Hello everyone. I've been reading this forum for a long time, but finally I have a problem which I can't manage on my own. Last time I noticed a new problem with my Sli3er software used for printing with RepRapPro Mendel. I prepared a simple .stl model of a cube 15 mm x 15 mm x 15 mm. Then I set values of speed for print moves in Sli3er Advanced mode. And this is the strange part. I set 1 mm/s (for all speeds to simplify gcode analysis) and I have "F30.000" in gcode for every layer. I set 5 mm/s -> I have "F150.000". I set 20 mm/s -> I have "F600.000". This is OK, but when I set higher speed for example 25 mm/s or 30 mm/s I will have no more than "F600.000" in gcode when it should be "F750.000" etc. It looks for me that somewhere the max speed value is limited. With bigger 3D model for example cube 20 mm x 20 mm x 20 mm this limit is higher ("F793.360" in this case). Have you got any solution of this problem? Of course I can manually modify my gcode but I sometimes conduct a public presentations of my 3D printer and this is a serious issue. (sorry for my English, it's not my mother tongue) https://reprap.org/forum/read.php?4,649350,649350#msg-649350 Sun, 09 Aug 2026 00:10:21 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?4,649350,649828#msg-649828 https://reprap.org/forum/read.php?4,649350,649828#msg-649828
Paul, thank you for your tips. I need to find out more details in Sli3er documentation. And yes, speeds were calculated for the first layer with a 50% setting.

James, your sugestion about cooling settings could be the easiest and the most probable solution for my problem. Sli3er documentation says about one option: "If layer print time is estimated below this number of seconds, print moves speed will be scaled down to extend duration to this value." I'm going to perform some tests, but I suppose I should be very close to solve my problem.]]> uragan Reprappers Fri, 08 Apr 2016 10:30:58 -0400 https://reprap.org/forum/read.php?4,649350,649608#msg-649608 https://reprap.org/forum/read.php?4,649350,649608#msg-649608 Paul Wanamaker Reprappers Thu, 07 Apr 2016 17:58:02 -0400 https://reprap.org/forum/read.php?4,649350,649591#msg-649591 https://reprap.org/forum/read.php?4,649350,649591#msg-649591
Why are the F values apparently 30x instead of 60x?]]> JamesK Reprappers Thu, 07 Apr 2016 16:33:02 -0400 https://reprap.org/forum/read.php?4,649350,649554#msg-649554 https://reprap.org/forum/read.php?4,649350,649554#msg-649554
As you may know, the values for the Feed Rate in gcode are in mm/min, so that's why you are seeing them x 60.

There are a few of things to look for, on the Print Settings, Speed tab.

Since you are doing testing, and want to be sure of the speeds - use values in mm/s in all the Speeds for all print moves, not a %. This makes it easier to be sure of what you are asking it to do.

Do the same for the First layer speed.

And finally, under Autospeed: Set you Max print speed to the max you are using (or higher), and set Max Volumetric speed to 0.
If you have something in that last setting it will slow down print moves so it does not exceed the maximum extrusion rate of your hot-end/extruder. When you are testing you do not want this interfering with your tests (and it may introduce problems).

Here is the location for some Slic3r tutorials and videos.

Hope that helps.]]> Paul Wanamaker Reprappers Thu, 07 Apr 2016 14:49:22 -0400 https://reprap.org/forum/read.php?4,649350,649350#msg-649350 https://reprap.org/forum/read.php?4,649350,649350#msg-649350
(sorry for my English, it's not my mother tongue)]]> uragan Reprappers Thu, 07 Apr 2016 06:24:11 -0400