Firmware extruder delay setting?

Do any of the common firmwares have compensation for extruder delay? I know this is an issue with Bowden-type extruders, but I also see the effects with my direct-drive extruder when printing fine, sharp details like small gear teeth. I see a slight over-extrusion as the motion decelerates at corners and slight under-extrusion as it speeds back up again. I'd like to have the extruder motion profile to be shifted forward in time by some number of milliseconds relative to the XY motion profile. Does this sort of compensation exist, either in firmwares or slicers?

What firmware are you using? I know that marlin keeps speeds regular enough that this isn't usually a huge issue.

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It's not that the motors aren't running at accurate speeds, it's that the there is a slight delay between when the extruder motor moves and the change in flow out of the hot-end.

I've grubbed around a bit and have discovered an "extruder_advance_k" parameter in Marlin's CONFIGURATION_ADV.H file. From what I can tell, this was a feature added in 2011. I haven't been able to find any details, though, on what reasonable values might be. Has anyone had success playing with this parameter?

You may have these fat corners for several other reasons besides firmware.
Even direct drive setups have built up pressures.
When you do a retract, if the cold end diameter of hole is not close to the filament diameter, the piston won't pull back the pressure as much.
If you have a j-head or teflon at the cold end, this diameter increases with use, as the piston fattens at the telfon/brass intersection.

also, i think using a tuned extrusion multiplier helps a lot. I see a lot of guys printing like they're icing a cake, just smearing plastic everywhere.
I like discrete roads, like a fine line. This reduces the corner blobs, although my picture still has one at the random start/stop point, enough to push out the perimeters.
the corners of the infill path are nice though and certainly results I'm happy with.
the two shell perimeters were not joined in this print, meaning the outside path was unattached. it's always something.........

The video shows you can get good results with good head speed, not sure what my setting were, but it looks like about 100+mm/s or so.

.4mm nozzle, 1.75mm PLA Ultimachine filament, Marlin (march2013 version)

blue box printing

I think I've got the extrusion multiplier dialed in - my solid infills just barely touch (maybe even a little underfilled). And doing a something like your blue box with rounded corners is not a problem because there is not a sharp change in the speed when going around the rounded corners.. However, when I do a box with square corners, coming into the corner (where the motion is decelerating) I am getting some over-extrusion and then when it accelerates again after making the corner, a slight under-extrusion (although this is harder to see).

On my extruder, the cold end diameter is 1.93mm which is a pretty tight fit on the filament. Also the teflon liner I'm using has only a 0.3mm wall thickness, so it is probably not deforming too much. But still, there is small time lag between when the extruder starts to slow down and when the flow out the hot end slows down. I believe this is what the "extruder_advance_k" value is meant to compensate for, but I have found no guidance on how to set this parameter.

Has anyone played with "extruder_advance_k" ?

Yeah I played with it last year, even went so far as to bug Evdz about it. I concluded it was more or less completely broken and did not work. I was using a bowden setup, 1.75mm filament. While it did alter the extrusion amount, it did not do so in a way that improved final output quality.

Sailfish firmware has a similar feature called JKN Advance which does work as intended (http://www.makerbot.com/sailfish/tuning/#5). It's a shame sailfish only works on MBI control boards.

in that capture1 pic, I can see your issue on the short infill sharp corners.
a slight overage at the sharp/square turn arounds, and then a slight thin underage as it exits the turn around.

same thing you are investigating.

I just looked around Marlin, and see ADVANCE in several areas, like config.adv, stepper.c and planner.c.

I'm not sure, but it appears to add/subtract a correction to the trapezoid planning logic.

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crispy1
Yeah I played with it last year, even went so far as to bug Evdz about it. I concluded it was more or less completely broken and did not work. I was using a bowden setup, 1.75mm filament. While it did alter the extrusion amount, it did not do so in a way that improved final output quality..

Bummer. Did you ever hear back from Evdz? Any indications it'll get fixed? Is Evdz Matt Roberts? The only reference I've been able to find on the extruder advance is this:

http://reprap.org/pipermail/reprap-dev/2011-May/003323.html

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Bummer. Did you ever hear back from Evdz? Any indications it'll get fixed? Is Evdz Matt Roberts? The only reference I've been able to find on the extruder advance is this:

He helped me experiment with different parameters. But he wasn't the one who wrote the code so he didn't know how it was supposed to work, or how to debug it. The guy who wrote it seems like he just dumped it into Marlin with no/minimal testing and disappeared.