speed travel wrong Unit in Cura [mm/s] - [mm/min]

[DonBernos 0]

Hello all,

 

I think I found a bug in Cura Software.

In start gcode you can implement the variable {speed_travel}. In Cura (German Version), it is related to the input field 'Bewegungsgeschwindigkeit' (travel speed)

The unit at input field in Cura is [mm/s]. If gcode is generated the value is transmitted 1:1 to gcode, that means e.g.

 

Input field Cura: 'Bewegungsgeschwindigkeit' (travel spped) = 120 mm/s

 

printer start code e.g. : G1 Z15.0 F{speed_travel} ;move the platform down 15mm

 

generated gcode        : G1 Z15.0 F120 ;move the platform down 15mm

 

but gcode uses as unit not mm/s, it uses mm/min !

 

I think when gcode is generated it must be 120 x 60 [mm/s] -> 7200 [mm/min]

 

Best regard

 

😉

 

 

[GregValiant 1,436]

Yes.  That F120 is mm/min.  Very slow.

Just out of curiosity, what is your z-hop speed setting?

[masterofscience 0]

Hi, does it was solved?

i have the same problem

[GregValiant 1,436]

The Cura max Z speed is in the Printer Settings (you may have to load the plugin from the Market Place).  That setting should place a limit within Cura.  If the person in the first post had it set to 2mm/sec (default is 10) then he can input 120mm/sec, but the Gcode would output 120mm/min.  

 

Within the printer, M203 stores the max feedrates.  No matter what you enter into Cura as a setting, the max speed is governed by M203.

 

echo:Maximum feedrates (units/s):
echo:  M203 X500.00 Y500.00 Z25.00 E50.00

 

The above is a response to M503 on my Ender.  You can see that the max Z feedrate is 25mm/sec.  If I enter 1000mm/sec in Cura, it's going to be limited to 25mm/sec when the printer sees the Gcode.

 

At the beginning of a gcode file, if you have:

M203 X900 Y900 X50 E50

M500

Then you will change the max feed rates of the printer to near their max possible.  M500 saves the change to memory (you only need to do it once).  Then check the Cura Printer Settings and make all the speed settings there match the M203 settings.

 

 

[masterofscience 0]

This is not my case. I have an old version of Cura, customized by the printer manufacturer (ver 15.02.1, but is really old, maybe 7 years ago). This work well
And I have a Cura version downloaded from the Ultimaker website (Ver 4.1). and this version does the conversion mm/s to mm/min wrong. This conversion is done with the factor 1 instead of factor 60. The code generated do not have the M500 or the M203 code. This is the beginning gcode (everything before the first line posted was commented by Cura). 
PD: I added my printer to Cura, because it was not in the list:
;-------------------------------------------------------------------------------------------------------
;-------------CODE GENERATED BY CURA FROM ULTIMAKER WEBSITE-------------
;-------------------------------------------------------------------------------------------------------
M140 S82
M105
M190 S82
M104 S225
M105
M109 S225
M82 ;absolute extrusion mode
;Sliced at: Thu 18-03-2021 01:11:13
;Basic settings: Layer height: 0.15 Walls: 1 Fill: {fill_density}
;Print time: 01:22:53
;Filament used: [2.29]m [16.0561306640625]g
;Filament cost: [0.0]
;M190 S82 ;Uncomment to add your own bed temperature line
;M109 S225 ;Uncomment to add your own temperature line
G21        ;metric values
G90        ;absolute positioning
M82        ;set extruder to absolute mode
M107       ;start with the fan off
G28 X0 Y0  ;move X/Y to min endstops
G28 Z0     ;move Z to min endstops
G1 Z15.0 F120 ;move the platform down 15mm
;----------------------------------------------------------------------------------------------------------------------
;----------------------------------------------------------------------------------------------------------------------
;----------------------------------------------------------------------------------------------------------------------

take a look to the last line:
"G1 Z15.0 F120 ;move the platform down 15mm"

this was done with the travel speed of 120 mm/seg
and take a look of the same code generated by the old cura, with the same configuration:
;----------------------------------------------------------------------------------------------------------------------
;------CODE GENERATED BY CURA CUSTOMIZED BY THE MANUFACTURER---------
;----------------------------------------------------------------------------------------------------------------------

M190 S82.000000
M109 S225.000000
;Sliced at: Sun 14-03-2021 19:43:15
;Basic settings: Layer height: 0.15 Walls: 1.2 Fill: 0
;Print time: 4 hora 1 minutos
;Filament used: 3.741m 28.0g
;Filament cost: None
;M190 S82 ;Uncomment to add your own bed temperature line
;M109 S225 ;Uncomment to add your own temperature line
G21        ;metric values
G90        ;absolute positioning
M82        ;set extruder to absolute mode
M107       ;start with the fan off
G28 X0 Y0  ;move X/Y to min endstops
G28 Z0     ;move Z to min endstops
G1 Z15.0 F900 ;move the platform down 15mm
;-----------------------------------------------------------------------------------------------------------------------------
;-----------------------------------------------------------------------------------------------------------------------------
;-----------------------------------------------------------------------------------------------------------------------------

Is clear that this is happening. how to solve it?
 

[GregValiant 1,436]

I have Cura 4.6 as my oldest install.  I checked on Github and didn't see any obvious references to the speed problem you are having.

The newest version is 4.8.  Can you update to that and see if the problem still occurs?  You can keep your older installations of Cura when you update.  

 

 

[Poikilos 0]

@GregValiant The program uses mm/s and G-code uses mm/minute, as the original post mentioned. It is an issue in which Cura doesn't support a standard. I've added it as a new issue: https://github.com/Ultimaker/Cura/issues/10636

[GregValiant 1,436]

PrusaSlicer, Ideamaker, MatterControl, Chitubox64, Mingda Printer, QidiPrint, Repetier, PrintRun, and Lotmaxx are all the same as Cura.  Input is in mm/sec and gcode output is mm/min.  It would be kind of interesting to know how that got started as it seems to have become a defacto standard.  I did some work cutting toolpaths for CNC mills but it was a long time ago and I can't remember what units were involved.  (I just want to be clear on this - I am NOT so old that it would have been "cubits/week".)

 

I had wanted to change my speed settings for my purge lines to give them some flexibility (for when I print TPU) but as you noticed there is no keyword for {speed_print_mm_per_min}.

 

I think it could be done in PrusaSlicer because it appears that math is allowed in StartUp Gcode so {speed_print}*60 may be viable over there.

[jacobdobbratz 7]

I would also find it useful to have the ability to do math in the start up script to accomplish this exact example of {speed_print_mm_per_min}. Is there a known way to accomplish this?

[ahoeben 2,023]

38 minutes ago, jacobdobbratz said:

Is there a known way to accomplish this?

No, there is no way to do this at this point.

[jacobdobbratz 7]

Sad to hear but understandable. Thanks for getting back so quickly and for all the work you do on here.