[HN Gopher] Smartbolts
___________________________________________________________________
Smartbolts
Author : tosh
Score : 241 points
Date : 2021-12-31 15:03 UTC (7 hours ago)
(HTM) web link (www.smartbolts.com)
(TXT) w3m dump (www.smartbolts.com)
| RivieraKid wrote:
| > Incredibly advanced. Surprisingly simple.
|
| > Unmatched Benefits
|
| > Unprecedented Value
|
| They think they are Apple, lol.
| asimjalis wrote:
| How do SmartBolts work?
| JohnJamesRambo wrote:
| I don't ride rollercoasters but if I did I would want them to use
| these.
| qbasic_forever wrote:
| I can guarantee a roller coaster track at any modern amusement
| park in America is inspected far more frequently and is much
| safer to travel on than the interstate highways and bridges
| that get you to the parking lot.
| avianlyric wrote:
| SmartBolts won't help if nobody looks at them. Unfortunately
| most rollercoaster accidents are caused by humans simply
| failing inspect structures, ignoring the results of inspections
| or disabling safety systems. Rather than inspections being too
| difficult to perform.
| blamazon wrote:
| I'm a mechanical engineer - smartbolts are cool but rarely used
| in my experience. Much more commonly used are DTI washers:
| https://en.m.wikipedia.org/wiki/Direct_tension_indicator
|
| Due to the washer style can be used with a wide range of
| fasteners. The most common type, in my experience, due to the
| ease of use, has a little bit of colored goo inside the arched
| cells. The goo squirts out when the specified torque is reached.
|
| That being said, there are a lot of approaches to this same
| problem. Another common technique is breakaway bolts that are
| driven with a piece that snaps away when a certain torque is
| reached: https://youtu.be/lrCoi3gaLfU
| lttlrck wrote:
| Smartbolts seem to be useful in applications where there is an
| expectation the bolts will loosen over time/the maintenance
| lifetime, reducing/easing inspection time.
|
| Similar to the tell-tales used on truck lug nuts:
| https://www.dealsonwheels.co.nz/trucks/features/1302/new-tyr...
| colordrops wrote:
| I need these in my garage door. I wonder how much more
| expensive they are.
|
| Edit: way too expensive.
|
| https://www.mcmaster.com/smart-bolts/
| lotsofpulp wrote:
| $26+ each? Now I am curious which applications it does make
| sense to use these in.
| [deleted]
| blamazon wrote:
| Installing to a known torque and painting a line on the
| fastener is a lot less expensive, which becomes important
| when your project has potentially tens of thousands of key
| fasteners, like a bridge.
|
| But for something like an MRI machine where there's fewer
| fasteners and higher stakes - would make a lot of sense to
| use Smartbolt I think.
|
| Tangential: related to trucks, there is a somewhat similar
| product to easily monitor tire pressure visually, which is
| popular: https://www.linkmfg.com/products/specialty-
| products/cats-eye
| bumby wrote:
| This is a common problem is aerospace with obvious
| potential for bad consequences. The general approach is
| safety wiring.[1]
|
| [1] https://en.m.wikipedia.org/wiki/Safety_wire
| PaulHoule wrote:
| Yeah, a quality torque wrench isn't cheap (particularly the
| kind you find in fixed installations like auto repair shops
| and factories) but there's got to be some crossover when
| you are buying enough bolts that you're better spending
| money on tools that are more idiot proof.
| [deleted]
| throwawayboise wrote:
| A problem with many torque wrenches is that they click
| (or beep) when the set torque is reached, but they do not
| prevent tightening beyond that, nor do they have any way
| to indicate how much overtightened the fastener might be.
| It seems to me that these bolts have the same issue.
|
| Ever wonder why the tire shop has tightened your wheel
| lug nuts so tight that you can't get them off with the
| hand wrench when you need to change a tire? They spin
| them on with a pneumatic impact wrench, and then "check"
| the torque with a torque wrench. Of course it clicks,
| because the nuts are already way too tight.
| bumby wrote:
| Slipper torque wrenches prevent over tightening
| Thlom wrote:
| That explains a lot. Had a tire shop tighten the bolts on
| my old car so extremely tight that the threading on the
| bolts were broken. Every time I changed the tires after
| that I had to use a wrench with a looong bar attached to
| loosen the bolts (In Norwegian we call this a
| "latmannsarm which directly translates to lazy man arm,
| not sure what the English word would be). No matter how
| much grease or how much care I took to not tighten too
| hard the bolts were stuck next season. Glad the car is
| sold and not my problem anymore.
|
| (I could of course have bought new bolts, but I always
| forgot about it after spending 2 hours changing the tires
| ...)
| enragedcacti wrote:
| in English we call that a Cheater bar, so it seems like
| that has carried across pretty well :)
|
| https://en.wikipedia.org/wiki/Cheater_bar
| auxym wrote:
| Adding on to that, tensioning bolts using torque is
| convenient and inexpensive but not very accurate at all.
| Some data reproduced in Shigley's Mechanical Engineering
| Design showed a +/- 30% variation in tension for properly
| torqued bolts, if my memory is correct.
|
| Emphasis on properly torqued: in the field threads or
| bolt heads might be dirty, or torque wrenches might be
| out of calibration, adding even more uncertainty.
| [deleted]
| WalterBright wrote:
| If you look at a tire from the side, you can precisely see
| the bulge of the tire, which I do all the time to check the
| pressure.
| [deleted]
| ominous_prime wrote:
| A problem with installation is that torque is only a proxy
| for tension. Torque alone is not incredibly accurate, so
| there are a lot of cases that could benefit from an easier
| way to accurately indicate tension than by externally
| measuring the stretch of the bolt (which often is not an
| option)
| blamazon wrote:
| True, but this caveat is generally pre-empted in design
| phase through safety factor principles - multiply certain
| design parameters by a coefficient greater than 1 to
| account for the inaccuracy in things like torque-tension
| correlation.
| sokoloff wrote:
| Even where you can't measure the stretch directly,
| torque-plus-angle is a better way to achieve consistent
| stretch than torque alone.
| Freak_NL wrote:
| Ah; so that's what those are for. I've seen them on lorry
| wheels, but never got around to formulating a sensible query
| for a search engine. These becoming commonplace seems like a
| recent thing (as in last decade or so).
| mojomark wrote:
| Out of curiosity, on a somewhat related topic, have you tried
| nord-lock washers [1] in any of your applications? We looked at
| them for a small work boat we designed and built, but they were
| a bit pricey and it was just a prototype, so we ended up just
| using a dab of lock tight to avoid vibration. Was always
| curious to find someone who had practical experience with these
| things. I may use them on an upcoming autonomous boat project
| where there's nobody around to do rounds and tighten loose
| bolts that have shaken loose unexpectedly.
|
| 1. https://www.nord-lock.com/nord-lock/products/washers/
| auxym wrote:
| When I worked on railway vehicles (bogies for passengers
| vehicles, more accurately), Nord locks (or equivalent clones)
| were standard on all structural joints.
|
| Especially on a prototype I'd recommend them. Prototypes are
| really expensive, a complete supply of Nord locks for your
| project is probably less than a single one-off CNC part.
|
| Note that Nord locks are specced to be single use. Not that
| I've never reused some on prototypes, but, well, I'd never do
| it on a life-critical joint that is meant to be taken apart
| often.
| mojomark wrote:
| > Nord locks (or equivalent clones) were standard on all
| structural joints.
|
| > Especially on a prototype I'd recommend them.
|
| > I'd never do it on a life-critical joint that is meant to
| be taken apart often.
|
| Very good/helpful feedback. This thread is giving me much
| more confidence to make the extra upfront investment.
| Thanks!
| blamazon wrote:
| I have used Nord-lock washers, they are demonstrated to be
| one of, if not the most effective thread locking washer
| devices under heavy vibration, but as you say they are quite
| pricey. I would certainly recommend them if you have the
| time/cost budget, especially for something like an autonomous
| boat where vibration is expected and routine inspection is
| challenging or impossible.
|
| When I've used them, it's been for critical fasteners where
| ease of assembly was important, and could not be effectively
| decoupled from vibration, and where our recommended
| inspection/maintenance cycle was not guaranteed.
|
| You might also consider something like a pinned castle nut,
| or safety wire, etc. These are not as simple to specify or
| install but more cost effective. Also, I've seen safety wire
| used as a conductive link to detect failure in a remote
| application.
| rsync wrote:
| "I have used Nord-lock washers, they are demonstrated to be
| one of the most effective thread locking devices under
| heavy vibration, but as you say they are quite pricey."
|
| Which is odd, given their simplicity and ease of
| manufacture, etc.
|
| Can you get them stainless or just HDG ?
| blamazon wrote:
| You can get them in various stainless alloys. My
| understanding is they have a really defensible patent.
| auxym wrote:
| Their patent might have expired? Im not aware of the
| situation but these seem to be an identical product:
| https://heico-lock.us/
| mojomark wrote:
| > I would certainly recommend them
|
| > When I've used them, it's been for critical fasteners
| where ease of assembly was important, and could not be
| effectively decoupled from vibration, and where our
| recommended inspection/maintenance cycle was not
| guaranteed.
|
| Taken to heart - sincerely appreciate the insight!
| smegsicle wrote:
| Their promotional video on the Junker test is pretty cool:
| https://yewtu.be/watch?v=IKwWu2w1gGk
| taneq wrote:
| The thing about torques is that they're often written into
| safety standards, and safety standards often have to explicitly
| detail how critical values are measured. So until fancy bolts
| are recognised in the current standards as best practice for
| confirming correct torquing (are they? I dunno), it's gonna be
| really hard to get them into production.
| pimlottc wrote:
| > I'm a mechanical engineer - smartbolts are cool but rarely
| used in my experience. Much more commonly used are DTI washers:
| https://en.m.wikipedia.org/wiki/Direct_tension_indicator
|
| Here's an (old) video showing how DTIs work:
|
| https://www.youtube.com/watch?v=s677UKFiRdA&t=60s
| maxmcd wrote:
| Nice video of the colored goo in action:
| https://youtu.be/5BMQE5XnKww?t=372
|
| Breakaway bolts are discussed/demonstrated a few seconds
| earlier.
| blamazon wrote:
| Fireball Tool is a great YouTube channel! I recommend it for
| any hackers interested in fabrication. The content is very
| approachable.
| jcims wrote:
| Thanks for the link, looks like a great channel!
| kortex wrote:
| Release the schmoo!
|
| That is pretty neat. The Wikipedia page on DTI does a pretty
| poor job of describing how they work, so thank you for the
| visual.
| mc32 wrote:
| I'm not an ME or anything, but it would seem washers attest to
| pressure (tension) at some point in time (when the nut was
| tightened -unless the washer is "springy", which I doubt as it
| seems it simply yields at some point), whereas smartbolts
| attest to the tension when you look at them --so during
| maintenance and not only during installation, so from that PoV,
| they are more useful (informative).
| blamazon wrote:
| That's true, but you can have a qualified inspector mark
| bolts with goo with a paint line that straddles to the
| fastening surface. Then you can just inspect the paint line
| for movement, which gets you most of the same functionality
| at significantly lower cost.
|
| Of course, that requires a trustworthy inspector, which is
| one application where smartbolts become useful, if you don't
| have a trustworthy inspector available at install time. But
| many projects that have importantly torqued fasteners
| (bridges, buildings, rollercoasters) have certified
| inspectors anyway... which is why smartbolts are a niche
| product I think.
|
| Speaking to the trust problem - if you trust the operator of
| the torquing install device, you don't need fancy torque
| indication at all, just mark the paint line at install. That
| is the most cost effective.
| mc32 wrote:
| Yes, that seems like a cheaper option; however, I think
| when you have constant stresses over time, bolts can
| stretch or simply parts can wear over time and a paint
| score or even a frozen nut won't reveal lessened tension.
| Though maybe in this case the issue would have become a
| concern way before the bolts start to indicate a problem?
| blamazon wrote:
| Interestingly that has kind of moved upstream to a design
| phase consideration in modern times due to the incredible
| depth of understanding we have about materials.
| Structures can be designed such that their expected
| loading will not stress fasteners beyond their 'yield
| strength', which is well characterized.
|
| Fatigue complicates the analysis, but we understand that
| too nowadays, although that is an understanding forged by
| many unfortunate consequences, such as:
| https://en.m.wikipedia.org/wiki/Aloha_Airlines_Flight_243
| mc32 wrote:
| Maybe the following has been designed out; however, I've
| on occasion seen the following wear pattern which
| compromises the initial strength of a fastener (usually
| due to friction over time):
| _ _ _______| | _| |__/ | |
| ______ | |_ ____/ |_| |_|
| blamazon wrote:
| First, I love the plain text diagram! (Edit: not fatigue)
| This failure should be predictable during the design
| phase and that fastener is either wrongly specified or
| should have a recommended number of cycles after which it
| should be inspected and replaced if found to be out of
| specification.
|
| Of course, many items in our built world do not receive
| the same level of design scrutiny as I would wish, nor
| the maintenance regime...
| auxym wrote:
| Unless I'm misunderstanding the diagram, it does not look
| like fatigue at all but rather yielding from shear
| loading.
|
| The definition of fatigue is a small crack (in fact
| microscopic in the beginning) that grows through the
| application of cyclical loading (typically about 10k
| cycles is the lower bound for high cycle fatigue, which
| does not involve macro yielding).
|
| Thus a fatigue failure would look like a fully ruptured
| part , usually with two distinct zones of the fracture
| face: one smooth zone from crack growth ( sometimes with
| characteristic "beach marks") and the final sudden
| rupture which is usually rough.
|
| https://en.m.wikipedia.org/wiki/Fatigue_(material)
| mc32 wrote:
| What I was trying to convey, which I didn't do well in
| the diagram, was you have a bolt holding two plates
| together or a splice, and you have wear on the bolt shank
| -not necessarily shearing.
| blamazon wrote:
| You are correct, I had a brain fart.
| lbhdc wrote:
| The paint line is the most common method I have seen. I was
| an inspector and for fasteners in a critical load path we
| would use an ultrasound machine to measure the length of
| the bolt (these were installed in flange like connections).
| We would measure them when first installed and compare
| measurements after that piece of equipment was used.
|
| For really critical components we would disassemble them
| after every use and would perform multiple tests on each
| piece including fasteners.
| mrjin wrote:
| Totally agree. And two cents to add. The so called smart
| bolt adds movable parts in side a part supposed to be
| inertia and at the same time might compromise the strength
| in comparison with ones with the same profile and body
| material. And when faulty, it actually more dangerous than
| ordinary ones: now your torque wrench and the bolt gives
| different readings, which one to trust?
| usrusr wrote:
| That line is fine if the bolt winding itself loose is your
| only failure scenario, but some might have others as well.
| What of they clamp a part that can subtly deform in certain
| exceptional situations? Then you could have a bolt with
| zero tension that is still perfectly aligned with the
| marker line from when it was properly torqued.
|
| What I find somewhat surprising is that they make the "ok"
| indication black. The cry for attention state in red seems
| nicely intuitive at first glance, but given the market they
| serve they should be far more concerned with false
| negatives than with false positives and I imagine that it
| would be very easy for dirt or bad lighting to make a red
| indicator remain unnoticed in an inspection. Perhaps the
| color choice is an inherent property of the chemistry
| involved?
| samstave wrote:
| Just curious = how do these SmartBolts handle under full
| tension load AND fire conditions...
|
| You have effectively drilled out the core of a bolt and
| replaced it with "goo" and you are using this as an indicator
| of the health of that fastening node?
|
| So what if you burn out the goo? What if you get
| side/compression damage on the device -- what does the thing do
| when you over-tight/strip?
|
| isnt a "goo core" less structurally strong than a solid bolt?
| Is a bolt tightened to a setting using a SmartBolt vs a regular
| bolt with tension wrench going to manage the same loads or not?
| avianlyric wrote:
| > isnt a "goo core" less structurally strong than a solid
| bolt?
|
| Yes, the oil used in the centre offers zero structural
| support.
|
| > Is a bolt tightened to a setting using a SmartBolt vs a
| regular bolt with tension wrench going to manage the same
| loads or not?
|
| Depends on what the original bolt is made out of, and what
| the SmartBolt is made out of. Two different bolts are always
| going to have different properties, it up to the designer to
| match the size and strength of the bolt to their application.
| You would need to validate you design with SmartBolts to
| ensure they have the properties demanded by your application,
| you wouldn't just swap normal bolts for SmartBolts without
| making sure SmartBolts were at least as strong as the
| original bolts.
| JKCalhoun wrote:
| The idea has been around since at least 1971.
|
| https://archive.org/details/PopularMechanics1971/Popular%20M...
| asah wrote:
| (not an engineer) I watched the video - smartbolts seem a lot
| more time & labor efficient and can be tested visually?
| dominicdoty wrote:
| I've always liked ultrasonic bolt length measurement as the ultra
| high reliability way of measuring preload.
|
| It can also be used for confirming the correct preload is still
| present, with the downside of having to track the original length
| of every fastener (which isn't really a big deal in high
| reliability applications)
| rsync wrote:
| I consult with a seismic expert at UC Berkeley about once
| yearly and he's pretty cavalier about pre-loading ...
|
| Which is to say, he wants me to "pre-load the shit out of it".
|
| Which is to say, our "indicator" is that we start to bend the
| HDB with the threaded rod. For instance, if we have two of
| these, horizontally, on either end of threaded rod:
|
| https://www.strongtie.com/boltedholdowns_holdowns/hdb_holdow...
|
| ... he tells me to tighten that threaded rod between them until
| we just start to see the hold downs bend (toward each other).
|
| So, not very scientific at all, but easy to tell that you're
| pre-loaded ...
| noughtme wrote:
| Some crazy canuck cut one in half to show how they (don't) work:
|
| https://www.youtube.com/watch?v=ClPwlpa86bY
| arminiusreturns wrote:
| Really informative comment on that video:
|
| "Nice video. Couple of points: 1: As per the title of your
| video, its worth emphasizing that these are tension indicating
| bolts, not torque indicating bolts. 2: With any bolted
| connection its the tension that is important. Whilst torque and
| tension should be correlated, that relationship varies
| considerably from bolt to bolt, lubricant to lubricant, hot to
| cold, state of corrosion etc... 3: So a bolt torqued to say
| 100NM may well have a tension variance of over 100%. The result
| is that bolts are often over or under tensioned, which can
| compromise the entire bolted connection. 4: Bolts like this
| (I've personally used Rotabolts, which are similar in concept
| but in my opinion better as they rely on a mechanical
| indication rather than a subjective color hue.) are very useful
| for certain applications, for example, sub-sea connections
| where divers have limited time and feeling, and sea conditions
| affect the bolt lubrication. 5: Other uses are for ensuring
| correct bolted connections on sensitive flanges, again offshore
| and sub-sea sees a lot of this. 6: Bolts like this are, in
| summary, brilliant for when you need a good quality bolted
| connection with correctly tensioned bolts. For most
| applications however they are unnecessary. Keep up the good
| work! :-)" - drawingboard82
|
| Side note: youtube mobile when I tried to copy the comment
| wants me to sign in, to just copy a comment! wtf youtube! I
| just opened it in newspipe instead and copied from there
| xyzzyz wrote:
| One thing missing here, but talked about (albeit not very
| clearly) in the video is that it's not even a tension
| indicator, but rather, _extension_ indicator. As long as we
| are in elastic regime, tension and extension are the same
| thing (Hooke's law). However, once you go beyond it, tension
| goes down even as extension goes up. This is what the canuck
| meant when he talks about people tightening the loose bolt by
| giving it extra tweak, around minute 3:40 in the video. Once
| you leave the elastic regime, the bolt holding strength is
| permanently reduced, and by periodic tightening, sooner or
| later you'll see it yield altogether.
| connor4312 wrote:
| When you said "some crazy canuck", I immediately knew it must
| be AvE
| hinkley wrote:
| If you think the head of a bolt with an indentation in it is
| going to stay clean, especially one that has to stay tight, then
| you have not held a wrench often enough, my friend.
|
| Once that red spot gets dirty, you're not going to be able to
| tell if it's brick red because it's loose, or brick red because
| it has dirt on it. It's probably going to take you longer to
| clean the bolt than to get the torque wrench on it.
| ycIsGarbage wrote:
| Most dirt isn't red though. I'd worry more about dirt
| _obscuring_ the red and making it look black.
| hinkley wrote:
| Look at the pictures on the website and I think you'll follow
| me.
|
| I was thinking of brown specifically but black has the same
| effect. When it's partially covered the color will be the
| average of the two. Probably black if it's near pavement,
| brown if exposed to nature.
| dmkolobov wrote:
| I was one of the folks who put together the steel for a
| waterslide in a certain amusement park in California. Our method
| consisting of putting a mark across the bolt and nut after
| tightening it all the way down with a spud wrench, and then using
| a breaker bar until the mark on the nut was at the 4 o'clock
| position( or maybe it was 8, I don't recall ).
|
| The inspectors would then use a telescope to check every mark.
| Completely blew my mind that they relied on this method, rather
| than something that measured the force directly.
| choonway wrote:
| or you could use a drone with a sufficiently zoomed in and
| stabilized camera.
| dmkolobov wrote:
| Totally, but the crazy part is that there is nothing
| preventing you from making these marks without following the
| appropriate tightening procedure. When the project is several
| months late and people are working 16 hour days, the
| temptation to cut corners is high.
| hinkley wrote:
| > making these marks without following the appropriate
| tightening procedure
|
| If you didn't torque the bolt tight enough then it will
| come loose sooner, and the lines won't line up. I'm sure
| there are situations where the torque of the bolt is
| critical for handling peak load on the system, but for a
| lot of situations where a torque wrench keeps you from
| damaging by over-tightening, and makes sure you got it
| tight enough that it stays tight.
|
| I should say there's one other failure mode a torque wrench
| can test that that the paint doesn't by itself, and that's
| a failing bolt. If you've ever seen a broken bolt, and the
| entire surface isn't uniformly shiny, then you've seen a
| bolt that cracked a long time ago and then failed recently.
| That crack is going to show up as less torque. So if the
| bolt hasn't spun but the torque has dropped, you might have
| a problem, rather than having a freak incident where the
| nut spun exactly 360deg since you checked it last.
|
| I could see an argument for using paint and smartbolts for
| fasteners with epic failure modes, like people dying or
| generators exploding.
| dmkolobov wrote:
| Is it standard for there to be a follow-up bolt
| inspection some time after the initial assembly? This was
| a one-time gig for us, as we were welders by trade and
| boss-man got the contract from a family friend, so I'm
| not familiar with inspection standards.
|
| For what it's worth, we tightened all the bolts down
| according to the procedure, despite pressure from boss-
| man to do otherwise for a few of them.
| hinkley wrote:
| I haven't wrenched professionally for anything bigger
| than a bicycle, and in that case one of the most
| expensive components (labor and parts) can be damaged
| immediately by too much torque or over time by not
| enough, so you did not want to do that without a torque
| wrench. Or at least not until you had muscle memory for
| what 'enough' felt like.
|
| On bikes, car repair and a few other items, mine and
| others, I've seen sheared off bolts. In at least two of
| those I was involved with the tightening prior to
| failure, and the lightbulb moment where we figured out
| why the sequence of events made sense.
| dalrympm wrote:
| I would love to see these on chair lifts. I wonder if the
| indicators can remain valid with the types of temperature swings
| you see on a ski mountain.
| rsync wrote:
| In my experience, the most common safety practice on chairlift
| (poles) is a double-nut. It's very common to see all through
| North America - no washer, just two nuts stacked.
|
| I've never inspected them to see if they have indicators
| painted on, etc. - one would assume they should ...
| dalrympm wrote:
| I've also noticed that the nuts go on top. I've always
| wondered if this was so it was completely obvious if a bolt
| dropped out (i.e. sunlight coming through the hole).
| sfifs wrote:
| Seems like something that would be very useful for furniture or
| mechanisms that are self assembled like Ikea, chairs etc by
| regular people. Easy visual inspection when things are loose.
| ycIsGarbage wrote:
| Way too expensive for that kind of application.
| karaterobot wrote:
| It's annoying that, as you scroll down the page, the bolt
| animates to show it turning, but it scrolls out of view before it
| gets to the point where the _main feature of the product would be
| shown_.
| disposableuname wrote:
| Not just me, then. I played around with scroll, with zoom,
| doing everything I could to try to see the actual main feature.
| alhirzel wrote:
| This reminds me of frangibolts: https://www.ebad.com/tini-
| frangibolt/
|
| Conop: an electric heater temporarily modifies the crystal
| structure and axially overloads the bolt, breaking it. We used
| these on a satellite that I worked on with deployable panels.
| WalterBright wrote:
| At Boeing, I learned that bolts should be lubricated before
| torquing them in order to ensure an accurate torque. I initially
| thought wouldn't the lubrication allow the bolt to unwind itself?
| Surprisingly, no.
|
| Since then, on my car, I always put a bit of grease on a bolt
| beforehand. It keeps the water out, preventing the bolt from
| rusting itself together. It makes for an accurate torque. I've
| never had one unscrew itself, and I can always get the lug nuts
| off!
|
| Of course, you still need to use lock washers. For critical
| bolts, use a cotter pin or a safety wire.
| smiley1437 wrote:
| I've always read that lubricating the threads can cause over-
| tensioning of the bolt if you torque it to the (typically)
| unlubricated torque spec:
|
| https://www.engineeringtoolbox.com/torque-lubrication-effect...
|
| If you are measuring the bolt tension directly then it doesn't
| matter but torque is only a proxy for tension.
| globular-toast wrote:
| I grease all the threads on my bicycle ever since I had a
| bottom bracket seize into a frame and lost the frame. I have
| heard that you shouldn't grease lug nuts on a car, though. I'm
| not sure why, so take it with a a large pinch of salt. It might
| be simply because most people don't regularly check the torque
| on the nuts and in that case it's more desirable to have them
| seize than fail.
| WalterBright wrote:
| I've been doing this for 40 years. I've never had a lug nut
| loosen, or rust in place.
|
| But this, of course, is anecdotal data. Do what you judge is
| best for your situation.
| auxym wrote:
| Anecdotally, I've been using loctite C5A (copper anti-
| seize) on lug nuts for years without an issue. I also
| torque them to the manufacturer spec with a torque wrench
| twice a year (when I switch summer/winter tires).
| frosted-flakes wrote:
| I think it's because torque specs for cars assume
| unlubricated threads. If you lubricate them and torque them
| to spec, you'll overtighten them.
| gannon- wrote:
| Could be interesting to apply this to crew boats which A) people
| are used to paying a lot for the equipment and B) people often
| have to assemble and disassemble with bolts, and loose bolts are
| certainly a point of failure during a race.
| hexnuts wrote:
| We need self sealing stem bolts.
| jamesakirk wrote:
| Got anything to trade for them?
| tadfisher wrote:
| Just 500 liters of yamok sauce.
| moreati wrote:
| In the UK (and elsewhere?) Lorry tyres have plastic caps on the
| bolts, with arrows aligned to each other in pairs, or some
| regular pattern. It's easy to see at a glance if a bolt has
| loosened.
|
| e.g. https://mechanics.stackexchange.com/questions/29690/what-
| are...
| GistNoesis wrote:
| I am surprised there aren't already some chip for it, or is there
| ?
|
| Something based on RF-energy harvesting, you beam it with radio
| waves, it uses the energy to take a pressure measurement and send
| you back the result, along with the id of the bolt. And you
| inspect all your factory bolts in a matter of seconds, and
| everything is nicely logged, even those hard to inspect bolts.
|
| To measure the pressure either some piezo-resistance, or some
| capacive-sensing between two washer separated by a squeezie
| dielectric (Could a FR4 pcb-washer hold the pressure ?), or an
| integrated MEMS-pressure sensor.
|
| If your technician needs to tighten the bolt, he has to get close
| so he can transmit more RF energy so you can even have a led,
| that could turn on when the pressure is right.
| Breadmaker wrote:
| there is: IoT bolts
| https://news.ycombinator.com/item?id=29123301
| thom wrote:
| No pricing on the site, but I hope it's in the region of five
| thousand wrappages of Cardassian yamok sauce for a hundred gross.
| oneplane wrote:
| I think the bolts listed in the article are less expensive than
| self-sealing stem bolts.
| jrockway wrote:
| They're "contact us for pricing" which basically means you
| can't afford them.
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