1/4" torque wrench

[Intheshop]

Torque free bedding; use gunfitter screws which are just headless,threaded studs. Then drop action in and I use surgical hose,because it's so easy but,in anycase the action just lays in the bedding. So whatever condition the round,or straight action is.... that's what the bedding mimics.

The angle torque is fine with pillars,which considering how easy they are to make,why wouldn't you use them? But there's a difference in angle vs measuring torque with a calibrated system. How different? Beats the snot out of me.... that's why I want a small 1/4" torque wrench.

This isn't the whole enchilada.... round vs flat/square receiver is a whole nuther ball of wax. Use whatever you're comfortable with is my feeling. They both have certain engineering principles or property that can show up on paper(ha). Generally,round is easier to fixture going roundy round(lathe),and since that "seems" to be where most gun plumbers spend most of their time? Another area IS bedding.

 

[Ian]

Angle is used for high clamp load, special fasteners which are essentially spring tempered and are thrown away after every removal. Pre torque to take the slack out and crank it around to get a measurable length stretch on the bolt. This does not emdescribe stock or scope screws exceot possibly base mounting screws but they are too short to really be an effective tty fastener.

Why anyone would skim bed a rifle without making pillars is lost on me too.

 

[Intheshop]

In the case of action screws, "angle" is about repeatability. Which is pretty important,but still doesn't give actual numbers.

 

[Intheshop]

Bedding with epoxy has been "discussed" so much that folks have made up their minds. I'll just sit back and listen..... have bought/used gallons of the stuff in bow building and certain wood engineering(construction).

 

[KeithB]

My prosthetics fitter has a T-handle torque wrench (click type) that has a hex socket to hold the bits. It's the same hex size (1/4", 5/16"?) as all the replaceable screwdriver bits, he just puts in a bit with the right size hex end to fit the set screws on my prosthetic. For the level of torque needed for very small set screws and similar you really don't need the leverage of a beam type anything. A reasonably healthy person with a good grip could probably twist the heads off any scope/action screw with just a T-handle. Next time I see my fitter I'll see what brand/model he uses. It's really a nice unit, but it may not be a CHEAP unit.

 

[RBHarter]

There are also several dedicated torque drivers intended for the 2-5 ftlb , 16-60 inlb needs of rings , mounts , and action screws .

I found a long time ago that the 30inlb on rocker covers resulted in lots of oil leaks and backed off screws and that my time tested 35# elbow didn't have a clue most of the time .

 

[Snakeoil]

The "angle torque" method may be the best for small screws. It negates any variance due to thread conditions. It also allows for wear on screws that are removed frequently. A quarter turn after full contact will always result in the same amount of screw stretch, which is what you are looking for.

 

[Ian]

No, no, no. Screws FATIGUE. Unless you are certain that you never exceed the elastic range of the material, your 1/4 turn or whatever arbitrary measurement you use is going to give you more and more clamp load each time you use it until the fastener pulls apart. Do you know your thread pitch torque vs clamp load for length, diameter, finish, and most importantly screw material/temper? This is where feel comes in since it is possible to feel the torque ramp up as the fastener stretches.... or k.i.s.s. and just use the commonly recommended torque force specification. A good average spec for clamp load is torque to 75% of the fastener's breaking strength.

 

[CZ93X62]

Ah--THESE discussions are what bring me here every day. THANK YOU ALL, SO MUCH.

FWIW, I do own a couple 1/4" drive torque wrenches, and have had at least one for 35 years+. 60 in/lbs on Rem 700 guard screws, and change them yearly--per FBI instruction. I certainly don't "buy" everything spewed by Famous But Incompetent's oracles, but their weapons care regimens are pretty sensible and haven't gone sideways for me in 42 years of contact and usage.

I own torque wrenches of 1/4" and 1/2" drive sizes, both "beam/pointer" and pivot-head designs. Trying to make a case that one system is more "accurate" than another would be a tough call. In torqued-bolt applications, my thoughts are that consistency is better found via clean threads (male and female) and light thread lubrication than between fights over wrench type. Also, one-and-same wrench and operator on an application is advisable.

 

[Brad]

Torque wrench? Do I look like a wrench monkey?

I have the Midway FAT system and that will just have to be good enough.

 

[KeithB]

I like friction thimble mikes but for inexperienced users I've found that ratchet/click type mikes give more consistent readings. Same with torque wrenches, I would bet that experienced users can do better with beam wrenches and inexperienced folks like me do better with clickers.

The basic science behind torquing a fastener is to pre -stress the material to about 90% of its elastic limit (which as Ian pointed out is about 75% of its failure limit) so that an external applied load that is less than the preload will not cause a fluctuation in stress in the material. What causes fatigue is cyclic stress, so if you can prevent the fastener from experiencing that you're fine. Steel will fatigue to approximately 50% of its ultimate strength after about a million cycles so prevent that and your fastener won't lose strength and fail from a load below the specified maximum material strength.

The angle of rotation method works best on long fasteners, by the time you have turned a short fastener a certain angle you may well have exceeded its elastic (yield) strength.

 

[Ian]

Operator aptitude and thread condition are indeed of critical importance.

 

[Ian]

The angle of rotation method works best on long fasteners, by the time you have turned a short fastener a certain angle you may well have exceeded its elastic (yield) strength.

Yes. Thank you for stressing (no pun jntended) that point. TTY fasteners typically have a very long, smooth, and uniform shank, often of diameter smaller than the thread minor diameter, to act as a spring section to isolate and absorb thermal expansion or other stress cycles without failure due to stress risers at thread roots. Also, all diameter transitions are radiused. This does NOT describe a scope base or ring screw.

 

[KeithB]

All the small gun screws I've seen have sharp corners at the head/body area.Sharp corners cause stress risers, You and I both know where those screws fail...

 

[Ian]

That may be on purpose, or maybe happy coincidence? When they do break from excessive torque it usually isn't down in the hole but right under the head and a person has a better chance of getting the remains back out. A loose or undertorqued screw will usually shear at the connection point between the parts, if the load is a shear load (as in scope bases).

 

[Bill]

I was an aircraft engine mechanic for over 20 years, none of the shops I worked in would allow the clicker type

Bill

 

[Intheshop]

Well,went and looked at our 3/8" drive beam type(also found a 1/2" beam type too). Goes to 600 inch lbs. The range for action screws,being <100 is the first hash mark on the 3/8 drive scale. Pretty useless from a practical standpoint. If you want to believe them,and I have right many of their hand tools in the machine shop,SK makes a made in USA 1/4" beam type. Proto and Snap-On are the "players" in the dial type. They both go for around 50$ used.

I've got 15, Craftsman 1/4" drive sockets that accept gunsmith screw tips. Well,got a bunch more,these are the ones headed to the loading room.

 

[Bret4207]

I lost my beam type decades ago and got a clicker. I haven't even seen a beam type for sale in years. Must still be made.

I wonder about torque recommendations sometimes. I recently put an engine back together and the rod bearing bolts called for 35 ft lbs. Seemed oddly low to me. I ran a couple in with a ratchet to "just snug" and then used the TW and found they were already at almost 35. No lock washers, no safety wire, just metal to cap. The thing is older than I am with a gazillion hours on it. I set it quite a bit more than 35 ft lbs using the USMC approved Torque Elbow, Mod 60. Right or wrong, it's done.

 

[RicinYakima]

Broke a head bolt on a Hudson once. Didn't read the fine print; bolt and block had to be cleaned and lubed with Hudson clutch fluid (sperm oil) and then torqued. 30 weight engine oil didn't work.

 

[RBHarter]

I've never broken a stud or bolt setting torque . But I'd have to have a counter to count the broken exhaust studs during tear downs .

Rod caps require surprisingly low torque . A dry torque value however is 25-50% higher when applied wet in terms of tensile load . A 3/8 rod cap bolt at 35# wet in non detergent 30 wt is equal to about 42# dry and I never had one come loose with the trusty Lubriplate #9(?) and STP 50/50 all over the place . Probably closer to 50-55# dry .