The FAL Files

The FAL Files (http://www.falfiles.com/forums/index.php)
-   Gunsmithing & Build It Yourself (http://www.falfiles.com/forums/forumdisplay.php?f=12)
-   -   Barrel torque--updated (http://www.falfiles.com/forums/showthread.php?t=343124)

tywest December 29, 2012 22:31

Barrel torque--updated
 
Ok so installed the barrel into the reciever tonight and it handtimes to about 11:10. I torqued it over to 12 by hand.

Now im an auto tech and pretty brute but this didnt feel like alot of force to get it there......but its by no means loose or easy haha. I just assumed it would have felt tougher the way you guys talk about yours in gigantor vises and huge breaker bars. Ill stick a torque wrench on it tomorrow as well.

ok so checked torque tonight and very unhappy......40ftlbs!! So if i get a larger breeching washer and kick it back to 10:30 ish with the breeching washer then the torque should go up considerably correct?
Is this going to change headspacing at all?

FUUN063 December 30, 2012 01:29

That's probably because it hand times to 11:10 in your words. Some people feel this is fine and others, probably the ones talking about how long a cheater baar they used, like them to time at about 10:45 or so. Not a problem.


Leland
:fal:

tywest December 30, 2012 06:22

Im to used to torquing head bolts haha or lug nuts

Thanks for the peace of mind leland

gunnutt December 30, 2012 09:14

You turned it by hand to 12? To me that says, I took my hand and twisted the barrel on without any tools to 12 O'Clock. If that is the case you have a problem. I suggest a washer if that is the case.

tywest December 30, 2012 12:22

No, used a 1/2 1.5 ft ratchet with barrel fixed in a vise

def90 December 30, 2012 12:27

http://www.falfiles.com/forums/showthread.php?t=195562

LaConservationist December 30, 2012 14:43

I usually try for 110 to 125 MAX ft/lbs......and yes I use a Full size 1/2" Drive Torque Wrench....(Snap-On if that matters) ;)

LaC

tywest December 30, 2012 14:56

Ill swing my torque wrench home monday and check the current torque. Im cool with it now just overly paranoid in everything i do, double and triple checking.

shlomo December 30, 2012 16:00

Quote:

Originally Posted by tywest (Post 3502059)
Im cool with it now just overly paranoid in everything i do, double and triple checking.

This is all to the good.

garyd1961 December 30, 2012 21:20

If you have 60 ft-lbs or more it will be good to go. I have one that's probably 50-60 lbs and it has held up just fine. The worse thing it can do is back out of time it's not going to fly off.

gunplumber December 30, 2012 21:57

My elbow clicks at 100 ft pounds. And again at 120. It's most annoying.

I doubt anything as low as 80 would be a problem.

60 - I dunno - feels too light to me, but I have no evidence it is a problem.

garyd1961 December 31, 2012 12:45

I've been using torque wrenches regularly for the last 15-20 years and I'm just estimating the torque on the barrel. I tried three different washers and decided to just let it ride and see what happens. That was about three years ago and maybe a 1000 rounds with no problem.

GMB74 December 31, 2012 17:56

I, too have an extensive background in auto repair. If the barrel were a lugnut, would you be happy with how tight it is? If so, you are good to go. If not, get a thin shim to put in there to increase the torque. As the other members stated, something in the 80-125 ft lbs range is good. If it's tight, it's right!

garyd1961 December 31, 2012 22:13

I have tightened more lugnuts than most people. I have never seen or heard of a wheel coming loose from not being torqued enough. I have seen them come loose from not being torqued at all.

shlomo December 31, 2012 22:38

Quote:

Originally Posted by garyd1961 (Post 3503652)
I have tightened more lugnuts than most people. I have never seen or heard of a wheel coming loose from not being torqued enouugh. I have seen them come loose from not being torqued at all.

I have seen lug nuts tightened so much that a cross-type lug wrench was twisted into a pretzel by the owner, while trying to break the nuts loose.

First hand. :mad:

garyd1961 December 31, 2012 23:02

I have broken a Craftsman 1/2 inch drive breaker bar on them. I also have wrung a quite few studs off because the lugs were cross threaded.
I do recomend tightening the lugs to the proper torqe. But if the correct torqe is 100 ft-lbs I had rather have 75 than 150. Over torquing damages the threads and is more dangerous than under torqing.

shlomo December 31, 2012 23:11

Quote:

Originally Posted by garyd1961 (Post 3503705)
I have broken a Craftsman 1/2 inch drive breaker bar on them. I also have wrung a quite few studs off because the lugs were cross threaded.
I do recomend tightening the lugs to the proper torqe. But if the correct torqe is 100 ft-lbs I had rather have 75 than 150. Over torquing damages the threads and is more dangerous than under torqing.

Because of the above, I have started requesting that the tech just bump the lugs down with the impact, and let ME come and final tighten when the vehicle is back on the ground. That way I KNOW I can get 'em off. I'm sure that makes me a PITA for some techs, but tough shit.

tywest January 01, 2013 08:10

Quote:

Originally Posted by shlomo (Post 3503715)
Because of the above, I have started requesting that the tech just bump the lugs down with the impact, and let ME come and final tighten when the vehicle is back on the ground. That way I KNOW I can get 'em off. I'm sure that makes me a PITA for some techs, but tough shit.

Im willing to accomodate just about anything personally, they are paying my bills. My impact torques to right at 98ftlbs on setting 2 and i double check it twice a day but if someone needs something else for peice of mind then so be it.

garyd1961 January 01, 2013 12:20

I always use torque sticks on the inpact wrench. They will set the torque pretty close. It's still a good idea to go behind and use a torqe wrench but I seldom did on account of management didn't want to waiste the time. At one place I use to work they made you use a torque stick then a torque wrench then another tech had to use a torque whench then you had to go into the parking lot and do a figure 8 and torque them again.

shlomo January 01, 2013 13:09

Quote:

Originally Posted by garyd1961 (Post 3504114)
I always use torque sticks on the inpact wrench. They will set the torque pretty close. It's still a good idea to go behind and use a torqe wrench but I seldom did on account of management didn't want to waiste the time. At one place I use to work they made you use a torque stick then a torque wrench then another tech had to use a torque whench then you had to go into the parking lot and do a figure 8 and torque them again.

I never thought of this as being that involved.

There's gotta be a pretty wide gap between where they stay on when ya want 'em to, and where they come off when ya want 'em to.

yovinny January 01, 2013 13:34

AHHHHH,,,:tongue:
Watch a few bench rest guys switch barrels with a barrel block in a 4" Chinese vise bolted to a tailgate and a 12" long 1/2" ratchet and you'll be cured of any 'adequate' barrel torque fears.

TideWater 41009 January 01, 2013 16:46

Years ago someone quoted part of a British repair manual that said to torque the barrels between 140 and 190 ft/lbs as I recall.

Anything less than 140 is too little IMHO.

gunplumber January 01, 2013 17:18

Are you sure you're remembering correctly? I have all the REME files since the 50s, and IIRC, 120 was a minimum with no upper limit listed.

shlomo January 01, 2013 17:41

Quote:

Originally Posted by yovinny (Post 3504198)
AHHHHH,,,:tongue:
Watch a few bench rest guys switch barrels with a barrel block in a 4" Chinese vise bolted to a tailgate and a 12" long 1/2" ratchet and you'll be cured of any 'adequate' barrel torque fears.

Like to see them jokers get thru a bayonet course with a rig like that.

TideWater 41009 January 01, 2013 23:19

Quote:

Originally Posted by gunplumber (Post 3504423)
Are you sure you're remembering correctly? I have all the REME files since the 50s, and IIRC, 120 was a minimum with no upper limit listed.

That could be, but it seems to me there was a lower and upper limit with the specs indicated in my post above. The manual might have been Australian rather than British. Some time ago there was a very avid collector from there or New Zealand that used to post a lot of L1A1 pictures and technical data, and I think it was he who provided the data.

FUUN063 January 02, 2013 05:29

I have posted this before from my Canadian Manual:


http://i1185.photobucket.com/albums/...abarrel001.jpg


Leland
:fal:

shlomo January 02, 2013 07:23

I seem to wanna ask whether 140 psi of hydraulic pressure on the gauge is the same thing as 140 foot-lbs of torque, and if there something in the literature that says so.

tywest January 02, 2013 16:12

Quote:

Originally Posted by shlomo (Post 3504922)
I seem to wanna ask whether 140 psi of hydraulic pressure on the gauge is the same thing as 140 foot-lbs of torque, and if there something in the literature that says so.

140psi of hydraulic pressure is in no way comparable or convertable to ft/lbs....that i know of

Id like to see the measurements of the tool or a picture of the tool to get an idea of estimated pressure......even if we only knew the line diameter we could probably get an idea


ok im really taking the torque wrench home today and checking

tywest January 02, 2013 16:18

Quote:

Originally Posted by FUUN063 (Post 3504893)
I have posted this before from my Canadian Manual:


http://i1185.photobucket.com/albums/...abarrel001.jpg


Leland
:fal:

leland........can you interpret haha, i seriously imagine it wouldnt take alot of FT/lbs to create 140psi in a cylinder...but then we dont know what this contraption looks like

according to one spreadsheet 2800 psi=55ft/lbs......that aint right for this though

tywest January 03, 2013 07:51

so I added .005 to my .056 breeching washer and it handtimed to 10:20-10:30.......so would I need about a .060 #8 washer to bring the torque up or a tad less?

guess ill order a #8 and thin if needed

FUUN063 January 03, 2013 09:18

Here's the device pictured with this text:

http://i1185.photobucket.com/albums/...arrel002-1.jpg



And, it sounds like you got it about right. Just get it tight. Done.


Leland
:fal:

shlomo January 03, 2013 09:26

Quote:

Originally Posted by FUUN063 (Post 3505769)
Here's the device pictured with this text:

http://i1185.photobucket.com/albums/...arrel002-1.jpg



And, it sounds like you got it about right. Just get it tight. Done.


Leland
:fal:

God, there are so many force variables in that system, both hydraulically and mechanically, there's no telling HOW much foot/poundage you are delivering to the barrel torque.

gunplumber January 03, 2013 09:29

how does 100 psi convert to ft pounds or newton meters

shlomo January 03, 2013 09:31

Quote:

Originally Posted by gunplumber (Post 3505776)
how does 100 psi convert to ft pounds or newton meters

Verrrry carefully, is my guess.

Deltaten January 03, 2013 09:45

Jeezus! Rube Goldberg is creamin' his (dead) jeans :biggrin:
What a confuxtulation of 'quipment!!!!!!!?!?!?!

tywest January 03, 2013 10:26

Quote:

Originally Posted by gunplumber (Post 3505776)
how does 100 psi convert to ft pounds or newton meters

psi (pressure) doesnt convert to ft/lbs (torque) directly. with this picture we can only get an idea.......using lots an lots of math and a similar hydraulic cylinder and length of stock mounted to receiver wrench.

gunplumber January 03, 2013 10:31

Looks like Tidewater was pretty close. I dug out the Aussie spec - they use a similar contraption. But have a note that the acceptable range is 269 to 375 psi which corresponds to 120-181 ft pounds. I guess the shorter Aussie wrench requires more psi than the longer Canadian for the same torque.

shlomo January 03, 2013 10:40

Quote:

Originally Posted by gunplumber (Post 3505815)
In other words, the post is irrelevant to the discussion?

I think it was intended as a historical/technical footnote.


That said, one of the things I've wondered about for years is what the effect is on the ACTUAL torque on the fitting, when using an extension plate, such as the typical FAL action wrench you see with a wrench lug hole a couple inches away from the real axis of torque.

I'm starting with a presumption that the torque wrench is calibrated at the center of the ratchet, and that extending the length of the lever will alter the actual torque delivered at the fitting from the reading set on the thimble of the tool.

But not being a mechanical engineer, I don't really know how to analyze this or calculate the effect. Anybody got an insight?

29sedan January 03, 2013 11:31

Quote:

Originally Posted by shlomo (Post 3505774)
God, there are so many force variables in that system, both hydraulically and mechanically, there's no telling HOW much foot/poundage you are delivering to the barrel torque.

Looking at the drawing, one would have to make some assumptions, not having the tool drawing and specs on hand. It appears to my eyes the arm (lever) with the hole in it rotates at the barrel to receiver axis, which would be a basic device just like a standard torque wrench is designed. In other words the length of the lever determines the torque value. If the center point of the lever were not at the center of rotation then that would change the torque value and one would need to use some kind of a multiplier value. One of my assumptions is in regards to the hole in the lever. It seems to have a clearance built in so that the lever can only go so far. Maybe this was their safety feature to keep from over torquing the barrel? Clear as mud?

tywest January 03, 2013 12:07

so like GP said

the longer lever arm reduce needed pressure for torque
and
would correspond to a shorter lever with more pressure needed for same torque

so then aussie/canadian/brit or whatever would still be the same? and so then theres a fairly standard torque spec across the board no bones about it---thats what im looking for.....i dont think id feel good about anything under 80ft/lbs but if spec is a bit more....your already there tightening it so why not keep going (unless your already at 12 with less.....some would be ok with that)........i cant honestly be satisfied with hand timed slightly past 11 and 40ft/lbs to 12.....thats asking for issues

garyd1961 January 03, 2013 17:24

Quote:

Originally Posted by shlomo (Post 3505821)
I think it was intended as a historical/technical footnote.


That said, one of the things I've wondered about for years is what the effect is on the ACTUAL torque on the fitting, when using an extension plate, such as the typical FAL action wrench you see with a wrench lug hole a couple inches away from the real axis of torque.

I'm starting with a presumption that the torque wrench is calibrated at the center of the ratchet, and that extending the length of the lever will alter the actual torque delivered at the fitting from the reading set on the thimble of the tool.

But not being a mechanical engineer, I don't really know how to analyze this or calculate the effect. Anybody got an insight?

I always wondered the same thing.
I don't know a formular to get the exact torque but I bet these guys torquing to 140 or more are going way over the specs. Maybe someone can make a two inch extention for the ratchet end of a torque wrench, torque a few bolts then check the torque without it.

kotengu January 03, 2013 21:17

Quote:

Originally Posted by shlomo (Post 3505821)
I think it was intended as a historical/technical footnote.


That said, one of the things I've wondered about for years is what the effect is on the ACTUAL torque on the fitting, when using an extension plate, such as the typical FAL action wrench you see with a wrench lug hole a couple inches away from the real axis of torque.

I'm starting with a presumption that the torque wrench is calibrated at the center of the ratchet, and that extending the length of the lever will alter the actual torque delivered at the fitting from the reading set on the thimble of the tool.

But not being a mechanical engineer, I don't really know how to analyze this or calculate the effect. Anybody got an insight?

You are correct, sir - the offset multiplies the torque, so you are actually applying more torque than what is shown on the dial (or whatever your torque wrench shows). In general - just take the offset in inches, add twelve, and divide that sum by twelve to get the torque multiplier (assuming you're using a ft-lb torque wrench).

For example - if the center of your receiver/barrel were 2" away from the center of your torque wrench ratchet hole, the torque seen at the receiver/barrel joint would be (2+12)/12=1.1667 times more than shown on the torque wrench. If your torque wrench were set at 100 ft-lbs, you would actually be applying 116.7 ft-lbs to the joint.

Torque is a funny measurement though, which is why you usually see such a wide tolerance in torque specs. No one would ever say "torque that to 116.7 ft-lbs", because it would be about impossible to do with that much precision, and meaningless even if you could.

shlomo January 03, 2013 21:55

Thankee, Matt. I knew somebody would come along and rescue me.

kotengu January 03, 2013 22:23

Anytime, sir - I'm with you on the lugnuts, for the record. I've had more morons at tire shops overtorque lug nuts and cross-thread studs than I care to count.

On the FAL barrels, I think enough has been said already. Too much torque deforms things more than you want them deformed. Not enough torque will probably run just fine, but might come unscrewed just enough to malfunction when you're butt-stroking and bayonetting.

If I had to choose I'd rather take a slightly off torque spec instead of a hand-filed barrel shoulder or not very uniform breaching shim.

tywest January 03, 2013 23:07

Quote:

Originally Posted by kotengu (Post 3506349)
Anytime, sir - I'm with you on the lugnuts, for the record. I've had more morons at tire shops overtorque lug nuts and cross-thread studs than I care to count.

On the FAL barrels, I think enough has been said already. Too much torque deforms things more than you want them deformed. Not enough torque will probably run just fine, but might come unscrewed just enough to malfunction when you're butt-stroking and bayonetting.

If I had to choose I'd rather take a slightly off torque spec instead of a hand-filed barrel shoulder or not very uniform breaching shim.

I hear yah but what is slightly off?

So in your opinion 40 is ok just might come loose :biggrin: im gonna get a bit more on it haha. Im sure youd agree as well.

As far as the applied pressure from leland's pic.......140psi exerted on that leverage arm is quite a bit of pressure, with my 1/2 impact 90 psi of pressure will torque a lugnut to 85-110 ft/lbs and it to is applying pressure to a small area albeit through a straight vane drive and such but the principle is that a drive area of about 2 sq inches can torque that much so this tool at 140 psi has (IMHO) got to be over 100ft/lbs of force exerted at the axis of the receiver.

The air tool torques to 85-110 with a bypass at 90psi......that tool doesnt look to have one, looks like you can very accurately apply controlled pressure incrementally and hold it static.

Potshot January 04, 2013 02:47

Let's be clear, what we're really after is two things:

1. Correct preload of the bolted joint
2. Alignment of the damn sights (i.e. timing)

Torque is not necessarily the indicator of preload. For example if one used differing assembly lubes, one can see a great difference in the relationship of applied torque to fastener load. I'm talking difference between correctly assembled to stripped threads at the same torque.

When torquing an FAL barrel one would want to get the maximum preload with the minimum torque (i.e. assembly lube that yields the lowest coefficient of friction). Load is a function of elongation of the fastener, which is governed by 'timing' of the barrel.

Due to my activities in my professional life, the best stuff I've run across for a situation like torquing FAL barrels (or Garands for that matter) is Cop-A-Slip.

If one knew the diameter of the hydraulic piston and the length of the lever arm of the Rube Canuckaberg contraption, torque vs. hydraulic pressure would be pretty easy to figure. Interesting device though. I've become enamored with use of one of the laser thingys for doing AK's. Wished I had one for my last FAL build.....and the Garand...

tywest January 04, 2013 03:14

Forgive me Potshot but

What your saying exactly is? I know what your talking about with preload from bearing assemblies i replace at work.....but for me thats drag loading on rotation not a nonrotating assembly like an assembled barreled receiver. I was assuming while resding your post that since preload is a rotational resistance measurement for the most part that the torque value IS the preload since youd have no other way to measure it or fastener stretch independantly.

So i guess what im getting at is.........what do you mean by maximum preload with minimum torque? Are you simply talking about the difference between torquing a dry to a lubed fastener? In my line of work torque measurement are on dry fasteners.

kotengu January 04, 2013 06:36

Quote:

Originally Posted by tywest (Post 3506417)
I hear yah but what is slightly off?

So in your opinion 40 is ok just might come loose :biggrin: im gonna get a bit more on it haha. Im sure youd agree as well.

Depends - if it's just a fun gun I'd probably shoot it and see what happens. At a worst case your zero will wander as the barrel (and front sight) wiggles around, or the piston will bind and the rifle won't cycle. You can always rebarrel with a shim later.

If you do, make sure to shoot some groups with the 40ft-lb torque, and then again with the 120 ft-lb torque. There's been a lot of discussion and speculation about the affect of barrel torque on accuracy, and I'd be curious to see your results.

tywest January 04, 2013 07:38

Well id be happy to oblige haha

shlomo January 04, 2013 08:56

I love this place. :)


All times are GMT -5. The time now is 05:43.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
©1998-2018 The FAL Files