you measured 1st layer height vs the intended one, at which speed are you printing this 1st layer?
Have you cleaned you print bed before this print? Sometimes I have simmilar bad spots, when I touched the build plate too much :wink:

Take a look at my thread here. I’m having some similar issues with the white PETG. https://forum.lulzbot.com/t/fun-with-petg/2814/1

I have fine first layers, and good walls, but when I get to the top layer, it drags the filament into clumps like sharp peaks.

I got it to finish a successful piece last night by slowing the top layer speed to 20mm vs default 30mm (per sec.), but it was still dropping those seemingly “burnt” chumps. Got a few peaks, but nothing like the original images show.

Still not 100%, and I’ve only printed long flat objects, not tall ones.

Still a learning curve.

P.S.

Looking at the inconsistent extrusion, have you checked that your hot end is clean inside?

Inconsistent extrusion with PLA and PETG can both be caused by either hotend barrel cooling fan failure (or partial failure) or not tight enough idler arm springs. Try adjusting the idler arm springs so that only 8mm exists between the washers on either side of the springs on both arms. If that doesn’t solve the issue, you may want to check the fan and see if it is putting out any air at all, and if it is enough. PLA in particular will tend to expand slightly and “heat lock” in the bore before the melt chamber if the bore isn’t cooled enough. Sourcing a 40mm 5 volt fan and replacing that stock fan with the barrel mount fan from the Taz 6 (http://devel.lulzbot.com/TAZ/Mangrove/production_parts/printed_parts/heatsink_fan_mangrove/) or one of the other variants in the Taz modification thread and see if that improves things.

A blocked nozzle is unlikely, because a blocked nozzle usually stays blocked. The filliament pressure doesn’t tend to release in waves like that. It can happen, and pulling the filliament when it is down around 80-120 degrees or so can sometimes remove a blockage, but all evidence to the contrary an actual blockage is extremely rare.

Starting too close to the bed, or layer lifting can cause an apparent blockage, but what happens in those cases is the bed or the part itself acts like a cap on the nozzle. It’s basically the same thing that happens if you put your thumb over a water hose.

Bad end layers can often be caused by too loose idler arms, overextrusion related blockage, or in the case of PLA or similar, heat creep bore lock on the filament due to the above mentioned cooling fan issue. I don’t know if PETG is similarly affected. Hexagon infil can also cause problems due to excess retraction. You may need to adjust the retraction settings quite a bit to get a good surface with hexagon infill, or switch to rectilinear infil which is not as problematic. There may also be other PLA tricks that I don’t know of since I don’t print it all that much.

Those small squirrel cage fans are known to provide inadequate cooling while appearing to be fully functional. I have had this problem with two units. They still spin but repeated filament jams in the cool section occur. Lulzbot replaced one of the fans and I upgraded the other printer to the Taz 6 fan config. I love the Taz 6 config. and will eventually use that setup on all the printers. It is great.

If the small fan is working properly, you should hear it buzzing a little. If it is spinning but seems to be silent, it is probably failing.

Where is this taz 6 fan? Is it using a 40mm fan in place of the tiny cage?

Yeah, the Taz 6 prototype barrel cooling fan uses a 5 volt 40mm fan. You can source them off Ebay if nothing else. The fan shroud is downloadable from the link I posted above. You also may want to grab two additional 24 volt 40mm fans and print out the Taz 6 prototype strengthened extruder carriage and Left and right fan, as that will improve your print quality with PLA for sure. Those parts are in that same directory structure. But the squirrel cage fan replacement is one of the ones I would consider a major, must do upgrade.

Awesome thanks. I’m wondering if this is an eSun issue and am going to switch back to a green spool I just ordered. I’m liking the strength of PETG over PLA but I think the signs of it failing at height would make me think the longer it’s on the more it’s heat soaked (thinking like an automotive intercooler here for a turbo) and I happen to have a 5v 40mm fan on hand.

My first spool of PETG is still in the mail so I don’t have any experiance with it or how bad the heat conduction is compared to PLA… I will say that very long prints with PLA are successful even with the stock squirrel cage fan IF the fan is operating properly. I have a mini and a Taz still running the stock fan with no issues, even in an 80 degree F room.

If you are getting heat creep, and it sounds like that might be the problem, your fan is probably wounded and not cooling properly. If I were you, my next print would be Taz6 hotend mount parts for that big fan! :slight_smile:

Let us know how it works out.

So I printed it and can not figure out where or how it mounts. Is this for the Taz 5?

It’s designed to screw into the Taz 6 X carriage. You’ll have to either make an adaptor, screw it directly into the existing carriage or extruder plastic to mount it to the existing chassis,

edit:
http://devel.lulzbot.com/TAZ/Mangrove/production_parts/printed_parts/extruder_mount_mangrove/
It goes into the right hand side hole M3 heat set insert on this carriage on the front in stock configuration.