Random poor quality layers in large prints

[jones4642 0]

I apologize if this topic has been addressed already, but I wasn't quite sure what to search for, and didn't find anything relevant. I've been running a lot of pretty long print jobs (3 to 5 days) on a U3 and a couple of S5s, and while the majority of the parts print fine, on a significant portion there seems to be a change in feed-rate at random times through the prints, creating under-filled sections that are weak and easily break.

The parts I am printing typically use the 0.25 nozzle and are typically very low-fill parts. The first time I noticed the problem was on a large shell structure that had 4-layer walls, and was otherwise completely empty. About 2 days in, the material feed rate seemed to drop off for a couple of hours (middle of the night), leaving about a 1/2" of build height thinner than the rest. Both below and above the thin section, the print was fine. I just finished a 5 day print, and yesterday there was a similar issue with a very thin line of under-filled material. This was even a lighter construction, with 0.48mm walls (2 layers) and modeled internal structure (as opposed to partial fill).

 

It seems like there is a higher probability of seeing these defects on new rolls of material, although the latest 5-day print was on a roll that was about 1/2 used, so pretty light. I mainly print with PLA and CPE, and have experienced this on both. I have re-printed parts that have failed, and had them come out perfect, so it is definitely not an issue with the Cura file. I'm guessing that this is either an indication of defective material, but I only use Ultimaker material, or the feed mechanism. On all of them, the feed tensioner seems to be about mid scale, and we have never adjusted it. The U3 is a couple of years old, one S5 is maybe 9 months old, and the other S5 is just a few months old.

 

On the first S5, after maybe 5 or 6 months I started to see issues where the printer reported that it was out of material, when clearly it was not. After doing some research on this forum it seemed that this was a known issue, and following advice from other users we disabled the sensor. This of course means that we have to plan large prints carefully to make sure we don't run out of material. The newer S5 had this issue on the first print, so we disabled the sensor immediately. The forums suggest that this is frequently caused by using oversize spools of material, or spools not mounted in the stock position, but as mentioned, we only use Ultimaker material, and only on the built in mount.

 

Any advice, suggestions would be much appreciated, as seeing a print fail 4 days in is pretty disappointing, in particular when it is on a $6k machine.

[Carla_Birch 116]

The sensor works fine, long you have the latest firmware installed. The problem is likely down to not having the right tension set on the feeder on the back of the printer, you adjust it with the little bolt that you can access via the small hole on top of each feeder.

 

Also be sure to clean the feeder out from time to time and also the print core's. If the filament slips at any point due to wrong tension or a part blockage you grind a part of the filament away in the feeder and it will be unable to feed and so the sensor will give the error that the filament as run out because it's stopped feeding. If the tension is to loose its far more easy for the feeder to slip and not feed the filament and so giving the error.

[jones4642 0]

Just now, Carla_Birch said:

The sensor works fine, long you have the latest firmware installed. The problem is likely down to not having the right tension set on the feeder on the back of the printer, you adjust it with the little bolt that you can access via the small hole on top of each feeder.

 

Also be sure to clean the feeder out from time to time and also the print core's. If the filament slips at any point due to wrong tension or a part blockage you grind a part of the filament away in the feeder and it will be unable to feed and so the sensor will give the error that the filament as run out because it's stopped feeding. If the tension is to loose its far more easy for the feeder to slip and not feed the filament and so giving the error.

Thanks for the feedback. I'll check FW versions. One of the S5s is only a few months old, so I would think newer FW, but perhaps it sat on the shelves for a while before we bought it.

 

Looking at the tensioning gages, they seem to be about in the middle of the slot. Should we just crank them up higher? Is there such a think as too high? If so, how do we know when we hit that?

 

With regard to nozzle blockage, what's the test/treatment for that - or perhaps this is answered in the FAQ.

[Carla_Birch 116]

23 hours ago, jones4642 said:

Thanks for the feedback. I'll check FW versions. One of the S5s is only a few months old, so I would think newer FW, but perhaps it sat on the shelves for a while before we bought it.

 

Looking at the tensioning gages, they seem to be about in the middle of the slot. Should we just crank them up higher? Is there such a think as too high? If so, how do we know when we hit that?

 

With regard to nozzle blockage, what's the test/treatment for that - or perhaps this is answered in the FAQ.

 

You can go to tight with the tension and it will show because it will big indents in the filament, most the time it only needs a small turn to tighten it up to stop any small slips that will set off the filament sensor warning.

 

As for nozzle blockage its best to just get some the cleaning rods and run the nozzle clean via the menu, i do mine about every 3 . months and my S5 is running almost none stop.