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Thread: NASA fastener design manual

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    Jon
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    NASA fastener design manual

    NASA Reference Publication 1228, from March 1990: Fastener Design Manual. By Richard T. Barrett, Senior Aerospace Engineer of NASA Lewis Research Center.

    NASA Fastener Design Manual

    This is a not-too-technical useful guide, loaded with plenty of debunking of fastener myths, and complete with numerous helpful charts and tables about fastener styles, torquing, identification, plating, lubrication, etc. Covers nearly all types of fasteners and fastener-related products, including many common commercially available parts and materials. Comes with three useful appendices: Bolthead Marking and Design Data, Bolt Ultimate Shear and Tensile Strengths, and Blind Rivet Requirements.

    Looks like Barrett is/was (probably retired now) "The Fastener Guy" at NASA. In addition to the manual above, he has a lengthy 9-part fastener design course on YouTube (part 1 below):



    Barrett also published his Fastener Design Course in PDF. Barrett's fastener educational efforts were so comprehensive that he was awarded the Federal Laboratory Consortium Award of Excellence in Technology Transfer for 1993.

    Some screenshots from the PDF link above:









    And here's the PDF again:

    NASA Fastener Design Manual


    Previously:
    astronaut loses $100,000 tool bag during spacewalk
    International Space Station tools
    English/metric measurement error in the Mars Climate Orbiter

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    NortonDommi's Avatar
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    Thanks Jon,
    This is a subject that concerns us all and I for one always have something new to learn. It is also one of the biggest problems I come across. My all time favorite being 3/8" bolts in M10 holes and always in the most inconvenient and hard to access place. Second is wrong tensile rating and not torquing to correct tension or stretch followed by incorrect and/or mismatched bolt heads/ nuts. Dodgy anti-vibration control is up there too.

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    Spent some time as a Mechanical Inspector for a considerable manufacturing corporation. Grade marks and countries of manufacture for fasteners was a regular assignment too. Rc hardness, plating, size and pitch, headstamps, design related dimensions like you see in the Machinery Handbook, are just a few.
    Counterfeiting of hardware is widespread; hence screening EVERY package, regardless of distributor, even those purchased for maintenance department. Now, to some it would seem obvious that substandard hardware is unacceptable in items built for the government. But maintenance? Sure.
    You want SAE Grade 5's holding up that overhead conveyor or just some interpretation of same? Crosby or equivalent lifting eyes or something marked 'China'?
    Sincerely,
    Toolmaker51
    ...we'll learn more by wandering than searching...

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    Jon
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    Taking a deep dive into fasteners might be one of the next chapters for online DIY communities. There are various anecdotal examples of well-placed people insisting that problems with vehicles, machines, and parts are frequently traced to fastener failure. But these statements don't correlate with significant fastener knowledge among hobbyists. We've all seen countless DIY builds of all kinds on the net. Very few of them pay much attention to fastener selection.

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    NortonDommi's Avatar
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    Very true. Torquing to correct tension is often overlooked as well, I spent a lot of time at one job repairing the stuff-ups of a bloke we called 'Stupid Man',(he was a body builder and wanted everybody to use 'Super Man' as his nick-name),who once told me he liked to do bolts up tight and then "give them a tweak until I feel them give".
    Jaws dropped at this statement and it explained why I spent so much time on my shift re-doing everything he touched.
    I've also seen people torque down a fastener and just leave it instead of backing it off and re-torquing. A recent article in Engineering 360 on this subject stated that initial give occurs in 50 - 100 milliseconds so it is no trouble to do the job correctly.
    I also used to win 'smoko' bets by getting fellow workers to torque by hand bolts in a torque tester with the readout covered. It was amazing how far out most were on small fasteners but good to see how close a few well experienced hands were. I had the advantage of practice using a scale.

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    Jon
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    This part about how helical spring lock washers are useless for locking is interesting:


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    I see in the N.A.S.A. Fastener Handbook that as with life the universe and everything the answer is 42. That is an astounding 42% of joint failure is due to installer error! 14% wrong preload and 28% improper assembly.
    A common cause of both that I have seen regularly is dirt. I see people pull things apart without cleaning the area first and then give a cursory wipe with a dirty rag before assembly, or more correctly this is what I find has happened when doing repairs. A collection of old blunt taps are ideal for cleaning tapped holes and the smaller sizes can be run in and out very quickly with a reversible air driver,(drill), an air nozzle with an extended reach can be made to blow out debris. Studs can have a die nut run down them or wire brushed and a few minutes at a wire brush on a bench grinder will clean up various bolts, in the field shaking fasteners around in a bucket with solvent will usually suffice.
    The worst thing about diagnosing a failure caused by lazyness or stupidity is that you usually know the problem was caused by someone who should have known better.

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    Interesting topic No time for an in depth response just now. My through the life experiences have enabled me to witness just about every type or cause of failures imaginable many caused my me while going through the learning curve starting at a very young age. but by far the most interesting ones were the ones others caused from shear lack of attention to the task at hand IE using the wrong fastener for the task over / under torquing, using too short of a bolt in blind hole assembly stripping out the hole or bolt then trying to compensate by replacing with a too long bolt and washering up to compensate for over length when the proper way to do the repair would have been to make a thread repair in the hole by either drilling out threading and installing a thread repair incert or drilling out threading and installing an oversized fastener if possible or a stepped down stud so the assembly would be held with a nut, or extreme cases having to drill out the hole to a taper then filling the hole with weld re drilling and taping the hole back to original
    I learned early on to never allow a helper to use my extended length combination wrenches during re assembly of anything always give them a shorter version and a torque wrench preferably one that is adjustable with a torque limiting clutch not one that simply clicks at the preset torque other wise they inevitably would over torque
    Never try to tell me it can't be done
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    Quote Originally Posted by Jon View Post
    This part about how helical spring lock washers are useless for locking is interesting:


    It is also baloney. Split lock washers, at least good quality ones will highly resist the unscrewing of a bolt or nut. I've seen this first hand may times trying to take apart devices assembled with such lock washers. They will very much dig into the underside of the bolt head and very much resist your efforts to disassemble the joint.

    Now maybe he has a different definition of what it means to lock the joint. If so it would be wise if the manual was updated with full qualification.

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    Jon
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    Quote Originally Posted by wizard69 View Post
    It is also baloney. Split lock washers, at least good quality ones will highly resist the unscrewing of a bolt or nut. I've seen this first hand may times trying to take apart devices assembled with such lock washers. They will very much dig into the underside of the bolt head and very much resist your efforts to disassemble the joint.

    Now maybe he has a different definition of what it means to lock the joint. If so it would be wise if the manual was updated with full qualification.
    Yup, he can also be variously defining the phrases "normally flat" and "fully torqued", and he's careful to qualify his statement with "At this time". Also, if the fastener comes slightly loose, the lock washer is no longer equivalent to a solid flat washer; it can then maintain friction.

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