Flow rate decreases after first layer

Hello all,

I’m using a Taz 5 to print impactsticks for testing of polymers. With my current project i’m using a flow rate of 150%. When i start the first layer is printing at this flowrate but after the first layer the flow decreases suddenly to 100%. I can increase it back to 150% again mannualy but i have to print a lot of them so it would be easier if there would be a fix for this problem. I’m using cura for lulzbot. Does somebody knows how to solve this problem?



How are you setting the 150% flow rate?

If you are setting it manually via firmware command or LCD before printing, then using Cura LE will reset that flow rate to 100% after first layer. This is because Cura LE has an “Initial Layer Flow Rate” field which is implemented not in the slicer code, but rather via firmware using M221 commands. Before layer 1, Cura LE sends an M221 with whatever is in the “Initial Layer Flow Rate” field, then before layer 2 it sends another M221 setting 100%. (Note: This effectively means that the “Initial Layer Flow Rate” is not an absolute value, but rather a multiplier of whatever the “Flow” field specifies.)

If you set the 150% flow in the “Flow” field, and set 100% in the “Initial Layer Flow Rate” field, you should get 150% throughout the print – as that 150% will be implemented by the slicer internally, resulting in larger extrusion values in gcode. (Note: The 100% for “initial layer flow rate” is a firmware modifier or multiplier of the base Flow rate used in the gcode commands – so 100% in “Initial layer flow rate” really means 100% of the 150% Flow being used for calculations by the slicer.)

Thanks for the great response! I’m using 150% flow because that the filament i’m using is very flexible and if i use a lesser flow it won’t print nicely.

Makes sense – I know I had to jack the extrusion up to 120% or more (and slow way down) to get decent results from Ninjaflex.

As long as you put the 150% in the “Flow” field of CuraLE, it should work. But since CuraLE uses M221 (firmware feed rate scaling) for first layer flow and resets it to 100% after the first layer, any manual setting made before the print via M221 or LCD gets obliterated by the M221 commands CuraLE adds for the first layer.