2,85mm same as 3mm Filament?

today i pulled the trigger on a Lulzbot Mini.
Now i wanted to buy some extra filament for it but i got a little confused:

On some places i read, that when they state its 3mm Filament, its actually 2.85. Is this true?
I’m quite unsure… why name it 3mm when it is not 3mm? 1.75 mm is also not called 2mm.

I checked the shop, there are some filaments called 3mm and in the specification it says 2.85 (https://www.lulzbot.com/store/filament/high-temp-pla) or 3mm (https://www.lulzbot.com/store/filament/sale-pla) or 2.9 (https://www.lulzbot.com/store/filament/pla-verbatim).

Where im from there is almost only 2.85mm filament, so i guess i can just buy that and change the diameter in cura?

Sorry i this question was already asked, it wouldn’t let me search for 2.85 in the forum-search…

thanks in advance

good question phil. I only recently learned all this myself.

Most good 3mm filament i guess is actually 2.85mm filament as that is kind of the standard now and i guess with bowden-style extruders on some 3d printers any larger and the filament may get stuck in the long plastic tube (or so i’ve read). That is not an issue on the mini so dont worry about that.

So the quick answer is yes and 2.85 and 3mm filament are the same and should work.

The longer answer is that cura is set in the advanced settings by default to 2.85mm filament and is optimised to extrude the correct amount of filament. The bad news is that if you buy cheap chineese filament you may get filament that is NOT 2.85mm and as such you might need to adjust the cura setting so you dont underextrude or overextrude.

I also just ordered some igus tribo filament on amazon and one of the reviwewers said it is actually 3.1mm in diameter, so i guess not all companies know that 2.85mm is kind the standard when it comes to 3mm size filament. But in theory every filament should be usable if cura is set properly (as long as the diameter does not fluctuate throughout the spool that is).

Thats all i know. hope that helps. Get yourself a pair of digital calipers to keep on hand.

The short answer is yes. “3mm” fillament covers a range of fillament sizes from 2.7mm to 3.2mm. Most manufacturers aim for 2.85mm to be compatable with smaller 3.00mm bores that were common with the oldest 3d printer nozzles. The 3.2mm size is common for ABS plastic welding rods, so some manufacturers (usually the chinese ones with bad quality control) sell that size as 3.00mm because the black plastic is readiliy available. Sometimes less honest manufacturers will also deliberatly size down to 2.7mm, sell it on a 3.3lb roll, and figure that no one is actually going to weigh their fillament. You sometimes find this in no name ebay special fillament, and those are the same people who add filler to their mix.

Generally when printing you want to stick to a reputable fillament supplier. For example Village plastics and Push plastics ABS which I use is usually pretty consistant at 2.85mm. There are some slight differences is various colors. I don’t know if it is because the dies have worn at diffferent rates, or if different colors expand more, but Blue fillament from Push tends to be slightly bigger than black across multiple rolls.

At any rate, the size dowsn’t matter all that much as long as it is in the general range to work properly. you need to make sure you put that exact measurement into your slicing program (cura, etc.), and be aware that on poor quality control (cheap) fillament that value can change throughout the roll. it’s critical for keeping your extrusion rate constant so you aren’t over or under extruding though. Think of fillament diameter like bucket size. if you have a 1 gallon bucket, and you need to fill a 10 gallon tub exactly, it should take you 10 trips. If your bucket was actually 1.1 gallon, by trip number 10, you have an extra gallon spilling over the edge. If you have an extruder that is programmed to think it has 2.85mm fillament in it, and you actually have 3.1mm, you end up with an overextruded blobby part.

Thank you both for the detailed answers, that helped me a lot, now i can shop some 2.85 filaments :smiley:.

I already own two printers, both 1.75 and i tested a lot of filament already and also came to the conclusion to rather pay some more but than get a good quality with exact diameter over the whole spool.

Thx again