Perfect?Almost!

?Perfection is a standard set so that you will never finish anything??

Nevertheless, it sure is fun when you achieve something that is almost indistinguishable from that goal, isn?t it? Such is the case of a D-Sub connector I was building the other day. I have been dabbling in airplanes for over three decades, and avionics for almost as long. I have assembled more D-Subs than I can count, and believe me, I know how many ways they can be screwed up. ?Functional? is not that hard, but ?Perfect? is rare. This little project was part of a much larger Autopilot/EFIS upgrade, and involved running a new cable for the pitch servo to the back of the RV-8. The interior is all stripped out, but it still took a couple hours of careful teasing to run a brand new multi-strand servo cable from front to back. Once the run was finished, the overall job was (mostly) in the bag ? just routine installation from then on (a couple days work). The first thing was a new nine-pin female D-Sub to join the cable to the servo. Sitting backwards in the empty passenger space, I had nice lighting, all my tools neatly arranged, new pins, bodies, and back shells ? everything I needed.

I left the cable a little long so I didn?t have to stretch and do the job laying down on my side. The cable had EXACTLY the right size snake skin cut to perfect length. I slipped on a couple inches of the correct size heat shrink to terminate the snake skin, then pushed both of those back to give me good access to the wires. Those were cut perfectly to the same length ? I love a new cable where everything is still parallel! I stripped and crimped on 8 perfect D-Sub sockets ? all met aerospace standards. It looked so good, I took a picture!



I took a little break to go check on the drawings, and when I came back I installed a brand new connector body ? all 8 sockets clicked satisfyingly in place. I pushed the heat shrink up tight and gave it a blast from the heat gun ? just right! Next came the strain relief clamp for the back shell, and it fit perfectly over the end of the snakeskin to make a really fine joint. The back shell went together without dropping any of those little screws ? even assembled it with knurled knobs so I won?t need to use a jeweler?s screwdriver backwards and upside down to connect to the servo.

I sat back and marveled at my perfect connector . Years ? nay, DECADES ? of practice had brought me to this point. And then I paused. And looked. Yes, I had a perfect connector. But wasn?t I going to run the cable through the grommet in the aft baggage compartment bulkhead before I put the sockets in the body? A perfect connector? on the wrong side of the wall! That?s what you get for taking a break at JUST the wrong time in a process?

Paul

I HATE it when that happens!

Ironflight said:

A perfect connector? on the wrong side of the wall! That?s what you get for taking a break at JUST the wrong time in a process?

Paul

Click to expand...

I feel your pain. I've made the same mistake a few times, although I didn't have to undo such perfection to fix it.

Hey Paul... I think this is the first instance where I've seen someone actually use those little strain relief clamps that come in the bag of d-sub hardware! I usually just throw 'em away and wrap the cable with silicone fusion tape.

mcb

I know your pain Paul. Several years ago I had done what I thought was the perfect 64 pin soldered connector in sub zero temperatures only to realize I had left the shell off. I had to scrap the connector get a new one and start over.
I took a course once about how mistakes are made in the service industry. If you are working on a project eg. repairing a radio or engine etc. and there are shall we say 20 steps involved and you are doing maybe step number 7 your brain is quite likely to be at step 9 or 10. If you are interrupted doing that step you will most likely return to pick up the work and start at step 10. This is where a lot of seeming stupid mistakes are made.
Oh by the way nice job on the connector.

Norman

LOL! Man, Paul, till you got to the end -- where the tale ended like most of mine do -- I was really concerned that you needed to get out more. I've never seen someone so ecstatic over a D-sub connector ...

I too can appreciate the marvel and subsequent dismay .

Messing up

Hi Ironflight

I rarely log on to reply to people on the site but have to say your post brought a smile to my face!!!

Perhaps the best post I have seen this year.......... been there done that, got the T shirt, but what I really like is that like me you can say to the world, look I messed up.....

Brilliant!!!

Been there done that

Hey,
Look at the bright side, it could have been a multi-cable 25, 37 or dare I say 50 pin DB connector. A de-pinning tool is a great investment for those of us who are sequence challenged

You have reached the Zen master level of cable terminations.

D Sub Humor

Paul,
41st rule of homebuilding, "If all seems to be going well, you have obviously overlooked something".

No Problem

Paul
Just cut the cable at a convenient place, push cable through grommet. and use crimp on connectors to spice the cable.
Shouldn't take more than 3 minutes.!!!
Oh, BTW I'm getting ready to replace the Blue Mountain Sport in my-9A with a AF3400 and Tru Trak Sorceror Auto pilot. What do you think are the chances of me having the same brain f--t you had????
Regards
Jack

WAM120RV said:

Perhaps the best post I have seen this year.......... been there done that, got the T shirt, but what I really like is that like me you can say to the world, look I messed up.....

Click to expand...

If that is the biggest mistake he made in 2009, he's doing pretty darn good in my book

%%*!@@

Put the nut on before flaring. Put the nut on before flaring. Put the nut on before flaring. Put the nut on before flaring.

You, Paul Dye, are an excellent writer.

I've been building d-subs for abouto 25 years, and that looked fine.
I prefer just a touch more fan to the end pins, to ensure straight entry into the pin tunnel if I can. I bought into the production story, feeling the familiar rhythm of d-sub-ness, grooving it.

And then you crushed me. Man, that really hurts - worse because I've done that. Got the right kind of pins (M/F) and connector? Maybe there's a bright side

There is a bright side...

We all know it could be a LOT harder to fix. At least you didn't use a solder-on connector...it just a case of extractings the pins from the connector, poke it through the grommet, and now make that connector perfect.

Jeez ....

...just when we all thought you walked on water, you go and tell us you actually sink ankle deep. Woe is us.

Thanks for another great post ... it's those kinds of "doh!" experiences that connect us all.

dlloyd3 said:

Put the nut on before flaring. Put the nut on before flaring. Put the nut on before flaring. Put the nut on before flaring.

Click to expand...

Roll edges before dimpling. Roll edges before dimpling. Roll edges before dimpling. Roll edges before dimpling.

Confessing Screw ups

I drilled the holes on my roll bar for two handles to help in getting in and out of the cockpit. The trick is to drill the holes such that the handles go all the way through and you can put a bolt on the end that will not interfere with the windshield. I had the handles installed, bolted in and realized they were on the windshield side and not the cockpit side. I was so embarressed I took the roll bar to a machine shop and they welded over the holes. Then they ground down the weld so it was flush and as good as new minus $50. They asked what he roll bar was for and I was evasive as I did not want to let them know I was building an airplane if I could not even get the holes on the right side of roll bar. When I came back to pick it up, they asked what type of airplane I was building. There is no place to hide when you screw up, just admit it and move on.

S S Anderson
RV 7A Flying
Lafayette, La.