Stringing mystery

[jens3 11]

I don't know if this belongs here or not but I got to start somewhere ....

 

I have two Creality CR10S printers. One is the standard 'S' model and one is the much larger S5 model.

The smaller printer uses a standard Creality controller and the hotend has been upgraded to a Micro Swiss hotend.

The larger printer only uses the mechanics from Creality - it has a Duet WiFi controller and uses an E3d clone Chimera hot end.

 

The problem - I am getting a lot of stringing on the S5 and I am running out of things to check.

I spent hours messing with retraction settings and everything else I could think of with no improvement.

I am using Cura as a slicer for both printers. I am also using the same stringing test object from Thingiverse.

I finally copied all profile parameters from the small printer that prints with minimal stringing to the large printer with no reduction in stringing.

Having tried everything I could think of, I decided that the only other major difference between the two printers was the length of the bowden tube. I installed a tube of the same length as was in the CR10-5S in the smaller printer. The end result was that the smaller printer with the longer bowden tube showed a tiny amount more stringing but it was really insignificant.

 

At this point I am grasping at straws .... could the fact that one printer uses a Creality controller and the other is a Duet controller cause a difference ? The Creality controller uses Marlin, the Duet controller uses RepRap. Does Cura generated gcode differ significantly between RepRap and Marlin ?

 

I have messed around with nozzle temperatures both lower and higher (from 180 to 225) with very little change.

Can anyone suggest something I could try to figure out why the larger printer is stringing badly ?

[obewan 37]

Not sure if reprap gcode is different, but if you go into manage printers/machine settings  there is a option to choose the gcode flavour.

 

[jens3 11]

I don't understand what you are saying. The Duet speaks RepRap and the Creality speaks Marlin. If I choose Marlin gcode and send that to the Duet, isn't it like sending French to someone who only speaks English ? The French content may be identical to the English content but it would not be understood by the English speaking person.

[jens3 11]

I would like to add that I am continuing to search for the magic configuration that will work but I am seeking to understand why, with the same settings, one printer produces a nice print and the second printer produces all kinds of stringing.

What makes one printer string and another not string? Is it the luck of the draw? Let's say that I had two identical printers .... is it reasonable to expect them to print identical given identical settings or is the nature of the beast such that two physically different printers may print the same but also may be completely different (in which case I can understand what is happening).

I would also like to add that there are two rolls of filament involved .... but they are the same brand, the same color and received at the same time so I excluded the filament as a source of the issue. Maybe I need to explore that side of things more .....

Late edit: both rolls are from the same production batch

 

Edited July 22, 2019 by jens3

[ahoeben 1,981]

I have experience with neither printer, but I think the difference in hotends could explain the difference. Due to differences in temperature sensors, conductivity between the heater and the nozzle, insulation of the nozzle, etc, the temperatures of the molten material could be different. Hotter material means more stringing, because the material is more oozy at hotter temperatures. The geometry of the hot zone could also play a role; I can imagine that if the hot zone is bigger, there is more molten material being pulled down by gravity so more material oozes out. That would suggest you would need more retraction in the stringy printer.

[jens3 11]

Thank you for your input Ahoeben! I agree that different hot ends produce different results. Initially I had an E3D Volcano mounted on the stringy printer and, just like you mentioned, I thought that the extra volume of molten filament would possibly produce more oozing. That is why I changed to a regular E3D (clone) hot end. The heat block and the nozzle volume appear to be more or less identical to the Micro Swiss mounted on the non-stringing printer. Of course the heat sink of the non stringing printer is much smaller than the Chimera heatsink that is normally expected to cool two hot ends.

I agree, there are some differences in the hot end between printers. Question now is 'is it worthwhile to pull the Chimera hotend and replace it with a Micro Swiss hotend to trace the issue further?'

What is your opinion on the hypothetical question of two identical printers with the same controllers and same hotends - is it reasonable to assume that given the same settings they would print the same or do you feel that each printer is an 'individual' with it's own quirks?

 

[jens3 11]

Just to close this thread out, I determined that replacing the hot end with a Micro Swiss hotend was not practical as I am using a piezo z sensor and would have to design and print new mounting hardware for it and re-tune everything.

I am now doing many many prints and also printing out the settings for those prints. When each print is done it is taped to the sheet with the settings on it.

I found that when I was doing this in a more casual manner (without recording settings) I was getting myself more confused rather than figuring out what works. Hopefully, doing the systematic approach will get me to where I want to go.

 

Thanks again !