Surprise PETG failures

Sovol SV08
1

Until recently I’ve had no problems printing both PLA and PETG. PLA (last time I tried) was still printing just fine. I’ve had the printer for more than a year. I’m by no means an expert but I’ve had no difficulties until now. I was using the stock hotend that came with the printer and was freely swapping between PLA and PETG as needed. After adding the Sovol Eddy sensor I had no difficulties printing PLA. I’ve recently added the enclosure kit and after removing the lids and leaving the doors open there again have been no problems with PLA. I didn’t have an occasion to print PETG until now. Now using the same spools of PETG and profiles that used to work, now fail utterly.

PETG_fail
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Every attempt produces similar results. This was the start of a standard OrcaSlicer temperature tower. The nozzle cleaning blob and purge line always look normal as do the skirts and brims. Then a mess.

After the first few failures I switched back to PLA and it continued to print just fine. At first I suspected the filament was too wet. It had been in a ziplock bag with a small packet of desiccant. I dried it with no change.

I swapped back and forth between PLA and PETG with the same results. PLA prints fine and PETG fails. I began to suspect the filament and swapped to a different spool (dried) of the same age and brand. It still failed.

I know about the axle slipping out from the idler gear in the extruder. It appears to be in place, and the gear spins freely when the tension is released. For good measure I tightened the thumb screw a bit and checked the unloaded filament. It isn’t being ground down but does leave a little bit of an impression of the gear teeth.

Raising the extruder and just extruding filament seems to work normally.

I began to suspect the hotend and decided to swap the stock one with a hardened steel one. While doing the swap I noticed that the hole in the side of the heat block just above the temperature sensor had a little plastic that had oozed out and probably burned. I assume there’s a set screw in there holding the nozzle in. I re-calibrated the eddy sensor per the manual assuming that a hunk of hardened steel close by might screw things up. PETG still fails. I’ve read that the temperature should be increased by 10degC for hardened steel, which I did for the tower. I haven’t tried PLA with this hot end.

My last attempt as seen above was to slow the speed of the print down by 50%.

I’m currently out of ideas. Suggestions or hints will be greatly appreciated.

Thank you

2

Looking at your pic..some of that spaghetti looks thin, some looks think…
This makes me think you might have a partial clog,maybe even in the heatbrake since you switched nozzle & still have the problem.

Switching from PETG back to PLA, you really have to purge the nozzle 3 times as much to clear all the PETG out. I would use some cleaning filament if you have any or use PLA at around 265* and do a purge of at least 300mm. After maybe 100-150mm the PLA should be burning it’s way out & dripping on the bed. Once the purge is finished, load your PETG & purge around 30-50mm to clear the burnt PLA out & then try you tower again.

3

Thank you for your response.

Please forgive me if I messed up the names of the parts. Here is what I did.

PETG_fail
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The part on the left is the original supplied with the printer and what I removed. I was wondering about a partial clog in it which is why I tried swapping it out. I replaced it with what is on the right. Is the heat break not the thin tube that feeds into the heatsink? Or are you suggesting a partial clog somewhere within the heatsink I’m assuming at the top where the thin tube butts up against.

I’ll dismantle the thing again and carefully check the hole through the heatsink later.

And just to clarify I’ve not run anything but PETG through the replacement part.

I will obtain some cleaning filament for the use in future filament swaps and keep the currently installed hotend as PETG only until then. Thank you.

4

Yes, I was talking about the tube.