Want to get yourself frustrated? Just try to teach someone proper screw tightness!

[Jack Flash]

Regarding an earlier comment about greasing the lugs on a car wheel:

I used to do that. First used grease, then graduated to anti-seize. Never had a problem.

Then I got from a reputable source that if the lugs and nuts are not dry, you can't torque them properly.

So now I just clean both as completely as I can and then put them together dry. Just passing this along for what it's worth.

 

[Heymatt]

The use of battery screw guns instead of hand screws or wrenches causes much of this problem. I would bet that less than 5% of the "professionals" understand the use of the clutch on those tools.

Kevin

Clutch? We don't need no stinking clutch!

 

[Lance Boyle]

I remember as a young lad being my older brother's helper on his electrical side jobs. following his direction of "tight is right, too tight is stripped" I installed a bunch of outlets in a new addition. Early on he bitched me out as one place he had to return to as an outlet quit working. I hadn't got it tight enough to stay tight. I was doing snug and then snug it harder. Most of those devices have mediocre grade screws so the regular screwdriver blade will cam out damaging the slot if you go too crazy. That bothered me as I know any loose electrical connections can arc and get hot enough to cause a fire, same as a poor wire it connection.

After that I leaned more toward cranking really hard on those screws, damn the slot metal displacement. Electrical fires are no joke.

 

[Matt_X]

There's at least two problems encountered. One is about learning about the need to judge the situation and apply that knowledge and experience. The other is knowing how a threaded fastener is supposed to work because there are a lot of poorly, and technically faulty, threaded connections on products.

There's probably a a dozen ways to teach this as different folks learn different ways, but the bottom line is the threads need to very slightly deform below the yield point. In other words if the material deforms permanently, then there will be no tension and the screw will back out over time. If the material doesn't develop some tension, then its not tight. The other part of this is the screw must clamp the parts together. For a machine screw one would think this is pretty straightforward but we see lots of examples where this doesn't happen.

 

[Phenix]

I do quite a bit of mechanical work in my everyday retired life. That obviously requires screws, nuts, bolts, etc to constantly be removed and replaced. Teaching people how to make a fastener tight enough to hold properly but not come loose is a difficult thing, I have discovered. I encounter innumerable quantities of stripped screws, stripped sheet metal threads etc that others have cranked so tight, they have strip. I have used the expression many times right here on this Forum to "make screws tight - but not Gorilla tight". I also read many posts that people state things just come loose on their own - so they were most likely not properly tightened to begin with. Locktite is not the general purpose answer, learning what tight enough is and what over tightening is would solve many issues with fasteners and would not require the use of Locktite. This does not apply just to guns either but with everyday items as well.

When it comes to critical assemblies, yes I do use one of my half dozen torque wrenches. For the most part proper torque used on everyday items is something that can be learned by most people, assuming they are interested in learning in the first place. No one walks around with a torque wrench and most probably don't even own one. If they do, they are a tool that rarely gets used except when critical torque is required. Learning how to make fasteners tight enough is sort of a skill that is hard to teach people because they do not have built in torque wrenches - lol. That said, I constantly try even though it is frustrating at times.

I believe that more mechanically inclined people should try and pass this technique along to Guys and Gals who frequently have issues with fasteners coming loose on their own or fasteners that have been stripped out. Seems like such an easy thing for mechanical people but can be very frustrating when dealing with others who have no clue. I've encountering many fastener related issues on guns and attached accessories loosening up on their own and screws so damned tight they need to me persuaded off. Today I worked on a neighbor's ac unit and I'd say half the sheet metal hex head screws had stripped out the holes they were in. I had to replace the screws with the next size to hold the unit's covers in place and the stripping had apparently been done by so called professionals - now that is sad!! A simple task that is not easy to convey. Ok - well that is my 5:00am rant. Have a great day - hope this helps at least a handful.

Too many people use power tools to install sheet metal screws because it saves time, and in their haste they over-torque and auger out the heads/sockets.
I worked in the aviation maintenance industry for many years, and dealt with those same problems on a regular basis.
With aircraft, probably 90% of threaded fasteners have a torque value listed in maintenance manuals to be adhered to and documented.
Absent any guidance on how tight to install a bolt or screw, the proper method is to tighten 1/6 to 1/3 of a turn past a significant increase in felt resistance (torque). I use this method on lawnmower blade bolts, rifle scope ring and mount screws, wheel lug nuts, etc.
Anyone should be able to understand that, and with repetition becomes second nature requiring little thought.
I should mention that one of my top pet peeves (right up there with people that chew their food with their mouth open) is over-tightened screws, bolts, AND TIRE LUG NUTS.
More people having torque wrenches would only partially lessen the problem at hand unless the person has ready access to fastener torque value charts or manufacturer's guidelines, which most don't have and won't try to find anyway.

 

[Phenix]

I remember as a young lad being my older brother's helper on his electrical side jobs. following his direction of "tight is right, too tight is stripped" I installed a bunch of outlets in a new addition. Early on he bitched me out as one place he had to return to as an outlet quit working. I hadn't got it tight enough to stay tight. I was doing snug and then snug it harder. Most of those devices have mediocre grade screws so the regular screwdriver blade will cam out damaging the slot if you go too crazy. That bothered me as I know any loose electrical connections can arc and get hot enough to cause a fire, same as a poor wire it connection.

After that I leaned more toward cranking really hard on those screws, damn the slot metal displacement. Electrical fires are no joke.

PRO TIP: smearing a small amount of valve grinding compound on the tip of your Phillips head screwdriver tip does wonders for keeping the tip from jumping out of the crossed slots in screws and augering out the heads.
Works even better when trying to remove a screw with some damage to the Phillips head slots that some idiot previously damaged during installation.
For some reason this does not seem to be common knowledge, even among professional mechanics. I will admit I did not find out about it myself until someone told me when I started working on Army helicopters years ago when I was 25 years old.

 

[65-2x2]

Back in the days of galvanized pipe for water systems, I was an apprentice plumber. The old journeyman told me to tighen the pipe as tight as you can then go one more round.

 

[Lance Boyle]

PRO TIP: smearing a small amount of valve grinding compound on the tip of your Phillips head screwdriver tip does wonders for keeping the tip from jumping out of the crossed slots in screws and augering out the heads.
Works even better when trying to remove a screw with some damage to the Phillips head slots that some idiot previously damaged during installation.
For some reason this does not seem to be common knowledge, even among professional mechanics. I will admit I did not find out about it until I started working on Army helicopters years ago when I was 25 years old.

I am going to try that. I have an otherwise perfect M14 USGI stock with rusty butt screws and sling loop that is hung up. I soaked it in evaporust and I moved it a bunch of turns before the rusty fine threads hung up. The working back and forth on the threads worked until it locked up good. It's an extra stock that I wanted to camo up forest green and sand or maybe red dirt.

 

[Phenix]

Back in the days of galvanized pipe for water systems, I was an apprentice plumber. The old journeyman told me to tighen the pipe as tight as you can then go one more round.

Geez . . . .

 

[richrd]

Don't blame the tools.

 

[rosewood]

Too many people use power tools to install sheet metal screws because it saves time, and in their haste they over-torque and auger out the heads/sockets.
I worked in the aviation maintenance industry for many years, and dealt with those same problems on a regular basis.
With aircraft, probably 90% of threaded fasteners have a torque value listed in maintenance manuals to be adhered to and documented.
Absent any guidance on how tight to install a bolt or screw, the proper method is to tighten 1/6 to 1/3 of a turn past a significant increase in felt resistance (torque). I use this method on lawnmower blade bolts, rifle scope ring and mount screws, wheel lug nuts, etc.
Anyone should be able to understand that, and with repetition becomes second nature requiring little thought.
I should mention that one of my top pet peeves (right up there with people that chew their food with their mouth open) is over-tightened screws, bolts, AND TIRE LUG NUTS.
More people having torque wrenches would only partially lessen the problem at hand unless the person has ready access to fastener torque value charts or manufacturer's guidelines, which most don't have and won't try to find anyway.

How about oil filters too!

 

[Autonomous]

Random thoughts.

Someone smarter than me recommended Vibra-Tite VC-3 reusable threadlocker for firearms.

When using oil-grease-anti-seize on fasteners you need to decrease torque by a significant amount to prevent stretching them. Just because you have gotten away with not adjusting the torque value before does not mean you can't start using best practice going forward.

Lubricated Bolts and Reduced Torque

Lubrication effect on bolt tension and torque.

www.engineeringtoolbox.com

Back in the day before anyone had heard of Japanese Industry Standard (JIS) screws, everyone used Phillips screwdrivers on them and stripped the heads out. This required the use of a handheld impact tool to proceed.

 

[Jimbo41]

Some years back I bought a Wiha variable torque screwdriver. It really helped me calibrate my arm for mounting optics and the like.

 

[chief38]

Too many people use power tools to install sheet metal screws because it saves time, and in their haste they over-torque and auger out the heads/sockets.
I worked in the aviation maintenance industry for many years, and dealt with those same problems on a regular basis.
With aircraft, probably 90% of threaded fasteners have a torque value listed in maintenance manuals to be adhered to and documented.
Absent any guidance on how tight to install a bolt or screw, the proper method is to tighten 1/6 to 1/3 of a turn past a significant increase in felt resistance (torque). I use this method on lawnmower blade bolts, rifle scope ring and mount screws, wheel lug nuts, etc.
Anyone should be able to understand that, and with repetition becomes second nature requiring little thought.
I should mention that one of my top pet peeves (right up there with people that chew their food with their mouth open) is over-tightened screws, bolts, AND TIRE LUG NUTS.
More people having torque wrenches would only partially lessen the problem at hand unless the person has ready access to fastener torque value charts or manufacturer's guidelines, which most don't have and won't try to find anyway.

ESPECIALLY when it comes to sheet metal! It is extremely rare I work on something that is made of sheet metal (like an AC unit) that has been worked on by others and doesn't have a bunch of stripped screws! Whenever going to someones home to service an AC unit, I always bring extra and larger sheet metal screws to replace the stripped ones. Pretty sad actually!

 

[JimFr]

Now let's talk about those that use the common 1" micrometer as a "C"-clamp!

 

[MyTurn]

Random thoughts.

Someone smarter than me recommended Vibra-Tite VC-3 reusable threadlocker for firearms.

When using oil-grease-anti-seize on fasteners you need to decrease torque by a significant amount to prevent stretching them. Just because you have gotten away with not adjusting the torque value before does not mean you can't start using best practice going forward.

Lubricated Bolts and Reduced Torque

Lubrication effect on bolt tension and torque.

www.engineeringtoolbox.com

Back in the day before anyone had heard of Japanese Industry Standard (JIS) screws, everyone used Phillips screwdrivers on them and stripped the heads out. This required the use of a handheld impact tool to proceed.

Real world question, then. What should the torque be for an AR-15 barrel nut when using the grease recommended in the military manual?

 

[roundels]

Too many people use power tools to install sheet metal screws because it saves time, and in their haste they over-torque and auger out the heads/sockets.
I worked in the aviation maintenance industry for many years, and dealt with those same problems on a regular basis.
With aircraft, probably 90% of threaded fasteners have a torque value listed in maintenance manuals to be adhered to and documented.
Absent any guidance on how tight to install a bolt or screw, the proper method is to tighten 1/6 to 1/3 of a turn past a significant increase in felt resistance (torque). I use this method on lawnmower blade bolts, rifle scope ring and mount screws, wheel lug nuts, etc.
Anyone should be able to understand that, and with repetition becomes second nature requiring little thought.
I should mention that one of my top pet peeves (right up there with people that chew their food with their mouth open) is over-tightened screws, bolts, AND TIRE LUG NUTS.
More people having torque wrenches would only partially lessen the problem at hand unless the person has ready access to fastener torque value charts or manufacturer's guidelines, which most don't have and won't try to find anyway.

Yep yep. When I was doing automotive work I used to use the knob end on Craftsman screwdrivers to guesstimate torque on easily stripped or broken fasteners. Nestling the knob in the web and thumb/forefinger of my hand and tightening as much as my grip would allow gave perfect results.

 

[roundels]

Real world question, then. What should the torque be for an AR-15 barrel nut when using the grease recommended in the military manual?

35-85 ft. lbs. Aeroshell 33 is the customary grease. Make sure you use a high quality wrench with nubbies all the way around to completely grip the nut and a clamshell with a gas tube pilot rod-equipped receiver insert rather than the all in one that just goes off the receiver tabs. Don't skimp on paying for either of these unless you want to do the whole thing over and possibly ruin the parts as you go.

Also, the bigger the vise (at least 5") and the heavier the bench it's bolted to (no plastic event tables) the better your results will be. Any flex in either will affect torque specs. It's a good idea to cover the upper with 2 layers of masking tape before you start to keep the finish from being glossied up by being pressed hard against the inside of the clamshell, which will need to be clamped on fairly tightly. Torque and release the barrel nut three times to help mate the threads and then set final torque unless the nut lines up the first or second time at at least 35. If you are right at the high end spec and the gas tube still isn't lining up after mutiple attempts at torquing and releasing try a different nut. You'll have to take everything apart if you need to do this so you might want to start with a bare barrel just in case. Don't overtorque and whatever you do don't break out the files. Shims can also be used but as a last resort.

 

[Tiger 11]

Too many people use power tools to install sheet metal screws because it saves time, and in their haste they over-torque and auger out the heads/sockets.
I worked in the aviation maintenance industry for many years, and dealt with those same problems on a regular basis.
With aircraft, probably 90% of threaded fasteners have a torque value listed in maintenance manuals to be adhered to and documented.
Absent any guidance on how tight to install a bolt or screw, the proper method is to tighten 1/6 to 1/3 of a turn past a significant increase in felt resistance (torque). I use this method on lawnmower blade bolts, rifle scope ring and mount screws, wheel lug nuts, etc.
Anyone should be able to understand that, and with repetition becomes second nature requiring little thought.
I should mention that one of my top pet peeves (right up there with people that chew their food with their mouth open) is over-tightened screws, bolts, AND TIRE LUG NUTS.
More people having torque wrenches would only partially lessen the problem at hand unless the person has ready access to fastener torque value charts or manufacturer's guidelines, which most don't have and won't try to find anyway.

What has always been my method is to use the power tool until just before the screwhead contacts the metal - then finish up by hand, with or without a torque wrench.

 

[Doriangray6]

When I taught the V-Rod course at MMI there were always students that thought they had calibrated hands and didn't need to use torque wrenches so I'd have them tighten a fastener that required 100 to 120 inch pounds of torque to what they thought was the correct torque with a regular wrench and then use my dial face inch pound torque wrench to loosen it.
Their calibrated hands always tightened the fastener to at least twice the correct torque amount.