I'd heard of the Nomad ChargeKey, and wanted a similarly small usb cable, but I didn't want to pay $25. So I decided I'd spend $4 an a flat USB cable and hack it to make my own! You'll need:
- Soldering Iron (stand and sponge optional)
- (Optional) Helping Hands for Soldering
- Desoldering Wick
- Sharp Scissors (deli brand from Popular is good)
- Sharp Penknife/Craft Cutter (deli/olfa penknife blade from popular, or craft cutter from daiso)
- Small Flathead Screwdriver
- Flat USB cable ($7 from BoxBoss, $4 from IT fair/qoo10.sg)
- Super Glue (not in picture)
If you break the plastic connector in Step 1:
- Air-Dry Clay from Daiso
If you're bad at soldering
- Small Metal File
*Note: suggested shops are from Singapore
Step 1: Measure the Desired Length of Cable
Use your phone and your powerbank or whatever you'll want to use the cable for, e.g. laptop/wall plug to measure what length you want it to be. If you already know you want it to be, say, 7cm long, it's still advisable to check if it's a suitable length.
Use a pencil to mark out the desired length. Remember that the point where you cut the cable is not the full length of the finished cable because the USB head takes up some length too.
Step 2: Pry Open the USB Head Connector
I chose to pry open the USB side, so this instructable will be about reconnecting the USB side. If you pry open the micro USB side, similar steps may apply, but I'm not sure.
It may take some force, but do it slowly and carefully, and try not the damage the plastic because it can be reused later. If you do damage it, that's alright, we'll use something else later. Extract the connectors and wire.
Step 3: Desolder the Connections
The USB connector should be soldered to 4 wires. Desolder the 4 wires and separate them from the USB connector. I wasn't able to suck up all the solder without creating some brown marks on the chip, but skilled people will probably do better, heh.
It might help to pull on the wires are you're desoldering because even when most of the solder is removed, a small amount of solder can make the wire stick to the chip, so pulling on it can help separate it.
Step 4: Strip the Flat Cable
You may cut the cable to size before stripping the cable and wires once at the end, or keep stripping the cable and stripping the wires until you reach the desired length. This lets you practise stripping so the final strip will be perfect.
Use a sharp blade to gently cut the cable, then pull off the cut off segment. You may need to experiment with this to find the best way to strip it. In my case, I only had to slice it on one side to be able to pull it off with some force, but it may not be the same for other cables of other materials.
Be careful not to cut too deep, as the insulation around the wires might be nicked, weakening the wires. If the cut is too shallow, it might be hard to pull out the cut off portion.
The idea is to strip off the cable to expose a short segment of wire that can be stripped then soldered to the USB connector, ultimately mimicking the condition the connector was in before we cut the cable.
Step 5: Strip the Wires
When the cable is at the desired length and stripped off to expose a segment of wire long enough to allow it to be soldered to the USB connector with ease, the wires, too, need to be stripped.
Some people may have a wire stripper that takes care of this, but I don't, so I just used a pair of scissors.
Gently cut down on the insulation of the wire, then rotate the scissors around the wire so the insulation is completely cut off from the rest of the wire. Be careful to only cut the insulation, and not the copper wire inside, or you may have to shorten the cable more than you'd like.
Pull off the insulation (it helps if your fingernails are a little long), and repeat for the remaining 3 wires.
Step 6: Re-Solder the USB Connector
Try to make sure the wires are soldered evenly so that the USB connector is in line with the cable. I didn't, so my USB connector is a little slanted...
Step 7: File Off Excess Solder (optional)
Due to my bad soldering skills, there was a little solder at the back of the USB connector that was protruding and prevent it from being re-inserted into the plastic holder.
Solder can easily be removed by filing, but don't file too much because this might damage the USB connector.
Step 8: Fit the Plastic Connector Back
This step only applies if you managed to remove the USB connector without damaging the plastic. If so, use a little super glue to glue it back together and you're done!
If not, continue to the next step.
Step 9: Use Clay to Make an Outer Shell for USB Connector
I'm using this air-dry clay from daiso(again), but if you have Sugru or Oogoo or whatever else is moldable and dries to solidify it will probably work.
The USB chip is pretty small, and the final size of the USB together with the plastic housing is small too. If I tried to mold it to the right size directly, the small pieces of clay at the sides would crumble and drop off.
Mold the clay around the USB connector, and make sure there's enough clay covering the part where the wires are soldered to the USB connector, because that part may break under stress. It's okay to have excess clay at the sides and top for now since we'll cut it off later, just make sure the clay is well bonded and won't crumble.
Scrape off the clay covering the metal connections to get something like the picture above. Remember to use a piece of paper to protect your table! Do it on a flat surface so the other side remains flat, and shape the entire thing as you wish. One thing to note is not to make it too thick, since you can't change that later. If it's too thick it won't fit into the USB port. A good thickness is about 2.5mm.
I shaped it rather hideously, but I can't really change it now...
Step 10: Cut the Clay to Size
I tried using a blade but realised that scissors work better for my clay. Not sure what works better for other materials. Use a pair of scissors to cut off the excess because it won't crumble after it's dried and bonded, and test it out by comparing to the old plastic housing and inserting it into a usb port. If you made it too thick you can try to shave off some of it, but I'm not sure how that will turn out.
Step 11: (Optional) Coat the Clay With Super Glue to Strengthen
This will strengthen the clay, since it seeps into it and polymerizes to form connections in the pores of the clay. It will also give it a hard outer covering which won't crumble or damage as easily. Be careful while coating the clay; some reaction seems to occur between the super glue and this particular clay to release white fumes. It's uncomfortable if inhaled or if it reaches your eyes, so try to do it at a distance, or wear a mask and goggles.
This makes the connector look shiny and kind of ugly, but it now as a shell as hard as plastic! It will still be slightly soft inside (if the clay you used is the type that becomes spongy when it dries) because the glue won't penetrate deeply into all the clay.
Have some acetone/acetone-containing nail polish remover on hand to remove any unintentional super glue stains or to separate fingers which were glued together.
I'm not sure how durable this clay+superglue material is, but it seems fine for now!