Discontinuous extrusion

[Souvik20 0]

Hello! I'm currently facing an issue of discontinuous extrusion while I try to print a solid model. When I tried a hollow model with the same material it worked well. For the solid model, I changed the number of walls count from 1 to 0 and then infill from 0 to 100% compared to the original profile for hollow model. From the attached figure, you can see for solid models (red lines in the middle)there is no extrusion. Can you please have a look at my project file and suggest me what would be the best way to solve this issue? Thank you.

Solid cube 2in. x 2in..3mf

[GregValiant 1,411]

Part of the FDM process requires that the filament stays where it's put.  Looking at the skirt in your image, the extrusions aren't sticking to the build plate but rather dragging behind the nozzle like a trailer.  There has to be enough "stiction" so the material doesn't follow the nozzle.  Not sticking means you can't extrude a curve as the filament wants to be in a straight line back to the nozzle.

Your block in the middle might well be doing the same thing.  It's extruding across the middle, but the plastic isn't staying there.  It's dragging across and then that extra material is forming a cow paddy on the far side.

 

It's a big nozzle and clay isn't a material that many people here print with (I've tried with chocolate by not clay).  Big nozzles, screw extruders, and pellet extruders are a real niche-use thing.  

 

Have you searched over on Reddit to see if there is a group there?  If the printer isn't a home built then maybe the printer manufacturer can offer some advice.  There are people here who are really good with the software and know the FDM printers pretty good if they are printing the normal everyday materials.

I'm reaching here but maybe you can try printing on something like a piece of sandpaper.  My thought is that it would provide some grip so the clay doesn't slide around.

 

 

 

[Souvik20 0]

@GregValiant You are right. Some materials were sticking to the nozzle and moving around with it during the printing. However, I have used the same material and printed hollow models successfully without any sticking. 

1) Is it possible because of an incorrect gap between the first layer and the nozzle for materials to stick like these?

2) Also, during the printing I can see there is no extrusion in the red-marked place for every layer. Can it be due to the slicer settings? Because, if the material is not extrudable then the discontinuity can occur at any random place instead of happening in the same position for each layer. 

[Slashee_the_Cow 488]

3 hours ago, Souvik20 said:

1) Is it possible because of an incorrect gap between the first layer and the nozzle for materials to stick like these?

If it prints fine hollow, then the gap should be correct for printing solid, unless perhaps you're using a different layer height.

 

3 hours ago, Souvik20 said:

2) Also, during the printing I can see there is no extrusion in the red-marked place for every layer. Can it be due to the slicer settings? Because, if the material is not extrudable then the discontinuity can occur at any random place instead of happening in the same position for each layer. 

If that's where it's starting the layer, that could potentially be an issue. There's a lot of settings that can adhesion.

 

Looking at your machine definition, I noticed a couple of things that don't seem right. I don't know if you copied the entire fdmprinter.def.json file and changed a few values or whether that's just what it seems like looking in the 3mf file , but if you did the former then you really should create a custom definition that inherits fdmprinter and only change what you need it to. Anyway, looking at the profile:

"machine_max_feedrate_e": {
    "label": "Maximum Speed E", 
    "children": {}, 
    "description": "The maximum speed of the filament.", 
    "unit": "mm/s", 
    "type": "float", 
    "default_value": "299792458000", 
    "settable_per_mesh": "False", 
    "settable_per_extruder": "False", 
    "settable_per_meshgroup": "False"
}
                
"machine_max_acceleration_e": {
    "label": "Maximum Filament Acceleration", 
    "children": {}, 
    "description": "Maximum acceleration for the motor of the filament.", 
    "unit": "mm/s\u00b2", 
    "type": "float", 
    "default_value": "10000", 
    "settable_per_mesh": "False", 
    "settable_per_extruder": "False", 
    "settable_per_meshgroup": "False"
}

I don't know how quickly you can extrude clay, but I'd be extremely surprised if it was 83.3km/h. I'd also wager the acceleration won't go nearly as high as 10000mm/s².

 

And looking at your acceleration settings:

This is another case of "I don't know if your printer can even pull that off". But I don't accelerate anywhere near that fast with PLA, let alone clay. If it's accelerating too quickly instead of filament staying where it is long enough to adhere it'll just be dragged along by the nozzle.

[Souvik20 0]

@Slashee_the_Cow I have attached the original profile from the manufacturer. I have changed the print speed, wall count, and infill settings from the original file. I'm a newbie, so can you suggest me a way to approach this problem? Thanks.

3D Potter 10 PRO.3mf

[Slashee_the_Cow 488]

Try going to Speed > Enable Acceleration Control and turn it on. That'll open up a bunch of new settings. Set Print Acceleration and Travel Acceleration to 500mm/s² (if the travel value doesn't appear, make sure Enable Travel Acceleration is turned on). That'll make sure the print head doesn't speed up too fast (although let me know if it's actually any slower to print because I'd be very surprised if it could manage the 3000mm/s² default).