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Old 09-10-10, 02:02 AM   #1
vantassell
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No more torque wrenches

So I finally got an old beam style torque wrench because the click type that I have scares me. The click type seem like they can go out of calibration quite easily. Anyway, I'm tightening a bolt on my seat post (manufacturer spec is 9 Nm) and my beam wrench barely reads any torque (maybe 0.5 Nm) and I feel like I've tightened the bolt at least 2 full rotations. It feels like the bolt head is starting to strip a little but I still haven't reached any relative torque (according to the beam wrench).

I start thinking about how I'm not registering much torque on the wrench, even though I know i'm putting a lot into it. I realize that I grease pretty much every bolt on my bike (finish line teflon grease), this is probably affecting every torque value on every bolt. I've heard that friction accounts for about 85%-90% of the torque value on a bolt, so adding grease to a bolt probably affects the proper torque spec by a ton. I think i'm just going to do "good-en-tight" from now on, even on carbon parts. Using a torque wrench on a greased bolt (since most of the bolts are 4-5mm I feel like they need grease) seems like you're just asking to over tighten something.

Anybody else think the same or different?
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Old 09-10-10, 02:30 AM   #2
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Originally Posted by vantassell View Post
So I finally got an old beam style torque wrench because the click type that I have scares me. The click type seem like they can go out of calibration quite easily. Anyway, I'm tightening a bolt on my seat post (manufacturer spec is 9 Nm) and my beam wrench barely reads any torque (maybe 0.5 Nm) and I feel like I've tightened the bolt at least 2 full rotations. It feels like the bolt head is starting to strip a little but I still haven't reached any relative torque (according to the beam wrench).

I start thinking about how I'm not registering much torque on the wrench, even though I know i'm putting a lot into it. I realize that I grease pretty much every bolt on my bike (finish line teflon grease), this is probably affecting every torque value on every bolt. I've heard that friction accounts for about 85%-90% of the torque value on a bolt, so adding grease to a bolt probably affects the proper torque spec by a ton. I think i'm just going to do "good-en-tight" from now on, even on carbon parts. Using a torque wrench on a greased bolt (since most of the bolts are 4-5mm I feel like they need grease) seems like you're just asking to over tighten something.

Anybody else think the same or different?
Pretty much exactly my thoughts.
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Old 09-10-10, 06:13 AM   #3
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Originally Posted by vantassell View Post
So I finally got an old beam style torque wrench because the click type that I have scares me. The click type seem like they can go out of calibration quite easily. Anyway, I'm tightening a bolt on my seat post (manufacturer spec is 9 Nm) and my beam wrench barely reads any torque (maybe 0.5 Nm) and I feel like I've tightened the bolt at least 2 full rotations. It feels like the bolt head is starting to strip a little but I still haven't reached any relative torque (according to the beam wrench).

I start thinking about how I'm not registering much torque on the wrench, even though I know i'm putting a lot into it. I realize that I grease pretty much every bolt on my bike (finish line teflon grease), this is probably affecting every torque value on every bolt. I've heard that friction accounts for about 85%-90% of the torque value on a bolt, so adding grease to a bolt probably affects the proper torque spec by a ton. I think i'm just going to do "good-en-tight" from now on, even on carbon parts. Using a torque wrench on a greased bolt (since most of the bolts are 4-5mm I feel like they need grease) seems like you're just asking to over tighten something.

Anybody else think the same or different?
What's the range on your torque wrench?
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Old 09-10-10, 07:27 AM   #4
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Torque values are always assumed dry, unless specified otherwise - reason, because lubrication affect the torque so much.................
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Old 09-10-10, 07:31 AM   #5
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if a torque value was specced for clean dry threads, the torque that achieves the same tension using lubricated threads will be lower. it's a pretty straightforward conversion and you can look up constants in table 1:

http://books.google.com/books?id=NaZ...page&q&f=false

however, TBH it sounds like you aren't reading the wrench properly?
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Old 09-10-10, 07:33 AM   #6
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Your fear of click torque wrench's is unfounded. Beam type are NOTORIOUSLY unreliable. They are not able to be re-calibrated. Click type can be re calibrated. FYI, all fasteners have a rated torque. As Wanderer said all specs are assumed dry unless specified by the manufacturer. I use a click type and have it re-calibrated once a year.
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Old 09-10-10, 07:47 AM   #7
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Originally Posted by kycycler View Post
Your fear of click torque wrench's is unfounded. Beam type are NOTORIOUSLY unreliable. They are not able to be re-calibrated. Click type can be re calibrated. FYI, all fasteners have a rated torque. As Wanderer said all specs are assumed dry unless specified by the manufacturer. I use a click type and have it re-calibrated once a year.
There is a reason beam type torque wrenches don't get periodically recalibrated. THEY NEVER NEED IT. The modulus of the beam material (usually steel) doesn't change over time so they don't change. The only cal they ever need is to make sure that the pointer is on zero with no torque. This is done by gently bending the pointer rod. Only needs to be done once when new, unless the tool is mishandled.
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Old 09-10-10, 07:49 AM   #8
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Originally Posted by kycycler View Post
Your fear of click torque wrench's is unfounded. Beam type are NOTORIOUSLY unreliable. They are not able to be re-calibrated. Click type can be re calibrated. FYI, all fasteners have a rated torque. As Wanderer said all specs are assumed dry unless specified by the manufacturer. I use a click type and have it re-calibrated once a year.
Beam types are totally reliable and never need calibration, as long as the pointer reads zero, while at rest. If not, then most have ability to adjust the scale so it does read zero. I've had the same beam wrench for 35 years and it still works fine.

The grease/lube issue has been discussed before. It would be stupid to list a dry torque value and then expect users to reduce that value by 25% or so, just because they lubed the threads. It's also stupid to assemble bikes parts with no lube on the threads, unless you want to insure problems when making a future adjustment or removing the part.

Personally, I never use a torque wrench on small M4-M6 bolts, but I've been wrenching on bikes for 25 years. I use a short handled hex wrench or a 4-5-6mm Y-style wrench.
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Old 09-10-10, 09:43 AM   #9
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Originally Posted by MudPie View Post
What's the range on your torque wrench?
0 Nm - 20 Nm

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Originally Posted by zzyzx_xyzzy View Post
if a torque value was specced for clean dry threads, the torque that achieves the same tension using lubricated threads will be lower. it's a pretty straightforward conversion and you can look up constants in table 1:

http://books.google.com/books?id=NaZ...page&q&f=false

however, TBH it sounds like you aren't reading the wrench properly?
Oh yeah, really straightforward

I don't think I could really mess up and missread a beam style torque wrench, slowly turn until the pointer moves to the value you want...

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Originally Posted by kycycler View Post
Your fear of click torque wrench's is unfounded. Beam type are NOTORIOUSLY unreliable. They are not able to be re-calibrated. Click type can be re calibrated.
That's the first time i've ever heard that beam type wrenches are unreliable. Why do you say they are unreliable? Does the steel change over the years? I've always heard that I can 'recalibrate' a beam style wrench by zeroing out the pointer when there's no torque on the head.

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Originally Posted by DaveSSS View Post
Beam types are totally reliable and never need calibration, as long as the pointer reads zero, while at rest. If not, then most have ability to adjust the scale so it does read zero. I've had the same beam wrench for 35 years and it still works fine.

The grease/lube issue has been discussed before. It would be stupid to list a dry torque value and then expect users to reduce that value by 25% or so, just because they lubed the threads. It's also stupid to assemble bikes parts with no lube on the threads, unless you want to insure problems when making a future adjustment or removing the part.

Personally, I never use a torque wrench on small M4-M6 bolts, but I've been wrenching on bikes for 25 years. I use a short handled hex wrench or a 4-5-6mm Y-style wrench.
I feel the same way, on bolts that small I feel like they need lube to avoid problems. And if you're lubing them, you can't use a torque wrench. I've always heard that if you're using a Y-style tri-allen that you have to really try to over torque something because the wrench doesn't give you that much leverage.

Working on my car, I don't lube any of the bolts (ok, I do put anti-seize on the spark plugs) because the smallest ones there are 10 mm. I feel like on a big 10mm (relatively big compared to 4-6mm bike bolts) that even if it does get a little rusted/corroded/stuck that I won't easily snap the bolt like I would on a bike. Since I don't lube, I feel ok using a torque wrench on it (since torque ratings are for dry threads)
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Old 09-10-10, 10:24 AM   #10
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I don't think I could really mess up and missread a beam style torque wrench, slowly turn until the pointer moves to the value you want...
Not saying that you're doing this, but a common mistake with bean torque wrenches is having the beam rub on the gauge because you're pulling out or pushing in. They're remarkably easy to "misread" like this. I would imagine in a low torque application this could have very large ramifications (from a % error standpoint).
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Old 09-10-10, 10:29 AM   #11
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If beam type wrenches are so accurate how come the FAA will not let them be used on aircraft? FYI I am a licensed A&P mechanic.
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Old 09-10-10, 10:30 AM   #12
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Did you get a 1/4" drive small torque wrench , for the 5nm fasteners, or this using a 3/8 drive wrench?
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Old 09-10-10, 10:45 AM   #13
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Not saying that you're doing this, but a common mistake with bean torque wrenches is having the beam rub on the gauge because you're pulling out or pushing in. They're remarkably easy to "misread" like this. I would imagine in a low torque application this could have very large ramifications (from a % error standpoint).
Oh ok, that makes sense. I don't think that was the case here, I had plenty of room to work with and looked and saw the pointer being free to move (not rubbing on the scale or anything).

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If beam type wrenches are so accurate how come the FAA will not let them be used on aircraft? FYI I am a licensed A&P mechanic.
I don't know why the FAA doesn't allow them to be used on aircraft, I'm not an A&P licensed mechanic. Why aren't they allowed?

My guess would be that it's too easy to not be able to see, or not pay attention to, the scale while torquing.
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Old 09-10-10, 12:38 PM   #14
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http://en.wikipedia.org/wiki/Torque_..._between_types

Parallax error (viewing the gauge from any angle other than perpendicular) can result in a loss of accuracy.
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Old 09-10-10, 01:22 PM   #15
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I don't know why the FAA doesn't allow them to be used on aircraft, I'm not an A&P licensed mechanic. Why aren't they allowed?

My guess would be that it's too easy to not be able to see, or not pay attention to, the scale while torquing.
Because over time, they do go out of whack regardless of what people here have said. I have a 30 year old 1/2" wrench that is almost 12lbs off at 100ft-lbs and reads zero at rest. Metals fatigue and eventually, beam wrenches will not be accurate with no way to correct the errors.
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Old 09-10-10, 01:30 PM   #16
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Because over time, they do go out of whack regardless of what people here have said. I have a 30 year old 1/2" wrench that is almost 12lbs off at 100ft-lbs and reads zero at rest. Metals fatigue and eventually, beam wrenches will not be accurate with no way to correct the errors.
The FAA doesn't allow beam type wrenches because using them in tight quarters prevents them from being read properly and they also require much more attentive use whereas a click-type wrench gives a positive feedback on every single use and with the requisite calibration programs that airplane mechanics use, loss of accuracy in a click-type wrench is not an issue.
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Old 09-10-10, 01:46 PM   #17
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Just Googled to find out approximately how much it would cost to have a click type torque wrench calibrated. The first one I came to charges $35 to calibrate the small ones that would be used for bikes. That is a lot of coin for a garage mechanic to shell out annually for working on his own bikes, not to mention the bother and expense to pack and ship and of course remembering to do it. With my luck, the week it was gone for cal is when I would need it the most. For a professional aviation mechanic it obviously makes sense. You may be able to have yours calibrated in the same batch as your shop so it would be easier and possibly even cheaper.
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Old 09-10-10, 02:25 PM   #18
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For a simpler version of the torque adjustments needed for dry vs. lubricated bolts, here is a useful chart. It isn't perfect, of course, and different types of hardware may specify higher or lower torques than these for the same size bolt, but it is a good place to start if you don't have any other information: http://www.cncexpo.com/MetricBoltTorque.aspx

-Sam
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Old 09-10-10, 03:20 PM   #19
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I trust my fingers, calibrated over years of wrenching. I know I have done more damage trying to make the wrench read the right number while my spidey sense is screaming "to tight!"
By nature I am an undertorquer so the worst I see is an occasional seat slip.

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Old 09-10-10, 03:23 PM   #20
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Originally Posted by kycycler View Post
Your fear of click torque wrench's is unfounded. Beam type are NOTORIOUSLY unreliable. They are not able to be re-calibrated. Click type can be re calibrated. FYI, all fasteners have a rated torque. As Wanderer said all specs are assumed dry unless specified by the manufacturer. I use a click type and have it re-calibrated once a year.
Beam type are very reliable and all that is necessary to recalibrate is to bend the pointer back to center.
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Old 09-11-10, 06:49 AM   #21
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Torque values are always assumed dry, unless specified otherwise - reason, because lubrication affect the torque so much.................
Says who?
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Old 09-11-10, 08:13 AM   #22
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Because over time, they do go out of whack regardless of what people here have said. I have a 30 year old 1/2" wrench that is almost 12lbs off at 100ft-lbs and reads zero at rest. Metals fatigue and eventually, beam wrenches will not be accurate with no way to correct the errors.
So you're saying fatigue (without going into and/or beyond yield) causes a change in modulus for the beam?
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Old 09-11-10, 08:34 AM   #23
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Because over time, they do go out of whack regardless of what people here have said. I have a 30 year old 1/2" wrench that is almost 12lbs off at 100ft-lbs and reads zero at rest. Metals fatigue and eventually, beam wrenches will not be accurate with no way to correct the errors.
What did you calibrate your wrench against?
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Old 09-11-10, 08:45 AM   #24
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everyone up to speed on FSA's 2010 torque application bulletin? take a read...... torque theory and application from Full Speed Ahead from March of this year, its in their tech docs as a PDF.

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Stop when the component does not rotate under load.
simply feathery.
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Old 09-11-10, 08:53 AM   #25
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So you're saying fatigue (without going into and/or beyond yield) causes a change in modulus for the beam?
the beam would have to be flexed many many many times for the spring rate to change. a properly designed wrench will not go beyond yield anyways. sturtevant makes the best beam torque wrenchs
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