Extrusion problems

[okulo 0]

I have an Ender 6 with BL Touch which, apart from a few minor tweaking in the early days, has provided very good prints.

 

A few weeks ago, a friend asked me to print out a battery cover and it looked a bit of a mess. I was able to clean it up manually and he was happy with it but every print since then has been a mess and I have tried every suggestion I could find without success. Despite this happening without any changes to my Cura settings, I have tried making adjustments. I have recalibrated BL Touch several times and installed a new nozzle. I've tried lowering the extrusion temperature and raising it - any difference is unnoticeable. The nozzle size is set correctly in Cura and the layer height is 0.2mm. Everything on the printer feels secure and solid.

 

All my previous prints would have a near mirror finish on the bottom when removed but now, there are gaps of varying widths between print lines. layers are uneven and although I usually have ironing enabled, it isn't happening properly or when it does, the surface looks quite uneven (the enclosed photo is without ironing to show the infill.

 

I should point out that I added a PEI bed and silicone buffers which I had ordered before the problems started and installed afterwards - they have not affected anything one way or another. Also, I am mainly using Cura v 4.8.0 on a Mac Mini to preserve the environment which last produced good prints but have the same problem when using Cura v 4.13.1 on a MacBook Pro.

 

The enclosed photo shows most of the problems. This is a typical print exactly as it appears - along with all the debris. I ensure that the nozzle has no material dangling from it before a print starts but excess seems to get deposited all over the place.

 

I'd be grateful for any advice as I have practically had to give up trying to make anything of any quality.

 

 

[geert_2 558]

Have you tried a "known good" material, to see if it is the material or the printer?

 

Hard to say from the photos, but it looks a bit like it is burned? Maybe printed too hot, or wrong material setting?

 

Does your printer have a head/nozzle cooling fan? If yes, verify if that works well.

 

I don't know your printer, so this is just guessing...

[okulo 0]

Thanks for the reply.

 

I will test another filament but up to the sudden change in quality, the filament I'm currently using was a 'known good' material. The temperature is set to that on the spool, i.e. 210°C and the cooling fan appears to be working.

 

I'll try another print soon and pay particular attention to your suggestions, though - the printer is on my desk so I try to print when I don't expect to be sat next to it for long due to the noise.

[okulo 0]

I just tried a few prints with another filament and had the same problem. I checked the nozzle cooling fan when the print started and it was running but in the middle of the print, it wasn't. I checked the settings in Cura and Cooling was enabled at 100%.

[geert_2 558]

Just to make sure there is no confusion: in Ultimaker printers there are two sets of fans:

1) The nozzle cooling fan, blowing onto the upper area of the nozzle to prevent heat from creeping up into the filament. This is a little fan.

2) The model cooling fan(s), cooling the extruded filament and making sure it solidifies quickly. These are 2 somewhat bigger fans on my UM-printers.

 

I don't know if your printer has both sets of fans too?

 

I am talking about the nozzle cooling fan here, which should go on automatically, being hardware controlled, as soon as the nozzle goes above a certain temperature (40°C in UM-printers). As far as I know, there is no setting in Cura to control this, it is pure hardware. (I am not talking about the model cooling fan which you can select in Cura.)  If that nozzle cooling fan is broken, then the print would start fine, but slowly the heat would creep upwards into the filament and melt it above the nozzle, causing blockings.

 

So, if your printer has a nozzle cooling fan, and if it is broken, that might be a cause. Sometimes you can hear if the fan bearing is worn-out and going to fail, when it is making rough noises, typically a sort of "rheu-rheu-rheu" sound.

 

But there might be other reasons too.

 

[okulo 0]

There are two fans on the print head, one blows through a vent to the nozzle.

 

I'm actually just trying another print as I type and both fans are blowing so they both seem to be functioning and the gcode probably switched one off at some point when I tried previously.

 

I just read an article which said that lower print speeds could increase stringing and blobbing and I had reduced the print speed believing the opposite might be true. However, I can say now that looking at the print in progress, increasing the speed to 100mm/s from 50mm/s has not improved anything.

 

Also, I reduced the nozzle temperature from 220°C to 200°C (I'm using PLA+ and the box says 190°C to 220°C and 220°C had worked okay). That didn't make any difference to the problem I am having but also introduced the problem of poor adhesion between layers - they were easy to peel apart. I am just trying at 210°C.

[GregValiant 1,330]

I shouldn't think you would be getting all the debris from a PLA or PLA+.  PETG will collect itself on the nozzle and drop it off randomly, but not so much so fast.

Have you taken the cover off the hot end and checked for leaks where the heat break screws in, and at the nozzle?

 

For the PLA+ filament your print speed of 50 should have been fine.  I wouldn't call "50" slow.

 

I would move all the Cura settings back to what you know worked well, and then I'd take another look at the mechanicals of the printer.  That just doesn't have the look of a software problem (to me anyways).

[okulo 0]

I took the print head apart to replace the nozzle and everything looked fine to my untrained eye - there certainly wasn't any filament debris anywhere.

 

The maximum speed for the Ender 6 is 150mm/s and I think that that had been the default.

 

The problem with going back to the last working settings is that when I started using Cura, there was no built in profile for the Ender 6 and everybody seemed to use a profile created by somebody which had to be manually inserted into the application (I'm on a Mac, as I mentioned). Now Cura does have a built in profile for the Ender 6 and the 3rd party profile, which was the last version I remember using successfully has been replaced.

 

Once the 100mm/s print I was doing today which I mentioned earlier finished, it still had the debris but was at least a bit more usable than previous attempts.

 

I've posted the problem on Creality's forum as well as if it is a problem with the printer, there are probably more Ender 6 users on there.