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I want to input a custom G-code to a large format 3D printer, which has a pellet extruder. Having done the same for a small-scale filament-based printer, I'm familiar with the analytical model to compute the 'E' value (as given in this question).

However, how do I compute the 'E' value for a pellet extruder? Are there any analytical models to aid in this?

So far I have found a blog post by dyzedesign on this topic, but it is not directly applicable to my problem as they use screw RPM instead of 'E' value.

Trish
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Varun murugan
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1 Answers1

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Basically, the auger displaces volume when rotated. Ideally the manufacturer of the auger should give this information. Otherwise, you need to figure this out through some measurements and estimations and fine tune the end result.

An auger displaces volume, hence the exit area of the auger (total area of the auger π•(diamaugerexit)2/4 minus the area where the material of the screw is) and the pitch combined determine how much rotation is needed to extrude a certain volume. You just need to figure out how much rotation (expressed in E value) is required to get the correct flow. This is done by tuning the E-steps. When an extrusion for an object is requested, e.g. for a prime line, the E value in effect rotates the auger such that there is exactly enough for this request.

Note that the E-value is calculated by the slicer, it is you who provides the translation of that value to the rotation and thus extrusion of the auger. The slicer is unaware of the hardware that provides the extrusion, that is up to the firmware of the printer.

0scar
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