Testing accuracy of new torque wrench
02-20-10, 08:30 PM
#26
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Thread Starter
Have a torque wrench calibrated at a certified test center will cost about $150, more then you paid for the wrench! So the only practical way to certify it is at home. It's a little weird but it works for far less money then sending in.
Step1
Mark the center point of the wrench head on the back of the torque wrench. Use a a pencil or marker.
Step 2
Measure from the center point to the point at which you apply the most pressure when using the wrench. Write down this measurement as "Distance 1" either in inches (if your wrench measures in inch pounds) or feet (if your wrench measures in foot pounds).
Step 3
Clamp the wrench bit in a vise horizontally. Using string, hang a 20-pound weight from the handle of the wrench.
Step 4
Move the weight along the handle of the wrench until it measures exactly 40 foot pounds or 480 inch pounds. Measure the distance from the center point on the head of the wrench to the string and write this measurement down as "Distance 2."
Step 5
Divide "Distance 2" by "Distance 1" with the calculator to find the calibration ratio. This ratio is the difference between the the settings on your wrench and the actual force needed to acquire a "click" at that setting.
Step 6
Set your torque wrench for a specific application by multiplying the required torque of the bolt by the calibration ratio. For example, if a bolt requires 43 foot/pounds of torque and the calibration ratio is 1.124, multiply 43 times 1.124 and set your wrench to 48.3 foot/pounds.
BUT, and I mean a BIG BUT, really on a bike it's not all that critical and more then likely the wrench is calibrated from the factory + or - 4% which is more then accurate enough for what your doing.
Step1
Mark the center point of the wrench head on the back of the torque wrench. Use a a pencil or marker.
Step 2
Measure from the center point to the point at which you apply the most pressure when using the wrench. Write down this measurement as "Distance 1" either in inches (if your wrench measures in inch pounds) or feet (if your wrench measures in foot pounds).
Step 3
Clamp the wrench bit in a vise horizontally. Using string, hang a 20-pound weight from the handle of the wrench.
Step 4
Move the weight along the handle of the wrench until it measures exactly 40 foot pounds or 480 inch pounds. Measure the distance from the center point on the head of the wrench to the string and write this measurement down as "Distance 2."
Step 5
Divide "Distance 2" by "Distance 1" with the calculator to find the calibration ratio. This ratio is the difference between the the settings on your wrench and the actual force needed to acquire a "click" at that setting.
Step 6
Set your torque wrench for a specific application by multiplying the required torque of the bolt by the calibration ratio. For example, if a bolt requires 43 foot/pounds of torque and the calibration ratio is 1.124, multiply 43 times 1.124 and set your wrench to 48.3 foot/pounds.
BUT, and I mean a BIG BUT, really on a bike it's not all that critical and more then likely the wrench is calibrated from the factory + or - 4% which is more then accurate enough for what your doing.
I was a little unnerved when using the wrench on the seat post bolt and it kept turning even at its lightest setting of 3Nm, so I backed off. Again, as I mentioned in my first post, this is my first carbon bike and I have little experience with them. I'm a'scared! :-)
02-20-10, 08:41 PM
#27
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Thread Starter
Whoops! Be careful, a touchy subject for Operator. He can't decide if you should or shouldn't use carbon grit paste. One minute it's; "yes we use it on every bike", the next minute it's, "no we never use any of that crap."
02-20-10, 08:53 PM
#28
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Operator is correct. And a decent torque wrench is a precision tool, not one to be dropped on the floor or just thrown around loosely.
I'll tell you like I was told, and I grew up with a father that owned a precision machine shop: : "There's no such thing as a calibrated elbow" which is why you use the proper tool. Since all his work was MIL-SPEC, all tools like that had to be sent out to be calibrated.
I'll tell you like I was told, and I grew up with a father that owned a precision machine shop: : "There's no such thing as a calibrated elbow" which is why you use the proper tool. Since all his work was MIL-SPEC, all tools like that had to be sent out to be calibrated.
02-20-10, 10:24 PM
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https://www.teamtorque.com/documents/torquepricing.pdf
BTW, I bought this torque wrench this week. It looks like a rebranding of yours.
https://www.biketiresdirect.com/ppgtw..._wrench/pp.htm
Kam
02-20-10, 10:39 PM
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Have a torque wrench calibrated at a certified test center will cost about $150, more then you paid for the wrench! So the only practical way to certify it is at home. It's a little weird but it works for far less money then sending in.
Step1
Mark the center point of the wrench head on the back of the torque wrench. Use a a pencil or marker.
Step 2
Measure from the center point to the point at which you apply the most pressure when using the wrench. Write down this measurement as "Distance 1" either in inches (if your wrench measures in inch pounds) or feet (if your wrench measures in foot pounds).
Step 3
Clamp the wrench bit in a vise horizontally. Using string, hang a 20-pound weight from the handle of the wrench.
Step 4
Move the weight along the handle of the wrench until it measures exactly 40 foot pounds or 480 inch pounds. Measure the distance from the center point on the head of the wrench to the string and write this measurement down as "Distance 2."
Step 5
Divide "Distance 2" by "Distance 1" with the calculator to find the calibration ratio. This ratio is the difference between the the settings on your wrench and the actual force needed to acquire a "click" at that setting.
Step 6
Set your torque wrench for a specific application by multiplying the required torque of the bolt by the calibration ratio. For example, if a bolt requires 43 foot/pounds of torque and the calibration ratio is 1.124, multiply 43 times 1.124 and set your wrench to 48.3 foot/pounds.
BUT, and I mean a BIG BUT, really on a bike it's not all that critical and more then likely the wrench is calibrated from the factory + or - 4% which is more then accurate enough for what your doing.
Step1
Mark the center point of the wrench head on the back of the torque wrench. Use a a pencil or marker.
Step 2
Measure from the center point to the point at which you apply the most pressure when using the wrench. Write down this measurement as "Distance 1" either in inches (if your wrench measures in inch pounds) or feet (if your wrench measures in foot pounds).
Step 3
Clamp the wrench bit in a vise horizontally. Using string, hang a 20-pound weight from the handle of the wrench.
Step 4
Move the weight along the handle of the wrench until it measures exactly 40 foot pounds or 480 inch pounds. Measure the distance from the center point on the head of the wrench to the string and write this measurement down as "Distance 2."
Step 5
Divide "Distance 2" by "Distance 1" with the calculator to find the calibration ratio. This ratio is the difference between the the settings on your wrench and the actual force needed to acquire a "click" at that setting.
Step 6
Set your torque wrench for a specific application by multiplying the required torque of the bolt by the calibration ratio. For example, if a bolt requires 43 foot/pounds of torque and the calibration ratio is 1.124, multiply 43 times 1.124 and set your wrench to 48.3 foot/pounds.
BUT, and I mean a BIG BUT, really on a bike it's not all that critical and more then likely the wrench is calibrated from the factory + or - 4% which is more then accurate enough for what your doing.
Look at it this way, if you apply 40 foot pound (20lb at 2feet) and the wrench shows 40 foot pound than the calibration ratio is 1.0.
Kam
02-20-10, 10:46 PM
#31
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What this thread clearly demonstrates is that using tools and/or instruments they don't fully understand may or may not make inexperienced mechanics better, but it certainly will make them think they're better, and that's the rub.
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An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
02-20-10, 11:09 PM
#33
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cia dog, are you sure about this procedure? It does not seem right to me. I would think that 'distance 1' is not the place where you normally hold the wrench but the distance that you would expect a 20lb to apply 40 foot pound (2 feet?).
Look at it this way, if you apply 40 foot pound (20lb at 2feet) and the wrench shows 40 foot pound than the calibration ratio is 1.0.
Kam
Look at it this way, if you apply 40 foot pound (20lb at 2feet) and the wrench shows 40 foot pound than the calibration ratio is 1.0.
Kam
The other method for testing another poster already mentioned but another poster foo fooed it, and that was to make a beam wrench be used to calibrate a click wrench. A bolt is tightened with the click wrench. The beam wrench is then used to tighten the bolt again. Before the preset (on the click wrench) torque is reached, the bolt should not move. After the preset torque, the bolt should tighten up some more. This does actually works as long as the beam wrench was never dropped.
I have a dial torque wrench but never needed one for a bike because I own steel rides and none require accurate torquing like CF or some AL rides. That's one of the reasons I prefer steel, an argument I'm trying to avoid on another post and will try to avoid here.
02-20-10, 11:25 PM
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You have that backwards. As a boundary condition, consider a bolt that's rusted solidly in place. You can apply 10 times the specified torque and still get zero clamping force as a result, because the bolt's not turning. 100% of the torque is being consumed by friction.
That's an insightful question and the answer is yes, it's possible. One of the first examples that comes to mind is road bikes' front-derailleur clamps. With a dry bolt, they usually waste a lot of your exerted torque on friction. Lubricating the bolt's contact areas can increase the effective clamping force by a factor of probably 2x. This is an area where I'd hate to be a rookie, because there's no Undo button to re-laminate the carbon on your Cervelo (btw I'd stick to about 25 inch-pounds or less with a lubed bolt on your FD clamp if your Cervelo has a clamp-on type FD).
Your original questions were about stems and seatpost clamps, which traditionally have at least a half-hearted dose of grease on the bolts from the factory, so for consistent results, go ahead and grease the bolts.
if I grease the threads would that cause too little friction, so that as I tighten, the bolt is so...slippery that I overtorque before the torque wrench clicks?
Your original questions were about stems and seatpost clamps, which traditionally have at least a half-hearted dose of grease on the bolts from the factory, so for consistent results, go ahead and grease the bolts.
Last edited by mechBgon; 02-21-10 at 11:56 AM.
02-21-10, 12:30 AM
#36
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Just get some beam torque-wrenches at SEARS. The 'PARK' name just costs more. Reliable. Efficient. And more than adequate for bicycle work. And it's "soft-belly" called CF components.
<yawn>
<yawn>
02-21-10, 02:49 AM
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Sears doesn't seem to have any in the low-torque range that compare to the smaller Park model, though. Doing a quick Google shopping search, it looks like the Park Tool TW-1 costs less than the equivalent item from Armstrong or KD (plus it comes with a 3/8" step-up adapter), so it may not be a total crime to get the $35 Park-badged one.
02-21-10, 07:39 AM
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Well, Operator can be abrasive but I think you have mis-stated his position on assembly paste. He recommends it for carbon seatposts but says it's unnecessary for bar/stem interfaces. He is probably correct in both cases.
02-21-10, 08:55 AM
#39
Senior Member
That static test is representive of nothing, i've done the same thing with a throwaway 1 1/8 carbon fork that retails for ~ $500 - yes it takes more torque than the standard 5nm. So what? Can you guarantee that the part is not going to fail sometime down the road at 7nm? Maybe more?
Why even gamble in such a fashion, when there is a *tool* to allow you to properly set the torque, nearly exactly the same each and every time? Why retro-grouch like this? I don't get it.
My test was done to show that even a large amount of excessive torque is not likely to fracture a steering tube, as long as the stem and steerer are a good fit. It was done in response to a poster who over-tightened a stem and managed to break the steering tube while building the bike. With some of these broken steerers, there will be obvious compression lines in the steering tube due to the pinching at the gap in the pinch-bolt area. That is often due to the stem's ID being too large and/or raised edges that need to be filed-down.
I think that all riders should get a reasonable idea of what these small torques feels like. If they don't, they might break a bolt or strip threads while making a simple adjustment out on the road.
I use a large beam-type torque wrench for the large torque items like cassette lockring, BB cups and the Campy UT crank spindle fixing bolt. The rest get tightend by feel. A beam type should always be accurate as long as the pointer reads zero with no torque on it.
Checking a torque wrench with a dead-weight seems like a good way to check it's calibration, as long as the person doing the test properly figures the wrench's lever arm length and selects the correct weight.
Last edited by DaveSSS; 02-21-10 at 09:20 AM.
02-21-10, 08:58 AM
#40
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Thread Starter
The thread is here
However, to be succient here it is in a nutshell;
The OP asked:
FSA website shows a spray for fitting carbon parts and alloy i.e. handlebar to stem. They claim a 30% reduction in torque required thereby avoiding over-torquing. Anybody had experience with this?
Operator stated:
A solution looking for a problem. (oh yes, THAT was helpful Operator).
I stated:
When I recently purchased my carbon bike the LBS owner had shown me a gel like product that had tiny beads embedded within it. He stated that this product was spread on the seat tube and steerer tube where the stem attaches to help prevent slippage. It was called Fiber Grip from Finish Line.
The product doesn't prevent over torquing per se, rather I suspect that when the seat post slips it would cause the cyclist to torque down the bolt more, and run the risk of over tigtening. This product is supposed to reduce the chance of slippage, thereby removing the need for the cyclist to tighten the bolt more.
Operator threw a tantrum, of course I stirred the pot for my entertainment, but he would not read the posts in all of its context. I was merely pointing out what the LBS had shown me (the gel paste) and that this spray, the OP mentioned, seemed to be designed for the same purpose. I made no claims of my bicycle mechanical knowledge, or that this spray was required. Operator does nothing but confuse the issue, he is a social miscreant and irrational and unable to discuss a topic calmly. He feels that being belligerent impresses people, he obviously has a narrow point of view. I had tried giving him a taste of his own medicine.
In the very last post, I stated, yet again:
For those that do not have a the specific LOW-torque wrench, these products claim to help to reduce the chance of over torquing by increasing the friction. If a bicycle owner does not torque the bolt properly, obviously the post will slip. They then have to tighten the bolt and run the risk of over torquing. This product will help prevent slippage from a slightly under torqued bolt.
Last edited by digger; 02-21-10 at 09:26 AM. Reason: spelling
02-21-10, 09:11 AM
#41
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Thread Starter
However, you have a good point that lugging a torque wrench around for use "on the road" isn't feasible hence, people (like me) who; are moving from a steel frame to a carbon frame and do not have alot of experience with these low torque requirements this will be an instructional aid (as Operator stated).
02-21-10, 12:11 PM
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Yeah operator can be a ducebag[sic], but at least hes an experienced ****** who's opinions are actually worth hearing as opposed to yours.
If you think operators a hack mechanic don't listen to him, but seriously stop drudging this up
02-21-10, 12:36 PM
#44
Senior Member
Calibrating a torque wrench should not be that difficult. You should be able to measure the lever arm length with a tape measure. You certainly can with a beam type - center of the square drive to the center of the grip handle's pivot pin. My big 1/2 inch drive is 17 inches long.
Hang a weight of known value in the midrange of the wrench's capacity. Multiply the weight times the lever arm length to get the torque. I hung a 25 lb weight from mine this morning and got the predicted 35 ft-lb result (25 x 17/12). My 35 year old wrench still works fine.
Hang a weight of known value in the midrange of the wrench's capacity. Multiply the weight times the lever arm length to get the torque. I hung a 25 lb weight from mine this morning and got the predicted 35 ft-lb result (25 x 17/12). My 35 year old wrench still works fine.
02-21-10, 12:55 PM
#45
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Absolutely positively wrong. The opposite is true. A lubricated thread will achieve higher bolt tension in relation to a given torque, because less of the torque will be lost to friction
think of screw threads as a ramp (inclined plane). The force required to push something up the ramp is a function of the slope of the ramp and the friction between the object and the ramp. Oiling threads is like using a hand cart to roll the crate up the ramp vs. trying to drag it up.
So to achieve a given screw tension, or holding power, you'd need to adjust a torque spec lower if lubing a thread, or higher if assembling dry.
Also once, you've tightened a screw to a given torque, it will not move tighter unless you go well beyond the original torque to break it loose. Going back to the crate on the ramp. While sliding it, it's fairly easy to keep it going, but if you stop to rest it'll require a goodly shove to get it going again. This is beacuse static friction is always higher than sliding friction, the difference can be significant depending on the specifics of the thread surface.
think of screw threads as a ramp (inclined plane). The force required to push something up the ramp is a function of the slope of the ramp and the friction between the object and the ramp. Oiling threads is like using a hand cart to roll the crate up the ramp vs. trying to drag it up.
So to achieve a given screw tension, or holding power, you'd need to adjust a torque spec lower if lubing a thread, or higher if assembling dry.
Also once, you've tightened a screw to a given torque, it will not move tighter unless you go well beyond the original torque to break it loose. Going back to the crate on the ramp. While sliding it, it's fairly easy to keep it going, but if you stop to rest it'll require a goodly shove to get it going again. This is beacuse static friction is always higher than sliding friction, the difference can be significant depending on the specifics of the thread surface.
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An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
FB
Chain-L site
An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
02-21-10, 01:58 PM
#46
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Want a torque wrench that's pretty damn accurate?
https://buy1.snapon.com/catalog/item....re&dir=catalog
(Guaranteed within +/- 1% accuracy)
Want to see if your torque wrench is "off"?
https://buy1.snapon.com/catalog/item....re&dir=catalog
https://buy1.snapon.com/catalog/item....re&dir=catalog
(Guaranteed within +/- 1% accuracy)
Want to see if your torque wrench is "off"?
https://buy1.snapon.com/catalog/item....re&dir=catalog
02-21-10, 03:37 PM
#47
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Thread Starter
Absolutely positively wrong. The opposite is true. A lubricated thread will achieve higher bolt tension in relation to a given torque, because less of the torque will be lost to friction
think of screw threads as a ramp (inclined plane). The force required to push something up the ramp is a function of the slope of the ramp and the friction between the object and the ramp. Oiling threads is like using a hand cart to roll the crate up the ramp vs. trying to drag it up.
So to achieve a given screw tension, or holding power, you'd need to adjust a torque spec lower if lubing a thread, or higher if assembling dry.
Also once, you've tightened a screw to a given torque, it will not move tighter unless you go well beyond the original torque to break it loose. Going back to the crate on the ramp. While sliding it, it's fairly easy to keep it going, but if you stop to rest it'll require a goodly shove to get it going again. This is beacuse static friction is always higher than sliding friction, the difference can be significant depending on the specifics of the thread surface.
think of screw threads as a ramp (inclined plane). The force required to push something up the ramp is a function of the slope of the ramp and the friction between the object and the ramp. Oiling threads is like using a hand cart to roll the crate up the ramp vs. trying to drag it up.
So to achieve a given screw tension, or holding power, you'd need to adjust a torque spec lower if lubing a thread, or higher if assembling dry.
Also once, you've tightened a screw to a given torque, it will not move tighter unless you go well beyond the original torque to break it loose. Going back to the crate on the ramp. While sliding it, it's fairly easy to keep it going, but if you stop to rest it'll require a goodly shove to get it going again. This is beacuse static friction is always higher than sliding friction, the difference can be significant depending on the specifics of the thread surface.
WRONG! I've been working on bikes that cost more than your car and *I* know what the **** I'm talking about. If you knew anything you'd know that this is wrong, like I know this is wrong. Obviously you don't know anything, because you obviously have never worked on a bike in your life. Why don't you die, Die, DIE! Do you have any more stupid questions that I can answer? and while you're at it spray some ****ing carbon spray on that bolt!
02-21-10, 03:39 PM
#48
Senior Member
Thread Starter
Get the **** over it already, seriously.
Yeah operator can be a ducebag[sic], but at least hes an experienced ****** who's opinions are actually worth hearing as opposed to yours.
If you think operators a hack mechanic don't listen to him, but seriously stop drudging this up
Yeah operator can be a ducebag[sic], but at least hes an experienced ****** who's opinions are actually worth hearing as opposed to yours.
If you think operators a hack mechanic don't listen to him, but seriously stop drudging this up
"******" by the way, just....er, trying to help you with your insults.
Edit: Ah buggah, they edited it out, let's try this - d.o.u.c.h.e.
Last edited by digger; 02-21-10 at 03:47 PM. Reason: Y'all edited out ******!