Rotation_disance changes are inconsistent/opposite of expected

General Discussion
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Basic Information:

Printer Model: Elegoo Neptune 3 Pro
MCU / Printerboard: stm32f401xc (znp robin nano 2.2)
Host / SBC : RPI 3B
klippy.log
klippy.zip (1.5 MB)

Changing the Extruder rotation_distance in the printer.cfg has inconsistent/no result.

I’ve changed it from 6.9 (the default) down to 4ish, 3, 2, and more, and it still only extrudes maybe 60 to 80 mm of filament when I tell it to extrude 100. Its PLA, 215C.

I’ve been having a few issues lately honestly, for a while it seemed like I was underextruding a ton, but I tightened the grub screw for the extruder gear and it seemed to be working a lot better, but I checked the extrusion after the last print since it was giving me awful rippling which I thought might be overextrusion, or my Z offset was too low, so I was going to check extrusion since I’d been fiddling with Z offset for a bit already.

That’s when I found telling it to extrude 100mm just extrudes 60. So I’ve been working on the extrusion issue and that’s how I ended up fiddling with the rotation distance and finding that it isn’t changing or if it is, its very inconsistent. For instance, the last attempt I went from 6.9 to around 5ish, and it went from extruding 80 to 75mm. I read that you might need a gear ratio involved, but that didn’t seem to fix the issue either, though I can’t be sure I didn’t do that incorrectly. I set it to 3:1 since that’s what’s advertised for it, but I imagine if that is the issue I’d need to go count the gears to be exact, but the issue existed before I messed with the gear ratio option at all.

I’m probably going to end up taking apart the whole extruder thingy later if it keeps giving me problems, but I was wondering if maybe I was missing something obvious, or anybody had any advice.

Yes I’m saving and restarting between modifying the config.
Yes I’m modifying rotation_distance under the [extruder] heading, I saw a thread where people were messing with their z axis rotation on accident.

EDIT:

So I took apart the extruder and that didn’t help, but after the fact I checked and saw that the filament was slipping a little, but only when it was pulling the spool down. I’m gonna try to get a better roller for the spools, and maybe look into upgrading the hotend/extruder in the future.

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I’ve found spool binding to be a siginifcant cause of extruding issues in the past. So that’s definitely one thing to look at.

Besides that though, How did you calculate your original rotation distance? Or did you just use one in someone elses config?

I’ve noticed that people using the Neptune 3 Pro have theirs set to, what to me at least, looks ridiculously low. But I didn’t do the math to see if it’s viable and/or correct.

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I got my original firmware and configs from TheFeralEngineer’s github, but I did learn how to flash the firmware myself during my troubleshooting frenzy today. around 6.9 has been accurate for me in the past, so I was pretty concerned when all the sudden it extruded like half what it was supposed to. I think it might be a bit of wear too tbh, I know some people have had to replace the gears in the Neptune 3 Pro from the posts I was digging through. If the better roller works though I’ll update the post in case anybody finds it searching for a solution.

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From Googling the Neptune 3 extruder it looks like they use a copied version of the original Bondtech extruder setup. Those gears are readily available and pretty cheap from a lot of different places.

Even if you decide not to replace them right away it never hurts to have replacements for the future to reduce printer downtime.

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