# Extruder problem

When I am trying to print something on my home made 3D printer, I can print the first and second layer, then the Bowden extruder's gear starts slipping; it cannot push the filament anymore,the gear is turning but slipping; the filament cannot go forward.

I tried all configurations of the tightening screw of the spring, corrected PID settings, cleaned the nozzle, tried with 200 °C up to 215 °C (I am using PLA) but no result.

I am wondering whether this is related to speed, feedrate and acceleration settings. The Slic3r puts automatically a feedrate as F1800, is this too high ? Do I have to change it every time I slice something? I might proceed with trial and error method but I need a more rational method.

Any suggestions?

The slicer I use (Slic3r) puts F1800 as speed. Is this too high ? Could this be a reason for the filament to slip ?

My filament's diameter is 1.75 mm. In the G-code file created by my slicer (Slic3r), the flows are shown as follows:

; external perimeters extrusion width = 0.44mm (4.25mm^3/s)
; perimeters extrusion width = 0.42mm (8.02mm^3/s)
; infill extrusion width = 0.42mm (10.69mm^3/s)
; solid infill extrusion width = 0.42mm (2.67mm^3/s)
; top infill extrusion width = 0.42mm (2.00mm^3/s)
; support material extrusion width = 0.44mm (8.50mm^3/s)

• Welcome to 3D Printing.SE! This could possibly be a retraction problem, please share some of your settings of the slicer with us by edit of your question (print speed, retraction speed, layer thickness, etc.). See this template topic for information. – 0scar Jul 5 '19 at 6:04
• Probably you haven't installed a cooling system for the extruder – Fernando Baltazar Jul 10 '19 at 0:14
• :) The rational method is what you learn in the initial settings. Once you have calibrated your printer vs filament so you don't need to change parameters again. – Fernando Baltazar Jul 10 '19 at 0:18

The PLA isn't advancing as fast as the gcode requires. Since you've already tried higher temperatures, try printing at half the speed (F value). If that works, try 3/4 of the original F value, etc., until you find the best feed rate at this temperature for your material, printer, and model.

Feeding Too Fast?

The feed rate required of the extruder is related to the volume per second divided by the cross-sectional area of the filament. The Fxxxx number is not the filament feed rate directly, but is the linear motion rate for the nozzle.

The F1800 corresponds to a motion of 1800mm/min, of 30mm/sec. This is reasonable but could be made slower by changing the slic3r settings.

Units Set to mm?

Check that the g-code is specifying millimeters (mm) as the basic unit. There should be a G21 in the g-code to do set units to mm. If not present, add it to the "Custom G-code" section in the "printer parameters" for the start of a job.

Retraction Heating the Heat Break?

To eliminate the possibility of retraction bringing the heat up into the heat-break, try turning off all retraction. The print will be stringy, but this is trying to solve the problem, not yet to optimize the print.

Jam in the Heat Break or Cold End?

When the filament stops extruding, is it jammed tightly into extruder assembly?

With the extruder hot, is it difficult to pull out the filament?

If so, you may have heat creeping into the heat break, which should be cooled by the cold end and possibly a heat sink. Do you have air flowing over the cold-end and the heat-break? If you are getting heat-break or cold-end jams, the cooling is not adequate.

Heater Problem?

Is the heater heating well enough?

Is heat being transferred into the filament?

How big is your test object for which the first two layers print well? If the object is small, plastic that is already molten in the nozzle may be sufficient for the first two layers.

If you are using something like Repetier Host to control the printer over USB, you can see a graph of thermister temperature, which should not drop more than a few degrees when printing starts. If the temperature is dropping more than 5°C, there may be a heating problem.

If there is a heating problem, it could be anywhere in the energy chain, from the power supply, wiring, FET switch, PID settings, bad heater cartridge, and high thermal resistance between heater cartridge and the hot end.

I had such effects and fixed it by reducing the flow. It might be that your filament is thicker than it should be. Therefore too much filament ends up in the nozzle. Once the molten filament accumulates enough to rise to the cold end of the hot end it solidifies and nothing moves anymore -> clicking.

So either try to go with the Flow from 100% down to 96% or change the Filament width setting of the slicer. Both will have the same result of g-Codes that push less plastic. If you see under extrusion then you overdid it.

• One should (when possible) use calipers at random locations to establish how uniform the filament thickness is, and how close to the advertised value it is. For example, some filaments advertised as 3mm are nominally 2.85mm. – Davo Jul 10 '19 at 19:09