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What is the deal on MOLEX connectors in EAB aircraft? I see a lot of panels with harnesses using them. I have also read how many people are not big fans. Here is a short snippet from an RV14 builder. Apparently the newer VANS R14 kits come with ready to go harnesses using MOLEX connectors

Link: http://www.myrv14.com/buildlog/20141027/index.html

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I'm not so thrilled. I don't like the cheap, low quality Molex connectors that are used...I didn't even WANT connectors on the wires for my RV-10. I'd rather use nice round, twist lock connectors with shiny gold pins, and then seal them up well too. I also plan to run some ground wires for some things, rather than use exclusively airframe grounding. So when it comes time to actually connect the wires to the fuselage, I'm going to have to do a lot of chopping and re-pinning. I did add conduit, so any new wires will be easy to install. I wish, however, that Van's would have just provided a wiring plan and wire parts kit option, and parts list, so that the builder could add or change things as needed.

1. So, what are the Pros and Cons on using MOLEX?
2. Are there some MOLEX applications that are okay while others which need to be avoided?
3. What alternatives are better and how much better for how much more Money$$ and/or Effort?

I found it difficult to get good crimps on the pins. And to get the pin to nest into the plastic connector. Very thin metal on the pins. In my opinion a d-sub connector is easier and cleaner. Both are kind of bulky.

I can think of very few instances where a disconnect is actually necessary. Maybe wingtip lighting, or if you have something on the cowl that needs to be disconnected. Otherwise a little service loop goes a long ways.

I've heard some mechs refer to them as a work of Satan, with a frequent complaint of them not holding up to a dozen or so disconnects. They are also not waterproof. A double action crimper, at the very least, is necessary to prevent weak crimps.
If you aren't careful and crimp a fraction of a millimeter to close to the tip, the engagement mechanism will be damaged, and the pin will either go in too far or be forced out when "mating" the connectors. On the other hand they are lightweight and relatively inexpensive. As a hobbyist A&P, I frequently use them for interconnects, for example, the fuel flow or oil pressure modules on a CGR-30P. I put DC-4 dielectric grease on the male pins which aids in disconnects and helps avoid corrosion. I tie wrap the wires to adjacent harness when available, or allow extra wire and fold it over so there's a service loop and the wire can be tie wrapped so the connector isn't hanging on the crimps when its not. I also tie a double loop of lacing tape to hold the connectors together in high vibration areas. in 25 years, I haven't had any difficulties.

HTH

Molex is a brand, not a style. They make hundreds of thousands of different connectors and are one of the biggest interconnect manufacturers in the world. Their quality ranges from ok to excellent. They are typically fine for many mate/de-mate cycles, often in the hundreds of cycles for gold contacts. Even tin contacts will, properly installed, service dozens of cycles before any hint of failure.

Molex, and dozens of other makers, produce the D-styles mentioned above. They offer nice shielding integrity if that is desired, and are less expensive than circular styles.

Crimping is something you will need specialized tooling to accomplish repeatably and acceptably. You can choose an F style and get away with a sub-50 dollar crimper, or round styles and and have to pony up to 100 for used crimpers on E-bay.

With proper termination (crimping), the pins will go right into the connectors. Any difficulty indicates a defective crimp. This very rarely happens with proper tooling and technique. Removal of a pin from a connector requires a technique specific to the style of connector.

Like anything, proper cable assembly worksmanship is a skill. It is a breeze after you figure it out, and can be frustrating until you do.

The most important things to consider are current & voltage, isolation, shielding, strain relief, and cable routing in the selection of an appropriate connector system. Planning things deliberately for installation and service are super important. You might consider focusing on just two or three styles for your entire project and invest in the proper tooling. You'll be glad you did.

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Lesuther said:

The most important things to consider are current & voltage, isolation, shielding, strain relief, and cable routing in the selection of an appropriate connector system. Planning things deliberately for installation and service are super important. You might consider focusing on just two or three styles for your entire project and invest in the proper tooling. You'll be glad you did.

I hear what you are saying. I have used them a lot, but mainly with power supplies connected to communications gear, and not in avionics, panels, fuel sensors, etc. Personally, I have never liked them; they look too flimsy.

I was hoping folks might chime in with what the better alternatives are and for what specific types of applications and locations.

They work fine, just get a good quality crimping tool. They have been used forever in Cessna wing roots, Whelen has used them forever with their light kits. I've seen them used on fuel flow transducers on the engine. Buy an extractor too. It will save you a lot of time if you need to remove a pin from the housing. Over time the plastic will potentially crack but that really won't be for a while.

The style of Molex brand connectors you seem to be looking at are .10" mate-n-loks. If you would like something different, a visit to mouser.com or digikey.com makes the search easy...you can even search by picture.

Any way you look at it, termination is critical and deserving of good tools and planning. There are too many brands to go over, and many of them will lighten your wallet really fast compared to more appropriate, lrss expensive lines like Amphenol or Switchcraft. Choose the style you are interested in first. I like cablemounted circular connectors for a lot of applications, either mil spec or not. I base my tool set around the kinds of contacts I am likely to use. I dont generally use F style contacts shown in your picture...but round crimps instead since they are easier and more reliable when done properly. They require more expensive and specific tooling. They generally have higher current ratings and can be easier to extract. That is what I'm talking about with regards to priorities.

For tooling, I like the Daniels Mfg crimpers.

Aviation has fallen a long way down from the days of waterproof Cannon Connectors.

I would not expose Molex to firewall forward heat

Some good advise above about round pins and GOOD double click - color coded crimpers.
be sure to give each one a good "pull" test.
Get a couple of the extractors while yer at it.

The (very highly) qualified electronic/avionics guy I know recommends the Anderson Power Pole connectors over Molex. These are used in model airplanes all the time as power plugs, with much better results than Molex. I'm sure they are mass market commercial electrical connectors of some sort and not specifically made for models. They come in red/.black plastic blocks that slide together to form modular connectors for any number of wires.

The appearance and overall quality of the Power Pole is much more confidence-inspiring than the Molex.

I'm sure neither the Molex or the Power Pole units are FAA approved. The old dinosaur Cannon plugs are definitely the gold standard, and when you need the highest quality for some sort of primary flight safety then you probably can't do any better than the old Cannon plugs.

For less critical components, where regulatory compliance will be achieved by field approval, or where regulatory compliance is not a high priority, I would use the Power Pole system.

http://www.andersonpower.com/us/en/products/powerpole/

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EZFlap wrote:
For less critical components, where regulatory compliance will be achieved by field approval, or where regulatory compliance is not a high priority, I would use the Power Pole system.

http://www.andersonpower.com/us/en/products/powerpole/

+1

These have worked very well in mobile ham radio applications. I am beginning to appreciate how valuable a lot of the home brew ham radio expertise can be in constructing EAB wiring and powering of avionics.