I am glad to find this post. I am trying to tune pressure advance/acceleration/jerk and experimentally I also see that high jerk (like 30, so high that I did not expect my printer to handle it) and low accelerations work best.

My bowden is around 70cm, I print with PETG and use pressure advance of 2.1.

I don't understand the mechanics. Probably, with high pressure advance things stop being Newtonian and become relativistic.

@Phaedrux I am quite sure it is skipping, I see it on the prints as underextrusion. I use the recommended motor with rated current 2A, and I run it at 1.6A. I assembled it carefully too.

@Phaedrux said in Does M204 limit extruder acceleration?:

What is your retraction speed and extruder speed limit set to?

Here are my settings:

M566 X900 Y900 Z60 E1000:1000                      ; JERK (mm/min)
M203 X20000 Y20000 Z600 E15000:15000               ; MAX SPEED (mm/min)
M201 X3000 Y3000 Z125 E5000:5000                   ; MAX ACCELERATION (mm/s^2)
;M204 P2000 T3000                                   ; set print and travel accelerations
M204 T3000                                         ; print acceleration is limited by PA, except maybe extruder
                                                   ; would M204 P2000 limit extruder acceleration?

On another (but related) issue: I use voron mobius extruders, and they recommend extruder jerk of 8000. But I can't use more than 1000 because of skips. I don't understand what the problem might be.

@dc42 said in Does M204 limit extruder acceleration?:

Extruder acceleration and especially extruder jerk limits do limit the printing speed when high values of PA are used.

Yay! I agree. Still, do you remember from the top of your head if M204 limits extruder acceleration? Or only XY?

@Phaedrux said in Does M204 limit extruder acceleration?:

The extruder moves are generally so short extruder acceleration almost doesn't matter.

I really don't feel this way. With higher PA it is extruder which is limiting print speed: XY acceleration limits simply do not matter any more.

My question is a simple curiosity: in situations where extruder accelerations are the limiting factor, does M204 command limit extruder accelerations as it limits XY accelerations? In principle this should be possible to understand from the source code.

@bot interesting. I use a long bowden (around 70cm) and use PA of around 2. And I can print flexibles with PA 16. I see the extruder working really hard, and it is the extruder jerk/acceleration that limits my print speeds, as I am not even close to the limits on XY.

Is extruder acceleration used at all in PA? If I have high PA and I use M204 P1000, would that limit the speed because of extruder acceleration?

@deckingman Suppose I have a configuration where on some given move, the acceleration of XY is 1000 and acceleration of extruder is 2000. If I use M204 P1000, would such a move be slowed down?

Also what if pressure advance is enabled? Does M204 limit extruder acceleration which is used in PA?

just checking, since I could not understand this from the documentation

RepRapFirmware applies the M204 accelerations to the move as a whole, and also applies the limits set by M201 to each axis and extruder.