Scope mounting to maintain zero

[Formidilosus]

The 4-screws I assume?

-J

Yes sir.

 

[mxgsfmdpx]

Man I still prefer Nightforce UL pic rings to anything else. Warne Mountian Tech are good too.

You think Nightforce Mediums 34mm would suffice with a Minox ZP5 with 56mm bell? I'm looking at a set with the 6 ring cap screws and wondering if Medium or High? Will probably order both and sell the other.

 

[Formidilosus]

You think Nightforce Mediums 34mm would suffice with a Minox ZP5 with 56mm bell? I'm looking at a set with the 6 ring cap screws and wondering if Medium or High? Will probably order both and sell the other.

The 34mm 1.00 inch NF UL’s is what I am using.

 

[Formidilosus]

@mxgsfmdpx

That creates about .4” clearance between the T3 lite barrel and the bottom of the objective.

 

[mxgsfmdpx]

@mxgsfmdpx

That creates about .4” clearance between the T3 lite barrel and the bottom of the objective.

More than enough, thanks a bunch!

 

[longrange13]

Vortex even lists on their website now not to use loctite when mounting their scope to avoid crushing their tube. Maybe they should focus less on marketing and more on building a robust scope.

 

[Formidilosus]

Vortex even lists on their website now not to use loctite when mounting their scope to avoid crushing their tube. Maybe they should focus less on marketing and more on building a robust scope.

The saddest part about this, is that they even haven’t bothered to actually find out what the supposed “increase” in torque that Loctite adds, is. Or, they do know that it is less than any commercial torque driver can read to, and use it as an excuse fall back.

 

[pyrotechnic]

That’s cop out BS. Blue Loctite has a K value of .2. Functionally it means nothing- the difference in torque between dry and loctite is inside the variability of most torque wrenches. The same scope can and will get bound erectors with 17 in-lbs dry as well.




No. Torque to 25 in-lbs.

The saddest part about this, is that they even haven’t bothered to actually find out what the supposed “increase” in torque that Loctite adds, is. Or, they do know that it is less than any commercial torque driver can read to, and use it as an excuse fall back

This shows an overly simplistic understanding of bolted joints. Loctite's own publication shows a difference between Loctite K values of 0.2 for a SPECIFIC bolted connection ( pg65 )and no lubricant raging from 0.28ish to 0.35.

0.3 would be a 50% increase in clamp load. I'm not entirely up to speed on torque wrench variability but google told me +-10% which sound reasonable.

They specifically show loctite 243 increasing clamp load on page 64 for 4 out of 5 cases. So saying that loctite does not act a a lubricant in a bolted connections is not an accurate statement.

https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://dm.henkel-dam.com/is/content/henkel/LOCTITE-Threadlocker-Manual&ved=2ahUKEwiD05vg6fGCAxUrEEQIHRJGBWIQFnoECBsQAQ&usg=AOvVaw1_YdqHeUMxNfKa5SQKa9WN

 

[Formidilosus]

This shows an overly simplistic understanding of bolted joints. Loctite's own publication shows a difference between Loctite K values of 0.2 for a SPECIFIC bolted connection ( pg65 )and no lubricant raging from 0.28ish to 0.35.

0.3 would be a 50% increase in clamp load. I'm not entirely up to speed on torque wrench variability but google told me +-10% which sound reasonable.

50% increase in clamp load on a 6x48 ring cap screw at 18 in-lbs? And, is that from wet (lubricated with oil) as Vortex sends their screw in their scope rings? Or is that from dry to loctited if you degrease them?

We can ignore that the required torque to reach a clamp force depends on the ring and screws, which Vortex’s own rings call for a higher torque setting than they recommend. How does that work?

They specifically show loctite 243 increasing clamp load on page 64 for 4 out of 5 cases. So saying that loctite does not act a a lubricant in a bolted connections is not an accurate statement.

https://www.google.com/url?sa=t&source=web&rct=j&opi=89978449&url=https://dm.henkel-dam.com/is/content/henkel/LOCTITE-Threadlocker-Manual&ved=2ahUKEwiD05vg6fGCAxUrEEQIHRJGBWIQFnoECBsQAQ&usg=AOvVaw1_YdqHeUMxNfKa5SQKa9WN

I’m far from an engineer, however that is for a 3/8” bolt was it not? Not a ring cap screw.

Adding Loctite to a ring cap screw does not increase clamp load by 50% on a scope ring at 25 in-lbs. Which is even more silly that Vortex says don’t loctite because loctite can act as a lubricant…. and they send their own screws with oil on them from the factory, and do not say to degrease the screws before mounting.

 

[pyrotechnic]

50% increase in clamp load on a 6x48 ring cap screw at 18 in-lbs? And, is that from wet (lubricated with oil) as Vortex sends their screw in their scope rings? Or is that from dry to loctited if you degrease them?

We can ignore that the required torque to reach a clamp force depends on the ring and screws, which Vortex’s own rings call for a higher torque setting than they recommend. How does that work?






I’m far from an engineer, however that is for a 3/8” bolt was it not? Not a ring cap screw.

Adding Loctite to a ring cap screw does not increase clamp load by 50% on a scope ring at 25 in-lbs. Which is even more silly that Vortex says don’t loctite because loctite can act as a lubricant…. and they send their own screws with oil on them from the factory, and do not say to degrease the screws before mounting.

I can run some comparison numbers on a 6-48 screw tomorrow when i have some time. A 50% increase will be significant. Small screws produce an incredible amount of force for torque input.

I'm not sure as to what kind of lubricant gets shipped with Vortex screws. I would imagine that bolt shipped with lubricant is the reason that that single instance on page 64 shows a higher clamp load than with loctite. I recommend reading the linked publication.

 

[Formidilosus]

I can run some comparison numbers on a 6-48 screw tomorrow when i have some time. A 50% increase will be significant. Small screws produce an incredible amount of force for torque input.

I'm not sure as to what kind of lubricant gets shipped with Vortex screws. I would imagine that bolt shipped with lubricant is the reason that that single instance on page 64 shows a higher clamp load than with loctite. I recommend reading the linked publication.

I have read it. And, the numbers for the Loctite on ring cap screw have been run, in part by the company your link goes to. Adding blue Loctite to a ring cap crew or base screw is not functionally increasing the clamp force over without, and the difference certainly isn’t causing a scope failure. Unless you have a garbage scope…

But, we’re back to the response by Vortex being a cop out, and it appears- without them understanding what they are even recommending.

 

[pyrotechnic]

I have read it. And, the numbers for the Loctite on ring cap screw have been run, in part by the company your link goes to. Adding blue Loctite to a ring cap crew or base screw is not functionally increasing the clamp force over without, and the difference certainly isn’t causing a scope failure. Unless you have a garbage scope…

But, we’re back to the response by Vortex being a cop out, and it appears- without them understanding what they are even recommending.

I would be interested in seeing those numbers determining the K factor for a 6-48 fastener into aluminum or steel threads.

Just using a K factor of 0.2, a nominal diameter of 0.135 and 20 in-lbs nets 741lb of clamping load per screw. Increasing that K factor to 0.3 nets 494 lbs. For a 4 screw ring cap we went from 1976lb to 2964lb of force. Going from 20 to 30 in-lb of torque gives you the same increase.


Using K value is a simplified way of calculating faster tension and that value is determined by empirical testing. I used 0.2 and 0.3 as those were nominal values from locite's chart where they compare dry and lubricated bolts. I don't know what the K-value is for a specific fastener in a specific ring, but it is reasonable to assume that you will have a similar variation between dry and using threadlocker.

I'm not here to defend Vortex and what appears to be inconsistend messaging on their part. I wanted to point out that introducing lubricant into the threads of a bolted joint will definitely increase clamping force from clean and dry threads and that locite's literature supports that.

 

[Formidilosus]

I wanted to point out that introducing lubricant into the threads of a bolted joint will definitely increase clamping force from clean and dry threads and that locite's literature supports that.

Understood. That I never was arguing against. My issue has been that going from 18 in-lbs as the screws come from the package, to degreasing and loctiting them is not changing the torque on the screw enough to cause issues.

 

[Fowl Play]

Far from a shooting expert, but am experienced on bolted joint design, and have personally performed a ton of torque/tension qualification testing for spaceflight hardware.

Vortex telling you to not use Loctite, but then also not telling you what would be the best method to prepare the bolted joint -- just shows a lack of understanding of how any of this works. ( OR... just covering for too thin of tube wall thickness).

A "dry" joint (everything properly degreased) will exhibit preload uncertainty of over +/- 30% depending on material combination. Even a properly prepared/lubricated joint with an aerospace grade lubricant will still exhibit +/-15% preload uncertainty -- using qualified, test based frictional factors (K factors). When I design a joint, I have to use +/-25% preload uncertainty even after doing extensive testing -- that accounts for the +/- 15% torque vs tension uncertainty AND +/-10% uncertainty in the torque wrench/torquing process itself.

What any scope manufacturer should really do is tell you to properly degrease the joint AND use Loctite. As that is going to be the most repeatable / foolproof method to maintain preload for the most people. (AND they really should spec a test based torque value -- based on common material combinations).

If you want to nerd out over all this, read NASA-STD-5020: https://standards.nasa.gov/sites/de.../NASA/B/0/2021-08-06-nasa-std-5020b_final.pdf

 

[ljalberta]

@Formidilosus,

It may have been answered somewhere, but I haven't been able to locate it. What has your experience been with respect to a rail's ability to maintain zero based on its material. Ie) Have you seen Aluminum (7075) rails more likely to shift on drops versus a titanium or steel rail with all other aspects being equal (properly degreased, loctited, and mounted).

 

[Chris_in_Idaho]

My AI/AT attests to prudence.











Just saying..............

Only 30 shot groups are significant.


... just kidding, very nice!

 

[Formidilosus]

@Formidilosus,

It may have been answered somewhere, but I haven't been able to locate it. What has your experience been with respect to a rail's ability to maintain zero based on its material. Ie) Have you seen Aluminum (7075) rails more likely to shift on drops versus a titanium or steel rail with all other aspects being equal (properly degreased, loctited, and mounted).

Have not seen a difference.

 

[ljalberta]

Have not seen a difference.

Much appreciated. Just had a Murphy rail made up in aluminum. I’ll give it the shake down to confirm, but was having a debate between the titanium or aluminum.

 

[cowdisciple]

Any comments on rifle and scope levelling devices / kits? Do I need one, which ones have the right stuff, etc?

 

[Chris_in_Idaho]

Do you mean for installing the scope level to the rifle or do you mean for holding the rifle level while shooting?

Personally I'm interested in hearing responses for both...