Why 3mm?

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Why is OSE using 3 mm filament instead of the more common 1.75 mm?

The hobbyist world uses 1.75 mm filament. The advatage according to Stack Exchange is slight improvement in control over the extrusion. See https://3dprinting.stackexchange.com/questions/264/when-to-use-1-75-mm-vs-3-mm-filament. The general consensus is that 1.75 mm filament gives slight (insignificant?) improvement in printing detailed features with small nozzles - while the 3 mm filament gives performance increase with large nozzles

The 'slight improvement' should be studied: is there any side-by-side comparison documented - of 1.75 to 3 mm filament results as a function of nozzle size?

There are, however, 3 significant advantages of 3 mm filament from the OSE perspective.

  1. If we are interested in making our own 3D printer filament, it is easier to produce 3 mm filament than 1.75 mm filament. This is important for the possibility of distributed manufacturing of filament.
  2. 3 mm filament can print faster. Assuming that filament heating is not the limiting factor - you can simply push 3 mm with more force to get a faster extrusion rate.
  3. 3 mm filament can print more effectively with rubber. It can print rubber both faster, and it can print softer rubber. The metaphor is that pushing soft rubber is like pushing on a string of spaghetti: you can only push so hard before it kinks and jams in the extruder.

Why did the hobby world ever settle on 1.75 mm filament? Answer is not clear. It is undisputed that:

  1. 1.75 mm extruders need less drive force, so do not need to be as heavily-built as 3 mm extruders
  2. The 1.75 mm filament is more widely available on the market

Actual performance (speed of print, detail) should be explored side by side. This is difficult since 1.75 mm extruders can't handle 3 mm filament (3mm filament won't fit), though 3 mm extruders can possibly handle 1.75 mm filament. The Universal Gearless extruder is designed for both 1.75 mm and 3 mm filament.

- could it be that per each mm of filament pushed you have a little less than 1/2 the volume of material, so you can have ~2x the "steps" of extrusion variablity for small flow?