Switch Barrel Torque

Misc. torque comments

Some time ago I put barrels on 3 Stolle Pandas. The barrels had a fit, over the wires, as recommended by Kelblys. I lubed the threads and tightened and loosened them several times to seat the threads together.

I tightened them all to 35 ft/lbs, then I put a witness mark at the action-barrel junction with a pencil. Then I tightened them to 125 ft/lbs and they all advanced about another 0.030-0.040" radially. Makes me really wonder about this 35 ft/lb business.

Yesterday I was looking at the lug bolt torque for a 5 Liter Mustang. Keep in mind this is just a 9/16 SAE thread, the recommended torque is 85-105 ft/lb!!
 
Thread Torque

Dear Senile Member Guy,
I have never heard the term "over the wires". Care to expound?

Thanks,
Dan Batko

"Where are we going and why am I in this basket?"
 
Over the wires

wolf gray said:
Dear Senile Member Guy,
I have never heard the term "over the wires". Care to expound?

Thanks,
Dan Batko

"Where are we going and why am I in this basket?"
Click to expand...

Dan,
I believe he is referring to the degree of thread 'fit' or class by using specific dia. wires in the dedundum of the thread (valley or root) and measuring with a micrometer specifically for that purpose.

Lou Baccino
 
wolf gray said:
Dear Senile Member Guy,
I have never heard the term "over the wires". Care to expound?

Thanks,
Dan Batko

"Where are we going and why am I in this basket?"
Click to expand...

http://www.machinist-calculator.com/Thread-Measure-Eng.html

For example, on the Stolle Panda Kelblys suggests 0.032" diameter wires for a measurement of 1.0715" +/- 0.002". This allows proper diameter threads without special tooling. All you need in this instance is a set of 1-2" micrometers and (3) 1/32" drill bit shanks.

Machinerys Handbook gives greater details but this an old machine shop method of measuring vee threads.
 
Hand tight

nhkuehl said:
I guess 'hand tight' would be arbitrary, since that would very from person to person. nhk
Click to expand...

Just for the hell of it I went to our calibrated tool room and got a feel for what 120 ft-lbs. felt like by inserting the torque wrench tip in a padded and tightened vise jaw and noting when the pointer hit 120 ft-lb when I torqued the wrench by pulling on the handle. It is snug and tight but not overly tight for a standard 225 lb. man. I did this because I've been putting my barrels on by feel only with a rear entry Kelblys action wrench. I'm going to modify my wrench so that it will accept a proper torque wrench for the future.

I can say with a fair degree of confidence that my barrels have been torqued to at least 100 to 150 ft-lbs. but that is only guessing based on feel.

Lou Baccino
 
RE: hand tight

You are right; tight is a matter of perception to each person unless you use a gage method such as a torque wrench or witness mark. I was actually referring to hand tight being how tight an individual can turn a barrel by hand (grip), which would be the starting point for the 9/64" or whatever distance measured on the circumference. A torque wrench wouldn't be influenced by that. But the friction (thread fit), or lack of friction (lubrication), and ultimately the compression or stretching of the material will influence the torque reading.

I prefer the micrometer click torque wrench over the beam type. nhk
 
Last edited by a moderator:
Torque wrench preference

nhkuehl said:
You are right; tight is a matter of perception to each person unless you use a gage method such as a torque wrench or witness mark. I was actually referring to hand tight being how tight an individual can turn a barrel by hand (grip), which would be the starting point for the 9/64" or whatever distance measured on the circumference. A torque wrench wouldn't be influenced by that. But the friction (thread fit), or lack of friction (lubrication), and ultimately the compression or stretching of the material will influence the torque reading.

I prefer the micrometer click torque wrench over the beam type. nhk
Click to expand...


I prefer the click type as well but picked the indicator type because I wanted to observe the amount of 'arse' required from 100 ft-lb. to 120 ft-lb. without having to change the barrel setting as in a click type. I repeated this several times just to see how it felt. As mentioned, I'm going to modify my rear action wrench so that I can use a torque wrench on my actual rifle. In that application, I'll use a click type. The point I was trying to prove to myself was twofold:
1) to assure myself that I've been installing my barrels with sufficient
torque
&
2) to assure myself that I wasn't over torquing, which for that size
thread, would be hard to do by hand without a cheater bar or other
mechanical means.

Lou Baccino

p.s. This is but an example of cabin fever of projects which take place during the winter in PA.
 
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