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NASA Workmanship Guide for wire splicing
- crmrc114 3y agoLooks like the entire guide is here https://workmanship.nasa.gov/lib/insp/2%20books/frameset.html https://workmanship.nasa.gov/lib/insp/2%20books/frameset.htm... Pretty darn cool little site, will have to mirror it.
- ProllyInfamous 3y agoEven as a retired IBEW electrician, I learned several "workmanship tips" from this wonderful assembly guide: Something that I definitely "did wrong" for decades was over-twisting stranded wires before inserting them into a crimp connector. According to NASA's guide, the correct way is to strip the wire and insert it without additional compaction. Their reasoning makes sense: leads to individual strand breakage and/or loose crimps. Related, double-crimp terminals are designed to have one crimp over uninsulated wire, the second (closer to contact/space/barrel) mates with the stripped copper. Similarly, for twist-post connections, the first 1.5 twists should be of insulated wire, and then several more of stripped conductor.
- cuSetanta 3y agoHave used this site a lot over the years, really useful resource. I wish ESA was more willing to do this sort of guidance document rather than just the requirements.
- dotancohen 3y agoNASA has some terrific workmanship videos as well. Here is the one on soldering techniques: https://www.youtube.com/watch?v=_RXugDd0xik https://www.youtube.com/watch?v=_RXugDd0xik
- haaz 3y agoGreat guide, especially for beginners/laymen.
- gumby 3y agoI consider these advanced splices. Someone fixing a power cord in their house need not go to such extremes.
- gottorf 3y agoJust a reminder to all homeowners that the other extreme is also bad; you can't just wire-tape two Romex cables together in an attic and call it a day!
- dylan604 3y agoI wish someone had told the person that did nearly this very thing to the low voltage control cable to my external AC compressor. At least in the attic it would not be exposed to weather and UV. <facepalmEmoji>
- onetimeuse92304 3y agoI always splice wires considering these good practices, regardless of what application. I just like doing things correctly and reliably. I also have a little bit of a fetish. I really enjoy it when other people do their work correctly and do those small things that show their prowess. And I like to to think somebody someday sees what I did and will enjoy it the same. That's why, when I sail, I always have all my lines neatly tied and organised. And use proper knots for their applications. And look at other yachts when docked to see if their owners know what they are doing or not.
- semi-extrinsic 3y agoDo you knoll when building Lego?
- onetimeuse92304 3y agoThese days I leave Lego for my kids.
- gumby 3y agoHave considered those standards in some safety critical, high vibration applications. NASA aren’t kidding. It was eye opening to me to consider crimps superior to soldering in terms other than convenience. We never got out of the prototyping stage but it was clear that we wouldn’t use this approach for the parts of the system that weren’t vibrating. Of course if you’re building a space- or aircraft it’s worth doing this pretty much everywhere.
- hkhgjhgn 3y ago[flagged]
- chkaloon 3y agoI got trained in NASA soldering standards in the early 80s. Worked as a tech in college helping build test harnesses for an X-Ray telescope that was to fly on Challenger. Got delayed after the accident, but I think it eventually flew 20 years later. They were very serious about this stuff, for obvious reasons. No rework possible in space. I still use those skills on my home DIY hobbies.
- dylan604 3y ago> No rework possible in space. I suddenly started imagining someone trying to strip some wire, twist the strands together, hold a soldering iron and the solder and the wires all while essentially having Mickey Mouse fingers from being in a space suit. If something ever deserved the No User Serviceable Parts Inside sticker...
- calamari4065 3y agoI really hope someone stuck a "no user serviceable parts" or "warranty void if removed" sticker on JWST
- rickydroll 3y agoThat is why they made Wago lever nuts
- dylan604 3y agoBeing unfamiliar with this, I had to look it up[0]. While these look interesting, I can't imagine where I'd use them. They are HUGE. Like bigger than that even. I can't imagine unbolting the side panels of a satellite in space, being able to use one of these, and then it being able to fit back into the original position. [0] https://www.wago.com/us/discover-wire-and-splicing-connectors https://www.wago.com/us/discover-wire-and-splicing-connector...
- verisimilitude 3y agoThey're _excellent_ for wiring devices into junction boxes in construction; particularly when connecting the higher gauge luminaire wires of an overhead light to romex. For some reason they're polarizing among electricians in the US (they carry all necessary listings for use in the US...). By contrast, they're widely accepted and used elsewhere.
- idlewords 3y agoI want to compare this to the Boeing guide
- dylan604 3y agoWhen adjusting the bolts to the aircraft doors, adjust until finger tight
- jeffrallen 3y ago...if bolts are even present.
- dylan604 3y agoThis hole left intentionally blank
- r2_pilot 3y ago*unintentionally
- polishdude20 3y agoThe characters "u" and "n" have been unintentionally left out.
- dylan604 3y agoWe hope? With the info that has come to light about the processes and decision making within Boeing, I would not be surprised if some bean counter calculated that removing 0.5% of all bolts would reduce weight enough to improve fuel consumption. Of course this is totally made up conjecture on my part, but I would not be surprised by it one bit.
- zokier 3y agoAs I commented in the other thread where this comes from, not really current anymore. > That is very old reference, and afaik not used at NASA anymore. More current ref would be https://s3vi.ndc.nasa.gov/ssri-kb/static/resources/nasa-std- https://s3vi.ndc.nasa.gov/ssri-kb/static/resources/nasa-std-... but also note that NASA has been moving away from having their own standards and instead adopting industry standards: https://nepp.nasa.gov/index.cfm/26139 https://nepp.nasa.gov/index.cfm/26139 https://news.ycombinator.com/item?id=39227420 https://news.ycombinator.com/item?id=39227420
- beefnugs 3y agoI swear i recently was looking up torque recommendations per thread size into aluminum and NASA seemed like the only source to show up
- quakeguy 3y agoYour first link doesnt work fyi.
- zokier 3y agoOh right, it got mangled from copying the comment over. Here it is full: https://s3vi.ndc.nasa.gov/ssri-kb/static/resources/nasa-std-8739.4a.pdf https://s3vi.ndc.nasa.gov/ssri-kb/static/resources/nasa-std-...
- wolverine876 3y agoFrom the second link: The NASA Workmanship Standards Program has been working to adopt IPC/WHMA-A-620xS since 2008. The goal is to allow the use of IPC/WHMA-A-620B-S, Space Applications Electronic Hardware Addendum to IPC/WHMA-A-620B as an alternative to NASA-STD-8739.4, Crimping, Interconnecting Cables, Harnesses, and Wiring. This change facilitates a move by suppliers towards the industry voluntary consensus standard but does not force those suppliers who cannot accommodate the current IPC/WHMA-A-620B training options to do so. Notice that the statement is undated but says they've been working on it "since 2008"; possibly that statement is old too. I see that NASA is turning to space industry standards, not general electrical standards (e.g., for a commercial building). But I wonder why do it at all? I assumed NASA's internal standards met their quality and performance needs, but maybe it was just that there were no industry standards when NASA developed theirs?
- spacecadet 3y agoAh yes, this has graced these halls many times. I use the SOLDER SLEEVE SPLICE INLINE as often as I can.
- whoswho 3y agoPair the NASA documents with PACE soldering/rework videos to have a successful outcome each time, all the time.
- p1mrx 3y agoFor practical purposes, the lineman splice is probably the most useful one to learn. It's only moderately more difficult than the obvious "pair up and twist" approach, but the wires remain collinear.
- kbr2000 3y agoThere's another guide [0] for wire wrap technique (solderless, cold welded connections to square posts [1]). Used extensively in telephony switching/patching in the past, as well as digital circuit construction like computers. Quite nice for prototyping, although qualitative sockets/posts can be hard to acquire at a reasonable price nowadays. [0] https://workmanship.nasa.gov/lib/insp/2%20books/links/sections/301_Discrete%20Wiring.html https://workmanship.nasa.gov/lib/insp/2%20books/links/sectio... [1] https://en.wikipedia.org/wiki/Wire_wrap https://en.wikipedia.org/wiki/Wire_wrap
- CobaltFire 3y agoRebuilt a unit with over 7,000 wire wraps in it back in 2009 for F/A-18 flight computer testing. An electrical short had caused several runs to melt and basically run a hot knife through the internal wiring. Had to rebuild it from original hand written point to point wrap instructions (of which there was only the original) coupled with all the changes in the 30 years since original build. That was a hell of a project.