Changing a M2 from 1.75 to 3.0 mm Filament

[jcspball13]

Was still wondering what the disadvantages to changing to 3mm were?

[Matt_Sharkey]

Well it's a bit hard to really point out a disadvantage here. It's more of a lateral move if anything.

I personally don't want to give up precision with my prints, so I'm not even thinking about 3mm. I believe the main motivation behind 3mm is if you are looking for raw speed, and with that in mind, go for a Bowden style extruder. The 1.75mm simply cant be pushed through a tube to the extruder over those distances, so a thicker, 3mm, filament is needed.

Now with that aside, are you interested in 3mm because it appeals to you in an subjective way? If it's something you desire to have, try it out and let us know what your experience is. I'm all about going for the senseless upgrades because....well..."just because"

Perspective: the computer I'm using right now is a 3x SLI with a complete water cooling loop for CPU and all GPU's with 2 SSD in RAID 0 and 2 HDD in RAID 1.

Do I need any of that?
No.
Did I really want it at the time?
Hell yeah.

[wmgeorge]

Was still wondering what the disadvantages to changing to 3mm were?

I had two TAZ printers and they both used 3 mm. I had a lot of filament when I sold my last one and just made the TAZ 5 buyer a "deal". I think 3 mm is easier to work with but my change to the M2 required the 1.75 size. Having now owned printers that used both sizes I can see no difference in quality. Your pushing plastic into a heated nozzle that is .35 or .50 mm in size, its not that big a deal to get precision, its more in the gearing and feed control.

[jcspball13]

I was just thinking with 3mm you could push more plastic faster, since the filament is larger. Am I wrong?

[jsc]

The limiting factor in many filaments will be how much volume you can melt, not how fast you can push it. Even with 1.75mm filament, you will run into hard mechanical limits.

[ednisley]

with 3mm you could push more plastic faster

The force required to ram filament into the hot end goes up more-or-less as the square of the diameter to maintain the same pressure in the hot end and extrude at the same rate, so the extruder stepper must produce three times more torque: 2.9 = (3/1.75)^2. Extruding faster requires more torque to push more hot goo through the same hole.

More torque requires more current or a larger motor. NEMA 17 motors, even with reduction gearing, fall on the low end of what's needed, as witness the occasional reports of "clicking" extruders. Worse, reduction gearing reduces the maximum speed, so the drive can't push the filament as fast as you'd like with the torque you need.

You could increase the nozzle diameter by the same factor as the filament (0.35 mm diameter becomes 0.6 mm), drive the filament at the same speed, and extrude three times the plastic with the same hot end pressure and motor torque... more-or-less, kinda-sorta, at the cost of worse XY resolution.

Tradeoffs! Tradeoffs everywhere!

[wmgeorge]

Of course increased nozzle size and extruder speed also requires heating the plastic fast enough. It would be interesting for someone to try (not me) an analysis or study of the practical limits of the process.

[insta]

Of course increased nozzle size and extruder speed also requires heating the plastic fast enough. It would be interesting for someone to try (not me) an analysis or study of the practical limits of the process.

You can shove a imperial crapload of 3mm PLA fliament through a 0.66mm V3a nozzle at 220C: https://www.youtube.com/watch?v=BGJska4xnyw

I was running 120mm/sec print speeds at 0.5mm layers. I've only been able to do that on my modified V3a running overvolted at 19v and fan-cooled. The V3b and V4 haven't been able to approach that volume, even with large bores on the nozzles. I think the E3D volcano is the next closest possibility, followed closely by the Lulzbot Budaschnozzle (with ABS or HIPS, it can't do PLA that fast). There's a lot of tradeoffs involved though.

[Jules]

....the Lulzbot Budaschnozzle

Really? (Now that is a creative name!)

[insta]

....the Lulzbot Budaschnozzle

Really? (Now that is a creative name!)

It was actually one of my favorite hotends for ABS because of how well it worked. It's huge though and stands no chance of fitting on the M2.