Handshake/knife electrical connectors. Thoughts?

[Steve Crewdog]

Originally Posted by Canadian_JOY

"Knife" or "handshake" connectors are very reliable and robust. I used them extensively in helicopters operating in harsh environments and never experienced a failure.

With that having been said, the comments made by Mike, above, are worth reading again. I prefer to use clear heat shrink, cut about 1.5" longer than the length of the coupled connectors. I shrink one end only and tie the other end closed with lacing cord. This makes a service-removable insulator - just cut off the lacing cord and slide the tubing up the wire. Since one end is shrunk, the tubing stays on the wire and will not get lost.

BTW my preference for clear tubing is based on the desire to be able to look inside the tube to inspect the connection without disassembly.

Thanks Mark, especially the tip about using clear heatshrink. I used some dsubs, and because I was being cautious and not sealing it off too close to the connector I ended up being TOO cautious and sealing it too far off, allowing the connector to disengage. The clear heatshrink let me spot it before it became a problem.




http://seareybuild.blogspot.com/2020...-big-snip.html

[Bill Boyd]

I spent the past week with wings attached in the workshop, setting up and verifying connectivity between my panel and the "things in the wings"- servos, lights, trim, Pitot heat controller. Quite a few things on the Dynon SV Network didn't want to work or at least behave reproducibly, and I was growing frustrated, tired of tying up Advanced Flights tech support guys to no avail, and wondering if the project would best me and become a six-figure paper-weight for months to come. I got it all sorted out, but the issues ended up being in every case an improperly seated D-sub connector without TIGHT thumbscrews, a reversed wire pair or in one case a backed-out female D-sub pin - workmanship issues that were 100% on me.

Properly wired and mechanically installed, D-subs are ok. Handled carelessly, they are flakey - no two ways about it. I can see why in the mil-spec environment they would not replace circular connectors. I'm not a fan of the close side-by-side crowding of the D-subs on the Advanced Control Module - when installed behind the panel and behind a maze of service-looped interconnect cables it's a real challenge to reach some of the thumb screws and adequately seat the connectors. The ACM is a slick piece of avionics that could stand to be a tad larger for the sake of installation ergonomics.

When it came time to remove the wings one last time yesterday for the eventual trek to the hangar, I disconnected all the D-sub cables, aileron and flap linkages and fuel lines, removed the drift pins and gave my teenage helpers the heave-ho. That's when we discovered I had overlooked one connection - the heavy wire to the Pitot that was spliced with a handshake knife-blade connector. They are robust, enough to withstand the force of three guys trying to walk off with a wing!

[jliltd]

While specialty applications of one or a few wires needing to be removed and passed through a small hole then the D-Sub pins and sockets work great. But here's the thing. The hint to use sliding heat shrink above was given for "handshake" connectors. Not pins/sockets. Crewdog, with pins and sockets heat shrink the whole tube so it clamps the joint in place. Don't try to leave them loose like a handshake connector that has positive mechanical locking. It's no wonder you were having issues with the pins coming loose. So just shrink that whole clear heatshrink on down full length. Then if the day shows up in a few years to disconnect you just slit the heat shrink with a razor blade and remove it. Then use new heat shrink when you re-assemble.

With regards to the concerns about loose D-Sub backshell screws and contacts pushing in applications such as wing connections understand the OP was talking about free one wire to one wire connections without backshells. For full backshell connectors, take a look at Deutsch connectors. Similar to modern automotive Weatherpak type their shells snap together with weatherproof seals. Very sturdy and nice. And they come in standard (DT) and mini (DTM) versions for different connection applications. The pins and sockets can be inserted and extracted with standard hand tools instead of specialty tubular extractors.







I have been using them for years without a single failure and the contacts stay clean and shiny since they are sealed.

[Walt]

Personally I'm a fan of good old Amp butt splices, easy to install and bulletproof reliable. How often do you plan on replacing a part or removing the wings?

[Steve Crewdog]

Another thought: With all the puttin' together and takin' apart I accidentally broke the connector to the Dynon Skyview backup battery. But... in my search for a replacement, a light went off and I thought Hmmm.... if that carries power from a battery to the Skyview, then it should be able to carry more than enough power for a LED. Looks like the OAT sensor uses the same type of connector, and it looks like it would fit in an Oznium 11mm LED sized hole.




It did.




A quick post on the Dynon forum yielded the part number for the OAT sensor connector, by our own RV8JD (Thanks, Carl!!), a followup call to Mouser yielded the part number for the 3 hole backup battery connector, they're rated for 5A, 600V. Sierra Hotel, they'll be here Friday, in time for some good weekend work.


Ok, can anyone find a flaw in the logic?

[Ezburton]

There are spade connectors for micro switch terminals I used for generating different discrete signals which come in 0.110" instead of the standard 0.250" (or the 0.187"). They would lock up better than a d-sub if they fit through the hole.

I don't think you mentioned what these went to in the OP or how many times you may have to pull the wire back through the hole (instead of just disconnecting it). I personally wouldn't feel comfortable with using d-sub pins. I would be more apt to add a service loop and dyke off the connector if it ever needed to be removed.

A regular solder splice might work, if you can get a heat gun on it when you want to remove it.

MTCW

[oren_rokach]

I just received the Jrready criimpers ordered through amazon.
Done some testing yesterday, with a gauge, and must admit, that quality is very high.
I was looking to avoid spending 500$ on similar DMC tool w/ positioners, but since many times ordered cheap stuff and than had to buy again the expensive tool while paying twice. this one seems to be a success!!

https://www.amazon.com/JRready-M2252...385592&sr=8-14

I can send photos if you like

Oren