TORQUE AND OR LOCKTITE

[ESSCEE]

I was wondering what everyone does for the following screws on their builds, if you use locktite which flavor. Also if I forgot any other items that may be locktited or torqued please add them to the list

SCREW TORQUE LOCKTITE
BAS(bolt assembly screw)
Action Screws
Scope base screws
Scope ring screws

[Netz]

I like to use loctite on my scope rings and bases, I torque my action screws. BAS ? I have anti seize in mine, it's heavier than oil and won't run off.
Something I've learned from a Drag race engine builder is that every fastener should have something on it, I think this can apply to a rifle also, When torquing a bolt, a bit of oil on the threads will give a more precise torque reading.

[Stu]

When torquing a bolt, a bit of oil on the threads will give a more precise torque reading.

That depends on whether the manufacturer's torque specs are taken lubricated or dry. If they are taken dry, and you lube the threads before torqueing you may very well strip the threads or shear the bolt or screw.

[bgc]

Action Screws 45 inch pounds Dry
Scope Base (Bedded) 25 inch pounds or Specified Blue Locktite
Scope Rings 25 inch pounds or Specified Blue Locktite
110BA Stock screws 45 inch pounds Blue Locktite

[keeki]

loctite is good stuff, only problem is retailers try to rape you when you go to buy it. I use alot of it and several different kinds....242(blue), 609(green), 660(quick metal), 565 or 567(pst thread sealant), 404(instant adhesive) and I get it in the 50ml bottles for about the same price as the 10ml bottles cost from retailers. pm me and if i have what you need I'll ship it to ya for what it cost me.

[thomae]

I did a whole bunch of research on wet and dry torque values when I was working on one of my cars and managed to strip threads on a brand new part without really trying.
Unfortunately, I can't find or remember any of my sources right now or I would cite them, so I guess this now turns from documented fact to simply my opinion.

I will try to make this simple, not because I am "talking down" to anyone, but because I want both newbies and experienced individuals to be able to read this and not be confused by a lot of technical jargon.

By the way, in this post, I will use the term "bolt" to mean any bolt, machine screw, stud, or other metal threaded fastener.

Most torque values, unless stated otherwise, are for CLEAN and dry threads. Torque values are really used as an approximation. The actual value is the preload, or stretching of the bolt. Metal stretches. This provides tension and a resulting metal-to-metal friction between the male and female threads which keeps the parts together and keeps the whole thing from loosening (if properly assembled and torqued).

Without going into too much boring detail, problem arise when someone over-tightens a bolt, resulting in a deformed bolt that stretches so much that it loses it's inherent elasticity and is no longer able to return to the original shape or size. In extreme cases this results in shearing off of the threads or actually breaking off the bolt.

(Problems also arise when someone does not tighten a bolt or fastener enough and there is not enough friction to keep the bolt from wiggling/vibrating/loosening until the two parts that are supposed to be held together are no together no longer. But that is for a different thread.)

When threads are dirty, the torque required to turn the bolt becomes greater because the dirty threads are "rougher" and are "grinding" against each other.

When "wet" (which can mean either lubricated with some type of oil or anti-seize compound, or when using some sort of liquid threadlocker) the torque required to turn a bolt to a specific preload point becomes less because of the lubrication effect of the liquid between the metal surfaces of the threads.

Generally, when installing a bolt "wet" one reduces the torque value by about 40% (That's a rule of thumb that has stuck in my head, but I can no longer find a citation for the source document for that particular number - maybe it is 60%?). (personal note: I was installing some McPherson strut top mounts in my car and was using anti-seize on the threads. When I torqued them to the recommended (dry) torque value, I stripped the threads without even trying. It never really "felt" as if the bolts were failing. That's when I did a bunch of research and found out what I was doing wrong so I would not repeat this somewhat expensive mistake)

As an illustration of the above, please take a look at figure 143 at the following link. You may need to use "control +" to zoom in a bit, but if you look at the graph, it shows that for a specific fastener, to get to a certain level of preload (i.e., tight enough), you need less torque when it is lubricated.
For example, using the stated fastener in diagram 143, to obtain a desired preload of 9600 pounds, it takes approximately 300 foot pounds when the bolt is lubricated with graphite in petroleum jelly.
For the same desired preload, it takes almost 500 foot pounds when lubricated with engine oil, and 800 foot pounds dry. Big difference, and if you applied 800 foot pounds to the bolt lubricated with engine oil, you would end up with about 1.5 times the desired preload.
http://books.google.com/books?id=5a8937Pc6uEC&dq=engineer+to+win&pg=PP1&ots=QzGypyuf7m&sig=2fXeO2fdy1CSESmHLNdBQn9tDck&hl=en&prev=http://www.google.com/search%3Fhl%3Den%26q%3Dengineer%2Bto%2Bwin%26btnG% 3DGoogle%2BSearch&sa=X&oi=print&ct=title&cad=one-book-with-thumbnail#v=twopage&q&f=false

Warning: as you can see by figure 143, the relationship between these three particular torque values is not a linear one. Therefore if you use a particular "Percent" as a rule of thumb, you can still overtorque the bolt (Ok, so I have just contradicted what I said above. Yup, real life is like that.)

As for Scope mounts and rings: I use low strength thread locking compound (references to color are not important because although most people use the term "locktite" generically (Similar to "Kleenex" instead of "facial tissue") there are different brands with different colors for different strengths. Referencing brand and item number is gives a more precise identification of the threadlocking compound and, in my opinion, is less easily misinterpreted). I only need the thread locking compound to provide enough friction to keep the screws from backing out.

Recommended torque values for the various scope mounting screws are often lower than you might expect. I have seen references to many torque values in the 10-15 or 20 INCH-pound range (not FOOT pounds, please!). Some are higher, and it varies with the manufacturer and the specific mount and ring. Again, I can't find my source, but it might have been a phone call to one of the manufacturers tech departments (Note to self: I need to write this stuff down and file it better!)

Since I really like the Burris Signature Zee rings, I just now called Burris and was told by their tech support that they recommend 40-45 inch pounds for both the cross bolts and the ring bolts. I have a dial-type 1/4" torque wrench that I use to set and check bolt torque.

Here are some references that may be helpful:

http://www.brownells.com/.aspx/lid=12674/guntechdetail/Torque_Specifications_for_Gunsmiths

Some suggested Torque values: (As with all data, make sure you verify it first)
http://www.opticstalk.com/torque-specs_topic18389.html

Here is a good discussion about threaded fasteners by an extremely reputable web site. Although they are discussing bicycle repair, much of what they say can be used in other disciplines. (For those of you who don't know, Park tools are the "Snap-On" of bicycle tools. They've been in business a long time and have a very good reputation.
http://www.parktool.com/blog/repair-help/basic-thread-concepts

I hope this helps. As with everything except physics, your mileage may vary. Whenever possible, please try to verify what you do instead of simply relying on somebody (I include myself as one of those "somebodies") who has a rule of thumb. Doing your own research will make you understand much more.

All the best,

[gotcha]

WOW! I've got a lot to learn. I usually torque bolts 'til little wisps of smoke & metal chips appear then go another 1/2 turn for good luck ::)................. All kidding aside, nice info here. Dale

[thomae]

One other thing (My forgetter gets better and better each day!)

I have not used the FAT wrench, but have heard enough to think that I would not want to purchase one.
(Ok, the above is what I would classify as an ignorant opinion, as I really am not making a decision based on fact).

However, what I do use is a CDI dial torque wrench (0-150 inch pounds with accuracy of the reading down to 1 inch pound). I purchased military surplus some years ago for $10.00. New, it runs in the $200 range today.

I would look at Eeebay to see if there are any for sale. I recently saw one similar for $27.00 that did not sell. They run anywhere from about $130 to over $200 new, but used in good condition you can get them for much much lower. A 1/4 or 3/8 drive will both work well, all you need is a 1/4 inch socket and you can use just about any high quality screwdriver bit to tighten the fastener to your precisely desired torque.

Just checked: Here is a 1/4" drive MAC tools 0-75 inch-pounds (perfect for scope mounting, and other gunsmithing applications) still up for auction, current bid as I type is $20.50 with $11.00 shipping. Presuming it sells for about that price, one would get a precision tool useful for many applications for less than the going price for a FAT wrench. (By the way, I am NOT the seller, nor do I have any interest in the sale.)
http://cgi.ebay.com/ebaymotors/Mac-Tools-1-4-Drive-TWDFM75IN-Dial-Torque-Wrench-NEW-_W0QQcmdZViewItemQQhashZitem3a65e01889QQitemZ25081 7288329QQptZMotorsQ5fAutomotiveQ5fTools

[bgc]

Sorry, I wont take my PI or CDI to the range with me. Fat wrench is close enough for me and at 45 buck I wont be concerned about it sitting in the bottom of the range bag.