6
$\begingroup$

My Craftbot Plus Craftware slicer estimates cost per job based on filament prices I add as parameters. What costs per meter would you use? I created spreadsheets to calculate this for 1.75mm diameter filament and arrived at PLA = 6.6 cents per meter, ABS = 6.1 and PET XT = 18.6 cents per meter.

Edit: thanks for feedback! I paid \$22 per kilogram for PLA and ABS. I paid \$57 for .75 kilogram of Colorfab XT Black.

$\endgroup$
  • $\begingroup$ You might want to specify 1.75mm or 3mm filament. Although it's easy enough to calculate both. $\endgroup$ – Ryan Carlyle Jun 29 '16 at 18:18
  • 2
    $\begingroup$ A quick note from the economist part of my brain: While the raw material cost (and energy, etc.) is a contributor to product cost, the product price has to be based on consumer demand. Craft fairs, and etsy.com, are littered with stuff priced by labor cost and unsold because nobody wants it. $\endgroup$ – Carl Witthoft Jun 30 '16 at 11:20
  • $\begingroup$ I pay 36 euro for a spool (2.85 mm) of 90m PLA. That is 0.4 euro/meter. And that's a fact. And it's a lot higher than the numbers you guys are stating here. $\endgroup$ – Petra Van OOrsel Jan 30 '18 at 7:16
6
$\begingroup$

This strongly depends on the cost of the spool in question. Prices are not consistent among materials at all; a spool of ABS can cost anywhere from \$15 to \$60 and the same price range applies to pretty much all other plastic.

For the purpose of this question I am going to assume that a 1 kilogram spool costs \$25 (regardless of material) but you can scale the figures to what is appropriate for your brand of filament.

ToyBuilder Labs lists the density of ABS at 1.04g/ml, whereas PLA is somewhat more dense at 1.25g/ml. As such, a 1kg spool of ABS would be 400 meters (1.75mm filament) or 156 meters (2.85mm filament). PLA would come out to 333 meters (125 meters for 2.85mm filament)

We thus have the following costs (cost per meter for 2.85mm filament in parenthesis):

  • ABS: 6.25 cents/meter (16)

  • PLA: 7.5 cents/meter (20)

The density of PETG is roughly the same as PLA, so they have the same cost per meter (for similarly priced spools).

In general, to compute the cost per meter, you would use the following formula:

$$[\text{\$/m}]=[\text{cost of 1 }kg] \times [\text{density in }g/mm^3] \times \frac{[\text{diameter in }mm]^2\ \times \pi }{4000}$$

| improve this answer | |
$\endgroup$
  • $\begingroup$ Thanks Tom, good info. I googled PET density and saw 1.38 grams per mm^2 while PLA was listed as 1.25 g/mm^2. If so, that would make PET around 10% more expensive. Colorfab XT is much more expensive. The results from it are excellent. I'm still a newbie. :) $\endgroup$ – Dennis Rose Jun 29 '16 at 22:50
  • $\begingroup$ @DennisRose - PET is more expensive for the same volume of filament. In reality though, you may use different materials in different ways. For example: since PETG is notoriously a tougher material than PLA, you may end up using a lot less material by printing in PETG (say: infill 20% instead of 40%) than using PLA, so you may actually find that using PETG is in certain situations cheaper than using PLA. Also (unrelated) you may be interested in checking this out. $\endgroup$ – mac Jan 30 '18 at 21:47
3
$\begingroup$

The simplest method is to divide spool price by its length. That's obvious I think. If PLA 1.75 (1kg net) has about 120m length and it costs 16usd then it looks like 1m costs arount 13c. =price/length

I think everyone can buy different filament at different price from different vendors so there is no good general price to enter into your slicer app. It has to be calculated each time you use new filament.

There are also other parts of the price. Electricity, time, wear, depreciation, know-how even the rent is some part of the ending price of the final product. Of course most of them are incalculable as they are permiles or so. But if you don't plan to sell it you can base on the filament price only.

| improve this answer | |
$\endgroup$
  • $\begingroup$ +1 For mentioning additional costs. Further more time might be a factor to consider: both the time required to print, but also the time you personally spend to prepare, trial and error, and so on. $\endgroup$ – Tormod Haugene Jun 29 '16 at 20:44
  • $\begingroup$ The spools I have bought report weight but not length. How do you get length info for spools you buy? $\endgroup$ – Dennis Rose Jun 30 '16 at 2:36
  • $\begingroup$ @DennisRose If spool doesn't have it specified on the label then you can ask vendor or google it. Rewinding with measuring is definitely bad idea. $\endgroup$ – darth pixel Jun 30 '16 at 4:48

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.