Prints Failing: Melt Zone Travelling?
Hi Printers,
Re: Prints failing after a good start
Amateur printer here be gentle:
I am having this issue a lot, and I am not sure what is causing it. The print starts off fine, bed adhesion is fine and it completes somewhere between 20 and 50 % of a new small print and then you start to see the new filament on the print turn to what looks like small balls, putter out and stop.
The printer then keeps going and no more filament comes out. See attached pictures for examples of failed prints. So when I find the printer at least I am not wasting filament but the prints fail.
I stop the print, preheat the nozzle to the required temp and the use the load filament function to see if the nozzle is clogged and the filament comes through fine? So no clogged nozzle.
I thought it was a problem with moist filament. So I went out and bought and modified a dehumidifier for drying my filament. Dried a roll for 1.5 hours at 50 degrees and then tried again, same result.
I guess it is a problem where the melt zone progressively travels up the hot end and then causes the print to fail?
This printer has worked well in the past. So am wondering what is causing this. My thoughts
- Dusty filament
- Melt zone travel
- Hot end too hot / insufficient hot end cooling
- Moist filment
- Dust / material in the Bowden tube
Historically I have replaced the complete hot end and nozzle and the nozzle and thermostat holder part. Since then some of my prints have worked well. But now I have this problem almost every print.
Printer: Prusa i3mk2s
Material: PLA Silver from Prusa
Print Temp: Standard recommended Nozzle: 215, bed 55
Many thanks for any tips!
Cheers
Benjamin
Re: Prints Failing: Melt Zone Travelling?
Hi,
I assume that the distance to Z is not correctly adjusted. The first 10 mm to 20 mm works quite well. However, with each additional layer, the inaccuracy increases. But that's just my guess.
I would recommend reducing the distance to Z a little bit but before you maybe try this:
https://shop.prusa3d.com/forum/assembly-and-first-prints-troubleshooting-f62/life-adjust-z-my-way-t2981.html
I hope I could help,
cheers
Mario
Re: Prints Failing: Melt Zone Travelling?
Do you get the same problem if you print another model?
Have you tried something from the SD card?
Maybe the model is a bit problematic.
---
Gert
Re: Prints Failing: Melt Zone Travelling?
I was having this same problem with my MK2 and Prusa's silver PLA. It drove me crazy, and the worst part was that I eventually found that the silver PLA was part of the issue. None of my other PLA from other companies had the same issue. In my case, it was heat creep, but that silver is extremely susceptible to the issue. The filament stops because a ball forms at the throat of the heat break, which can't be pushed down far enough to re-melt and jams the filament. Once that blob is clipped, it prints like new.
In my case, it was likely due to a replacement heat break I used. The dual-threaded piece that connects the heat block to the cooling fins bent while I was doing some work on the hotend, so I swapped it out with a new one. However, I didn't have any thermal paste to apply to the part that threaded into the cooling fins half. That kept more heat in the throat for longer, and was causing my problem.
I bought some thermal paste and liberally applied it to the cooling half of the threads, reassembled everything, and it's been printing fine ever since. If you've been using your printer a lot, it's possible some of that paste has broken down, and it might work better by replacing it with new. That's just what worked for me though. I've read several posts in the forum here with others having the same issue with the silver PLA from Prusa. In some cases it was setting the temp too high during printing, in others it was the hotend thermister being loose and not reporting the true temperature of the nozzle. I also use silicone socks on my setup, which does retain more heat than without, so it was also a minor factor.
Hope some of that helps! It was definitely frustrating for me when I went through it, so I feel your pain!