Hi, I’m building a printer and currently have my choice on bowden system (most probably geared) but not sure should go with 1.75mm or 3mm?
I have heard a lot of positive respond from bowden user on 1.75mm but why does ultimaker still use 3mm? thank you in advance
Any thought would be appreciated
I was looking at this myself the other day, I am switching to dual extruders on my printer but need to go with a Bowden setup to do. I went with 3mm because you can apply more force to it and it’s supposed to have advantages while retracting (and I have a ton of it, which is an important factor).
I did a little bit of reading. What I found was each had it’s detractors and supporters and some people say run whatever you want, it will still work.
As to why @Ultimaker uses 3mm it could be a lot of reasons like existing hardware and supplies or or they like that you can apply more force on a 3mm filament than 1.75mm without it buckling. Maybe they’ll drop a response in tho.
3 mm is easier to machine parts for.
As for more pressure @Jon_Caywood thats relative as a small diameter needs less pressure to do the same job. There should be no difference as the surface area will be in proportion.
@Nigel_Dickinson I would have figured that the nozzle diameter of the extruder would determine the amount of backpressure, not the filament diameter, making a thicker filament which can take more pressure before buckling beneficial.
@Jon_Caywood nozzle diameter is not the only thing as you can go .1 and then you settings would be different. It all depends on heat pressure materials and nozzle size. Nothing to do with just adding more pressure.
@Jon_Caywood back-pressure is a function of the change in cross-sectional area. Since the nozzle diameter is usually the same for 1.75mm and 3mm extruders, the 3mm filament is being squeezed through a much smaller hole relative to its original size. This is why the back-pressure is so much greater.
@Whosa_whatsis when plastic is around hole of extruder is already melted for 1,75 and 3 mm. Pressure is more better for 3 mm
@Whosa_whatsis @Nigel_Dickinson thanks for the thoughts! So in the end, aside from aesthetics and assuming one has their choice of any equipment(extruder, bowden tubes and hot end) needed for either size filament, is there any functional reason to choose one over the other?
The main differences are in the optimal extruder design. 1.75 is better for making simpler extruder mechanisms that are small and lightweight (better for carrying around on a carriage), while 3mm extruders need more/larger parts. For a bowden it makes less difference.
One often overlooked benefit of 1.75 over 3mm is the fact that any 1.75mm filament you find will be manufactured with 3d printing in mind, while 3mm filament used to all be originally manufactured for use as plastic welding rod, which has much looser requirements in terms of diametric consistency, roundness, formulation, etc. There’s plenty of purpose-made 3d printing filament in 3mm today, but there are still some less reputable suppliers passing-off plastic welding rod. 1.75mm filament also results in a thinner, more flexible bowden tube that doesn’t require as much extra length.
OTOH, 3mm is better for TPE and other flexible filaments that are likely to buckle on the way into the extruder because 3mm filament is stiffer than 1.75mm, but TPE is unlikely to work in any bowden extruder.