Prints end up "printing in air"

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Jeff0042
Posts: 21
Joined: Tue Mar 24, 2015 10:18 pm

Prints end up "printing in air"

Post by Jeff0042 » Sat Jul 28, 2018 5:14 pm

I'm running into an issue printing... I haven't seen this type of issue ever reported (anywhere) and I'm stumped as to what the issue is.

I'm printing in PLA on my Taz 4 (I upgraded the bed to the new PEI sheet, but the nozzle is the original (not the all-metal one) and the firmware is still the same (4.1 I think)). Lately when I print, after an hour or so into printing I'll check on the print... the head will still be moving, the print it still attached to the print bead, and everything will seem normal, except the nozzle isn't dispensing any filament (event though the filament gears are moving)

Here are some recent prints
IMG_0181.jpg
IMG_0182.jpg
You can see that at the top where it fails there are wisps.

From this image you mighty infer that the issue has to do with the z-axis, but I don't think the z-axis is the case - other failed prints have failed at different heights.
IMG_0183.jpg

I think the issue might have something to do with the gears chewing up the filament - after a print fails, I've removed filament form the hot end, and noticed that its been chewed up.
IMG_0164.jpg
IMG_0164 copy.jpg
I thought the issue might have something with retraction, so I created a simple block, printed it w/no infill (this resulted in no retractions), yet the print still failed (and at the same height)
IMG_0184.jpg
It almost seems that the nozzle gums up and prevent the filament from being extruded, yet, when I remove filament from the hot end, clip the chewed-up end off, and then put the filament back it, it's able to extrude.

I've tried printing w/Cura as well as Simplify 3D but I get the same results. Any suggestions as to what the issue is? Or how to trouble shoot it?

Thanks,

Jeff

Jeff0042
Posts: 21
Joined: Tue Mar 24, 2015 10:18 pm

Re: Prints end up "printing in air"

Post by Jeff0042 » Sat Jul 28, 2018 5:31 pm

I may have posted too soon... I just read a few posts underneath mine a posting from JRAlvarez ("Filament grinding") and it looks like he's experiencing a similar problem.

Here's some more information on my situation though:
* The filament is PLA and is quality filament from MatterHackers (and the clear/white roll I'm printing with is new)
* I'm printing at 195 nozzle and 65 bed. MatterHackers recommends 205 +/- 15. I've tried 195 and 205.
* I am printing in a closed enclosure. I haven't checked in a while, and I forget the actual temp, but it's warmed up (been printing for several hours) it gets up to 50 C (not sure though... I'm going off memory here)
* I do run with the fan on (the stock Taz 4 fan). I've tried 40%, 80%, and 100% fan speed, and each time the results were the same (no difference)

kmanley57
Posts: 1072
Joined: Sun Feb 01, 2015 3:53 pm

Re: Prints end up "printing in air"

Post by kmanley57 » Sat Jul 28, 2018 6:57 pm

The Budaschozzle is a passively air cooled extruder and may need more cooling then you have. Try opening the enclosure and let more cool air in, and see if that helps. There was a fan duct on Thingiverse that redirected some of the cooling fan to the fins on the cold end that might help your problem.
I will express my CRAZY ideas at any time! So you have been warned. None of my opinions are Lulzbots and can be wrong at any second.

Jeff0042
Posts: 21
Joined: Tue Mar 24, 2015 10:18 pm

Re: Prints end up "printing in air"

Post by Jeff0042 » Sun Jul 29, 2018 8:15 pm

Thanks kmanley57, that was the issue. My printer is inside an enclosure I build, and this morning I removed the top and front panel. I printed one successful print this morning, and I'm 3/4 the way through another. I'm still using the stock fan that came w/my Taz 4... I searched thingiverse and this fan looks promising https://www.thingiverse.com/thing:431185

Thanks again!

Jeff

Brent.I
Aleph Objects | LulzBot
Posts: 419
Joined: Mon Jan 20, 2014 8:21 am

Re: Prints end up "printing in air"

Post by Brent.I » Mon Jul 30, 2018 7:13 am

Jeff0042 wrote:
Sun Jul 29, 2018 8:15 pm
I searched thingiverse and this fan looks promising
This is the fan we used to recommend a switch to for the TAZ 4 Budaschnozzle when printing PLA: https://www.thingiverse.com/thing:374906 It should swap in without additional hardware, and we recommended keeping the fan ot at 100% except for the first layer or two to help with heat creep. We hope this helps!

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