Crafts

There's more to life than just hardware and software! It's important that chumby looks good, and that it matches your lifestyle. The chumby is designed in a way such that the core electronics can be easily separated from its outerwear, enabling you to create that exact look you want without having to touch a soldering iron or write a line of code.

Altering or modifying the chumby may void the one-year limited warranty. Please read the Limited Warranty for complete details.

To our knowledge, this is the first open-source effort for outerwear.

Outerware Elements: Generation 3 Devices (hardware code 0307 "Ironforge")

The chumby frame is a flexible molded plastic piece onto which the fabric housing is sewed. In this generation, the core electronics are glued into place onto the frame. The glue is moderately reworkable; however, if there is serious Crafter interest, we will make available for sale naked plastics kits, so that your craftwork can look as good (or even better) than a stock chumby unit!

The chumby front bezel retains all of the core electronics and the LCD. The front bezel assembly is sandwiched in a fashion that enables heat to efficiently escape from inside the chumby. When modifying components in the front bezel be sure to preserve the integrity of the thermal stack or else your chumby will overheat and suffer a premature death.

The chumby rear bezel exposes all of the ports and the speaker.

The flat pattern for the chumby is subject to change. There are many modifications one can perform on the flat pattern to give the device a different look and feel. In our production process for hardware release code 0307, the flat pattern is optimized for use with genuine Italian leather skived to a thickness of 0.8mm (each fabric has its own character, and the flat pattern may need to be tweaked to make the device look perfect). The leather is cut using a set of dies that are created in China from a hand-drawn flat pattern (in other words, there is no convenient intermediate electronic file format available). As a result, we have presented 1:1 scans of the flat pattern pieces that you can print and then use as a cutting guide for your own fabrics.

The plastics for the chumby are also available for download, for those lucky enough to have access to a plastics prototyping process. They are provided in the IGES 3-D CAD interchange format (7.7 MB file).

Outerware Elements: Gen 1 and 2 ("FOO" and "Katamari")

frame

The chumby frame is a flexible molded plastic piece designed to hold the chumby core electronics. The plastic is soft enough to enable sewing.

The current design practice for integrating the frame is to cut off the excess molding on the frame, and sew a bag around the exterior border of the frame.

Note that there are two types of frames in existence today: a version made out of a Thermoplastic Elastomer (TPE), and a version made out of a Thermoplastic PolyUrethane (TPU). The TPE version has a rubbery soft feel to it, and it is chemically resistant to solvents so the only option for attaching it to something is to sew onto the frame. The TPU version of the frame is much stiffer, and the preferred method for attaching that to the frame is via a bonding process, such as a glue or heat bonding (TPU will melt-bond onto other urethane-backed fabrics).

The design for the frame is available in an IGES format file that can be imported into any of several 3-D CAD programs.

flat pattern

The basic DNA of a chumby's outerwear is a flat pattern. It is a paper pattern that you can print out and use to cut out the pieces of fabric that you can sew together to make the chumby's outerwear. You can modify the existing flat pattern or you can make one up entirely on your own.

plastics and emi shield

Aside from the flat pattern and the frame, the other pieces of the chumby outerware are the hard plastics that hold the core together, and the hard plastics that hold the daughtercard. Remember that the daughtercard is the small electronics board that breaks out the chumbilical to a set of standard connectors, such as USB Type A Female, 2.5mm DC power jack, and 1/8" stereo phono jacks.

If you are trying to mount chumby onto something other than our plastic frame, look at the engineering drawing we used to define the locations of the standoff holes on the chumby core board.

While a few of you may be lucky enough to have access to an SLA or milling machine that can leverage the 3-D geometry for these files, a more immediate possibility may be that you want to do an entirely new type of frame or housing for chumby. If so, check out the IGES-format files for all of the plastic pieces used in your chumby. Enjoy!

In addition to plastics, there is one metal piece, an RF shield, that covers the back of the chumby. If you want to tell other people about modifications you've made to this piece, e.g., drilled holes, pieces cut out, etc, look at the engineering data for RF shield.

sewing new leather outerware

Leather has the ability to stretch and squish and it has a nap. These make it easier to create a clean seam than on a synthetic fabric such as exoskin, which has very little forgiveness for mistakes. Here are the steps on how one chumby received new leather outerware:

  1. Copy flat pattern onto leather (example layout).
  2. Cut 1/4" allowance around the TPE frame for sewing.
  3. Cut flat pattern out of the leather, and punch holes using a hole punch tool.
  4. Coat the 1/4" edge allowance of frame with rubber cement, with care to include some of the lip. It is okay to get rubber cement on the exposed part of the frame as it is easy to clean off.
  5. Mate and sew the darts. The dart extent is marked with holes in the pattern.
  6. Put rubber cement on the back of the darts; once dry, pound the darts flat to prevent them from puckering.
  7. Mate the equatorial edges of the leather pieces together, and sew. On the side-to-back piece mating, one piece had to have its edges cut up so it spreads correctly without puckering. A technique where butterfly clips are used to jig the edges in place while sewing was used.
  8. Rubber cement the back side of the seams again and pound flat.
  9. Coat, on the back side, 1/4" of rubber cement around the mating edges of the equatorial leather strips. Use care to coat not only the back side, but the thin mating edge as well.
  10. Mate the equatorial edges to the frame. The rubber cement holds the two together well.
  11. Sew the frame onto the equatorial edges.
  12. Turn the bag inside out.
  13. Use butterfly clips again to hold the back panel onto the equatorial edges. No rubber cement is used for this operation.
  14. Sew the back onto the bag, going around and removing butterfly clips as you go around.
  15. Cut and burnish the thread with a flame so it doesn't come out.
  16. Clip back excess frame TPE plastic to the seam so the plastic underneath the edges is not "telegraphed" to the outside of the design. A proper, 3-d molded plastic will not exhibit this problem, but because a constant force is required to deform the 1-d frame into 3-d you will always have a bit of a rim near the seams.
  17. Turn the frame outside-out.
  18. Clean rubber cement off using a tacky eraser tool.
  19. You're finished! (see finished chumby)

looking for more?

Check out the Crafts section on the Chumby Forum.