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Smartbolts

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Re: Smartbolts

#91

Post by frosted-flakes »

globular-toast wrote: post #71
WalterBright wrote: post #69

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 its…

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.

Re: Smartbolts

#92

Post by [deleted] »

lotsofpulp wrote: post #60
colordrops wrote: post #56

Earlier quoted context omitted.

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/

$26+ each? Now I am curious which applications it does make sense to use these in.

[deleted]

Re: Smartbolts

#93

Post by enragedcacti »

Thlom wrote: post #89
throwawayboise wrote: post #61

Earlier quoted context omitted.

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…

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

Re: Smartbolts

#94

Post by smiley1437 »

WalterBright wrote: post #69

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 its…

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.

Re: Smartbolts

#95

Post by mrjin »

blamazon wrote: post #5
mc32 wrote: post #4

Earlier quoted context omitted.

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).

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…

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?

Re: Smartbolts

#96

Post by sokoloff »

ominous_prime wrote: post #13
blamazon wrote: post #8

Earlier quoted context omitted.

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 moni…

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.

Re: Smartbolts

#98

Post by TheDudeMan »

lttlrck wrote: post #6
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…

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...

Except that black == good == red + dirt/grime/grease.

Re: Smartbolts

#99

Post by johnnyApplePRNG »

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.

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?

Re: Smartbolts

#100

Post by alangibson »

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

AKA Cheater Pipe in Texas.
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