Sli3er speed settings problem

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)

Hi Uragan,

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.

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My printer: Raptosaur - Large Format Delta - [www.paulwanamaker.wordpress.com]
Can you answer questions about Calibration, Printing issues, Mechanics? Write it up and improve the Wiki!

...and don't forget that there is a setting for slowing down in the filament section under auto-cooling. That is likely to impact small prints with fast layer times.

Why are the F values apparently 30x instead of 60x?

He may be looking at first layer speeds with a 50% setting.

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My printer: Raptosaur - Large Format Delta - [www.paulwanamaker.wordpress.com]
Can you answer questions about Calibration, Printing issues, Mechanics? Write it up and improve the Wiki!

@Paul Wanamaker, @JamesK: I really appreciate your help.

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.

Edited 1 time(s). Last edit at 04/08/2016 10:32AM by uragan.