There are a few common ways to age or force "natural" patina onto bronze and copper alloys.

  • Bright green verdigris: copper carbonate
  • Dark green verdigris: copper II acetate
  • Dark brown or black shading: ?? (some sort of copper sulfide?)

The verdigris can form spontaneously just from cleaning, and will "stick" best to very clean (polished) bronze. They can be prevented with light waxing, and can wipe off with a soft cloth.

The darker color, as an "oil-rubbed bronze" finish, is an integral part of the surface material and can only be removed with aggressive wire brushing, sanding, or other surface removal.

skulls with various finishes

Note: this is an addendum to the 3rd step of a print / sinter / polish process.

Solid bronze can be finished and polished to a bright luster, not unlike jewelry. It's a very hard, beautiful metal with some cool properties. It cleans up similar to metal-filled plastics, but there are a few steps specific to solid metals.

tl;dr: pickle, brush, shape, tumble, maybe brush again, polish, buff, wax.

Note: this is step 3 of a print / sinter / polish process.

Now that you've successfully printed with "metal" filament, and possibly sintered a solid metal part, you want to make it look nice. These steps are generally chronological, but you can always go out-of-order or do a step again. If you do plan to sinter, I highly recommend a pass of trimming & shaping before the sinter, then further cleanup after.

Note: this is step 1 of a print / sinter / polish process.

This is a quick overview for how to print metal filaments in a "normal" 3D printer: Colorfab (Brassfil, Bronzefil, Copperfil), Proto-Pasta (composite SS, Iron, and Copper), and Virtual Foundry (Filamet in bronze, copper, cluminum) sell filaments with at least 50% metal content. Other "metal" filament with less content can be printed like normal PLA (or whatever base plastic) and is therefore less challenging.

Note: this is step 2 of a print / sinter / polish process.

I've spent sort a lot of time figuring out how to print and polish metals. Just because it's neat. There was a LOT of trial and error, and very little actual material I could find reliably, so I hope this log helps any others (or future me) reproduce the results.

3D Printed Fidget Spinners

I got these designs off of a site called http://www.thingiverse.com, where you can design templates and share them with the public, or download someone else’s. If you have a 3D printer, I highly suggest you use this site. I managed to find some designs and press the bearings and/or steel balls into them. Enjoy!

Shark fin spinner- http://www.thingiverse.com/thing:1936727

Triangular spinner-http://www.thingiverse.com/thing:2126470

Steel ball spinner- http://www.thingiverse.com/thing:1821445

Shark fin spinner Triangular spinner Steel ball spinner

Spinner w/ shark "fins" Spinner shaped like a triangle Spinner w/ steel balls for weights

Spinner model
Caps

update: I stopped development on this project, for a few reasons:

  1. cost
  2. functionality
  3. flexibility

The handset unit fits in a Nintendo Nunchuck. Assembly is straightforward, but involves a dremel and a lot of relatively fine soldering. Nunchucks cost $10, and the remaining components are about $30-50 in small quantity: LiPo battery ($5ish), radio ($2-5), mcu ($10-20), BMS ($5-10), LED & discrete components (<$1). They take about 1-2h to build. Performance is as good as or better than the Nyko wireless unit. I ultimately made functional prototypes with the NRF24L01 chipset (inexpensive and easy to program) and a 433/915MHz radio (harder to find and program, but better range).

The receiver end is much simpler. It's about as big as wiiceiver, costs about the same ($20 + radio), and is about the same difficulty to produce -- 20-60 minutes of assembly and soldering.

Functionality: as a 2-axis remote it works great, but one of the target applications was for a surfboard. 2.4GHz doesn't penetrate water well at all, so I went to 413/933MHz radios. They work, but still not great through water.

Flexibility: Libraries for the NRF24L01 and 433 / 915MHz radios are *significantly* different. Enough that it's not practical to use one software stack for both.

Based on the combination of the above factors (it's expensive, hard to make, and can't easily support cheap/plentiful radios) I've stopped development. It was a cool project though!


note: working title

Wiiceiver has been awesome -- it lets people use an inexpensive wireless nunchuck + standard ESC to drive their skateboard. But the internet is running out of nunchucks, and there are some features still missing.

Wiiceiver X is a two-module system, controller ("Chuck") + receiver ("Board"):

  • wireless, ergonomic, rechargeable handheld controller w/ battery status
  • receiver module with battery disconnect, current & voltage measurement, and servo (ESC) output.
  • fully hackable: exposed pins on both units, standard NRF24L01+ transmitters, simple bidirectional communication

Wireless Chuck features:

  • LEDs for board battery status
  • configuration interface for the receiver (same as Wiiceiver's configuration routine)
  • channel bonding & checksumming for managing cross-talk: board <-> chuck will share a provate channel, up to 100 channels available

Receiver / Board features:

  • LEDs for management / troubleshooting
  • channel bonding to a chuck
  • on/off ESC power management & voltage monitoring
  • up to 4 ESC outputs (any can also serve as BEC connector)

FAQ

  1. When will it be available?
    • I don't know, I'm working on it now. Probably $75
  2. How much will it cost?
    • see #1
  3. Can I install it in my own skateboard / go-kart / unicycle project?
    • Sure.