LBS and Torque Wrench

[slowmotion]

Unfortunately you can't assume that. Firstly, the torque to undo something (a properly greased something anyway) is almost certainly less and, more pertinently, drops off very rapidly indeed once movement starts (try that, undoing with a torque wrench). .

I can see that the forces required during the process of undoing are not going to be the same as those that were required during the tightening operation, but I still think that the two forces will be very similar at the point at which the screw actually "breaks away" and untightens. I'll be reunited with my torque wrenches in a few days and will try a couple of simple tests.

 

[Pat "5mph"]

I made a light-hearted joke with him about it and he says he never uses one and knows exactly what 4Nm feels like.

I do trust the mechanic in this, because I know what 140 Celsius feel like just by touching the milk jug, I know when a food is above 63C by touch, I know when a fridge is below 5C just by opening it.
I have confirmed this knowledge many times at work by checking with calibrated thermometers.
I have also tightened crank arms without torque wrench (got one now), go tit checked by a mechanic, he said I was spot on
What I'm saying is if you do routine jobs at work, after years of doing them you know stuff by feel - not the crank arms in my case, that was just a fluke

 

[minininjarob]

Unfortunately the torque wrenches and torque values that are bandied round the cycling world nowadays I think are just a way of manufacturers getting out of warranty claims. The torque wrenches sold to the cycling public are cheap things, inaccurate and are nothing like the sort of torque wrench you'll see a decent engineer using. My father was an industrial engineer all his life and laughed at torque values for bike stuff. Correct torque depends on so much, the type of fastening, the lubrication, the type of metal used, the thread pitch. ALso the TR's need calibrating, you can't drop them or they go out of calibration. So picking up your £30 TR and tightening to 10Nm means absolutely nothing.
Much better to have a good feel for components and your tools. A good rule is that your controls only need tightening until they don't slip in normal use.
In the OP if the mechanic tightened the post just enough to stop it moving when you were riding it then it was perfect. In that way if you crash things are likely to move rather than snap or bend. Seatposts/brake lever/gear levers/stem can all be treated this way.
I am so thankful my father taught me how to use tools properly. Yes I broke stuff when I was a kid but I was an idiot.
All you need are quality tools and an understanding and sympathy of how mechanical things work.

Oh, and a Park workstand, I should have bought one of those 20 years ago.

 

[rogerzilla]

Torque wrenches aren't a panacea. The clamping force varies massively depending on lubrication, cleanliness of threads and whether the fastener has been used before (a new bolt in a new thread will have some extra surface roughness).

I would only use a torque wrench for a clean and greased/oiled fastener that had previously been fitted and removed.

 

[screenman]

I do trust the mechanic in this, because I know what 140 Celsius feel like just by touching the milk jug, I know when a food is above 63C by touch, I know when a fridge is below 5C just by opening it.
I have confirmed this knowledge many times at work by checking with calibrated thermometers.
I have also tightened crank arms without torque wrench (got one now), go tit checked by a mechanic, he said I was spot on
What I'm saying is if you do routine jobs at work, after years of doing them you know stuff by feel - not the crank arms in my case, that was just a fluke

You might want to proof read that lot

 

[Pat "5mph"]

You might want to proof read that lot

LOL I meant Fahrenheit, too many long shifts is my excuse.

 

[Heltor Chasca]

I was taught NOT to use a torque wrench to undo or loosen fittings. What do you think?

 

[DRM]

If you are earning a living mending bikes, then the comment that you know what a certain torque feels like wouldn’t stand up in court in the event of a failure that caused an injury, anyone that is in this line of work needs to cover their back.

 

[DCBassman]

I was taught NOT to use a torque wrench to undo or loosen fittings. What do you think?

Because there's no point to it, and the wrench isn't designed for that anyhow. They are for tightening.

 

[DRM]

Torque wrenches aren't a panacea. The clamping force varies massively depending on lubrication, cleanliness of threads and whether the fastener has been used before (a new bolt in a new thread will have some extra surface roughness).

I would only use a torque wrench for a clean and greased/oiled fastener that had previously been fitted and removed.

So you would advocate reusing cylinder head bolts when the manual says not to due to them stretching

 

[Heltor Chasca]

Because there's no point to it, and the wrench isn't designed for that anyhow. They are for tightening.

Thank you. If you do, will it be damaged?

 

[DCBassman]

Depends on the wrench. Some, certainly.

 

[DCBassman]

So you would advocate reusing cylinder head bolts when the manual says not to due to them stretching

I may be out of date here, but, after using all new bolts for your cylinder head, weren't you supposed to recheck the torque after a certain amount of time? So the point is valid.

 

[rogerzilla]

So you would advocate reusing cylinder head bolts when the manual says not to due to them stretching

We're talking about bikes here, which don't use stretch bolts or angle-tightened bolts. But thank you for playing.

 

[screenman]

LOL I meant Fahrenheit, too many long shifts is my excuse.

Try again.