Torque wrench question

[TooLy]

Hi,

I got a click style torque ratchet.
The manufacturer manual says to use it only for tightening, never for opening or it will damage.
Why it will damage ? I ask this because the it has direction selector so I can choose sides. (Maybe they just installed the ratchet mechanism for comfort while tightening?)

Second, if I don't have the torque table for some bolts, can I open them with my torque ratchet and measure roughly the torque for tightening?
Or if it's bad to open with it, can I try and tight the bolt a little bit more (before I open it) until I find the torque I can still tight it slightly and that will be roughly the closing torque ?

Thanks,
Roei

 

[blackrodd]

I help a mate out sometimes, tractor engine overhauls, welding etc, he tells me, The torque wrench goes both ways for the odd occasion of a left hand thread.
And Heaving to undo nuts etc will just break the mechanism, as tempting as it may be for those really big nuts and bolts use an 1" square drive, it's built for it, tractors, lorries and plant.
Regards Rodders

 

[CHJ]

When tightening you stop the levering when the 'ratchet' snaps, You do not continue to apply excessive pressure against the rotational stops.

If used for Undoing a seized nut and the ratchet snaps there is a temptation to continue applying extra load using the mechanical rotational stop and long handle leverage which could damage the head mechanism.

 

[n0legs]

Try one of these when undoing a bolt set at an unknown torque. Not 100% but it will get you close.
http://draper.thetoolstoredirect.co.uk/ ... 40x640.jpg

It will save you damaging the mechanism in your torque wench.

I use Torque Leader screwdrivers and they are not to be used to find the torque setting of a fixing. If in doubt BFT it :lol:

 

[TooLy]

When tightening you stop the levering when the 'ratchet' snaps, You do not continue to apply excessive pressure against the rotational stops.

If used for Undoing a seized nut and the ratchet snaps there is a temptation to continue applying extra load using the mechanical rotational stop and long handle leverage which could damage the head mechanism.

But what if I won't exceed my torque wrench max limit ?

 

[CHJ]

When tightening you stop the levering when the 'ratchet' snaps, You do not continue to apply excessive pressure against the rotational stops.

If used for Undoing a seized nut and the ratchet snaps there is a temptation to continue applying extra load using the mechanical rotational stop and long handle leverage which could damage the head mechanism.

But what if I won't exceed my torque wrench max limit ?

As long as it is the tool that is making the decision on the tools max loading and not you.

As long as you use the torque ratchet and stop when the 'ratchet' snaps and don't continue applying pressure against the mechanical stop it will be OK.

 

[Duncan A]

The comments above all make good sense but there are a couple of other points you ought to consider:
1. Even if you do use the torque wrench to undo the bolt, the loosening torque would would be extremely unreliable as a guide to the tightening torque due to stiction, galling, corrosion etc.
2. Some applications require a particular torque to preload a bolt, or to avoid distorting or damaging a component, but if you're just tightening fairly basic stuff, there are standard max torque tables on the internet for various bolt sizes, material grades, and coatings. These may be helpful although you rarely need to go to the maximum.
3. Even if you are using the correct value from instruction manuals, it is pretty meaningless without knowing what sort of thread lubricant to use because it can make a big difference to the resulting stretch to which the bolt is subjected for a given torque. Even where to put the lubricant can be critical since if it gets under a bolt or nut head it can a massive difference (reduced friction).
4. In short, if you don't know the correct torquing procedure, do it very carefully!

Duncan

 

[JimB]

It's a bad habit to get into and, like most bad habits, sooner or later you go too far. :wink:

 

[TooLy]

I emailed the torque wrench support and asked them about the reverse direction selector.
They answered:
"Do not use the torque wrench in reverse or apply any pressure in reverse. This reverse feature is there for some users who may need it to locate the torque wrench in the correct orientation for clockwise torque application & you do not have to use it if you do not want to"

From this answer I can only understand the ratchet mechanism to the right side/clockwise, but still can't think on application/use that require me to change direction, that will open my bolt/nut.

 

[Downwindtracker2]

The click type torque wrench can be off. Maybe some one left it set, instead of backing it off, stretching the spring. I've had to buy ever more expensive torque wrenches over the years. I'm up to Snap-On quality now. However checking it is pretty easy, a $5 ex-rental beam torque wrench.