Nozzle diameter, and diameter of extruded material

I own a Taz 4 (with a 0.35 mm nozzle), and I have a question about nozzle diameter. I just extruded 10 mm of filament and measured what was extruded, but the diameter of of what was extruded was 0.75 mm, not 0.35 mm. What I did was this:

  1. On my printer I have some gray PLA filament (recently purchased from 3D universe)
  2. I heated the nozzle up to 205 C
  3. I homed the hot end, moved it to the center-X position, then raised it 50 mm above the build plate.
  4. I then extruded 10 mm of filament (into the air, not onto the bed), and then snapped it off
  5. I then measured the diameter with a digital caliper (and I measured in a few different spots)

I also repeated steps 4&5 a few times just to make sure I got accurate readings. In every case, the diameter of the filament was 0.75 mm. I was expecting 0.35 mm… I have a 0.35 mm nozzle - shouldn’t it be extruding 0.35 mm?

I’ve owned my Taz4 for several years, I’m the original owner, and I’ve never replaced the nozzle. I’ve only printed in ABS and PLA (I’d say that 90% of my prints were ABS, and 10% were PLA), and I’ve never printed anything abrasive. So my questions are:

  1. Over time, does ABS or PLA wear out the nozzle? (I know abrasive material does, but I’ve never heard of this being the case with ABS or PLA).
  2. Does extruding material with a 0.75mm diameter from a 0.35 mm nozzle sound correct? (the diameter of what’s extruded is over 2x the nozzle diameter)



That’s interesting… Maybe its the precision of the digital calipers? Do you have metal feelers to check the calipers?

I’ll have to try this sometime.

@kcchen_00 I have two calipers - one pretty inexpensive (sub $50) and another that’s pretty decent (was in the $100-$150 range if I remember correctly), and both are telling me 0.75.

All filament passing though the nozzle will abrade it. The fact that you measured 0.75mm is irrelevant unless it used to measure smaller. All filament “expands” when passing through the nozzle. It has to with material compensation, heat, humidity, and many other factors.