How to Correctly Increase Printing Speed in Cura Instead of Using Speed Factor in Klipper

[iannortnau 0]

Hello, I have a KP3S printer with a Raspberry Pi 3 running Klipper to optimize its performance. After using it for a while, I've become accustomed to using the Speed Factor feature to speed up my prints. From the beginning, I knew it wasn't the correct way to increase speed, but I've been satisfied with the results as I can set the Speed Factor to 400% without failures and it significantly reduces printing time.

I would like to know how to properly increase the printing speed by configuring settings in Cura, so that I can get accurate time estimates from the slicer and avoid having to adjust the Speed Factor each time.

 

[GregValiant 1,342]

The speed settings are almost all in the "Speed" section of the settings.  The speed "limits" are controlled by different settings and you will need to go to the MarketPlace and install the "Printer Settings" plugin.

That will allow you to access the "Maximum Speed" and "Maximum Acceleration" settings and set defaults for Jerk (there is no "Maximum Jerk" setting either in Cura or in the printer).

There is no direct connection between Cura and the printer so Cura can't tell what you might have in the M203 and M201 registers in the printer.  The numbers contained in a printer definition file should fill the boxes with the defaults the printer was delivered with but that isn't always the case.  If you have a "Custom FFF" printer installed in Cura the defaults may be the speed of light expressed in mm/sec.  You can change the values in the "Max" boxes to whatever you want.

If you bounce up against the "Minimum Layer Time" (in the Cooling settings) Cura will adjust the speeds downward to insure adequate layer cooling.

The function of the Max settings in Cura is to turn a setting box red when you enter an illegal value and Cura won't slice if a box is red.

These are the settings for my Ender as stored in "Printer Settings".  As long as I don't enter larger numbers into any regular "Speed" setting box, Cura will slice.

  I don't know if Klipper is capable of reading printer responses to commands.  If you use something like PrintRun/Pronterface you can see the printer response to an M503 query and see what the firmware has in M203 and M201.  This is a Marlin response:

 

echo:  G21    ; Units in mm
echo:  M149 C ; Units in Celsius

echo:Filament settings: Disabled
echo:  M200 D1.75
echo:  M200 D0
echo:Steps per unit:
echo:  M92 X80.00 Y80.00 Z400.00 E97.00
echo:Maximum feedrates (units/s):
echo:  M203 X200.00 Y200.00 Z45.00 E50.00
echo:Maximum Acceleration (units/s2):
echo:  M201 X2000 Y2000 Z100 E1000
echo:Acceleration (units/s2): P<print_accel> R<retract_accel> T<travel_accel>
echo:  M204 P1000.00 R500.00 T1000.00
echo:Advanced: S<min_feedrate> T<min_travel_feedrate> B<min_segment_time_us> X<max_xy_jerk> Z<max_z_jerk> E<max_e_jerk>
echo:  M205 S0.00 T0.00 B20000 X10.00 Y10.00 Z0.40 E5.00
echo:Home offset:
echo:  M206 X-1.00 Y-6.00 Z0.00
echo:Material heatup parameters:
echo:  M145 S0 H185 B45 F0
echo:  M145 S1 H240 B70 F0
echo:PID settings:
echo:  M301 P28.41 I3.54 D57.03
echo:Stepper driver current:
echo:  M906 X 650 Y 650 Z 650 E0 800
ok

 

If the firmware settings are lower than the Cura settings, the firmware settings will take precedence.  You can set Cura to 1000mm/sec but if M203 is M203 X50 Y50 Z10 E5 then those numbers will determine how fast the printer will move.

Edited August 15 by GregValiant

[Slashee_the_Cow 410]

Standard Slashee Disclaimer:

Just because you can print fast doesn't mean you should. Most materials are designed to be printed at a certain speed (often listed on the side of a spool or a paper flyer that comes in the box). Depending on the material, for some things (like detailed stuff) you may have to go even lower for an ideal result.

 

Even if a printed part looks okay, if it's been printed too fast its strength may be compromised as the filament has not had time to set, or sometimes it can just be dragged by the nozzle and not fully form a particular part.

 

With regards to acceleration and jerk, setting these too high can result in several possible different effects, depending on your machine. I've personally had parts of prints pulled away with the nozzle as it's gone for a travel move at maximum acceleration. If jerk is too high it may result in the filament appearing to cut corners as it hasn't had sufficient time to dry in the corner before being pulled along by the nozzle in a new direction. With tall models especially you don't want it very high or else they are very likely to sway, even just based on the movements of the print head.

 

Depending on your printer, with high jerk you also run the risk of a sudden change causing vibrations which make a motor skip a couple of steps. This will result in subsequent printing being slightly out of line with what is already there, known as "layer shift".

 

Slashee's Golden Rule of speed: Slow print > bad print.