An Experiment: Using Dual Extrusion to 3D Print a Plastic Object with a Bronze Shell

I just ordered some of this new bronze filament. It is made up of 80% real powdered bronze. It prints on normal FDM type 3D printers, but after polishing, it looks like actual bronze, as you can see in the photo below.


http://www.3dprinterworld.com/article/bronze-age-colorfabb-bronzefill-3d-printing-material

It looks beautiful, and I can’t wait to try it, but I do have to say – it’s pretty expensive stuff! A 1.5kg spool of it, including DHL shipping to the USA from The Netherlands, was $130. I’ve calculated this to be about 11 times as expensive as an equivalent amount of ABS.

Here’s my math on that:
(Note: I’m not great at math, so let me know if you see anything I missed)


ABS Plastic Filament (1.75mm):
Density: 1.04 g/cm^3
Volume: 960 cm^3/kg
Price per kg, including USA shipping: $30
1.75 mm filament length for 1 kg spool: ~ 400 meters
Price per meter, including USA shipping: $0.075 (7.5 cents)

PLA Plastic Filament (1.75mm):
Density: 1.25 g/cm^3
Volume: 800 cm^3/kg
Price per kg, including USA shipping: $30
1.75 mm filament length for 1 kg spool: ~ 330 meters
Price per meter, including USA shipping: $0.091 (9.1 cents)

bronzeFill  Filament (1.75mm):
Density: 3.9 g/cm^3
Volume: 256 cm^3/kg
Price per kg, including USA shipping: $87
1.75 mm filament length for 1 kg spool: ~ 106 meters
Price per meter, including USA shipping: $0.82

Based on weight, the bronzeFill is only 2.9 times more expensive than ABS. But because the bronzeFill is so dense, a 1kg spool only has about 106 meters of 1.75mm filament on it. So when it comes to how much you can actually print with it, you need to compare cost per meter. Based on that, we have a cost difference of about 11x.


A Bronze 3D Printed Prosthetic Hand??

I personally don’t mind the price if this stuff performs like I hope it will. I’ll just need to use it sparingly.

But I have a special purpose in mind. I know a young lady (in her 20’s) whose dream is to receive a metallic version of a Cyborg Beast 3D printed prosthetic hand (she was born without most of her fingers on one hand) and has always had self-confidence issues as a result.

Before coming across bronzeFill, I was looking at ways of 3D printing a Cyborg Beast in ABS and then applying some kind of metallic plating to that after printing to achieve the look she wants. Now, I’m thinking that maybe I can use my dual extruder FlashForge Creator X to print the shells of the parts in bronzeFill and print the infill and supports in PLA (plastic).

I use Simplify3D software, which is one of the few programs that makes this possible. I can choose which extruder to use for the outlines (the shells of each object), the infill, and the support.

I have no idea if this will work, but the bronzeFill seems to be based on a PLA material, so I’m guessing it’s going to be able to stick to the PLA in a dual-extruded print. Even if it doesn’t work, it’ll be a fun experiment!

While discussing the bronzeFill material, someone in the e-NABLE volunteer community recently asked how much it costs to print a Cyborg Beast (how much filament it takes), and how much it would cost if bronzeFill was used.

OK, let’s do some more math…


What does it cost to 3D print an entire Cyborg Beast prosthetic hand?

Assumptions:

  • Using 150% scale (for sizing the parts)
  • 30% infill
  • 10% support infill

ABS Plastic Filament (1.75mm)

Hand parts:
Filament length: 41.6 meters
Material cost: $3.12

Gauntlet (Frankie Flood’s short gauntlet design):
Filament length: 26.4 meters
Material cost: $1.98

Cost for an ABS Cyborg Beast print: $5.10
Total cost with assembly materials: $50.10

PLA Plastic Filament (1.75mm)

Hand parts:
Filament length: 41.6 meters
Material cost: $3.79

Gauntlet (Frankie Flood’s short gauntlet design):
Filament length: 26.4 meters
Material cost: $2.40

Cost for an PLA Cyborg Beast print: $6.19
Total cost with assembly materials: $51.19

bronzeFill Filament (1.75mm)

Hand parts:
Filament length: 41.6 meters
Material cost: $34.11

Gauntlet (Frankie Flood’s short gauntlet design):
Filament length: 26.4 meters
Material cost: $21.65

Total cost for a bronzeFill Cyborg Beast print: $55.76
Total cost with assembly materials: $100.76


As you can see, when we factor in the cost of assembly materials, we find that a hand printed entirely in bronzeFill would only cost twice as much as one printed in ABS. Not too bad…

However, a hand printed entirely in bronzeFill will weigh close to 1kg, which is way too heavy for a prosthetic hand. That’s what gave me this idea to try printing the shells in bronzeFill and the infill and support in PLA. I’m hoping this will result in a nice bronze outer shell, with the lighter weight PLA material filling in the inside of the parts. I’m guessing this should reduce the overall weight significantly (compared to an all bronzeFill print).

Hopefully, the bronzeFill will arrive soon, as I can’t wait to get started with the experiment! Regardless of the outcome, I’ll post again with the results, including photos and videos.

To purchase bronzeFill, please visit:
http://colorfabb.com/bronzefill

To purchase Simplify3D, please visit:
http://shop3duniverse.com/products/simplify3d-software

To purchase the assembly materials for a Cyborg Beast, please visit:
http://shop3duniverse.com/products/e-nable-hand-assembly-materials-kit-cyborg-beast-edition

Shopping with 3D Universe helps support our charitable work, making free 3D printed prosthetic limbs for as many people as we can.

For more information about the e-NABLE volunteer community, or to get involved, please visit:
http://enablingthefuture.org
https://www.facebook.com/enableorganization