Custom Zippy Retractable Cables Keep Bench Tidy!

Necessity is the Mother of invention.

I can't speak for you, but I know that I have a hard time finding, keeping, storing, and using cables connected to the myriad of outputs and supplies on my bench.  It's not that I don't have a good storage system, it's just that I'm a bit of a blindsided fart and when I'm into a project I forget some of my good housekeeping skills.  So, after a while I end up with a spaghetti mess of wadded-up cables from continuously pushing the ends back out of my workspace when I no longer need them, only having to fish them out again in a short while.  It's a pain, and causes mishaps and occasionally blue smoke when I use the wrong ones.  So, enter the Zippy Cable!

I wanted something that would retract and stay connected to my bench supply and then be easily retrievable.  Those cheap retractable USB and headphone cable sets are generally crappy, except for their unusually functional retraction mechanisms. 

Now, I suppose you could just lop the ends off and solder on the appropriate connectors, and I did try that, but I found that the wires had a lot of resistance and were just too thin to do anything with.  Since I wanted to get at least 200ma at 12vdc with little to no drop, this simply wouldn't do.  So, I ripped these buggers apart and rebuilt.

I found a number of varieties in the dollar store, but these were the smallest and fit the profile I was looking for.  I also picked up a couple of the bigger ones I found with actual AC power cords on them.  They are beefy, but unfortunately glued together as well as screwed.  I will probably use them for heavier cables later.

Just a note:  

You will need a couple spares.  There is a tiny little detent type ball in these that is the key to the mechanism.  YOU WILL LOSE IT.  I killed one for every two that I successfully made.  Fortunately I bought a dozen of them for less than a buck each at the dollar store, so I was really only out about four dollars.  UPDATE: I have good news; you will get better at making them.  I am now at about one lost ball for every six I make, and I found the exact sets I need in five packs for three bucks on a certain auction site.

Since my frustration is usually surrounding power supply cables running to my breadboard or project board, it makes sense that the first and so far only ones that I have made have all been bi-polar with bananas on one end and either gators or dupont pins on the other.  But, I plan to expand that!

Ok, down to business:

You will need a couple of things.

From Left to right, top to bottom:

• Dupont Crimper
• Rainbow ribbon, or IDE cable (2.5mm)
• Victim
• Magnet (handy for keeping the little ball from getting away)
• Spring clamp
• Dupont Connectors
• Gators
• Bananas
• Tweezers (Optional)
• Pliers
• #0 Phillips/Flathead

Not pictured:

• Soldering Iron
• Shrink tube.

Step one:

Pry the little sticker off one side, it is merely there to hide the screw head.

Once that's out of the way, put the clamp on the whole works and THEN remove the screw.  The unit is under spring pressure, and this is where things can go horribly wrong... 

Step Two (Trickiness warning!):

Now, here is the deal.  You have to remove the half of the assembly that had the screw in it, and maintain pressure on all the works and cables, keeping it clamped to the other half.  The little ball will be free to fall out and disapear forever when you do so.  Be careful!  I found that doing it over a magnet (and if you have a sheet magnet you can put underneath, even better!) saved a lot of headache.

Note the wee ball just at the lip of the clamped area.

Now, suck the ball off the top with the magnet.  Don't tweeze it, it WILL fly away tiddlywinks style!

Step Three:

Slowly remove the clamp, keeping pressure with your thumb, and then let the spring uncoil.

Once that's done, you can start to remove the center drum.  It has the mainspring in it, and is wrapped around the center post that is attached to the bottom half.  Releasing the pressure as you did, allowed that spring to expand to the outer wall inside the drum, leaving it relatively free to come away as one piece; Spring and Drum.

Yes, I bite my nails.  You would too if you had been dinged in the face a half dozen times from flying balls and springs.

Step Four:

Flip that drum over and press the spring flat into it.  You can now take a deep breath and chill a bit.  It shouldn't go anywhere now.

Carefully remove the cable from it's little recess and discard the crumby headphones or whatever. 

Step Five:

Now peel off a pair of wires from either your rainbow ribbon cable, or your IDE cable.  I found that I could fit about 20 inches on a reel.  After that it got sticky and would retract too slowly.  The ribbon cable is just a hair thicker than the flattened cord that I removed, but still fits nicely.

Find the middle of your length and place it in the same recess as the one you removed.  

One end goes out a funny little step-shaped notch and the other goes out a square-shaped notch.  The reason for this is the step-shaped notch keeps that end of the cable on a lower plane than the opposite side.  This will become clear when you first reel it in, later.

Step Six:

Ok, now it's time to re-assemble the whole deal.

Put the drum back on the centre post, being sure to get the middle of the spring through the post's split.  Then wind it (counter-clockwise on mine) until it feels too tight to be comfortable.  About 16 turns on mine.  You can't wind it the wrong way, it won't let you.

When that's done, line up the cable ends with their appropriate notches.  Note one of the notches sits lower than the other, now that little step notch in the drum makes sense, right?

Step Seven:

Back to playing with the little ball.  

Take a look at the top half.  See the little groove cut in it? 

That's where the ball rides.

Now, figure out where that groove it going to lie over the drum when the unit is reassembled.  Then place the ball on the drum in that spot.

See my nicely lined up wires?  The clamp is because the unit is now under tension again.

Step Eight:

Now place the top half back on, try to trap the ball it it's little groove, keep the tension on the drum, and make the little pegs go back in their holes... while you are at it, make free, unlimited energy and a sandwich.

There was a lot of cursing at this stage for me.

My lab partner was his usual helpful self:

If you didn't hear a *Plink* across the room, then congrats!  You just made it past all the hard parts!

Step Nine:

Put the screw back in.  I placed the clamp over the whole works, and used one of the gators to keep the cable from getting sucked into the works and then slowly let the spring reel it up until it stopped.  

Cut both ends about three inches past where it naturally stops.

Step Ten:

Attach what ever lead you want or need to the ends and shrink tube as appropriate.

I am not going to list anything about that here, but if you would really like to know how to crimp a dupont connector or attach a gator, etc.  Email me and I will be happy to walk you through it! 

The Finished Product!