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Torque Wrench Reviews?
- Thread starter FourT6and2
- Start date
The US Navy has studied just about everything you can Imagine and developed specifications. I remember reading about screw threads and torque values. The info is available to the public, I used to have a link to it but can't locate it. Any old Navy chiefs around that might know what I'm talking about?
You bring up an issue that I have somewhat related to this that our aviation members might be able to answer: is there such a thing as a torque wrench for keenserts? Even an attachment that could get me to the 35 in 7075 aluminum?
You seem a little slow on the uptake.
You asked if this is a good idea. I explained just a few reasons why its a waste of time and worthless endeavor.
Luckily for you there are enough ignorant clowns in here he will cheer you on and tell you its a good idea. They are just as clueless. The idiots in this world far outweigh the intellegent, so there will be lots of company.
Sorry you do not like the answer, but its the truth.
Just FYI note. At Barrett last week for the MRAD and 82/107A1 Armorers courses. Discussed with instructor that the Fix-It-Stick 140in-lb torque limiter shipping with their MK22 Deployment Kit is specified at +/- 10% by manufacturer.......126-154in-lb range.......whopping wide. Instructor noted that. Said their testing shows about 4-5%, fine for their design. He indicated the Fix-It-Sticks is more accurate than the Snap-On torque wrenches shipped with early units. I find that hard to buy into based on findings by my Metrology Dept techs in a previous life.
Yep. 10% for the all-in-one and 6% for the pre-set limiters. They are made by Sloky and rebranded by FIS. I presume the all-in-ones are 10% because they rely on the user to stop at the right value and you have to rely on the markings etched on the device lining up. So you have that error, plus any user error. I have the 15 in/lb, 55 in/lb, and one of the all-in-ones.
There are a number of mfg. charts for fastener-torque recommendations with addendums for any thread added material(s).
Some tables I have in my library.
Warning: we're on trajectory for landing in tl;dr territory. That will at least filter out a few of the noisier bitches and allow for a nuanced conversation among the remaining three people that actually give a shit.
I don't want to get into Threaded Fastener 101 or rewrite MIL-HDBK-60, but let's briefly state the goals of tightening a bolt:
1) Achieve the maximum joints preload that can be accomplished without unacceptable component damage. This is generally a result of applying strain to components, and typically the male fastener represents the majority of that strain. We generally want to remove things like scope rings multiple times (mainly because most people change their optic more often than they change their underwear), and so we're not going to talk about things like torque-to-yield bolts that utilize plastic deformation.
2) Obtain sufficient friction torque to avoid unintentional loosening of the fastener. The source of this friction torque is dependant primarily on the forces generated by fastener strain; the other sources of torque (which we'll discuss more in a moment) are lost almost immediately upon cessation of the fastening process (or at least as soon as the joint is loaded in normal operation).
We measure fastening torque because it's easy to measure, not because it's the end-all-be-all method. There are reasons that one will see bolt length measured in "serious" engine builds, and engineers will develop target torque values by using test fasteners that have strain gauges inserted into the bolt shank. These techniques are not practical for most consumer applications, but they exist which proves the point.
A useful graphic to back up your point:
Underhead and thread friction torque should be self-explanatory. "Pitch torque" is what results in the stretch of the fastener, which is what we are trying to accomplish. Maximizing pitch torque is useful - recall that it's the only one that matters in operation - and we need to keep maximum total torque low enough to avoid breaking something (usually the male fastener at the point where it first enters the female fastener, which is instructive as to where maximum loads occur during tightening).
We also want to minimize "torque scatter", which is often attributed solely to the torture limiting device but generally can be applied to anything which influences the relationship between torque and strain.
Friction variation is often far more prevalent of a factor than tool variation, but lubrication can often reduce this factor which is why most "serious" work is performed with generous lube applied to the mating parts.
The type of lubricant will certainly affect frictional values - really slippery moly stuff can cut friction in half, where as Loctite claims that there is minimal reduction caused by the use of its standard products (note that there are specialized threadlockers for large fasteners that are specifically designed to also lubricate the threads). But even if we carefully take this into account, it wouldn't affect the torque we apply since the primary concern is usually fastener breakage due to excessive torsional load. The exception are situations where changes in load and/or distortion have undesirable effects - scope ring caps and action screws might be two obvious cases of this on a rifle.
Finally, note that there are several fasteners used on firearms that will come nowhere close to the ultimate strength of the joint itself, because the drive head is insufficient. If you have a 6-40 screw with a 5/64" hex socket, odds are that you'll strip the hex way before reaching the ultimate strength of the screw. Since this limits the achievable strain, use of either lubrication or threadlocker is warranted (note that each will accomplish different functions in the joint, but both may potentially reduce the risk of inadvertent loosening).
^^^^ It's also not always about the strength of the fastener or the joint. For example, clamping a scope. The bolts and the rings themselves can take plenty of force. But the scope tube... not so much. The bolts in my rings can take more than 15 in/lb easy. But the scope itself will deform with anything more and cause the parallax knob to bind.
Also I don't use thread lock at all on any of my rifles and in the last seven years, I don't think I've ever had a single screw come loose.
Also I don't use thread lock at all on any of my rifles and in the last seven years, I don't think I've ever had a single screw come loose.
Yes, as I stated above:
I use threadlocker sparingly on rifles. Scope rail screws are a good application because they're often too short to achieve any meaningful strain and they're taking a significant load.
Scope rails are a great application.
I had a scope base come loose during a match, and that's not fun.
Some things certainly make sense for thread locker. Scope bases, bolt knobs, timed brakes/mounts, suppressor mounts, etc.
Oh you know what, my bolt knob does have thread lock on it. Forgot about that. I want to put it on my brake because it does spin loose sometimes. But I wonder how the heat will affect it and what type to use. I've always used that aluminum paste anti-seize so it doesn't gall.
