Input Shaping driving me nuts

Exerqtor

@Al_Capwn
Glad to see you getting some visible results! I've started testing with 150mm/min jerk today too.
Spewing out some test prints atm ✌

@dc42

Maybe it should be covered in the jerk documentation now that input shaping has become a thing.
What you just said would be valuable info for alot of us when we start tuning 😅

Exerqtor

Ok so in the quest to get this ghost into the proton pack I've and still being able to run high(ish) accelerations on most of the print WITHOUT using the PrusaSlicers built in acceleration control (I want to handle as much as possible in RRF) i think I've come up with a working solution.

By using regex in the PS G-code substitutions I'm now setting global.line_type to represent what kind of line/extrusion the printer is performing. Im doing this with Find: ^;TYPE:(.*) Replace with ;TYPE:$1\nset global.line_type = "$1".

Now that RRF know what's going on we have a bit more freedom to "manipulte" what happens. As of now i'm only changing what happens for External perimeters & Top solid infill since that's what we end up seeing anyways Ii'm also lowering the first layer acceleration, but that's for bed adhesion purposes).

The changes are done with daemon.g, who looks like this:

  ; Print acceleration & input shaping controll
  if global.accel_controll
    if global.layer_number = 1
      M204 P500                                                                ; Set printing acceleration(mm/s²)
    else
      if global.line_type = "External perimeter"
        if move.printingAcceleration != global.low_accel
          M204 P{global.low_accel}                                             ; Set printing acceleration(mm/s²)
        if move.shaping.type != global.input_shaper
          M593 P{global.input_shaper}                                          ; Configure input shaping
      elif global.line_type = "Top solid infill"
        if move.printingAcceleration != global.low_accel
          M204 P{global.low_accel}                                             ; Set printing acceleration(mm/s²)
      else
        if move.printingAcceleration != global.def_print_accel
          M204 P{global.def_print_accel}                                       ; Set printing acceleration(mm/s²)
        if move.shaping.type != "none"
          M593 P"none"                                                         ; Disable input shaping

The globals referenced in daemon.g get set in globals.g at startup and look like this:

if !exists(global.input_shaper)
  global input_shaper = (move.shaping.type)

if !exists(global.def_print_accel)
  global def_print_accel = (move.printingAcceleration)

if !exists(global.low_accel)
  global low_accel = 1500

if !exists(global.accel_controll)
  global accel_controll = true

if !exists(global.line_type)
  global line_type = "N/A"

if !exists(global.layer_number)
  global layer_number = 0

global.layer_number is also set automatically by PS by the "After layer change G-code" seciton with set global.layer_number = {layer_num+1}

Note that everything else is set like usual in config.g except global,low_accel,

Haven't gotten time to do more any test prints yet, only some preliminary 2-3minute test's to see that the code works.

Anyhow this should allow us to bump up the accelerations for everything that's not visible in the finished print without relying on the slicer doing the "right" thing.

droftarts

@Exerqtor said in Input Shaping driving me nuts:

@dc42

Maybe it should be covered in the jerk documentation now that input shaping has become a thing.
What you just said would be valuable info for alot of us when we start tuning 😅

Yes, we've been discussing this. I'll update the documentation next chance I get.

Ian

Exerqtor

@droftarts said in Input Shaping driving me nuts:

@Exerqtor said in Input Shaping driving me nuts:

@dc42

Maybe it should be covered in the jerk documentation now that input shaping has become a thing.
What you just said would be valuable info for alot of us when we start tuning 😅

Yes, we've been discussing this. I'll update the documentation next chance I get.

Ian

Glad to hear!

Out of curiosity, if we take a look at this motion analysis:
alt text

What would be the best shaper center frequency? My logic wants me to put it somewhere in the middle of the X / Y spikes at 39Hz, is that reasonable? Putting it at the X-axis peak / highest frequency totally smooth's out one axis (like one would suspect), but leaves something to be desired on the other in the test prints.

sebkritikel

@Exerqtor said in Input Shaping driving me nuts:

What would be the best shaper center frequency? My logic wants me to put it somewhere in the middle of the X / Y spikes at 39Hz, is that reasonable? Putting it at the X-axis peak / highest frequency totally smooth's out one axis (like one would suspect), but leaves something to be desired on the other in the test prints.

This is a totally reasonable approach, and one I've seen recommended a few times. Some shapers have a failry broad range, and can address two (or more ringing frequencies).

In the left column, tick 'estimate shaper effect' and then the 'show original values option'. Move your mouse over to the right, and click in the 'shaper centre frequency' after selecting a shaper. You can then scroll through the frequencies with your mouse wheel, and see how the frequency and damping factors change the results.

Exerqtor

@sebkritikel
Okok, nice to get confirmation that my brain works from time to time😅

Yeah i've tried playing around with those estimated values, but in my case they haven't really been representative of what ends up happening once i do a testprint.

I'm doing a testprint with zvd-ei3 @39Hz with zero dampening to see how it turns out.

On another tangent though, what M204 P value we have does effect the motion analysis right? Those still get applied on the test moves?
I haven't seen any mention of it in the documentation, but i would assume it gets applied.

OH YEAH! One more thing, does the Shaper center frequency support/allow for decimal numbers?🤔

sebkritikel

@Exerqtor M204 question is a good one (and unfortunately I don't know the answer), may be a good note that gets added to the documentation.

I just tried a decimal value for the shaper frequency, and it seemed perfectly happy to report it back to me.

Input shaping 'ei3' at 49.5Hz damping factor 0.10, min. acceleration 10.0, impulses 0.221 0.498 0.758 0.925 with durations (ms) 10.97 9.90 9.70 9.69

To be honest though, I can't imaging you wold need that extra significant digit for your shaper frequency.

Al_Capwn

@dc42 Hello and thank you for your time,

I have been... WAY busy with work so the past few days has been work, sleep, mess with 3d printer, work, sleep >_<; Only now reading through the thread.

I have done a LAWT and have a question for you @dc42 if you would, what amount of acceleration Should I set for the extruder if my X/Y acceleration is set to 7000? I currently have it set to 1500 and have not seen issues.

Ok, now for the BIG UPDATE

To all of those still watching here, and sorry again for not posting in a few days... I have finally gotten to a stable/workable slicer profile/printer settings etc. as far as jerk goes.. The old print was with input shaping and zero jerk where the new is 14 jerk for the walls and 10 for the top/bottom.

alt text

Ran out of filament when printing this one and had to start on a roll that was a little waterlogged.
alt text

alt text

if you want to see the rest here is the galley https://imgur.com/a/6oXPUVE

I will try out lowering my damping factor a little bit later and report on how that goes, later tonight or tomorrow and report on the results with pictures probably.

Thank/thanks again all who showed interest and/or offered assistance/advice, it was welcome/apricated

dc42

@Exerqtor said in Input Shaping driving me nuts:

What would be the best shaper center frequency? My logic wants me to put it somewhere in the middle of the X / Y spikes at 39Hz, is that reasonable?

From that graph it looks to me that you need to cancel about 25Hz to 52Hz. The Input Shaping plugin will allow you to select a shaper type and centre frequency, and overlay on the graph the effect of the shaper. The frequency range is about 2:1 so a ZVDD or EI2 shaper may be sufficient.

Al_Capwn

@dc42 hello again and sorry for pinging you again,

As well as the question about acceleration, what max jerk should I have my printer set to? Continuing to tune my printer and noted something strange. I have a bondtech BMG, when I first started to dial things in and set up linear advance I noticed a strange, not quite grinding sound that had popped up, apparently this is just a thing with dual gear extruders (or at least my googling told me.)

Ok, now for the strange, I had forgotten about this because at some point I had turned down my extruder jerk down to 300, switching it back to 900 has caused the not quite grinding sound to come back. SO, if 300 jerk is fine I would leave it there just to save on noise pollution, otherwise, if 900 or greater jerk is the best way to go I'll deal with the added sound.

Thank you again ^_^

Exerqtor

@dc42 said in Input Shaping driving me nuts:

From that graph it looks to me that you need to cancel about 25Hz to 52Hz. The Input Shaping plugin will allow you to select a shaper type and centre frequency, and overlay on the graph the effect of the shaper. The frequency range is about 2:1 so a ZVDD or EI2 shaper may be sufficient.

Aha i thought one should base on the peaks not where the peaks "start/stop" to climb/fall. I've adjusted the center frequency to 38.5Hz and ZVDD now to see i if i can see a noticable difference on a print i just ran with 41,8Hz & EI2.

dc42

@Al_Capwn said in Input Shaping driving me nuts:

I had forgotten about this because at some point I had turned down my extruder jerk down to 300, switching it back to 900 has caused the not quite grinding sound to come back. SO, if 300 jerk is fine I would leave it there just to save on noise pollution, otherwise, if 900 or greater jerk is the best way to go I'll deal with the added sound.

Input shaping works better with low jerk, however if the jerk is too low then the printer may be jerky when printing some curves. By all mean stick with 300, but be prepared to increase it if printing curves becomes jerky.

Exerqtor

@dc42 Yeah i had to turn my jerk back up to 900 since the prints turned out horrible at 150.

I'm about to trash the lightweight x gantry on my machine now. Gone through 1kg of plastic just running test prints now

CCS86

@Exerqtor said in Input Shaping driving me nuts:

Ok so in the quest to get this ghost into the the proton pack I've and still being able to run high(ish) accelerations on most of the print WITHOUT using the PrusaSlicers built in acceleration control (I want to handle as much as possible in RRF) i think I've come up with a working solution.

By using regex in the PS G-code substitutions I'm now setting global.line_type to represent what kind of line/extrusion the printer is performing. Im doing this with Find: ^;TYPE:(.*) Replace with ;TYPE:$1\nset global.line_type = "$1".

Now that RRF know what's going on we have a bit more freedom to "manipulte" what happens. As of now i'm only changing what happens for External perimeters & Top solid infill since that's what we end up seeing anyways Ii'm also lowering the first layer acceleration, but that's for bed adhesion purposes).

The changes are done with daemon.g, who looks like this:

global.layer_number is also set automatically by PS by the "After layer change G-code" seciton with set global.layer_number = {layer_num+1}

Note that everything else is set like usual in config.g except global,low_accel,

Haven't gotten time to do more any test prints yet, only some preliminary 2-3minute test's to see that the code works.

Anyhow this should allow us to bump up the accelerations for everything that's not visible in the finished print without relying on the slicer doing the "right" thing.

I think this is a cool approach, and I have tried something similar.

The issue I see with it at the moment, is that a change to the input shaper or pressure advance parameters causes a small print head dwell, and with it, a printed bulge.

Exerqtor

@CCS86
Yeah I noticed that with my testing too, so I added the same IS & PA parameters to regular perimeters too, but with much higher accelerations. That removed the "dwell-blobs".

CCS86

@Exerqtor said in Input Shaping driving me nuts:

@CCS86
Yeah I noticed that with my testing too, so I added the same IS & PA parameters to regular perimeters too, but with much higher accelerations. That removed the "dwell-blobs".

If each IS and PA command causes a motion dwell, I can't imagine how adding more of them causes less dwelling.