Single Nozzle Print Setup?

[Bossler 8]

I wanted to print with just one nozzle.

Since there was PVA in number 2 I unloaded the filament and took out the 2nd printcore as well.

Guess what - I could not start a print that was sliced for just one nozzle...

 

I also recognized that the printer always seem to heat up both printcores - even when the 

printfile is using just one nozzle. While that may seem to be not a big deal, I think it is.

Because heating up the filament without extruding later on degrades the material over time 

and can easily lead to clogging over time. 

Since there are always remains, even when you did unload the filament, this might be one of the reasons
why a print head cleaning seems to be quite often needed with the UM3.

 

[kcel 11]

I noticed this as well adn it made me scratch my head a little.

 

The other oddity that can happen is if you want to print something with whatever filament you happen to have in print core 2  Cura will (by default) want to draw the skirt using both print cores.  So you need to remember to go into the custom settings and tell it that all adhesion aid items should be printed with print core 2.

 

I think there should be an option through Cura to effectively ignore a given print core and it won't try to print anything or even care if it is installed.

[kmanstudios 1,120]

As far as heating up both cores (extrapolating a bit here) it is probably to even out the temperature differential in the print head to prevent warping and other things from happening to the electronics.

 

Also, yeah, you do have to make sure that you choose the right settings so that you only use what you want as far as what gets laid down. Although I have not had it want to draw two skirts.  If I make a brim out of Extruder 1, then it will draw a priming skirt around it with Extruder 2 if it is being used, say for support.

 

By having the options of what gets drawn in there and where already, you have that ability to have either core ignored at any time.

[SandervG 1,518]

Hi, I double checked just to be sure and the second print core should be installed because without there can be a negative effect on the airflor. I assume without a print core in 'slot 2' the cooled air can escape in the opening and this can affect your heating and cooling of the print. But the second print core does not need to be operational. Therefore it also shouldn't heat up. If you think it is heating up, what firmware are you using/are you using the latest firmware? 

[Bossler 8]

19 hours ago, SandervG said:

Hi, I double checked just to be sure and the second print core should be installed because without there can be a negative effect on the airflor. I assume without a print core in 'slot 2' the cooled air can escape in the opening and this can affect your heating and cooling of the print. But the second print core does not need to be operational. Therefore it also shouldn't heat up. If you think it is heating up, what firmware are you using/are you using the latest firmware? 

 

Hi Sander,

 

thanks for the info.

 

My UM3e uses the latest stable firmware as of Jan-31-2018.
(can't check the number now since it's printing;-)

 

I can't remember the exact value right now but I have noted that at the start the printer "pre-heats" both print cores

to some temperature which is below the final print temperature (sort of standby-temp.?).

This seems to be regardless of the actual print settings (e.g. using just one nozzle) and yes,

it seems to be a function of the firmware, not from the gcode (that just heats the left nozzle in the gcode, as it should).

 

[tomnagel 123]

Both nozzles are heated before active levelling. This is because we need to squish possible plastic remains during the first probe with each nozzle. 

@Bossler, you mention "print head cleaning seems to be quite often needed with the UM3". What do you call often? Internal tests have here have shown that print cores do not clog even when not cleaned for 2000h print hours, although there is a slight build-up of yuck inside the melt channel. That is why we advise to clean the BB core every 400h. I think that is pretty reasonable.

[kmanstudios 1,120]

1 hour ago, tomnagel said:

.......Internal tests have here have shown that print cores do not clog even when not cleaned for 2000h print hours, although there is a slight build-up of yuck inside the melt channel. That is why we advise to clean the BB core every 400h. I think that is pretty reasonable.

I am going to say that would be a very best case situation. We have had a very, very dry winter, and not always using UM PVA due to cost, I ding that I have to clean it about every week to get maximum quality out of it. Also, the amount of retractions will have an impact plus overall humidity. A lot of my stuff has been very heavy on retractions lately and I have noticed it does not help a lot. And, even though there is not much moisture in the air, it is not 'desiccant dry' so there is always some moisture being absorbed.

 

Now, the AA core...yeah, that thing chugs like a champ. I could agree with a 200 - 400 hour clean up depending on material changes and such.

[Bossler 8]

3 hours ago, tomnagel said:

Both nozzles are heated before active levelling. This is because we need to squish possible plastic remains during the first probe with each nozzle. 

Ah, understood, makes sense. Thanks for the info!

 

3 hours ago, tomnagel said:

 

@Bossler, you mention "print head cleaning seems to be quite often needed with the UM3". What do you call often? Internal tests have here have shown that print cores do not clog even when not cleaned for 2000h print hours, although there is a slight build-up of yuck inside the melt channel. That is why we advise to clean the BB core every 400h. I think that is pretty reasonable.

Well, I have this printer just for one week as of today.

I have cleaned both cores three times now.

Must say that I did change filament types in between. 

So far I have used UM PLA, BioFila PLA, Taulmann Nylon and TPU95.

 

Especially the TPU95 did not extrude well before I cleaned the print core.

 

Guess it's one thing to have a printer running for 2000hrs on one type of filament but another to use different filaments for 2000hrs.

[tomnagel 123]

True that. Switching between different materials may mean extra cleaning although my personal experience is that it is not needed. Some flushing suffices. 

pro-tip: there is now a timeout on the last bit of the filament loading procedure. After you have confirmed the filament is fed into the feeder, the printer will feed the filament to the printhead and extrude slowly for a minute or so. You can leave the printer unattended, and use this time-out as a flushing procedure.

use the latest firmware, because earlier versions do not have this time-out.

 

[Bossler 8]

Thanks, Tom.

Already noticed the timeout but did not know it's a new feature - I only know the current version of the FW;-)

 

According to my experience, I would always recommend cleaning - at least with a hot pull - when switching 

to  

a) a lower temp filament or 

b) a softer filament

 

So switching from PLA to ABS w.o. cleaning should not be a problem, vice versa it could be.

[dvclabtech1 0]

So if you are not using the BB core for support, is it OK not to load that core?

[kmanstudios 1,120]

On 2/1/2018 at 8:24 AM, Bossler said:

So switching from PLA to ABS w.o. cleaning should not be a problem, vice versa it could be.

Correct.

 

8 hours ago, dvclabtech1 said:

So if you are not using the BB core for support, is it OK not to load that core?

If I remember correctly, the printhead requires that the cores be in place. But Cura will not factor it in for slicing info.