I initially measured my extruded lengths which didn’t make sense to me that the measured material was actual less than what I had extruded. Measured to 40mm extruded 20 thru Cura and remeasured at 20.83mm so only 19.27 actually extruded. With that same rate my prints were highly over extruded. I spent most of my morning working through the flow percentage settings as my first prints were highly over extruded. I finally found a percentage that turned out much better in testing prints. My final setting landed on was 72%. So my question is, is the flow % the same adjustment as the e-steps? If they are the same adjustment is there a way to equate the flow percentage to adjust the e-steps on the machine? Is one better than the other? What’s the best practice for this?
Hmm… that’s a good question. The e-steps really calibrate the stepper motor so that it feeds the correct amount of filament.
The variable which the flow % (flow multiplier in some software) solves is the composition of the filament and what’s actually deposited. For instance, different colors from the same filament manufacturer produce different results. Examining and feeling the top layer is a non-scientific, visual way of recognizing over-extrusion. If the top layer is rough where the infill overlaps the perimeter, there’s probably some over-extrusion going on. Back to the colors, I find Black eSUN ABS is “thicker” and requires less flow % to produce accurate parts.
Maybe the best way to gauge this is to create a calibration print consisting of a donut and a post which would fit in the hole. If the post fits loosely its under-extruding, and if the post is tight over-extrusion.
Changing flow % will have the same effect as changing e-steps. If you drop your flow rate from 100% to 95%, it will have the same effect as setting your e-steps to a number that is 5% lower.
I think of it this way: there are four things that influence how much is extruded: the diameter of the filament, the e-steps setting, the flow rate setting and the density of the filament (not entirely sure how much of a variable that last one is, but that’s how I think of various other “fudge factors” that might affect extrusion).
I’ve not yet run a lot of different filament, but I’ve got my e-steps dialed in as accurately as I can on the PLA I’m running now. My plan is to use that setting for e-steps, and then adjust the flow rate to fine-tune for different types of filament (after adjusting for the actual diameter of the filament in use).
There are a couple of other good threads on here about calibrating the extruder. The main point of them is that using the 100mm/min speed called for in the calibration instructions is too high. The increased back-pressure from the high-speed extruding can effect how much is extruded, causing it to extrude less. The result of calibrating e-steps at a high extrusion speed is over extrusion during actual printing. It’s better to calibrate at something closer to an actual printing speed, like 40mm/min.