Hello all,
I searched high and low but can’t seem to find a definitive answer to my question. Because of this I figured I would bring the question directly to current Hub owners and operators.
I never had the need to come up with a cost for printing. I usually print for friends so I print their item and then find out how much the print weighs in grams and then calculate the per gram cost of the filament I used. Then I add a dollar or two as a processing fee of sorts.
I finally took the plunge and decided to start up my own Hub here but can’t get a grasp on how to calculate a Cubic Centimeter cost of the filament I am using. I want to make sure I’m not hurting myself by not covering the cost of the filament and don’t want to guess.
From my research the cubic centimeters of filament depends on it’s density. (Correct me if I’m wrong). Is there any way to figure out the cubic centimeter cost with information I have readily available?
For example:
If I have a 1kg spool of Proto-Pasta and it cost me $69.99 USD. Is there any formula I can use by weighing a certain length of the filament to determine the cost of a cubic centimeter of this particular filament?
Maybe I’m tired or maybe I’m completely dense but I can’t seem to wrap my head around it.
Thanks in advance!
MB3D
3
First of you need to know, what density is and how to calculate with it: Density is a factor, that describes the mass, that a specific volume of material has. Therefore it’s measured in weight / volume, which is mostly listed as g/cm3. cm3 does mean cubic centimeters. 3d hubs calculates it’s prices related to the printed volume since that’s what they know about the order, when just the 3d model is available as source of information. To calculate the weight of one cubic centimeter you will need to know the density of the material, that you’re using. Most plastics have a density between 1,1 and 1,2 g/cm3. Just Polyesters and exotic materials are more dense with a density of 1,4 g/cm3. Special material blends, like mixtures with wood or other fibres, or metal composites can highly vary in density, look it up on the producers website. Next up you need to know, how to calculate the weight (or volume) of a random amount of plastic when knowing the density. Density = Mass / Volume Mass = Volume x Density Volume = Mass / Density Given a spool has 1000g of ABS and costs 25$ then it contains around 833 cm3 of material and has a value of 0,03$ per Cm3. Taking the 3rd equation: Volume = Mass / Density = 1000g / 1,2 g/cm3 = 833,3 cm3 Spool cost / spool volume in cm3 = cost per cm3 25$ / 833 cm3 = 0,03$ If you cant find the density of pure plastics (no composites) then you can look it up on Wikipedia. A density of 1,2 g/cm3 was probably a little too high for ABS, but should be OK for an example calculation. As you can see you can even make quite a big profit (only considering material cost) when charging around 0,2-0,5$ per cm3. Aiming for around 5-15 times the material cost is a good starting point as you also have to include the working time, investment into a 3d printer, the power consumption, other costs for replacement parts, spares, the initial investment into a set of spools to be prepared for orders,… You also have to take the 3dHubs fee into account, when setting your prices, just Google a math guide for calculating with percentages, if you need some help on that. You will have to take a closer look into each model when someone is setting up an order, the prices, that 3d Hubs calculates is for 20% infill. Given the customer requests a more solid print, then you will have to adjust the price to what you think is reasonable anyways. Also model complexity and variety of printer settings etc. make it nearly impossible to create a tool, that gives out fair prices all the time, the method, that 3d hubs uses is a very general one to have at least a basic idea of how much the model should cost.
I find volume is not a very good pricing criteria. For me the running time of the machine is a larger factor then the volume. And runtime depends on print quality required. It makes lot of difference to print something at 0.3mm or 0.1mm layer height. Or a higher print speed as draft option.
For pricing prints, I use:
- grams of material (support when needed included),
- time,
- and electricity consumed.
The most of the cost is time of printing, and as was said before, there’s a big difference in time between 0.10mm and a 0.30mm layers.
Hope it was useful 
Yes time pricing is much better. It reflects printing costs much better instead of just counting how much plastic. What do you charge per hour? Im thinkng 4.50 but it equates to about $.70/cm^3 which is double what people usually charge per cm^3
