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Extruder

The Extruder tab looks like the following:

 

Extruder List

What is this?
This section lists all of the extruders you have on your printer, and is generally a "set it and forget it" setting. For the AON-M, you'll have 2 labelled "T0/Left Extruder" and "T1/Right Extruder" corresponding to the Left and Right extruders when looking at the printer from the front.

How do I use it?
By selecting one of the extruders, you can assign different settings to each. For example if you had different nozzle sizes installed on each toolhead, you would adjust the settings under Overview accordingly. If you were using different materials for each toolhead, you would input Ooze Control settings appropriate to that material.

Why does the numbering start at 0 and not 1?
This is a carryover from the CNC world where the numbering convention typically starts at 0. 

 

 

Overview

Extruder Toolhead Index

What is this? 
This setting allows Simplify3D to communicate properly with the firmware, assigning the toolhead settings to the correct toolhead.

How do I use it?
Make sure T0/Left Extruder corresponds to the Tool 0 index, and T1/Right Extruder corresponds to the Tool 1 index. Now, this never needs to be adjusted again. 

 

Nozzle Diameter

What is this?
The Nozzle Diameter setting is used by Simplify3D to calculate the Auto Extrusion Width and generally should correspond to the size of the nozzle you have installed in the printer (How do I determine what size my nozzle is?). By default, AON-M ships with 0.6 installed on both toolheads.

How do I use it? 
Whenever you change out the nozzle to a different size, update this box.*

*In reality, this setting can be arbitrarily set with no impact on the actual print. See the section on Extrusion Width for more details on this setting. 

 

Extrusion Multiplier

What is this?
Simplify3D calculates the volume of material to extrude along a toolpath by taking settings such as extrusion width and layer height into account. The Extrusion Multiplier applies a global linear scaling factor to the volumetric extrusion rate. 

How do I use it?
Different materials have different viscosities which results in varying levels of back-pressure in the hot end's melt zone which then causes different rates of 'slippage' in the toothed extruder gear that drives the filament into the hot end. By adjusting the Extrusion Multiplier, one can easily compensate for this phenomenon without having to recalibrate the extruder feedrate entirely. 

The AON-M is calibrated such that with a Multplier of 1.00, our recommended brand of ABS at 250C extrudes exactly 100mm of filament when it's told to. Lower viscosity materials such as PLA would overextrude with a Multiplier of 1.00 so should be adjusted downwards, while higher viscosity materials such as Nylon would underextruder with a Multiplier of 1.00 so should be adjusted upwards.

For more information, see our article on dealing with over/underextrusion.  

 

Extrusion Width

What is this?
The Extrusion Width actually determines the width of the extrudate bead that comes out of the nozzle during printing. When "Auto" is selected, Simplify3D reverts to the default of using 1.2 times the Nozzle Diameter, but it can be overriden manually to any value you like. This setting is what actually affects the physical toolpath of the gcode generated, not the Nozzle Diameter setting.

For example, one could set two arbitrary Nozzle Diameters but if the same Extrusion Width is set for both, the generated toolpath and flow rate out of the nozzle will be identical. 




In contrast, the same Nozzle Diameter with different Extrusion Widths will change the toolpath and flowrate.




How do I use it?
In general, the auto setting works perfectly well. The most optimal Extrusion Width setting is a function of a material's flow characteristics, extrusion rate, temperature, part geometry, nozzle size, and often overlooked - the geometry of the nozzle tip. Extrusion Width selection is particularly important when thin walls or small geometries are involved. 

Consider a part with a thin wall. In the example below, the wall thickness of the model is 0.8mm. If we were to slice the model with an Extrusion Width of 0.4mm, two passes will be sufficient to precisely create the geometry. 

 

If we slice the model with an Extrusion Width of 0.6mm, the toolpath still makes two passes, but the extrusion will overlap resulting in poor surface finish quality. 

If we slice the model with an Extrusion Width of 0.7mm, only one pass is generated by the slicer resulting in an undersized wall thickness. 

If we slice the model with an Extrusion width of 0.9mm, the geometry is ignored by the slicer altogether. 

In general, a larger Extrusion Width results in greater part strength but at the expense of detail resolution and occasionally tolerance depending on the complexity of the surface geometry/topology. A smaller Extrusion Width yields higher detail resolution, and improved surface finish, but at the expense of significantly longer print times and lower strength. 

It should be noted that the nozzle size selection should still match the desired Extrusion Width ie. trying to print 0.8mm extrusion width with a 0.3mm nozzle will not only result in severe underextrusion, the print quality and layer bonding strength will also be poor. Avoid choosing an Extrusion Width greater than 1.5 times the nozzle diameter (especially with more viscous materials), and do not choose an Extrusion Width less than the nozzle diameter. 

Pointed nozzle tip geometries will result in a poorer surface finish if the Extrusion Width is much greater than the nozzle diameter, while "flat" nozzle tip geometries are more forgiving of a higher range due to the bead-forming effect the flat surface has when the material flows out of the nozzle. 

 

Ooze Control

Retraction
What is this? 
During travel moves (movement of the toolhead from one point to another without extruding material), the extruder will pull filament back from the hot end and then return to its original position at the start of the next extrusion move to reduce material leakage from the nozzle tip which can create a messy print (known as "oozing" or "stringing"). This behaviour is referred to as Retraction. Contrary to what you may read elsewhere, retracting filament does not create a "suction" effect on the polymer melt zone - it merely reduces the melt zone pressure to reduce but not completely eliminate material leakage. 

Details on strategies to combat stringing will be addressed in a future article. 

How do I use it?
Retraction Distance defines how far the filament is pulled back during a retraction movement. If this value is too small, the pressure reduction will not be sufficient resulting in stringing. If this value is too large, the retraction movement will take too long allowing the material to leak in place and create a blob at the location where retraction is occurring (however, the Coast at End and Wipe Nozzle settings can compensate for this). In general, a retraction value between 0.5mm to 1.0mm is sufficient for most materials, and between 1.0mm and 2.0mm for naturally "stringy" materials such as Nylon and PETx. 

For parts requiring many consecutive retraction movements in a row, a high Retraction Distance can also result in print failure due to a) insufficient priming of the extruder and b) the extruder feed gear wearing down the filament and losing grip. 

Extra Restart Distance can be a positive or negative value and can compensate for one of two situations. 
1) Short or consecutive rapid travel moves where the melt zone pressure drops but actual ooze does not occur: the hot end will extrude extra material at the start of the next extrusion move resulting in a blob. A negative Extra Restart Distance will compensate for this. 
2) Long travel moves where there is sufficient time for material to ooze: the hot end will not be fully primed at the start of the next travel move resulting in a gap where no material comes out. A positive Extra Restart Distance will compensate for this. 
Unfortunately, the slicer cannot selectively apply different retraction strategies by automatically detecting the type of travel move. Depending on your part geometry, a balance between Retraction Distance and Extra Restart Distance must be found. Typical values will be +/-0.1 to 0.2mm.

Retraction Vertical Lift is the amount the Z axis moves up/down during a retraction/travel move, and is recommended to be 2-2.5 times the value of your selected Layer Height. 

Retraction Speed is how fast the extruder moves filament for a retraction move and should generally be set to the maximum feed rate of the extruder, which is 40mm/s. 

 

Coast at End/Wipe Nozzle
What is this?
Coast at End and Wipe Nozzle are two complementary approaches to "wipe" the nozzle at the end of an extrusion move and before/during a retraction move to combat not only stringing but the quality of the surface seam which occurs at the end of an extrusion movement. The correct settings will minimize the visual messiness of the seam. 

How do I use it?
Coast at End stops extruding filament before the end of the extrusion movement by the selected distance. A value that is too high here will create a gap in the surface of the print, while a value that is too low will result in a blob at the seam. Typical values will be under 1mm. 

Wipe Nozzle extends the toolpath movement beyond the end of the extrusion path by the selected distance without additional extrusion, effectively wiping off any ooze that occurs during retraction. A value too low will be ineffective at minimizing ooze/surface blobbing, while a value too high creates a larger seam artifact. Typical values are between 1mm and 3mm. 

The ideal values for Coast at End and Wipe Nozzle are defined mostly by the Retraction Distance (as the intention is to compensate for any negative effects of retraction), and may be used in conjunction, one over the other, or none at all. For example, a material like Nylon is particularly susceptible to oozing and will call for a larger Retraction Distance, which means Coast at End/Wipe Nozzle is recommended as a compensating measure. A material like ABS may print just fine without Coast at End or Wipe Nozzle. 

 

We're always looking to improve our knowledge base. If you'd like to add your experience or would like clarification on a topic, please let us know at help@aon3d.com!

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