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2/23/2017 5:55:53 PM
Posted: 2/28/2013 9:07:21 AM EST
After reading so many posts regarding torque specs for barrel nuts, I have to ask this question because I would like people's opinions. Does placing the square drive of the torque wrench off center from the barrel give you an accurate reading when torquing using an armorer's wrench? Maybe this has been addressed before but I'm curious. I believe it throws your torque readings out the window but I also feel this proves torque specs for the barrel nut are not that critical like some people make them out to be. Anyways, I would like your opinions.
Link Posted: 2/28/2013 9:41:19 AM EST
[Last Edit: 2/28/2013 9:50:25 AM EST by adelbridge]
the torque wrench will accurately stop at set limits. The off center axis of your wrench could create more or less leverage increasing or decreasing your perceived input strength. In regards to torque specs not being necessary please take into consideration the fact that you are joining a soft metal in the aluminum upper to a hard metal in the barrel extension. A rifle might shoot well with too much torque but the aluminum threads may be stressed to catastrophic failure. Too little torque and the nut comes loose when your life might be on the line. There are plenty of examples of companies that build rifles taking shortcuts in quality controls like torque specs and you can probably guess what their reputation is like.
Link Posted: 2/28/2013 9:59:01 AM EST
Originally Posted By lof5494:
After reading so many posts regarding torque specs for barrel nuts, I have to ask this question because I would like people's opinions. Does placing the square drive of the torque wrench off center from the barrel give you an accurate reading when torquing using an armorer's wrench? Maybe this has been addressed before but I'm curious. I believe it throws your torque readings out the window but I also feel this proves torque specs for the barrel nut are not that critical like some people make them out to be. Anyways, I would like your opinions.

By now maybe hundreds of times.
If you read the Tech Manual you will see that the torque specs have been calculated using the USGI barrel nut wrench inline with the torque wrench and with moly grease applied to the threads.

No offset conversions, no 90 degrees to the wrench....no brain fukking required.
Just follow the TM.



Link Posted: 2/28/2013 12:10:14 PM EST
[Last Edit: 2/28/2013 12:12:50 PM EST by lof5494]
I understand the two metals, I was just trying to figure out the offset on the wrench and the thinking behind it. If I set the torque wrench to 50 ft/lbs i'm not getting that on the barrel nut, so why shit over +/- 10-15 ft/lbs? Or maybe you have it figured out when you do torque the barrel nut?

Link Posted: 2/28/2013 12:53:04 PM EST
Originally Posted By lof5494:
I understand the two metals, I was just trying to figure out the offset on the wrench and the thinking behind it. If I set the torque wrench to 50 ft/lbs i'm not getting that on the barrel nut, so why shit over +/- 10-15 ft/lbs? Or maybe you have it figured out when you do torque the barrel nut?



Link Posted: 2/28/2013 12:58:34 PM EST
Originally Posted By lof5494:
I understand the two metals, I was just trying to figure out the offset on the wrench and the thinking behind it. If I set the torque wrench to 50 ft/lbs i'm not getting that on the barrel nut, so why shit over +/- 10-15 ft/lbs? Or maybe you have it figured out when you do torque the barrel nut?



THERE IS NO OFFSET. You install the barrel nut wrench IN LINE with the torque wrench, just like in the pictures in the TM. It's on page 3-41 of the manual (the 155th page in the document), which you can conveniently find HERE. Here's the picture:


No calculations, no worries. "At least 30 ft/lb, but no more than 80 ft/lb" is the spec, measured with the barrel nut wrench in line with the torque wrench. That's all you need to worry about - getting those numbers with the wrenches lined up together.
Link Posted: 3/2/2013 9:59:56 AM EST
Ok, enough said. Thanks for the opinions. Here is a diagram of the question I had and I see the manual says the torque is measure when both wrenches are used.

http://i1278.photobucket.com/albums/y509/lof47350/Torque_zpsfff8d28f.jpg
Link Posted: 3/2/2013 10:14:33 AM EST
Originally Posted By lof5494:
Ok, enough said. Thanks for the opinions. Here is a diagram of the question I had and I see the manual says the torque is measure when both wrenches are used.

http://i1278.photobucket.com/albums/y509/lof47350/Torque_zpsfff8d28f.jpg


So that looks like you actually torque the nut LESS than what your torque wrench is set.
Link Posted: 3/2/2013 10:40:45 AM EST
[Last Edit: 3/2/2013 10:41:58 AM EST by Direct-Drive]
Originally Posted By JameyF:
Originally Posted By lof5494:
Ok, enough said. Thanks for the opinions. Here is a diagram of the question I had and I see the manual says the torque is measure when both wrenches are used.

http://i1278.photobucket.com/albums/y509/lof47350/Torque_zpsfff8d28f.jpg


So that looks like you actually torque the nut LESS than what your torque wrench is set.

OK, so here's why this is a useless conversation ^^^.....FNG gets confused as someone tries to over-think the process without first consulting the TM.
Let's try again....

The torque specs in the Tech Manual are adjusted to the torque wrench stand-off distance produced by the USGI barrel nut wrench.
Most aftermarket wrenches abide by this stand-off distance, which I believe is 1-1/2".
The use of moly grease on the threads is also in compliance with the TM torque specs.

GHPorter above has clearly, in a crystal clear fashion, supplied a TM illustration and a link to the source.

If the above is unacceptable to you, by all means contact the company whose name is on the receiver below.....







Link Posted: 3/2/2013 11:24:17 AM EST
Honestly I have found it's simply easier, after more experienced guys chimed in, to turn the nut pretty tight while aligning the slots/holes on the barrel nut with the receiver gas tube hole. Every time I tried using a torque wrench it seemed the ideal settings would be to one side or the other of alignment. Or course I did use the torque wrench a few times to get a good idea on "about" how much tightening was required for a ballpark setting.
Link Posted: 3/2/2013 11:29:11 AM EST
Originally Posted By BamaInArk:
Honestly I have found it's simply easier, after more experienced guys chimed in, to turn the nut pretty tight while aligning the slots/holes on the barrel nut with the receiver gas tube hole. Every time I tried using a torque wrench it seemed the ideal settings would be to one side or the other of alignment. Or course I did use the torque wrench a few times to get a good idea on "about" how much tightening was required for a ballpark setting.

This is true, especially if you've had other wrenching experience where you have a good point of reference as to what various torque amounts feel like.
For anyone just starting out, you should use the torque wrench, no question.
Link Posted: 3/2/2013 12:11:23 PM EST
Originally Posted By JameyF:
Originally Posted By lof5494:
Ok, enough said. Thanks for the opinions. Here is a diagram of the question I had and I see the manual says the torque is measure when both wrenches are used.

http://i1278.photobucket.com/albums/y509/lof47350/Torque_zpsfff8d28f.jpg


So that looks like you actually torque the nut LESS than what your torque wrench is set.

The spec is not for the actual torque applied to the nit, but for the torque indicated on the wrench when used according to the instructions.

For some reason, people seem to either WAY overthink this (trying to calculate actual torque when that number is irrelevant to the procedure), or WAY underthink it and completely ignore that the nut needs to be torqued to some specific value (regardless of whether it has anything to do with the numbers in the TM). The barrel nut wrench adds a small amount to the length of the torque arm, but the torque is applied at a point that is that same distance away from the axis of the nut, which makes the actual torque applied to the nut a very complex thing to calculate. But that is completely unnecessary, since following the procedure gives the appropriate torque. Following well-illustrated, very clearly written procedures should not be hard. I don't know why it seems to be so hard for so many people.
Link Posted: 3/2/2013 5:26:28 PM EST
Originally Posted By GHPorter:
Originally Posted By JameyF:
Originally Posted By lof5494:
Ok, enough said. Thanks for the opinions. Here is a diagram of the question I had and I see the manual says the torque is measure when both wrenches are used.

http://i1278.photobucket.com/albums/y509/lof47350/Torque_zpsfff8d28f.jpg


So that looks like you actually torque the nut LESS than what your torque wrench is set.

The spec is not for the actual torque applied to the nit, but for the torque indicated on the wrench when used according to the instructions.

For some reason, people seem to either WAY overthink this (trying to calculate actual torque when that number is irrelevant to the procedure), or WAY underthink it and completely ignore that the nut needs to be torqued to some specific value (regardless of whether it has anything to do with the numbers in the TM). The barrel nut wrench adds a small amount to the length of the torque arm, but the torque is applied at a point that is that same distance away from the axis of the nut, which makes the actual torque applied to the nut a very complex thing to calculate. But that is completely unnecessary, since following the procedure gives the appropriate torque. Following well-illustrated, very clearly written procedures should not be hard. I don't know why it seems to be so hard for so many people.


I'm not intentionally trying to overthink it. I simply want to learn EXACTLY what is happening. I get that this isn't brain surgery or rocket science where a 5-10% off would really make a difference. BUT, I'm the kind of person who wants to know when I'm 5-10% off even when it doesn't matter. I can live with being less than exact, but I hate not knowing it. The previous explanations say 1 1/2" for the wrench is factored in to the process. So, assuming that is the case with the wrench being used, I can live with that.
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