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Smartbolts

smartbolts.com

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Re: Smartbolts

#101

Post by gkop »

sokoloff wrote: post #96
ominous_prime wrote: post #13

Earlier quoted context omitted.

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)

Even where you can't measure the stretch directly, torque-plus-angle is a better way to achieve consistent stretch than torque alone.

In case anyone else needs to look this up, torque-plus-angle means seating the threaded fastener to a base torque, and achieving the target tension from there by further turning the fastener a specified angle. So super duper simple and something that many of us have done instinctively or from instructions, now we know there is a term for this general technique. Cf https://dannysengineportal.com/torque-specification-torque-t...

Re: Smartbolts

#102

Post by WalterBright »

auxym wrote: post #86
WalterBright wrote: post #74

Earlier quoted context omitted.

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.

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).

I use hi temp wheel bearing grease for the lug nut lube, as it won't melt and run when hot. Don't want grease dripping on the brakes! The amount is also a tiny dab, half a drop is plenty. I don't use a torque wrench, just give em a hard twist, lower the tire to contact the ground, then twist them all again just to be sure.

Re: Smartbolts

#103

Post by alangibson »

johnnyApplePRNG wrote: post #99
frosted-flakes wrote: post #91

Earlier quoted context omitted.

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.

How does a torque wrench know the nuts are lubricated? Is 80 foot pounds of torque not 80 foot pounds of torque no matter the level of lubrication?

No (sort of). You're not looking for torque, you're looking for tension on the bolt as it stretches. Torque is just a proxy

To tension on lubed and unlubed bolts will be different at 80 ft-lbs due to friction loses.

Re: Smartbolts

#104

Post by WalterBright »

frosted-flakes wrote: post #91
globular-toast wrote: post #71

Earlier quoted context omitted.

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.

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.

Many bolts have a lubed spec and a dry spec. The dry one is, of course, completely unreliable. If it is lubed and ain't turning smoothly, take it out and clean the threads. Or get a better grade of bolts.

Re: Smartbolts

#106

Post by gkop »

blamazon wrote: post #21
ominous_prime wrote: post #13

Earlier quoted context omitted.

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)

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.

I’m not getting your point here, won’t there always be inherent trade offs?

If you scale the specified torque, you risk over-tensioning.

If you scale the dimensions of the fastener, that has lots of consequences.

Is there some safety factor here you can add “for free” that I’m not seeing?

Otherwise, why is it that you “generally” pre-empt this caveat with safety factor versus coming up with a more reliable way to achieve the right tension?

Re: Smartbolts

#107

Post by toss1 »

mojomark wrote: post #17
blamazon wrote: post #3

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 re…

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 autonomou…

NordLocks are excellent - I was told about them by a very experienced racecar engineer who helped me work on my racecars - he couldn't say enough good about them, and recommended them for anything close to critical importance (or that you just wanted to stay fastened). Another engineer friend had a biz providing racecar component kits (think brakes, suspension, etc.), and also enthusiastically all his kits with NordLocks. I've had less experience but never seem them fail. Good stuff

Re: Smartbolts

#108

Post by gkop »

enragedcacti wrote: post #93
Thlom wrote: post #89

Earlier quoted context omitted.

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…

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

Not mentioned on that page, but you can make one out of two ordinary wrenches, which is both practical and may impress your friends! All I found online describing this was a video: https://youtu.be/5DShRItYxLA

Re: Smartbolts

#109

Post by alphabet9000 »

karaterobot wrote: post #34

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 .

lol i just noticed that

here is the desired effect they were looking for (added margin-top to ) https://i.imgur.com/tehEWx9.gif

Re: Smartbolts

#110

Post by gkop »

qbasic_forever wrote: post #59
JohnJamesRambo wrote: post #2

I don’t ride rollercoasters but if I did I would want them to use these.

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.

Would you say more on this? Curious
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