What are the reasons for my 3D prints having large numbers of strings between parts of a layer?

hexafraction
  • What are the reasons for my 3D prints having large numbers of strings between parts of a layer? hexafraction

    I am printing a print using PLA on a Prusa i3 printer and an MK8 extruder, at 210 degrees celsius, 60 mm/sec, sliced with slic3r. The print consists of a base, with 4 tower-like projections that then join with a near-vertical overhang slope that isn't posing a problem for my printer.

    However, even before the overhang begins, I am getting large amounts of strings as the extruder head jumps between the four towers in the print, leading to a "spiderweb" effect between them. How can I deal with these strings, and are they a warning that there might be something amiss with my printer, or possible other failures in other parts of the print?

  • Stringing is often a result of too-high a temperature, or insufficient retraction. When there is highly liquid filament in the nozzle tip, it can adhere to the remainder of the print while dripping as the nozzle moves, leading to a thin string of the filament forming. As further travel moves are performed in each layer, this turns to a web.

    The high temperature causes filament to be very liquid, causing it to move downward in the nozzle chamber easily, as opposed to having to be extruded forcefully due to viscosity. The temperature setpoint of 210 was high enough to cause this to happen.

    A second possible cause, insufficient retraction, can also be blamed for this issue. Retraction is a process in which the extruder reverses its movement to pull filament back up the hotend, preventing it from dripping at the tip, and forming a string. Most slicers will allow specifying a numeric value in millimeters of filament to be retracted. Remember that printers with Bowden tubes between nozzle/hotend and extruder motor will require increased retraction and priming (extrusion when starting to print after a retract-and-move). Note that too much retraction can cause other problems, such as insufficient plastic in the hotend chamber at the start of the next printing move, which can cause gaps and other issues.

  • Here's just a few of the things you might want to look into.

    • plastic - some plastic types are more stringy than others and there's also variation between brands and colors.
    • moisture in filament - water turning to steam tends to cause the extruder to ooze when it isn't printing, which can cause stringing.
    • temperature - too hot or too cold can cause stringiness.
    • retraction distance - not enough retraction can leave some nozzle pressure, causing it to ooze during travel moves (not sure how much retraction speed matters but I suspect it can make a difference too).
    • acceleration - if it's too slow it's more likely to draw out strings.
    • travel speed - faster travel speeds are more likely to prevent strings or make them thinner and less of a problem.
    • z-hop - raising the extruder on travel moves makes stringing more likely.
    • wipe - a longer wipe distance can be helpful to reduce stringing, especially with some of the more stringy filaments.
    • combing - avoiding passing over open spaces can reduce stringing in some cases
    • part cooling fan - more cooling might help to reduce stringiness.

    There are other things too, the extruder design makes a big difference with longer bowden tubes being more challenging to tune. The order in which the layers are printed can make a difference too in some more specialized cases.

Tags
quality fdm pla extrusion
Related questions and answers
  • A few weeks ago a shift between layers in the y-direction (from the front to the back of the printer) of my Makerbot Replicator 2 appeared. All prints have some small shifts between layers, but if the extruder has to move large distances (e.g. when I print the same object near the front and near the back of the print bed), they can reach up to 2 cm or so. In those cases the extruder seem... of the shifted layers are quite reproducible. From what I understand problems such as these along the x-axis, are generally caused by broken cables, which are pressed upon as the extruder moves

  • of taking the material in spool form. My aim is to build a 3d printer which can take materials either in the form of pellets or any other shape. The materials that I want to work with are COC(Cyclic olefin copolymer) and polycarbonates.I have these materials in pellets so need to design an extruder and hot end setup which can directly use these and print . currently I have a Lulzbot Kittaz 3d printer with a single extruder( hexagonal end). Any suggestions where should I start?

  • I am looking to others who have successfully printed in ABS using a Wanhao Duplicator I3. I have tried and get a lot of warping and delamination. I tried putting a large box over the printer which did help with the warping some but I am still getting some layer seperation. I used 235 for the extruder and 100 for the bed. I am printing at 40 mm/s and .2 layer height. If someone has ABS and PETG settings for this printer, your help would be appreciated. Thanks, Bill

  • I am planning on building a large enclosed (Cartesian XY-Head) 3d printer. I want to keep the inital build time minimal and it is very likely I would need to build the ~50x50cm heatbed from scratch, because it doesn't exist in ebay. The enclosure itself is not separately heated, but depends on waste heat from the printing process. The enclosure will eventually be vented outdoors with a 12V CPU vent via ducting (air flow unknown). Do I even need a heated print bed, when I am planning to only print PLA?

  • the "goal" temperature. This results in a failed print, with the filament sticking to the extruder in a clump. What is going on here? I am trying PLA with the same file, and it seems to work fine...I have just got a Monoprice Maker Select 3d printer (which is really just a Wanhao Duplicator i3). I want to print a model that came on the included SD card (1.gcode) with ABS filament. I first press "Preheat ABS" and wait for the display to show the correct temperatures, 245°C for the extruder and 90°C for the print bed. Then, I mount the SD card and select the file to print. However, once I

  • I have a HE3D Prusa XI3 Specs are linked here. Its came with a MK8 Extruder, and I ordered the 0.3mm nozzle with it. I have Repetier v.91 loaded onto the printer right now, and Repetier-Host v1.5.4 on my computer. I have been able to print the test object that came on the SD with ok quality but when I switch to using the computer it just doesn't work at all. It starts up and heats the bed and extruder then zeros out the axis. After coming to temp which I set to 192c for the PLA plastic and bed temp of 60-65c it tries to print. Now comes my problem. It acts as if not enough plastic is being

  • Suppose I want to to print several copies of a large, flat object, such as a hollow frame. If I make an STL file consisting of several copies floating just above each other then my 3D printer's software happily generates supports for the upper objects to sit on, as shown below: My question is, is this a crazy idea? If it will work it seems it has several advantages. I can print more copies at once than if I tried to fit them next to each other on the platform, and if one of the prints fails the ones below it will still be OK. It doesn't take that much more filament than printing them all

  • Suddenly, my printer has started producing prints that have a very pronounced layering. Normally, the alignment between layers is very good, and the prints look very smooth. Suddenly, the prints have become much worse and the layers are misaligned with respect to each other. The part on the left is my "normal" quality, while the part on the right show the deterioration. Here is another picture (in which the good part is on the right): The parts are both printed with 0.1mm layer height, and identical slicer settings/filament. I am printing on a custom-built FDM printer; the mechanism

  • I am new to 3D printing and I am assembling/calibrating an ulmaker original + for my college. I am done with all the assembling and the printer works fine except for one thing. The print bed moves way up. It touches the extruder and pushes it upwards. So, the extruder cannot extrude any material. I tried to set the Z axis value before string the print but as soon as I start the print the platform just moves up and blocks the extruder. Please let me know if you need any more information from my side.

Data information