Does Loctite alter torque on scope rings

[Formidilosus]

Warne customer service really knows their stuff….

 

[nighthawkf-117]

So you not only followed their thread locker recommendation, but also torqued 10in/lbs less than their recommended torque. I think the scope should also be checked to ensure the tube is within stated diameter and roundness. If that comes out normal I would say Warne owes you new rings and a scope.

 

[HandgunHTR]

The rings were good, still are.
The problem was over torquing. You used the dry torque rating, on a wet torque application.
The difference is the added lubrication really increases the force on the screw at the same torque. Without reducing the torque for a lubricated screw, you could easily hit the yield strength of the screw, or create a problem like you have.
The screws are junk now btw.

You obviously aren't a journeyman mechanic are you?

Blue loc-tite doesn't appreciably change the k-factor of fasteners.

Also, if you think that putting 18 inch-lbs of force on a 10-32 screw, even if it was covered in lubricating oil will come anywhere near the yield strength of the screw, you should probably do some research on yield strengths of various fasteners.

 

[journeyman713]

Locktite is not oil. I am doubtful that even oil would meaningfully alter the K value enough to have a meaning effect on torque.

No one said Loctite is Oil. What was pointed out was, Dry screws and Wet screws have different torque ratings, due to the "Wet" has some lubrication qualities and he friction is reduced as a result. Meaning there is more force on the screw with the same torque.

 

[journeyman713]

I've seen a lot of mixed feedback on whether this is actually true or fuddlore. Any sources for how much the loctite would increase the K value?

It is typically a 25-30% reduction for a Wet torque.

 

[journeyman713]

No way loctite made any noticeable difference to cause that damage. Something else is going on.

Check post #14

 

[journeyman713]

You obviously aren't a journeyman mechanic are you?

Blue loc-tite doesn't appreciably change the k-factor of fasteners.

Also, if you think that putting 18 inch-lbs of force on a 10-32 screw, even if it was covered in lubricating oil will come anywhere near the yield strength of the screw, you should probably do some research on yield strengths of various fasteners.

Exactly what to you think you have contributed to the solution here?
You may want to look into your statements. Dry torque vs Wet torque reduction, and btw, scope screws are smaller than the size you pointed out.

 

[Lentuk]

journeyman713​

Sounds like you work for Warne to me....

 

[Mike Islander]

It is a myth that Loctite blue (242) changes the required torque specification for proper bolt preload.
According to Henkel/Loctite's technical documentation, threadlockers like Loctite Blue 242:

Do not significantly affect the torque required to achieve proper bolt preload
Should be applied after determining the correct torque specification for the application
Their primary function is to prevent loosening after proper torque is applied, not to change the torque requirement itself

 

[Wrench]

You obviously aren't a journeyman mechanic are you?

Blue loc-tite doesn't appreciably change the k-factor of fasteners.

Also, if you think that putting 18 inch-lbs of force on a 10-32 screw, even if it was covered in lubricating oil will come anywhere near the yield strength of the screw, you should probably do some research on yield strengths of various fasteners.

I'll happily argue this.

Grab any edition of machinery handbook and find that there is in fact a difference in torque for wet vs dry and that everything has a coefficient of drag. The percentage reduction is directly related to pitch. A 48tpi IS going to stretch more than a 13tpi.

Now....let's talk metrology, you're not likely using a tool that has ever been calibrated and probably couldn't be anyhow. So you have a tool that's within 10ish percent and a fastener that could be out 30 plus percent.

Did anyone measure the screws before they were sent off? They will often hourglass when over torqued.

 

[pacoalcracker]

Installation procedures are the culprit 99% of the time and all manufacturers know this. Neither Warne nor Trijicon will take on any liability for it. Yeah, it's a tough and costly lesson.

 

[SDHNTR]

I’ve mounted several Trijicons in rings with 20#. Nary a dent in one.

Do we know if your receiver holes were straight?

 

[Mike Islander]

I'll happily argue this.

Grab any edition of machinery handbook and find that there is in fact a difference in torque for wet vs dry and that everything has a coefficient of drag. The percentage reduction is directly related to pitch. A 48tpi IS going to stretch more than a 13tpi.

Now....let's talk metrology, you're not likely using a tool that has ever been calibrated and probably couldn't be anyhow. So you have a tool that's within 10ish percent and a fastener that could be out 30 plus percent.

Did anyone measure the screws before they were sent off? They will often hourglass when over torqued.

Wet vs dry depends on what the "wet" is. Affects are measurable. Loctite 242 changes K-factor by less than 10%.

 

[AZ_Hunter]

Locktite wasn’t the problem. It was either tightened down asymmetrically or there is a lack of concentricity/misalignment or size issue.

That is why it is good to check ring alignment with alignment bars before mounting the scope and if needed lap… or if way off, ditch the rings/base.

 

[Wrench]

strength of 6-48 compared to 8-40

How much stronger is 8-40 compared to 6-48 ? Is it a function of the area of thread ? Is there a reason not to use 5mm-0.8 for a rail ?

forum.accurateshooter.com

Wet vs dry depends on what the "wet" is. Affects are measurable. Loctite 242 changes K-factor by less than 10%.

Great quote, now at what pitch are you quoting.

 

[journeyman713]

journeyman713​

Sounds like you work for Warne to me....

First you assemble your scope like an amateur, now you sound like one.
This is your mistake, own it.

Your problem was clearly pointed out as 2 fold.
1. You assembled it wrong. Failure to make sure the split rings were evenly gapped before tightening.
2. You over tightened it.

Simply put, the thin walled scope tube got elongated because the forces were not evenly distributed, then you cranked it down too much.

 

[Wrench]

Locktite wasn’t the problem. It was either tightened down asymmetrically or there is a lack of concentricity/misalignment or size issue.

That is why it is good to check ring alignment with alignment bars before mounting the scope and if needed lap… or if way off, ditch the rings/base.

I mostly believe this is the issue as well. There could be some squareness issues between the counterbore and the mate surface or the rings could be out of square. This is one time where alignment dowels before it was torn down would answer a lot....like who's at fault.

.....But there's so much google foo going on with this thread without knowing exactly what questions to ask it's disgusting.

 

[Mike Islander]

strength of 6-48 compared to 8-40

How much stronger is 8-40 compared to 6-48 ? Is it a function of the area of thread ? Is there a reason not to use 5mm-0.8 for a rail ?

forum.accurateshooter.com

Great quote, now at what pitch are you quoting.

"Given the already high uncertainty in torque application for these small fasteners (often ±15-30% in real world conditions), the pitch-related variation in Loctite's effect on k-factor is probably not practically significant enough to warrant different compensation factors. The installation technique and joint friction variations would likely overwhelm any subtle differences from thread pitch."

 

[JohnJohnson]

2. You over tightened it.

You think the loctite turned his 15 in/lbs torque into more than the 25 in/lbs torque that Warne recommends (see picture Form posted)?

People get caught up in theoretical minutia and argue that too much. Did loctite change the K-factor in any PRACTICAL way?

 

[TxxAgg]

First you assemble your scope like an amateur, now you sound like one.
This is your mistake, own it.

Your problem was clearly pointed out as 2 fold.
1. You assembled it wrong. Failure to make sure the split rings were evenly gapped before tightening.
2. You over tightened it.

Simply put, the thin walled scope tube got elongated because the forces were not evenly distributed, then you cranked it down too much.

I'm not trying to be argumentative, but how are you deducing 1 & 2 from 2 pictures?