dougie wrote:I do like the fact that it can go in line with the torque wrench. Makes the calculation easy
Actually, being in-line with the torque wrench axis requires a recalculation of the reading in order to get the proper end torque at the bolt. Having it 90 degrees to the torque wrench requires no recalculation...now that's easy!
Kurt in S.A
Watch out Kurt - Stephen will beat on you with a physics book!
I find using it inline with the torque wrench less clumsy (just me?), and at exactly 2" the re-calc was easy. 40Nm = 35Nm (34.9Nm).
I've spent most of my money on women, motorcycles, and beer.
The rest of it I just wasted.
dougie wrote:Watch out Kurt - Stephen will beat on you with a physics book!
I find using it inline with the torque wrench less clumsy (just me?), and at exactly 2" the re-calc was easy. 40Nm = 35Nm (34.9Nm).
Let him beat away...a 90 degree join on the torque wrench means no recalculation is necessary, which is as easy as it gets. But, maybe in your case, you have the calcualtion prefigured which makes things easy. But a straight extension (ie, increasing the distance from the wrench handle to the actual bolt/nut) does require some kind of recalculation.
Kurt in S.A. wrote:...But a straight extension (ie, increasing the distance from the wrench handle to the actual bolt/nut) does require some kind of recalculation...
Kurt in S.A.
Sure does Kurt. Good observation, few think of this...
1971 R75/5 (SWB) If you're going to hire MACHETE to kill the bad guy, you better make damn sure the bad guy isn't YOU!
I bought one off E-Bay (not cycleworks) that looked like yours. You should try yours out. The one I got deformed and stripped on the first bolt. I returned it.
I've spent most of my money on women, motorcycles, and beer.
The rest of it I just wasted.
Actually 90 degrees is not exactly the same as no extension. I haven't calculated it for my wrench, but the angle has to be such that the distance from the wrench handle pivot to the bolt is the same as the distance from the handle pivot to the driver on the wrench. The angle between the wrench and extension will always be some less than 90 degrees. It varies with the length of the wrench being used with the extension.
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George Ryals wrote:Actually 90 degrees is not exactly the same as no extension. I haven't calculated it for my wrench, but the angle has to be such that the distance from the wrench handle pivot to the bolt is the same as the distance from the handle pivot to the driver on the wrench. The angle between the wrench and extension will always be some less than 90 degrees. It varies with the length of the wrench being used with the extension.
I wasn't going to say anything George, for I thought that was not how I recalled it either and I certainly could not reconcile it in my mind when I read it. Besides, since my brain often fails on such things (discard this knowledge when "cramming in" that...) I keep all of those (and plenty of other things I might confuse) on a card taped in the top of my tool chest. I don't recall any of them being too hard to calculate; I'm sure I did them either in my head or on scratch paper in the lab, but that has been a while for me... I'm sure Google should have all of them (I would like to hope at least; if not, what is this World coming to???)
1971 R75/5 (SWB) If you're going to hire MACHETE to kill the bad guy, you better make damn sure the bad guy isn't YOU!
Funny, we went through this on the old version of the forum...guess no one was convinced before...likely won't again!
It's not the direct distance from hand pivot to the bolt, but the perpendicular distance between the line of action at the hand pivot and the bolt. Engineering equations state that for a 90 degree extension at the drive head of the torque wrench results in the perpendicular distance of the line of action and the bolt to be identical to the length of the torque wrench (hand pivot point to the working end of the wrench). Thus, no adjustment is needed in the applied torque...it will equal exactly what the wrench indicates. The torque is Force * Distance where the distance is the perpendicular distance of the line of action.
For an extension that is directly in line with the axis of the wrench (ie, 0 degrees), the line of action is moved farther away from the bolt being torqued. However, the wrench only reads the torque being applied at the end of the wrench, not at the end of the extension. Thus, the torque read by the wrench will always be lower than what is actually applied. That is why it was said that if you want 40nm at the bolt, then shoot for 35nm on the wrench's dial or indicator. This correction value depends on the length of the torque wrench and the length of the extension.
As the extension is rotated from the 0 degree orientation to the 90 degree orientation, the amount of "correction" is reduced until it becomes no correction at the 90 degree position.
That's the engineering facts. Many websites will compute the numbers for you.
