DIY Cable guide

In the box you should find all the components to make a cable about 1.6m long with a 13cm reversed coil.

You will need the following items to do the build :

  1. Soldering iron. Anything with a reasonably fine tip should do the trick.
  2. Heat gun
  3. Leaded solder (lead free also works, but is harder to work with)
  4. Side cutters
  5. Wire strippers
  6. A lighter
  7. 38mm painters tape and PVC insulation tape
  8. Thin pointed object ( I use a 0.5mm mechanical pencil)
  9. Mini bench vise
  10. Small phillips screwdriver

Optional

  1. Multimeter

Process:

The easiest way to make the cable is to sleeve the wire with paracord and flex sleeve, then fit both connectors and test the cable before coiling. It is easier to solder connectors onto an non coiled cable.

Start by measuring 3.2m of cord, and then removing the inners.

Now “milk” the cable slightly so there is about 2 – 3mm of the outer sleeve extending past the inner core. Use the lighter to melt this slightly and make it into a round end with your fingers, careful , it’s hot. This is so that when feeding through the paracord, the inner wires don’t get stuck.

Start feeding the cable through the paracord outer, using a caterpillar type motion. Once you have about 5cm fed, run the lighter very briefly over the ends on the cable to seal then slightly to stop fraying. Don’t melt the cable!

Continue feeding all the paracord over the cable. Once it’s all done, melt the end of the paracord to the end of the cable you did earlier. This is to keep the cord on the cable when feeding it through the flex.

Turn on your soldering iron at this point.

Repeat the feeding through process, but DO NOT use the lighter to do the end when just starting. Techflex melts VERY easily. Rather put a small piece of masking tape loosely around to stop fraying.

Feed the cable through the flex.

When you get to the end, use the soldering iron to melt all the way around about 25mm back from the cable end. This ensures the paracord, sleeve and cable stays together.

Now milk the cable all the way to the other end to ensure all the slack is worked to the end, and repeat the melting process.

You should now have an approximately 2.8m long sleeved cable with two ends like this:

Using your thin pointy thing, start to separate the screening braid. This is easiest done by starting from the cut end, inserting the pointy bit behind one strand pair and working the point towards the open side.

Complete this and you should have two pairs of thin wires. Twist them into two bundles, and then snip these off.

Now remove the plastic wrapping, and the two thin strings. You should be left with 4 wires, Red, Blue, Green and Yellow.

Use the wire strippers and strip each one back so that there is about 8-10mm of sleeved wire remaining. Use the soldering iron to tin the exposed wire. Be careful, the heat can easily melt the remaining insulation.

Trim the tinned wires so about 1 – 1.5mm of tinned wire remains.

The colour coding I use is as follows :

  • Blue – GND
  • Green – D+
  • Yellow – D-
  • Red – VCC / 5V

Clamp the USB C connector and tin the pads in preparation for soldering.

Carefully solder each wire . If you are right handed , start from the left so you are never working over something you’ve soldered already.

Trim 30mm of heatshrink for the USB C connector. Assemble the two shell pieces around the connector. Then slide the shrink over, and apply heat gently (Flex melts VERY easily).

Now do the USB A side. It is the same process, just use 38mm of shrink. If you have a multimeter, use it to check for shorts before installing the USB A connector in it’s shell.

At this point the cable should be fully functional, and you can test it.

If your PC complains about the port drawing too much power, there is a short somewhere.

Coiling

Assuming everything went well, now is the time to add the coil.

Measure 7.5cm either side of the middle of your 10mm rod and make a mark. This is the beginning and end of your coil. Tear off two pieces of painters tape about 10cm long each.

Place the tape on the end of your cable, just behind the USB C connector ( or if you want more space between your keyboard and coil add more here).

Tape it to the rod on the mark you made.

The side of the keyboard your usb connector is on determines which way you wind the coil. For a connector on the left, hold the rod in your right hand, with the space for the coil to the left. Now start winding away from your body. This may seem wrong, but remember the coil gets reversed later. Keep winding until you get to the mark you made. Tape the tail to the rod. I will sometimes go over the painters tape with PVC just to be 100% sure.

You should now have a neat tight coil on your former. Take a break.

I like to stand my heat gun on the desk and rotate the coil above it , moving from side to side. Lots of videos on youtube. Check out CruzCtrl. I heat my cable until it gets almost to warm to hold. Watch out for getting too close . Melting the flex at this point is annoying.

Let it cool, and do this another two times. While it’s cooling, look up coil reversing videos on youtube.

Get some more tape ready, and reverse that coil. I then tape it back onto the former and give it a slight heat before putting the whole assembly in the freezer for about 45 minutes. Take it out, and let it get back to room temperature before taking it of the form.

You now have a coiled cable that should be fully functional. (Test it again just to be sure)

Cut four pieces of heat shrink 30mm long.

Measure about 70mm from where the tail exits the coil, and melt all the way around with your soldering iron again. Measure another 40mm and do it again.

Now take your side cutters and cut in the middle of the 40mm section.

Place the heat shrink onto the cable (both ends) and shrink gently.

Apply a second piece to each cable end and shrink.

Now take the male aviator and unscrew the small screw on the barrel to remove the front connector piece. Keep the screw somewhere safe.

Unscrew the two screws on the back strain relief completely and keep safe.

Slide the shell over the heat shrink onto the cable. Now prepare the wire for soldering like we did before.

Clamp the connection piece in the vice and tin all the connection points with solder.

Now solder the wires to the numbered pins, in this order . 3 Green , 2 Yellow , 4 Blue and 1 Red.

Slide the shell over and put in all the screws and tighten them up.

The process on the female connector is exactly the same, pay attention to the pin numbers as they will be mirrored from the male side. Note the female connector has a twist lock in addition to the screw securing the body to the connector.

Your cable should now be complete and ready for final testing.