This is a follow-up to a snap fabric I created when I started experimenting with 3D printing onto fabrics . With the snaps being conductive a whole modular system could be created for snapping on and off wearable electronics. I'm excited to finish this because it has taken a lot of experimentation and time to get this far. There is still so much more to explore. Rachel Freire has joined me on my conductive snap adventure, so look out for her own developments of eTextile connectors. She has printed a snap socket that fits existing metal studs! One idea that I intend to incorporate into my own work at some point.
The swatches I show/create in this instructable were made for eTextile SummerCamp, a camp that is held in France yearly. It's an event that eTextile and wearable electronic practitioners go to to share ideas and create. Along with many activities is the eTextile Swatch Exchange. Anyone who participates in the exchange makes a swatch for themselves and all other participants. It promotes sharing work that you are developing pertaining to eTextiles and everyone gets a lovely book full of incredible work and concepts.
My swatch this year consists of two swatches. One is a woven cotton with a snap socket. the second is a knitted cotton with a printed post. Both are printed using conductive PLA on top of the conductive thread traces.
The designs used in this instructable are meant to be morphed and explored. This is just a starting point for those of you looking for custom connectors. Download and change the shape of the snap halves. Print them onto ironed-on conductive fabric, woven bespoke fabric or change the materials of the snaps (use PLA and cond. PLA!). Better yet, print a sensor... with snaps! The conductive filament is actually fairly resistive (good for sensors) which needs to be considered when designing your circuit or choosing to use it for connectors in your project.
Ready to learn how to make some snap connectors for your wearable? Let's do it!
Step 1: Materials
You are welcome to change the materials. If you do change them, you will need to experiment printing onto the chosen fabric and conductive element. I chose to link to one of the fabrics I used but all fabrics can be substituted.
Any conductive thread will do, here are two:
- Shieldex 235/34 4 ply conductive thread
This is silver plated and I have not used this is any long term projects. Meaning I'm not sure how fast or severely this thread will oxidize and lose some of its conductivity. Some silver threads have coatings to prevent oxidization like the Shieldex above, I'm not sure if this one does. Double check with the manufacturer if using in a long-term project.
I have a specific profile for the conductive PLA for the Ulimaker 3. You can use other FDM printer. Other printers I've used:
Lulzbot Taz 5 - The Lulzbot edition of Cura comes with a preset profile that can be found in the "quickprint" mode when "Expert" is chosen in the "Material ease of use:" menu. It works well! If you need to make changes to the settings switch to "full settings" mode.
Other versions of the Ultimaker could probably work as well (I haven't tested them but I don't know of a reason why it wouldn't). I had really good results from this printer considering I was using a MakerBot before. The option for dual extrusion is so exciting too! I have been able to get a dual extrusion to print with two different PLAs including the conductive one which leads to exciting design prospects! That's for another Instructable. :)
Get a ~1" wide roll. If you can, get a ~4" wide roll too. If you only have a think roll you can put down multiple strips.
This 'ible includes profiles for printing with the Proto-Pasta Conductive PLA on an Ultimaker 3.
Step 2: Traces
If starting from scratch, sew traces using conductive thread onto the fabric of your choice. I used a domestic sewing machine with poly thread in the top and conductive thread in the bobbin.
The snap designs are 1"/ 25.4mm apart from one another as-is. You can move the snaps around in Fusion360 to match up with the traces in your project.
My swatches are meant to be very simple and straight forward so I used straight traces but yours may be curved or angled depending on your project.
If sewing traces onto a knitted stretch fabric use a zig-zag stitch so the stitch line can move with the fabric while it stretches.
If you want to print onto iron-on conductive fabric traces turn off the heated bed of your printer (if it has one like the Ultimaker). Otherwise, the hot-melt adhesive keeping your conductive fabric on may reheat and detach itself.
Step 3: Tape Platform
Lay tape down on the platform where your print will be. I always center my prints so I have an idea of where that location is. This layer of tape is not for adhesion as it usually is while printing. Instead, it's for marking where the snaps are so you have a guide in which to place the fabric by.
Step 4: Load Filament
Load the Proto-Pasta Conductive PLA filament into your 3D printer and get it extruding from the hot end. Whatever the PLA preheating setting is on your printer will work.
Instructions for the Ultimaker 3
First, make sure you use an AA print head just like you would with any other PLA. Select to "Load" filament on the Ultimaker 3 and follow the instructions.
The Ultimaker is built to read the RFID tags embedded into the spool of their branded filament. The printer will not recognize the Proto-Pasta PLA and will ask you to choose material manually. Choose PLA.
Once you insert the filament end into the hole in the back and it's been grabbed and taken up by the gears let it be pushed up so you can see about 2" of it through the clear tube. When you hit OK the printer will then feed the filament towards the hot end to extrude. Letting it climb 2" before hitting OK prevents it from falling short of the hot end which is a bummer since you will need to load it again which means waiting for the hot end to cool to start the process again.
Step 5: Download Design Files + Profiles
2 x profiles for printing Proto-Pasta Conductive PLA on an Ultimaker 3 Extended. One for a printhead loaded on the right extruder, the other is for one loaded on the left. Usually, the AA printhead loaded on the left.
This is what is photographed in this 'ible. It has two split designs to help the stiff PLA to flex around the stud. One design has two splits, the other has four.
Also photographed. Slit down the middle to help the stiff PLA flex while pressing into the socket.
This design is used with a semi-flex material. I've included it because there is a semi-flex conductive filament out there right now by BlackMagic 3D. I've also used the design with WillowFlex a biodegradable flexible filament.
The split in the studSplit may not be necessary, I used it in my final swatches but this design should snap fit into the socketSplit designs too.
Step 6: Print, Mark and Place
The final designs I used together in the swatches photographed here are SockerSplit and StudSplit.
- Import the factory file profile into Simplify3D depending on what side your AA printhead is on. Choose to Add a process and then choose the imported profile and name it something descriptive. Hit OK to save the process.
- Open up one of the .stl files in Simplify3D. You will most likely need to rotate 90º so the right side is up. Center and Arrange.
- Click Prepare to Print and choose the newly saved process. Save the gcode file to the Ultimaker's USB drive (or print from a USB connection).
- Pop the USB drive into the printer.
Note: Before printing the model it's a good idea to extrude some filament to make sure the nozzle is not clogged. For example, specialty filaments can expand if they get too hot and sit and stick to the inside of the nozzle fairly easily. they tend to be more finicky to work with. To do this on the Ultimaker, go to Material, and then Move. Wait until it gets to 195º (the print temp) and then rotate the wheel to extrude filament
5. Start the print
When the print in done take a pencil and mark where the print hits the blue tape.
Put a piece of tape on one side of the fabric swatch. Line the stitch lines up with the centers of each mark and tape down. Proceed to tape down the rest of the edges pulling ever-so-slightly on the fabric to flatten it. For the print to bond with the fabric, the printer head needs to be very close to the fabric. So close, that it may drag across the fabric a bit. So, it's important that the fabric is held securely and taut.
Step 7: Adjusting Z-height
Simplify3D cost money, but the one thing that makes it worth it in my book is the ease and accuracy at which you can adjust the z-height. To adjust, click on a process and then go to the "G-Code" tab. This is crucial when printing onto fabric. A positive number means UP AND AWAY from the print bed. Always keep your finger close to the abort button on your first print anyhow, just in case.
For my prints, I started adjusting the z-height .5 mm at a time. A 1mm offset worked well with the fluffier knitted fabric. However, for the print to have a chance to stay on the fabric you want the filament to be pushed through the fabric as much as possible. So, I got brave and didn't add any offset for either of the fabrics I used and the prints turned out just fine. Use caution when printing without an offset! The nozzle can clog if the filament doesn't have anywhere to go.
Step 8: Unclogging Extruder
If the extruder does get clogged grab a small pin and use it to clean the nozzle out. Then extrude some filament to see if you can clear out the tip. If that doesn't help, do a cold pull until all the black filament is gone.
The conductive PLA tends to like to hang around in the extruder head. It's good to keep the filament moving as much as possible and to do some cold pulls every now and again.
Step 9: Print!
You are ready for your final print. Everything should be set. 3D printing with table-top FDM printers are an act of patience.
Once done, remove tape and check out the print. Prints hold better to some weaves and knits that others. You can head over to my How to 3D Print onto Fabric 'ible to learn more about how prints can be attached.
Here are some final thoughts I'd like to see someone run with:
- Dual extrusion printing for multiple signal lines in one connector.
- Microcontroller docks
- Matrix of conductive snaps
It takes a village!
Step 10: Insulate
My swatches do not show this step but it's an important one if you are making a project to wear or interact with! In my final photos, you can see that the traces of the two swatches face each other. If a ground and power touch that will create a short and cause the circuit to stop working or worse, like over heat. For a proof of concept, like these swatches, I didn't take the extra time to insulate the traces since the focus was the connector and I needed to make 25 of each side!