Need Help W/ Torque Wrench, Please

[JWG223]

I agree with doing things right. I just think buying a $200+ torque wrench to use once is silly.

Buy/borrow/steal *whatever* torque wrench. Apply Rocksett. Screw on muzzle device. Torque to 23ft/lb. Even if the wrench is off +/- 2lb you'll be in spec. You could've properly installed 400 muzzle devices in the time you've spent researching it. It should be done right, but it's not rocket science.

That's exactly what I'm doing.

 

[JWG223]

That is correct the torque is calculated at the head of the wrench if the head of the wrench is extended with the socket you use, making the handle longer, the torque applied would be more than what the wrench is set to, if the socket you use is behind the head of the wrench then the torque applied would be less than what the wrench is set to.

without a picture this is the best way to explain.

s=socket
h=head of the wrench

a) s--h--------------handle you will apply more torque than the wrench is set for in this configuration
b) h--s------------handle you will apply less torque than the wrench is set for in this configuration
c) (sh)-------------handle you will apply the torque the wrench is set to in this configuration unless using a long extension to the socket


the only way configuration a and b would come into play is if you are using a crowsfoot type socket, that can extend or shorten the length of the torque wrench from the head of the wrench


if you are using a regular socket that does not extend or shorten the length of the torque wrench then configuration c would apply.

This is the "wrench" I am using:

I am told that is a 1/2" socket hole (although those proportions look a bit odd, that's what was on Brownell's FAQ portion under this part...), so it looks like about a 1/2" extension of the handle, or so.
This calculator is telling me that any offset is within the error range that I have determined acceptable, and likely within the error range of the torque wrench's settings themselves.
http://www.cncexpo.com/TorqueAdapter.aspx

 

[general mills]

what I am talking about is a extension like this

http://www.machias.org/i-couldnt-find-it-to-buy-or-to-borrow.aspx

it will increase or decrease the length of the wrench and hence the applied torque unless it is positioned 90 degrees to the length of the torque wrench.

In the example I provided, you can see how a 6 inch extension on a 12 inch wrench changes the torque from 50 ft, lbs to 75 ft. lbs, no small number.

JWG223, your wrench won't extend far beyond the torque wrench end, it's up to you.

 

[Crimson]

This is the "wrench" I am using:

I am told that is a 1/2" socket hole (although those proportions look a bit odd, that's what was on Brownell's FAQ portion under this part...), so it looks like about a 1/2" extension of the handle, or so.
This calculator is telling me that any offset is within the error range that I have determined acceptable, and likely within the error range of the torque wrench's settings themselves.
http://www.cncexpo.com/TorqueAdapter.aspx

yes but that calculator seems accurate so just use a protractor to find the angle and you should be set.

 

[JBP55]

Crimson, He is in Shreveport and you are in Monroe. If he can not understand after all these posts you may as well drive over and torque it for him.

 

[03protege]

That's what I was talking about. I fixed my "diagram" to maybe make more sense. The thing on the left is the wrench and the thing on the right is a nut. I couldn't understand how increase the distance between the arrows would change the torque except for the play in everything not being rigid. Just making sure I wasn't missing something.

I've twisted a cheaper extension like a candy cane before, I'm sure under higher amounts of torque even the nice ones have a very slight amount of play, although most of the time I am sure this is negilible.

 

[JBP55]

I've twisted a cheaper extension like a candy cane before, I'm sure under higher amounts of torque even the nice ones have a very slight amount of play, although most of the time I am sure this is negilible.

With a long extension and high torque you do lose a small amount due to torsional twist but it is slight.

 

[JWG223]

yes but that calculator seems accurate so just use a protractor to find the angle and you should be set.

I played with the calculator and the distances involved made if a moot point. Set to 23# and rock and roll. ABC didn't have the wrench I needed. Got the fh in today, though. Should have everything by Monday morning and throw it on before I leave for Fayetteville on a week trip.

 

[JWG223]

Everything went okay. I do have questions, though...

I used a barrel clamp from brownells. It was lined with polyeurethane. When I tqed the mount in place, the barrel was flexing the lining a bit as as to rotate. I tqed it extremely slowly, stopping when the wrench broke. I then backed off, and re tqed it slowly again to make sure it was good to go, at two lb more tq.

Did the barrel squirm negate some of the tq? I would think not, since I went so slow.

Surefires timing wheel rocks. It is my first install, and I ended up about 2* "off". The point I was using to line up was not the logo and top vent (212a fh mount, I used the notch bottom center, the straight edge thereof, to line up.).
Anyway, I also noticed while timing it that setting the wrench to 20#, I could slowly tighten until it broke, and then reverse it (it worked both ways) and remove the fh without it breaking. Why? I would figure it would break over before it unscrewed, given same tq setting?

 

[SpeedRacer]

 

[JWG223]

damn your mona Lisa enigmatic smiley.

 

[jdindadell]

Nothing against threads on guns, but these items should really be pinned in place. Interference pressed by 1 thou or so, then pinned. Never really cared for loctite as it always failed on me (I did alot of high power electric rc) and welding can be '"too" permenant. Especially if you plan to hang a can off the end.

I bought one of the cheapo HF torque wrenches recently and have used it to break down a few ar15s. Not sure what the spec is for the barrel nut (30ft/lbs?) but most were on "finger tight" or not much more. I also found that during reassembly I had to put the barrel nuts on "farking' tight to get the notches to line up. Guessing I should have milled a bit off the backside of the nut till they indexed correctly at the spec-ed torque.

But I did not, and all of them still work. Plus the barrel nuts are tight, and not relying on the gas tube to hold the barrel on. Which seems more like what old stoner would want.