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Circuit Knitting

Machine knit working circuit boards from downloadable digital patterns

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I've developed a method to knit circuitry, using a knitting machine. There are a number of projects out there for hacking knitting machines so you upload a custom pattern. With circuit knitting, the custom pattern is the circuit board. This method works with my Brother KH-940, and should work with any single bed Brother. I have not had the opportunity to try it on other models, but hand knitters have reported success with it.

I'm designing patterns to share, and I'm hoping the method will be useful enough for others to use, and perhaps design and share their own patterns. I see this as a way to make electronics more appealing to knitters, and perhaps introduce a bit of knitting circle culture to electronics. I also see it as a way to rapid prototype / mass produce / CNC e-textiles.

Introduction

E-textiles (a.k.a. soft circuits or wearables) is a rapidly growing field of electronics. Projects generally consist of interactive circuits embedded in textiles using conductive thread and Arduino-based microcontrollers. The components commonly used are designed to be hand-sewn and worn (for instance, the Lilypad and Flora).

I've developed a new method for creating wearables, machine knitting with bus wire.

Bus wire is pre-tinned copper wire used in electronic circuits. It is inexpensive, solders easily, has stable conductivity, and negligible resistance.

Home knitting machines are designed for rapid production. Patterns can be uploaded as electronic files, and shared in jpeg or bmp formats-- a form of CNC production.



Advantages

  • Unlike conductive silver thread, bus wire does not tarnish and lose conductivity. It also has negligible resistance, unlike stainless steel thread (e.g. resistance of stainless steel thread might be in the range of 18ohm/ft). It's also much cheaper than these fibers. (Spools of several thousand feet of bus wire cost less than $15.)
  • Bus wire is easily solderable, unlike conductive threads which generally require careful hand knotting/stitching to components.
  • The wire is machine knittable, which allows for rapid production and digital sharing of patterns.
  • The method works with conventional electronic components as well as components designed for e-textiles. This opens the door to a much wider range of possible circuits.


Limitations

Lead solder should not be worn against the skin. Circuits need a lining for the wearer's protection.

  • I am exploring other options for when safety and comfort are a priority: sealing joints with liquid electrical tape, lead free solder, and solder free crimp connections.

Wires should not be handled roughly or bent. The wire should not be worn where it will be repeatedly bent with a tight radius. However, if treated with the same care usually reserved for hand knitted textiles, it holds up fine.

  • I've successfully been able to machine knit stainless steel thread, and have developed a method for soldering with it. I plan to eventually explore this approach further, specifically for creating circuits that can handle more wear.



Who this method is for:

  • Artists. As an artist, I'm creating large circuit knit sculptures for gallery display (not wearing). Rapid production and inexpensive materials is important in this application.
  • Costumers. People often create e-textiles for "special occasion" wear (i.e. costumes, party wear). For these kinds of projects, rapid production is more important than ruggedness. This is especially true with accessory pieces (i.e. a bracelet or hat). I had these makers in mind when developing this method.
  • Electronics novices. Bus wire makes knitted circuitry easy to solder. This makes it approachable by novices. I've already conducted a "learn to solder" workshop with it, and plan to develop more workshops, which will hopefully appeal to a wider, more craft-oriented audience.
  • Knitters (machine and hand). Sometimes the means is just as important as the ends. :-)



Project Plans:

A library of stitch pattern circuit diagrams. 

Diagrams for easy reading by hand knitters + bmp versions of the files that can be uploaded directly to electronic knitting machines for printing the circuit board.

Patterns to include:

  • Educational patterns that demonstrate principles of electronics. These are inspired by the electronic circuits I use to teach my students (on breadboards) in my class.
  • E-textile patterns that embed circuits particularly useful for wearables/textiles.
  • Written tutorials/explanations for each pattern.
  • Circuitry designs for knitting sensors.

Hardware: 

  • A catalog of methods for employing electronics hardware into machine knitted circuitry.
  • Components designed for knitting machine circuitry.

Resources

My work continues from the work of many others before me. 

Hi-Low Tech Research Group of...

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  • We can do it!

    Jesse Seay08/20/2014 at 06:00 0 comments

     I created the circuit design below specifically for a circuit building workshop I run in Chicago at Pumping Station: One. I made cuffs for the participants on my knitting machine before the workshop. During the workshop, we learned about electronics and circuit design. Then the participants soldered their choice of LEDs onto the bracelets.

    Afterwards, I asked participants to send me photos of them with their finished cuffs. Angeleah Daidone sent me the Rosie the Riveter self portrait-- you rawk, Angeleah!

  • Knitted Circuit Diagrams

    Jesse Seay08/16/2014 at 16:48 0 comments

    I've been working on the best method to diagram knitted circuits. So far I've been able to use the PCB view in Fritzing to create this image. Thrilled to see that they added lilypad components to their library for pcb view.  Fritzing support suggested I use a pin header symbol as a stand in for the knitted stitches, to use the schematic view, so I may play around more with that, too.

     This is the circuit as a traditional schematic.

    The circuit can be built on a knitted circuit board made with this pattern.


    And if you've got a knitting machine, this file loaded on the machine will knit the pattern.


    I'm working on an instructable that goes into the details of this design. Plus I'll be posting it on Hack A Day as part of my entry for the Hack A Day prize.

  • Diagramming Circuits with Fritzing

    Jesse Seay08/14/2014 at 17:55 0 comments

    I sent Fritzing an email about using it to diagram knitted circuits:

    From: Jesse Seay (jeseay@colum.edu)
    via fritzing.org contact form

    I've created a method to knit circuit boards and I'd like to make a circuit diagram that connects to the knitted pattern. Details of my knitted circuit are here on Instructables.

    http://www.instructables.com/id/Knit-a-Working-Circuit-Board/

    I've been experimenting with Fritzing and something like the pads in the PCB view would work well. The problem is, the pads aren't visible in the diagram view, only the pcb view. Can this be changed?

    If not, can you send me info/cost on getting this created? Also, do you have any discounts/funds for artists/educators? (I'm an artist and professor at Columbia College Chicago in USA).


    thanks,
    Jesse

  • Diagramming the circuit

    Jesse Seay08/14/2014 at 17:44 0 comments

    In order to share circuit patterns, this really needs a method of superimposing a circuit diagram over a knitting chart. I'm thinking Fritzing would be a good way to go. I've never designed a part for Fritzing before, but I've got a pretty good sense of how the part would need to work:

    - Users should be able to define the stitch height and width (like defining the size of your breadboard)

    - There should be a default stitch pattern grid, that allows you to easily erase/create stitches as you create your board.

    - You can place components on the chart, and they will "click" into place.

    That's the basics. What would make it completely awesome:

    - You could define the size of the stitches, to create an "actual size" diagram that will allow you to see how the components will fit into the space.

    - You could export the knitted pattern only:

    -- as a graph (for hand knitters)

    -- as a b/w bitmap with 1 pixel = 1 stitch, to make it easy to upload to a hacked knitting machine

View all 4 project logs

  • 1
    Step 1

    Designing the Circuit

    The circuit is sketched onto a knitting chart with the wire pattern.

    Extra stitches are eliminated and a pattern is produced for the machine to “read”.

    Wide gaps in the row create places to cut the wire, creating separate electrical nodes.

    Multiplied, the circuit pattern creates textile patterning.

    Long floats of wire are easily removed with cutters.

    Components are soldered in place. Long jumper wires can easily be hidden between stitches.

    The finished circuit

    Electronic Damask.mov from Jesse Seay on Vimeo.

  • 2
    Step 2

    Additional details can be found on my instructable for knitted circuits.

View all instructions

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