Quote:
Originally Posted by Russell James
To do it right,
.........I'd rather not do 240 on one tooth with a screwdriver,
At 240 lb ft, I'm hanging off the tq wrench.
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I've often wondered about this, and maybe my mis-conception is in the size of tools I work with...
This is in no way a slam, and I intend no offense...
You are either a little guy, or the torque wrench is out of calibration, or something...
torque is rotational leverage...
ex: A 1' bar with ten pounds hanging on it = 10 ft lbs. A 2 foot bar with the same weight = 20 ft/lbs. etc... up to a four foot long torque wrench = 40 foot/lbs.
We typically use a four foot torque wrench for our small stuff, up to 600 ft/lbs. Yes, that is very small for us... I torque some bolts up to 55,000 and 60,000 ft/lbs.
Back to the subject... if you are hanging off the wrench for 240 ft/lbs, and your wrench is 2 feet long, then you either weigh less than 120 lbs, or you're not able to get any good leverage...
The floor hands on this and most any other rig fail to understand this and destroy many torque wrenches due to overloading them... We have to tighten riser dogs up to 600 ft/lbs. They perform this with a 4 foot long wrench... and it always ends up that they can't hear the click... and so two of them get on the end of the wrench and bounce it. Bouncing exponentially increases the force exerted, and their combined weight of 400+ lbs at the end of the wrench is already exerting 1600 ft/lbs...before the bounce.
How do I get them to understand this...
Suffice it to say that we spend huge amounts of money on torque wrenches, and I keep my personal use wrenches locked up at all times...
I waste my breath telling all the guys on the drill floor that I could care less if the damn thing clicks... I wish they would do away with the click device... Regardless of whether it clicks or not, if you have 120 lbs on the end of a two foot wrench, that is 240 ft/lbs. If you have 60 lbs on the end of a four foot wrench, that is 240 ft/lbs... or 80 lbs on a 3 foot wrench..... etc....
Where does all this go... Bear in mind your personal weight in reference to torquing a bolt...Measure the wrench... know your weight, and do not over torque stuff... Which is often going to lead to a more catastrophic failure when the bolt shears under load... Loose bolts back out over time, tight elongated stretched bolts fail suddenly... there goes the harmonic balancer through the hood across the highway and into another vehicle...
Over exagerrated the last but you get the point... wheel lugs and suspension items are just as susceptible...