Rod Bolt Question?

[af2]

How does a cap screw bolt have the same stretch as a nut and bolt and have the same strength?
Is the "rod" better metallurgy than the bolt? How would a 2000 be better than a 8740 going into the same rod with the rod being 4340?

Something I have thought about and can not see why. HMM

[swampbuggy]

The same way a grade 8 or grade 9 bolt clamping two pieces of metal together would be superior to a grade 2 or 5 bolt . Mark H.

[af2]

The same way a grade 8 or grade 9 bolt clamping two pieces of metal together would be superior to a grade 2 or 5 bolt . Mark H.

But!!! who knows the rod thread clamping? And don't roll the eyes palease.LOL
We all know the different grades of bolts... What about the rods?

[pamotorman]

my guess there is more mass in the rod than in the bolts so the bolts see the most strain per their mass and better material bolts make the assy stronger. better material bolts would not lose the clamping force under strain as lesser ones. BWTFDIK

[af2]

BWTFDIK

Clem?

[af2]

BWTFDIK

Clem?

Looking at a BBC rod I have Made me wonder because the shoulders don't seem as big if there was a nut there? That's all

[MadBill]

How does a cap screw bolt have the same stretch as a nut and bolt and have the same strength?
Is the "rod" better metallurgy than the bolt? How would a 2000 be better than a 8740 going into the same rod with the rod being 4340?

Something I have thought about and can not see why. HMM

Not trying to nit-pick, but actually it won't. All else equal, the 'nut & bolt' assembly will always be quite a bit longer from the bolt under-head to the first engaged thread, so that it will take proportionally more stretch (although the same torque) to create the same tension.

As far as the required strength of material of the rod or nut, the load on the female thread root is substantially less than on the smaller diameter of the bolt, so any decent (steel) rod material can handle the maximum bolt load.

All steel alloys have essentially the same stiffness (modulus of elasticity). The benefit of the more exotic alloys is that they have a higher yield strength, so can be stretched to a higher tension without permanent deformation.

[Schurkey]

The benefit of the more exotic alloys is that they have a higher yield strength, so can be stretched to a higher tension without permanent deformation.

Don't forget about fatigue resistance. It's not ONLY about the "strength", it's also about the service life.

[modok]

The rod itself being threaded is a lighter and more compact design, because it needs no nut.
A nut does not have to be as good material as the stud/bolt, because the OD of the threads has more area than the ID of the threads.
It's just a lot easier job to be a nut than it is to be a bolt.
You can have a brass nut, or an aluminum nut, just make it a little longer for more thread engagement and it works OK. It can be strong enough you'll pull the stud apart before you strip out the "weaker" nut.
it does not work well the opposite way. Brass or aluminum stud.... you not going to pull the threads out of a steel nut. Should be self explanatory. You've broken off studs in aluminum. Right?

[pamotorman]

BWTFDIK

Clem?

but what the f--k do I know

[swampbuggy]

Pamotorman, don't discount yourself, i'll bet you have more knowledge than most...........! Mark H.

[BOOT]

Never had cap screw rods so idk but Is there more thread engagement/depth in the threaded rod than a nut?

[340king]

Proper bolt and nut engagement requires a softer nut than the bolt material. This allows the nut to seat the bolt threads completely. As long as a sufficient amount of thread is engaged on the bolt, the nut material isn't as important. It is only stressed from the top thread down progressively, whereas the bolt is stressed across its minimum cross section. If you look at the cross section of most nuts, they have more meat than the bolt in the same area. So that is how it is done by design.

[gruntguru]

Better still is a nut with slightly coarser pitch than the bolt, such that bolt stretch and nut compression when tensioned result in constant stress along the entire contact surface. (I am not aware of this technique being in use anywhere.)

[pdq67]

All I am going to say is that a, "300M", anything when quenched and tempered for the job at hand is one hell of a material, imho!

Probably only a handful of, "steel", materials that are better..

pdq67