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July 26, 2018
With the use of low quality filaments or intense feeding, after a while a clogging of the extruder may occur. Below we are going to detail several cases in which a filament clogging may occur. However, in the case of a clogging, we should first test if the problem is a simple clogging. To check this we must overheat the filament and extrude to see if it is released.
To overheat we heat the extruder to:
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If the printer is left in hot standby with a temperature relatively higher than necessary according to the filament used, then there is a risk that the filament will be heated by induction in the "cold" part of the extruder (the upper part), therefore the filament will widen producing a jam.
Ex: We leave the printer on standby with the extruder at 230º C but we are using PLA, which has a reference temperature of 200º C.
The standard filament diameter is 1.75 mm. If there is a factory error in the filament diameter, the filament will not pass through the extruder (in the case of being larger than 1.75 mm), therefore it breaks or gets stuck in the machine.
If the user neglects the tip of the filament when handling the spool, there is a risk that the tip will go under one of the turns and generate a knot. This will run as the printing starts and if not caught in time, then once running it will jam.
If too much shrinkage occurs, filament is heated where it should not be, it will widen and clog (this is defined in the print parameters). The shrinkage values are different depending on the 3D printer. In the case of the Printbox range, the optimum value is to retract 0.7mm at a speed of 25mm/s.
The normal printing speed is around 60/70 mm/s. If I increase it, I must also increase the temperature because the higher the speed, the higher the temperature must be for the filament to melt in time. Although 3D printers in general can make faster movements, what limits the printing speed is the fluidity of the filament. The symptom of this lack of temperature (or too high speed) is the step jump made by the extruder motor. If we notice that the toothed wheel that introduces filament makes abrupt jumps backwards and the extruder motor makes"tick tick tick tick" noises then we need to decrease speed or increase temperature to increase the flow.
The reference printing temperatures are those of PLA (200º C) and ABS (230º C). However when setting the printing parameters we need to think in terms of the requested flow to vary these temperatures in a range of about +/- 10º C.
The main variables affecting flow are:
The hotend fan must be on when the printer is turned on, because if it is off the heatsink heats up. The metal body requires a ventilation system to be on at all times, as it can overheat.
When we print we must make sure we are doing it at the right temperature. If the material used is PLA we must operate at a temperature of 180ºC, in the case of ABS or FLEX 230ºC. These are reference stand by temperatures.
Once the temperature is assured, we proceed to remove the seal that holds the cables in position.
Unplug the motor plug from the extruder, squeezing it from the sides.
Using the M4 Allen wrench, remove the two screws, one on the left and one on the right, from below
Then we disassemble the whole mechanism to see the Teflon tube. This way we can see the filament that is finished.
In case it has jammed, we pull with a tweezers from the Teflon tube and force it out and pull out the whole core, filament and tube together.
Once the filament is removed, we put the Teflon tube back in place.
We put the mechanism that we disassembled in step 4 and place the two screws.
We reconnect the plug to the motor of the extruder.
With a seal we put the wires back in position.
We verify that the filament flows.
