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Why is this print failing?  

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paul.a13
(@paul-a13)
Eminent Member
Why is this print failing?

Tried to print this Dire Wolf miniature ( https://www.shapeways.com/product/S324M3VL4/dire-wolf ) twice now, and both times it has failed in the same way. The base is fine, but once it starts on the legs and supports there are problems. It gets a couple of mm up and then the printer starts missing spots. Eventually there are only a few parts actually being printed, the rest it's trying to print into thin air. Then it all goes in the same way, the nozzle moving around, trying to do its job, but printing on nothing.

Why would this be happening? I'm guessing that it's because the print areas are so small, but how can I get around this? Should I increase or decrease speed? Change temperature? Something else?

Would love to understand why it's failing and how to fix it!

Napsal : 04/07/2018 10:03 am
Asraff Amzani
(@asraff-amzani)
Estimable Member
Re: Why is this print failing?

It looked like underextrusion or you might have a bad filament, try different filament and print, see how well it goes

Napsal : 04/07/2018 10:53 am
paul.a13
(@paul-a13)
Eminent Member
Topic starter answered:
Re: Why is this print failing?

The filament worked fine for other prints. If it's underextrusion do I just fix that using the flow rate?

Napsal : 04/07/2018 11:13 am
alejo.v2
(@alejo-v2)
Eminent Member
Re: Why is this print failing?

Maybe try generating the Gcode again, it may solve the problem. Sometimes I experienced that the slicers do not generate the gcode well. Try that and let me know the news.
Good luck!

Napsal : 04/07/2018 2:13 pm
paul.a13
(@paul-a13)
Eminent Member
Topic starter answered:
Re: Why is this print failing?

THanks for the suggestion, but unfortunately it didn't work. Tried in Cura and Slic3r. THing is, the same is happening every time I try a similar model. Went for a badger, the base was fine, but it failed in the same way just a couple of mm up the legs. Exactly the same happened with a bull. Also tried a calibration model which involved some 2mm diameter pillars - exactly the same happened to them, after a very short while the printer fails to deposit a layer and proceeds to print in thin air.

This is driving me nuts now! I've tried changing hot end temps, flow rate and Z-axis calibration. Nothing seems to work. Do you think the issue could be insufficient cooling time? I set print speed to 25mm/s, going up to 60mm/s for infill. Should I set a minimun layer time? Also, would it be advisable to set up a small USB fan at the side of the buildplate for extra cooling?

Napsal : 05/07/2018 8:22 am
JoanTabb
(@joantabb)
Veteran Member Moderator
Re: Why is this print failing?

Could you try 0 retraction?

Regards Joan

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Napsal : 05/07/2018 9:38 am
paul.a13
(@paul-a13)
Eminent Member
Topic starter answered:
Re: Why is this print failing?

I'll give that a try Joan, thanks. Got another print running right now, successfully so far, but will try after that.

Napsal : 05/07/2018 9:49 am
Protoncek
(@protoncek)
Reputable Member
Re: Why is this print failing?

It looks very similar as my problem HERE. Do you experience filament clogs?

Napsal : 05/07/2018 10:08 am
paul.a13
(@paul-a13)
Eminent Member
Topic starter answered:
Re: Why is this print failing?

Well, now I've broken my printer.


It looks very similar as my problem HERE. Do you experience filament clogs?

Yeah, I did experience a couple of clogs. I tried to take off the nozzle as recommended in that thread you linked. Pliers on the hot end to keep it from twisting. Wrench on the nozzle. The pliers managed to rip off the wires to the thermistor so now I get MINTEMP error all the time. I'm no electrician, can't put that back together. Have to order another hot end from Prusa, hope it arrives before I go on holiday, and take it all apart so I can fix it.

Can't tell you how discouraged I am right now. Had a few highs from good prints, then fail after fail, and now this due to my carelessness. Gutted. Maybe I can put it back together and pass it on to one of my friends who might be able to do this stuff better than me 🙁

Napsal : 05/07/2018 12:57 pm
Protoncek
(@protoncek)
Reputable Member
Re: Why is this print failing?

Uff...it's sad to hear this... (BTW...i rather use wrench instead pliers to hold hotend, but i guess it's too late to be smart now...)
I guess that thermistor would be hard to fix even if you would be electrician, since wire is probably broken right at the element itself. Ask Prusa if you can get only thermistor or lower part of extruder (just aluminium hotend with sensors) for replacement.

Regarding broken prints: i'm back on FW3.2.1 now and yet to see if it is the cause. So far my prints are ok, but it will take several prints to see if FW is the cause...

Napsal : 05/07/2018 3:28 pm
paul.a13
(@paul-a13)
Eminent Member
Topic starter answered:
Re: Why is this print failing?

I noticed you could buy just the thermistor, but on trying to remove my damaged one I encountered a problem. I successfully released the grub screw holding it in place but I could not remove the thermistor from the block. No matter how much I pushed it would move even slightly. Totally blocked. Also, I still could not make the nozzle move at all. So I ended up ordering the complete hot end uinit - could have just got the lower part and thermistor but right now I'm playing it safe.

I'll be interested to hear how your continuiong experiment with FW3.2.1 goes, maybe something for me to look into once the new part arrives.

For what it's worth, I'm looking at this as a learning experience now. I know to be more patient and careful with the machine for sure. I know that it will have issues and that I need to fully research them before wading in. Mostly just learned that I have a LOT to learn! I think I tried to run before I could walk with the prints I was trying. There's no rush, I'll slow it down and learn all the basics first before I step up to more complicated pieces.

Thanks for your feedback, really appreciate it.

Napsal : 06/07/2018 2:02 am
Protoncek
(@protoncek)
Reputable Member
Re: Why is this print failing?

I just went through forum and found (not so old) threads about guys have exactly same problem as me, so it really seems that problem is too hot extruder motor, since some of guys put heatsink or fan on this motor. Check out THIS thread, you'll find adapter for extra fan there, too. I'm printing it as we speek...

Napsal : 06/07/2018 3:19 pm
alejo.v2
(@alejo-v2)
Eminent Member
Re: Why is this print failing?

Don´t worry, when you fix that thermistor, the printer will work perfectly for a long time. I have experienced the same, my printer broke up, thermistors , heaters , and all the calibration , all was destroyed. I had to disarm it and reassemble it from 0. It´s a lot of work but at the end, my printer works perfectly, even better than before, for several months. Don´t worry and keep printing!
And with your main problem, look if your layer fan cooler is too high and cool the piece and nozzle lot.
Good luck and don´t be disappointed!

Napsal : 10/07/2018 9:26 pm
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