# Not sure why, but we recently received a whole bunch of questions about how

(Joseph Chiu) #1

Not sure why, but we recently received a whole bunch of questions about how much filament is on our 1 kg spool of filament. The simple answer: 1 kilogram.

(Joseph Chiu) #2

For length and volume, see http://toybuilderlabs.com/blog/2013/7/13/filament-volume-length

(Jeremy G (WeisTek Engineering)) #3

Or 2.2 lbs for people who don’t do well with kilos.

(Mano Biletsky (Open MAKER)) #4

People just want to know how many meters there are on a spool. (I don’t think this is odd at all!)

Pronterface tells you exactly how much fillament will be used. If you know how many meters there are on a spool, you can calculate if you have enough to finish your print.

(Jeremy G (WeisTek Engineering)) #5

Repetier does the same thing. I’ve gotten pretty good at eyeballing the amount needed.

If your good you can add another spool before the last one goes through the extruder (I’ve also gotten good at this)

(Joseph Chiu) #6

But isn’t the more appropriate way to measure the object by mass or volume, not length of filament? Unless I’m printing small objects that only need a meter or two of filament, measuring the filament length before a print job seems a bit unwieldy?

I understand why length is often used. It just seems wrong to me.

(Jasper Janssen) #7

@Joseph_Chiu I’d love it if my software would tell me both weight (and, hell, multiply it by my cost per kilogram as well, why not) and length, but as it is with just length easily available, I need that information to make the calculations myself.

(Jonathan “se5a” Sorensen) #8

Sounds like when I used to make trampolines.
we got a fair number of people asking us how many sides our octagonal trampoline had.

(Al Williams) #9

@Jonathan_se5a_Sorens I would imagine that’s a business with a lot of ups and downs

(Eric Mack) #10

I think it’s mostly an issue of how information if provided. Since two key host applications specify meters of filament used, it’s logical that people would want to understand that. I know I do. Weight and volume are irrelevant until the applications help me put that into perspective.

(Mano Biletsky (Open MAKER)) #11

@Eric_Mack I couldn’t have said it better!

(ThantiK) #12

@Jasper_Janssen KISSlicer does that.

(Mano Biletsky (Open MAKER)) #13

@Joseph_Chiu maybe you should think about giving in on this one and just mention the length when asked.

About the volume and mass being easyer;
Ofcourse not. We have to make extra calculations (wich, personally i don’t know howto) and convert numbers we allready got from our software.

(Joseph Chiu) #14

@Mano_Biletsky_Open_M , I actually don’t mind providing the info. It was more that I had multiple customers ask the same question in a span of few days. My original post was my attempt at dry humor.

But, I would submit that using filament length at input is still wrong. What happens with direct-from-pellet extruders? Or when filament diameter compensation allows for wildly varying filament?

(Jasper Janssen) #15

@Joseph_Chiu it’s correct for the technique we use at the moment, though, where there are a bunch of variables going in but the result is that there’s GCode that extrudes a certain length. Which means that the length is The only one of the three we know with any calibrated certainty.

(Tony Hine (Nifty Access)) #16

I think the real problem is that is supplier is unwilling to quote in meters because this will depend on the consistency of the diameter of the filament. In other words it may vary considerably from one batch to the next.

Skeinforge would tell you in every possible way how much filament the print would use, how much your electricity would cost and whether or not the neighbor’s cat would get scared by your printer’s noise. Nowadays, @OctoPrint spits out both length and volume - weight in grams is virtually identical to the volume in cm³, and since i buy my filament (and pelleted resin) by the kilo, that’s the number that matters to me the most.

(Mano Biletsky (Open MAKER)) #18

Inconsistancy of diameter is no problem.

I mean, the fillament per spool is usually the same size. We have to calibrate the printer for that anyway.

(Joseph Chiu) #19

@Tony_Hine_Nifty_Acce I don’t think that’s it. I think it’s because length is simply not how they measure their product. Besides, they can always under-promise and over-deliver the length by a few percent to stay out of trouble.

But, let’s take a 25% cross-sectional area difference between a 1.85 and 1.65 mm filament That means filament length for a consistently manufactured 1.65 roll would be “25% longer” than a consistently manufactured 1.85 roll. So, should the buyer go for the 1.65 mm roll, since he’s getting more length? Clearly not.

Or, if the filament was indeed sold by length, then a manufacturer selling the 1.65 mm could sell less plastic to achieve the same length as the 1.85 mm filament.

(Joseph Chiu) #20

@Jasper_Janssen - I think length of filament extruded at one’s nozzle on the output end is at least more reasonable than based on the length of filament at the input end. At least that number is pegged to the machine.

Ultimately, the math comes out the same – but like any math equations, how you organize the variables in the equation makes a big impact on how easy it is to use.