|
Re: Torque Wrencch question
[Re: UCUDANT]
#95322
07/27/08 09:50 AM
07/27/08 09:50 AM
|
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
|
Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
|
a 3" C to C extension onto a 12" C to C torque wrench would increase your leverage by 25% so reduce your reading by that amount.
live every 24 hour block of time like it's your last day on earth
|
|
|
Re: Torque Wrencch question
[Re: RapidRobert]
#95323
07/27/08 01:33 PM
07/27/08 01:33 PM
|
Joined: Sep 2007
Posts: 14,889
up yours
Supercuda
About to go away
|
About to go away
Joined: Sep 2007
Posts: 14,889
up yours
|
I do not think he's talking about extending horizontally, just vertically. If it's vertical, no adjustment is needed. If it is indeed horizontal then yes it would need recalculating.
They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.
|
|
|
Re: Torque Wrencch question
[Re: RapidRobert]
#95324
07/27/08 03:57 PM
07/27/08 03:57 PM
|
Joined: Apr 2005
Posts: 12,271
Overpriced Housing Central
RobX4406
I Live Here
|
I Live Here
Joined: Apr 2005
Posts: 12,271
Overpriced Housing Central
|
Quote:
a 3" C to C extension onto a 12" C to C torque wrench would increase your leverage by 25% so reduce your reading by that amount.
????
Extending the length of a wrench (lever) might reduce the effort required to apply the required force. I wouldn't change a setting from say 60 ft/lb to 45 ft/lb because the lever was longer.
The fastener doesn't know the difference between a 12" or 12' torque wrench. Applied force at the fastener should not change.
Putting a 3" socket extension won't change your values as long as you remain consistent to the fastener center.
|
|
|
Re: Torque Wrencch question
[Re: RobX4406]
#95325
07/27/08 11:56 PM
07/27/08 11:56 PM
|
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
RapidRobert
Circle Track
|
Circle Track
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
|
Rob after I read your post I called an acquaintence who is a retired university of Nebraska professor(I forget what field) & he stated that with an extension you would indeed need to reduce the reading on the wrench but after thinking about it some more if you apply a certain amt of torque on that lever you would have the same amt of force all along it's length no matter how long it is. So I think you are right. So much for the value of education huh. Thank you for the enlightenment
live every 24 hour block of time like it's your last day on earth
|
|
|
Re: Torque Wrencch question
[Re: blaze]
#95327
07/28/08 07:33 AM
07/28/08 07:33 AM
|
Joined: Oct 2003
Posts: 21,345
Marysville, O-H-I-O
70Cuda383
Too Many Posts
|
Too Many Posts
Joined: Oct 2003
Posts: 21,345
Marysville, O-H-I-O
|
it would depend on where the extension is.
if you simply put a pipe over the handle to make it longer, now in order to crank off 75 ft/lbs to the fastener, it will only take you 25 lbs of effort instead of 50.
if you somehow managed to put an extension on the head of the wrench, picture an extended crows foot, then your 75 ft/lbs at the head of the torque wrench is going to be multiplied by the length of your extension...but I don't see that as realistic, because I've never seen such an extension, nor do I know what you would use it for!
**Photobucket sucks**
|
|
|
Re: Torque Wrencch question
[Re: 70Cuda383]
#95328
07/28/08 09:53 AM
07/28/08 09:53 AM
|
Joined: Apr 2004
Posts: 1,396
Mass
dgc333
pro stock
|
pro stock
Joined: Apr 2004
Posts: 1,396
Mass
|
Quote:
if you somehow managed to put an extension on the head of the wrench, picture an extended crows foot, then your 75 ft/lbs at the head of the torque wrench is going to be multiplied by the length of your extension...but I don't see that as realistic, because I've never seen such an extension, nor do I know what you would use it for!
Over the years I have done this on a number of occasions because the fastner was in a location I could not get the head of the torque wrench onto. I have a bunch of old wrenches with sockets welded to them just for this.
Anyway, if you put a 1 ft extension straight off the end of a torque wrench and you measure 75 ft-lbs on the wrench you are apply 150 ft-lbs to the fastener.
|
|
|
Re: Torque Wrencch question
[Re: dgc333]
#95330
07/28/08 10:23 AM
07/28/08 10:23 AM
|
Joined: Oct 2006
Posts: 4,165
Florida
cataclysm80
master
|
master
Joined: Oct 2006
Posts: 4,165
Florida
|
Quote:
Anyway, if you put a 1 ft extension straight off the end of a torque wrench and you measure 75 ft-lbs on the wrench you are apply 150 ft-lbs to the fastener.
It's called ft-lbs because thats how much weight in lbs is being applied 1 foot from the fastener.
Lets say for example that you don't have a torque wrench, just a 12 inch ratchet. You could bring out your bathroom scale and stand on it while tightening the fastener. However much of your weight is not on the scale, is on your 12 inch ratchet. Ft-lbs
If your ratchet is twice as long, you'll need 1/2 the weight.
That's the way physics work.
Using a crows foot type extension is in no way different than adding a cheater bar to make the handle longer. Either way, you're adding distance between the fastener and the force (your hand).
You can prove this to yourself by using your torque wrench with a long cheater bar on it to tighten a fastener to any set amount. Then remove the cheater bar and tighten the fastener to that same amount. If the fastener is already tight that would mean the cheater bar did not make a difference. If the fastener has bit to go before it's tight, then the cheater bar Does make a difference.
Another thing that concerns me is an extension between the ratchet and the socket. The length and diameter of this type of extension can make a difference. It will twist like the torsion bars on our mopars. How much of my ft-lbs applied force are absorbed by the twisting motion of this type of extension? The absorbed amount is not applied to the fastener.
Tav
|
|
|
Re: Torque Wrencch question
[Re: cataclysm80]
#95332
07/28/08 11:59 AM
07/28/08 11:59 AM
|
Anonymous
Unregistered
|
Anonymous
Unregistered
|
Quote:
Using a crows foot type extension is in no way different than adding a cheater bar to make the handle longer. Either way, you're adding distance between the fastener and the force (your hand).Tav
In the context of this discussion, this statement is NOT TRUE. You are applying X amount of force, as read on a gauge, or activating a calibrated "snap." When you add a crows foot, You CHANGE the accuracy of the gauge or snap. When you add a pipe to the handle, you do NOT change the accuracy
Quote:
Another thing that concerns me is an extension between the ratchet and the socket. The length and diameter of this type of extension can make a difference. It will twist like the torsion bars on our mopars. How much of my ft-lbs applied force are absorbed by the twisting motion of this type of extension? The absorbed amount is not applied to the fastener.Tav
This statement is ALSO not true, unless you are talking about an impact wrench, in which case a "rubbery" extension will indeed absorb torque. If you were to take something--like a small diameter torsion bar, and two identical torque wrenches, clamp one wrench at one end, and apply X amount of force with the other torgue wrench, you will find that REGARDLESS of stretch or twist in the torsion bar, the two wrenches will read THE SAME torque on the gauges.
|
|
|
Re: Torque Wrencch question
#95334
07/28/08 12:25 PM
07/28/08 12:25 PM
|
Joined: Oct 2006
Posts: 4,165
Florida
cataclysm80
master
|
master
Joined: Oct 2006
Posts: 4,165
Florida
|
Quote:
Quote:
Another thing that concerns me is an extension between the ratchet and the socket. The length and diameter of this type of extension can make a difference. It will twist like the torsion bars on our mopars. How much of my ft-lbs applied force are absorbed by the twisting motion of this type of extension? The absorbed amount is not applied to the fastener.Tav
This statement is ALSO not true, unless you are talking about an impact wrench, in which case a "rubbery" extension will indeed absorb torque. If you were to take something--like a small diameter torsion bar, and two identical torque wrenches, clamp one wrench at one end, and apply X amount of force with the other torgue wrench, you will find that REGARDLESS of stretch or twist in the torsion bar, the two wrenches will read THE SAME torque on the gauges.
So then, as far as the extension twisting and absorbing force, it will only affect things if...
1. The torque level you're trying to reach is less than what the extension will absorb. Example : if the twisting motion of your extension will absorb 20 inch pounds, then you couldn't use it to tighten something to 15 inch pounds. Once you get to 20 inch pounds and the extension stops twisting, then you'll have 20 inch pounds applied to the fastener. You could only use that extension to torque amounts higher than 20 inch pounds. In all practicality the amount of force absorbed by a twisting extension is probably negligible.
2. The torque level your trying to reach exceeds the breaking point of your extension. Example: Using a 1/4 inch drive extension to torque down your main caps will twist it right in two!
Tav
|
|
|
Re: Torque Wrencch question
[Re: RapidRobert]
#95335
07/28/08 12:27 PM
07/28/08 12:27 PM
|
Joined: Oct 2006
Posts: 4,165
Florida
cataclysm80
master
|
master
Joined: Oct 2006
Posts: 4,165
Florida
|
Quote:
440SIXPACK Can I inform this prof that he is full of it & that all of his higher education was a waste 
Nope, sorry everything else still holds true.
Tav
|
|
|
Re: Torque Wrencch question
[Re: cataclysm80]
#95336
07/28/08 04:10 PM
07/28/08 04:10 PM
|
Joined: Apr 2004
Posts: 1,396
Mass
dgc333
pro stock
|
pro stock
Joined: Apr 2004
Posts: 1,396
Mass
|
Quote:
Quote:
Anyway, if you put a 1 ft extension straight off the end of a torque wrench and you measure 75 ft-lbs on the wrench you are apply 150 ft-lbs to the fastener.
It's called ft-lbs because thats how much weight in lbs is being applied 1 foot from the fastener.
Lets say for example that you don't have a torque wrench, just a 12 inch ratchet. You could bring out your bathroom scale and stand on it while tightening the fastener. However much of your weight is not on the scale, is on your 12 inch ratchet. Ft-lbs
If your ratchet is twice as long, you'll need 1/2 the weight.
That's the way physics work.
Using a crows foot type extension is in no way different than adding a cheater bar to make the handle longer. Either way, you're adding distance between the fastener and the force (your hand).
You can prove this to yourself by using your torque wrench with a long cheater bar on it to tighten a fastener to any set amount. Then remove the cheater bar and tighten the fastener to that same amount. If the fastener is already tight that would mean the cheater bar did not make a difference. If the fastener has bit to go before it's tight, then the cheater bar Does make a difference.
Another thing that concerns me is an extension between the ratchet and the socket. The length and diameter of this type of extension can make a difference. It will twist like the torsion bars on our mopars. How much of my ft-lbs applied force are absorbed by the twisting motion of this type of extension? The absorbed amount is not applied to the fastener.
Tav
Tav, sounds like you are saying exactly what I said but are disagreeing. If you put a 1 foot cheater bar on the handle of a torque wrench and apply force until the wrench reads 75 ft-lbs it takes 1/2 the strenght in your arm than if you didn't use the cheater bar (thats why we call them cheater bars, more torque with less force). But if you put a 1 foot extension on the other end and pulled on the torque wrench until it reads 75 ft-lbs you have doubled the moment arm so you have doubled the torque applied to the fastner or 150 ft-lbs. In this case your arm will feel the same preceived amount of effort as if you didn't have the extension beacuse you aren't providing leverage to the measurement.
Take your ratchet example. With the ratchet horizontal and you hang a 75 lb weight 1 foot along the handle from the center of the socket you have 75 * 1 or 75 ft-lbs. Now move that same 75 lb weight to 2 feet along the handle from the socket and you have 75 * 2 or 150 ft-lbs.
When it comes to a ratchet extension between the socket and torque wrench. There is no loss of torque between the wrench and the socket. You may have to physically move the wrench more depending on the diameter and length of the extension to get to a give torque reading but no torque is lost along the length of the extension.
|
|
|
Re: Torque Wrencch question
[Re: dgc333]
#95337
07/28/08 05:45 PM
07/28/08 05:45 PM
|
Joined: Jan 2003
Posts: 10,718
North Dakota
6PakBee
I Live Here
|
I Live Here
Joined: Jan 2003
Posts: 10,718
North Dakota
|
I can't take it anymore. A picture is work 1K words.
"We live in a time when intelligent people are being silenced so that stupid people won't be offended".
|
|
|
Re: Torque Wrencch question
[Re: RapidRobert]
#95339
07/28/08 06:50 PM
07/28/08 06:50 PM
|
Anonymous
Unregistered
|
Anonymous
Unregistered
|
Quote:
440SIXPACK Can I inform this prof that he is full of it & that all of his higher education was a waste
You certainly can. But maybe you somehow misheard or misinterpreted something "he" said.
To reiterate:
An extension from the DRIVE end, in line with the handle, affects the reading on the dial.
An extension on the HANDLE end does NOT affect the accuracy of the dial, it only means that you don't have to pull as hard.
An extension down the centerline of the socket drive affects NOTHING. There is no "absorbsion of energy", because the extension is hooked from one end to the wrench, and to the other end to the socket. ALL THE TORQUE must "go" somewhere.
STILL ANOTHER EXAMPLE:
If you were to take a rubber band, like in the old wind up airplanes, and put a lever and scale at the tail, then wind up the rubber, then put an IDENTICAL lever and scale at the prop end, THE TWO SCALES WOULD READ EXACTLY THE SAME, assuming they are both accurate to each other.
|
|
|
Re: Torque Wrencch question
[Re: cataclysm80]
#95340
07/28/08 06:58 PM
07/28/08 06:58 PM
|
Anonymous
Unregistered
|
Anonymous
Unregistered
|
Quote:
Quote:
Quote:
Another thing that concerns me is an extension between the ratchet and the socket. The length and diameter of this type of extension can make a difference. It will twist like the torsion bars on our mopars. How much of my ft-lbs applied force are absorbed by the twisting motion of this type of extension? The absorbed amount is not applied to the fastener.Tav
This statement is ALSO not true, unless you are talking about an impact wrench, in which case a "rubbery" extension will indeed absorb torque. If you were to take something--like a small diameter torsion bar, and two identical torque wrenches, clamp one wrench at one end, and apply X amount of force with the other torgue wrench, you will find that REGARDLESS of stretch or twist in the torsion bar, the two wrenches will read THE SAME torque on the gauges.
So then, as far as the extension twisting and absorbing force, it will only affect things if...
1. The torque level you're trying to reach is less than what the extension will absorb. Example : if the twisting motion of your extension will absorb 20 inch pounds, then you couldn't use it to tighten something to 15 inch pounds. Once you get to 20 inch pounds and the extension stops twisting, then you'll have 20 inch pounds applied to the fastener. You could only use that extension to torque amounts higher than 20 inch pounds. In all practicality the amount of force absorbed by a twisting extension is probably negligible.
2. The torque level your trying to reach exceeds the breaking point of your extension. Example: Using a 1/4 inch drive extension to torque down your main caps will twist it right in two!
Tav
The only time your in-line extension is somehow magically going to "absorb" torque, is if you BREAK it in two.
There is no such thing as an extension somehow "twisting" and magically "absorbing torque." Even if you were speaking of something some kind of rubbery motor coupling, the drive might momentarily absorb some torque for an instant of time, but once the "end" of the twist is reached, ALL the torque will be transferred to the end of the shaft. The only alternative is the one you stated--it might break.
You can prove this to yourself very easily. Get yourself two torque wrenches, or two scales. Rig up an experimental shaft, like, say, 1/4" rod, something you can twist a little. Rig a temporary bearing setup, maybe out of two-x-fours, identical levers on both ends, and your scales. You'll find that the scales read EXACTLY the same, +/- the difference in accuracy between them. If you put X ft-lbs on one end, you'll have the very same on the other. you can twist that shaft into a pretzel, and the only thing that might change, is that it finally breaks.
|
|
|
Re: Torque Wrencch question
#95341
07/28/08 07:04 PM
07/28/08 07:04 PM
|
Anonymous
Unregistered
|
Anonymous
Unregistered
|
Dudes, there is a formula for calculating the required torque on the internet.
I had to make an adapter to torque the studs in the lifter valley on my hemi.
I don't have the formula here, but to get 75 ft/lbs at the fastener, I have to reduce the torque wrench to 45 ft/lbs, because of the 8" or so length of the adapter.
When you use a torque wrench, there is a mark that is supposed to be in the center of your hand when you pull. The distance between that and the center of your fasteneris your torque arm.
I'll post the formula later.
BTW, the torque loss through an extension is negligible, unless you're using something over 1 ft.
|
|
|
Re: Torque Wrencch question
[Re: Jack Zupan]
#95343
07/28/08 07:29 PM
07/28/08 07:29 PM
|
Anonymous
Unregistered
|
Anonymous
Unregistered
|
|
|
|
Re: Torque Wrencch question
[Re: 6PakBee]
#95346
07/29/08 12:16 AM
07/29/08 12:16 AM
|
Joined: Oct 2003
Posts: 21,345
Marysville, O-H-I-O
70Cuda383
Too Many Posts
|
Too Many Posts
Joined: Oct 2003
Posts: 21,345
Marysville, O-H-I-O
|
Quote:
I can't take it anymore. A picture is work 1K words.
exactly!
let's take the torque wrench out of this for a minute.
lever A is 1 foot long.
put 100 lbs on it, and you get 100 ft lbs of torque.
if you add another foot to that lever, it does not matter if the new length is between the pivot point and the original lever, or simply on the end of the old lever, you now have 200 ft lbs.
the issue comes in with the torque wrench and how it "snaps" at the set torque.
if you have a 1 foot torque wrench and set it to 100 ft lbs, you will have to put 100 ft lbs on the end to make it click.
if you add a 1 foot extension to the end of the torque wrench that's set at 100, the wrench will click 50 lbs of force, because 50 x 2 = 100
if you add a 1 foot extension to the pivot point, with say, the extended crows foot, and the torque wrench is set to 100, you will have to put 100 lbs of force on the end of the torque wrench to get it to click, however, this is actually putting 200 ft lbs of force to the pivot point.
so, to compensate, you have to re-calculate based on the length of your extension. and in this case, with a 1 foot extension, you will have to set the torque wrench to 50, and then put 50 lbs on the end of the wrench to get 100 ft lbs at the pivot point, because again, 50 x 2 = 100
but, the picture shows that clearly.
in order to tell your professor friend that he was wrong, make sure you understand what he meant, because he might have told you that "it makes no difference, the torque is the same" meaning that the torque at the pivot point is the same, and NOT that the calibrated wrench will work properly.
**Photobucket sucks**
|
|
|
Re: Torque Wrencch question
[Re: 70Cuda383]
#95353
07/29/08 09:44 AM
07/29/08 09:44 AM
|
Joined: Oct 2006
Posts: 4,165
Florida
cataclysm80
master
|
master
Joined: Oct 2006
Posts: 4,165
Florida
|
Quote:
exactly!
let's take the torque wrench out of this for a minute.
lever A is 1 foot long.
put 100 lbs on it, and you get 100 ft lbs of torque.
if you add another foot to that lever, it does not matter if the new length is between the pivot point and the original lever, or simply on the end of the old lever, you now have 200 ft lbs.
the issue comes in with the torque wrench and how it "snaps" at the set torque.
 This is what I was saying. My examples used a ratchet NOT a torque wrench.
Tav
|
|
|
Re: Torque Wrencch question
[Re: 70Cuda383]
#95354
07/29/08 09:48 AM
07/29/08 09:48 AM
|
Joined: Oct 2006
Posts: 4,165
Florida
cataclysm80
master
|
master
Joined: Oct 2006
Posts: 4,165
Florida
|
Quote:
the issue comes in with the torque wrench and how it "snaps" at the set torque.
if you have a 1 foot torque wrench and set it to 100 ft lbs, you will have to put 100 ft lbs on the end to make it click.
if you add a 1 foot extension to the end of the torque wrench that's set at 100, the wrench will click 50 lbs of force, because 50 x 2 = 100
if you add a 1 foot extension to the pivot point, with say, the extended crows foot, and the torque wrench is set to 100, you will have to put 100 lbs of force on the end of the torque wrench to get it to click, however, this is actually putting 200 ft lbs of force to the pivot point.
so, to compensate, you have to re-calculate based on the length of your extension. and in this case, with a 1 foot extension, you will have to set the torque wrench to 50, and then put 50 lbs on the end of the wrench to get 100 ft lbs at the pivot point, because again, 50 x 2 = 100
but, the picture shows that clearly.
in order to tell your professor friend that he was wrong, make sure you understand what he meant, because he might have told you that "it makes no difference, the torque is the same" meaning that the torque at the pivot point is the same, and NOT that the calibrated wrench will work properly.
with this also!
By the way, Excellent pictures 6PakBee & 446acuda!!
Tav
|
|
|
Re: Torque Wrencch question
#95355
07/29/08 09:56 AM
07/29/08 09:56 AM
|
Joined: Oct 2006
Posts: 4,165
Florida
cataclysm80
master
|
master
Joined: Oct 2006
Posts: 4,165
Florida
|
Quote:
An extension down the centerline of the socket drive affects NOTHING. There is no "absorbsion of energy", because the extension is hooked from one end to the wrench, and to the other end to the socket. ALL THE TORQUE must "go" somewhere.
STILL ANOTHER EXAMPLE:
If you were to take a rubber band, like in the old wind up airplanes, and put a lever and scale at the tail, then wind up the rubber, then put an IDENTICAL lever and scale at the prop end, THE TWO SCALES WOULD READ EXACTLY THE SAME, assuming they are both accurate to each other.
Quote:
I go through this topic at least once a month with one of our maintenance mechanics who always claims "you always lose torque through an extension". One even said he'd show me. Got out three 6" extensions old enough for Columbus to have used, puts them together with an electric impact and starts rattling away on a bolt. Whole lot of shaking going on but no action. Then he puts the impact on the socket and triumphantly shows me that he can spin the bolt right out. I went to the crib, got a new socket and a new longer extension (can't remember exact length) and asked him to try that. Worked like a charm. People seem to forget that an impact wrench only travels a fixed amount of rotation with every 'blow'. If the extensions/sockets/impacts are sloppy, all that travel is consumed before the fastener ever gets rapped.
 Hmmm, I see. So even if the extension twists it's still applying that amount of twist to the fastener. Any loss is only momentary.
Thank you for explaining my concern!
Tav
|
|
|
Re: Torque Wrencch question
[Re: cataclysm80]
#95356
07/29/08 10:15 AM
07/29/08 10:15 AM
|
Joined: Sep 2007
Posts: 14,889
up yours
Supercuda
About to go away
|
About to go away
Joined: Sep 2007
Posts: 14,889
up yours
|
Just to throw a monkey wrench inot the pile, they make torque wrenches that have removeable hades. You can swap out the rachet head for a crows foot head to get at bolts WITHOUT messing up the accuracy or having to recalculate anything, but it's engineered properly to do that. I know I used them daily at work. http://www.stahlwille-online.de/index.ph...93&cid=5022
They say there are no such thing as a stupid question.
They say there is always the exception that proves the rule.
Don't be the exception.
|
|
|
|
|
but I am going to stay with this until I find out.
