[GreenKeys] Molex Connectors and pins

[Keith Mc]

[it sounds like you've had some experience with this...]

Uh... you could say that. <grin> I've been doing crimping for many decades 
now, as both a tech and an Engineer. I also teach it every year at various 
high schools in my area, to my HS robotics teams' Electrical Group members.
(...Trust me, I've ruined my fair share of pins over the years, to finally 
master the finer points of doing it. :-)

DR HOUSE <k9tty at ...> wrote: 
> I agree,  It does take some talent to get them installed well. 
> It helps a lot to have the correct tools.  I do not trust myself to crimp 
> them properly so I carefully fold the insulation tabs and solder the pins.
> I have heard other folks giving up on the Molex connectors completely and
> changing them out to RCA phono and WECo 310 TRS jacks and 303 TS Jacks.
> However you must not leave any open holes, less the mice get inside...
> In most cases patience is a virtue.

Interesting.  FYI, studies have shown that *proper* crimping can actually 
form a BETTER and more reliable connections than soldering.  Just like with 
Wire-Wrapping, during crimping compression you can actually achieve a 
microscopic metal-to-metal weld.

The REAL trick is getting ahold of a DECENT crimping tool of the RIGHT type, 
and understanding the concept of (and how to execute) the "Tulip Crimp".

NEVER, EVER use the "oval" shaped crimping tools, like you often see 
sold at auto supply stores.  They make absolutely HORRIBLE crimps.
(IMHO, they are why many people give up on crimping...).  

What you want is to invest in a DECENT, "heart shaped" Tulip Crimping tool.

THIS one handles most of the electronic pin crimp sizes we'd be interested in:
... http://search.digikey.com/us/en/products/63811-1000/WM9999-ND/243789
... http://media.digikey.com/photos/Molex/63811-1000.jpg

It's made by GC/Waldom/Molex, and is good for virtually any basic electronic crimp.
The Waldom WM9999 is the tool that *I* use for most of my 14-30ga work.  
As you can see from the pic, for $35 you get a tool with *12* different 
sized Tulip Die (heart shaped) positions for crimping.  

Automotive and other bigger, power wiring are MUCH different animals,
and require a different kind of tool altogether.  They should be done with a
Dimple-Style tool, a third type of tool (which we can discuss later, if you wish...)

Next, you have to understand the concept of a Tulip Crimp.

Most crimp pins are "swaged".  IOW, stamped from flat plate stock, 
then folded up origami-style, by again stamping in a series of dies.

The pin will have TWO U-shaped sections.
... The one closest to the pin tip is for the bare wire, to connect electrically to the pin.
... The one at the back end accepts the INSULATED wire, as a Strain Relief.
Attaching this pin will require TWO crimps, using DIFFERENT sizes of die on your tool.

Strip the wire according to the pin's specs.  You will expose JUST enough 
of the bare wire so when the wire is positioned in the pin for the strain
relief to grab the insulated end, the bare wire will just BARELY overextend
beyond the wire crimping zone.  Too much bare wire and the strain 
relief won't work, or strands could flare out and touch other things.  
Too little wire exposed, and you may catch insulation in the wiring
crimp while trying to do the first crimp, or not have enough bare wire to grab.

Also make sure the end is CLEAN and shiny.  If too oxidized, clip off the
end of the wire and try again.  Most of the time oxidation is limited to the 
first fraction of an inch of long exposed wire on the reel.  If it is still 
oxidized after cutting an inch up, use a foldover of very fine sandpaper 
to pinch-and-pull to "shine it up" a bit. This insures a good electrical connection.

We will start with the BARE wire crimp.  
After doing it correctly, we THEN do the STRAIN RELIEF crimp.

In making a Tulip Crimp, ORIENTATION is essential.  
Start by placing the empty pin with its U in the "base side" of the Heart Die.
The two ends of the U are now facing the double curve of the other side of the die.  

If the flare of the U is too wide to enter the outer edges of the other side
of the die (the "double curve" side), you may have to first squeeze the 
two sides of the U together slightly, to make them parallel.  You can do this 
with either a pair of needle nose pliers, or it can be done with a gentle 
touch by placing the U facing sideways on the "two flats" portion of 
the tool, and giving it a GENTLE squeeze, until they JUST become parallel.

Now, with the U of the electrical crimp in the base of the Heart, squeeze 
JUST enough to grasp and hold the pin firmly in place (NOT crimping!), 
so you can insert the wire.  IMPORTANT:  The back end of the electrical 
crimp zone should now be FLUSH with the surface edge of the tool!

IF everything is right, you can now insert the prepared wire, and the 
insulation will "bottom out" just shy of the electrical crimp zone.

(Execute the BARE wire crimp)  SQUEEZE HARD.... Pause... Release...

Looking from the end, you should now have a HEART SHAPED CRIMP.
The two ends of the U should have followed  the curves of the double curve,
causing them to CURL BACK on itself.  This causes the two ends to turn 
180 degrees, and jam themselves back INTO the wire bundle, while 
the die holds the sides together to keep them from expanding.

The top now looks like "two bumps", just like a Tulip Flower (hence the name).
If done correctly, you should now be able to tug on the wire slightly,
and it won't come out.

If this didn't work (eg the wire is still loose), you may have used 
the wrong die for the selected wire size.  You can sometimes SAVE 
this by CAREFULLY moving the entire assembly to another die 
(typically one step smaller), and squeezing again.  Again, BEFORE 
squeezing make sure your orientation is the same as before!

Next, we do the Strain Relief Crimp, with a slightly LARGER die.

Depending on the thickness of the insulation, move one or two steps 
LARGER in die size.  Repeat the above directions as to orientation
in the tool.   

My Trick - Since adjacent sized dies on the tool are alternating in 
orientation, "The Move" consists of quickly FLIPPING the tool
between the two crimps.  Spin-flip the tool 180 degrees in your 
squeezing hand  while holding the wire&pin still in the other hand.  
Done correctly, it allows you to "crimp, flip, crimp" in succession.  <grin>

HOWEVER, this time, for the strain relief crimp we will squeeze LIGHTLY.  
The point is not to PIERCE it, but only to CURL the U back to wrap and 
HUG the wire to add support.   In fact, if you try to use the same
die as before (or squeeze too hard),  you WILL fracture, or even 
shear off the wire entirely!  

Therefore DIE SIZE IS CRITICAL here.  It is better to err on the 
LARGE size while getting used to executing the Strain Relief Crimp,
because you can always step back down in size and repeat it, 
if necessary.

On some pins, the strain relief U is way too long for the diameter
of the insulation.  If this is true,  you can shift this to an Overwrap 
Crimp by using needle nose pliers to fold the two U legs first, 
and THEN crimp it.  This forces the two sides to slide around each 
other, and keeps it from forming a High-U Tulip with an air gap 
under the arches (which doesn't hold against strain very well).

If both crimps were done right, you are now left with a correctly 
crimped AND strain relieved wire, ready to insert into the housing.  
(<snoopy dance> Yea!)

There is one exception I've found...  Trying to crimp a 22gauge wire onto
a pin to fit 0.100" center housings.   You sometimes have to do a THIRD,
VERY light crimp on the strain relief crimp with the next size smaller die, 
to just --slightly-- compress the insulation in order to get it to fit into 
the housings.

One more thing... On many Molex pins, the original swage-forming
process may leave the two tabs that keep it retained in the housing 
too close to the pin's surface to properly do their job of grabbing the housing.
So, to fix that I always make sure I GENTLY fan them out just a bit with 
a dental tool, before attempting to insert them into the housing.  
This makes sure both tabs will engage properly.
But be VERY careful!! More than once I've had a weak tab break off in 
my hand by trying to flare them too far, or with too much force.  
(...mumble grumble...)

Bottom line:  Proper crimping is a function of the RIGHT kind of tool
(tulip), proper pin and wire prep, using the RIGHT sized dies for the pin 
and wire combo, AND using the RIGHT squeezing touch...  
All of this experience comes with a LOT of practice (and ruined pins... ;-).
So again, please make sure you get a few extra pins in your order...

Does this all make sense?

- Keith Mc.