What is the real 3D printing speed at Ultimaker 2?

[Sean_06 0]

At Cura, I can set up print speed and travel speed. However, I found that the setting of print speed and travel speed is overwritten by the Ultimaker machine. For example, when I input print speed of 15mm/second or 9mm/second or 1mm/second, the outcome 3D printing speed is the same.

The only way to change the print speed is to select the percentage of print speed at Ultimaker. (eg. 100%, 60%). Therefore, I assume that 60% means 60% of the "default print speed".

The question is:

1. what is the default print speed and default travel speed? (I am using cura 2.3 and ultimaker 2, but I couldn't find the default print speed)

2. Whether the default infill print speed, wall print speed and top/bottom print speed is the same?

[gr5 2,172]

Well your answer changes depending on version of cura. There are "hidden" settings in cura 2.* that you can expose by clicking on the gear. It's probably there that you are having problems.

Printing speed is convered into the "F" command (for feedrate). Unfortunately that is in mm/minute. Not mm/sec. So multiply and divide by 60 to convert back and forth. So after you slice, open the gcode file and search for those F commands. Some control Z movement so ignore the ones on Z only or E only moves. For example:

G0 F600 E1000.473 <-- that says to change speed to 10mm/sec (60*10) and then move to extruder position 1 meter plus .473mm (the extruder value tends to just keep increasing forever). Whereas

G0 F6000 X10 Y10.1 <-- that speeds things up to 100mm/sec and tells where x,y should go.

The infill is often done at a different speed as some of the shell and the outermost shell is often a third speed. You can see this both in cura and in the gcode file.

Now on the printer itself you can set the % speed. This takes those F values and increases them by the percent you say. So set it to 300% to print 3X as fast or 10% to print 1/10 as fast.

There are a few exceptions! In cura there is a minimum layer time. Typically 5 seconds. If you are printing something very small it might normally print that in 1 second so cura slows it waaaay down. This is likely your issue.

Also due to accelration limits short line segments never actually reach the feedrate. So sometimes changing the % doesn't speed things up as the feedrate is the GOAL speed, not the actual constant speed. Although usually the goal is reached on most printed shapes.