Bead width varies with print speed

[R3DK 0]

Hello,

I see the bead width varies with print speed and I'm looking for an explanation.

See

The object:

 

• materiaal: PLA
  
• nozzle diameter: 0,4 mm
  
• object width: 2,4 mm
  
• wall thickness: 1,2 mm (i.e. the half of the object width, so ni infill is applied)
  
• prints speed 20, 60, 120 en 180 mm/s
  

 

Two questions:

• We expect 6 beads with a width of slightly more than 0.4 mm. Printed are 7 beads. Why?

• The wires are printed from the inside (road 1) to the outside (road 7) printed. The beads do not have a constant width as the print speed varies. Road 1 (the inside) is very wide at high print speeds and narrower at lower printing speed. I think this is only possible if the central bead comes out extremely slow out of the nozzle and its neighbors on the other hand extremely fast. I'd rather have expected a constant bead width on all seven beads. Do you have an explanation for this?

[Labern 774]

Are you altering the temperature when you adjust the print speed.

You can't expect to change the print speed without adjusting the temp and get the same width lines.

I find it hard to understand your pictures and explanation but to answer your first question I think it's due to the initial layer height which is effecting how many beads you end up with. But I'm not sure.