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Mike, Quote:
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Wow
I can not wait to see Allan's video example. He is completely correct and knows it. For many it will be very educational
The biggest problem is the poor formula for torque extensions. Allan's example in post #22 is no exeption. When converting, 12 inches is always used with ft/lb and 1 inch is always used with in/lb for "L" in the equation. This applies to all types of torque wrenches when using the indicated reading on the wrench. If the handle length is used the amount of neccessary force applied to the handle is calculated and would have to converted back to ft/lb's. George RV8 |
Spanner in the works
So, I have 2 foot long torque wrench but instead of pulling it at the handle, I decide to pull it in the middle 1 foot down its length.......will this alter the setting required.
It seems to me that a lot of intelligent people are getting themselves tied in knots trying to understand whats going on here. For Allans extension spanner to provide 100lbs/ft at the nut, it requires a certain pressure applied at the attachment point to the torque wrench. The amount of pressure will not change no matter how long the torque wrench is. What will vary is the amount of pressure applied by the operator to the torque wrench handle, and the amount of stroke required. Think about your joy sticks and the effect of varying their length. The loads on the control surfaces dont change, but the load you have to apply to the stick does vary, and the amount you have to move it. Your mileage and stick length may vary :D |
Ac 43.13-1B
Can someone show me how the formula in AC43.13-B figure 7-2 for the torque wrench adapter is wrong.
It dissagrees with using .8 as a constant. My torque wench manufacturer says the handle length is 22.57 inches and my extension is 3". If the formula from AC43 is used, 70.61lbs shoud be my setting on the wrench If the .8 constant is used, 64lbs should be my setting on the wrench. Thanks for your help Tim |
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-Jim |
Try this link
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Edit add: It turns out I might be wrong about part of this. A video linked from a later post seems to demonstrate that applying force to the middle of a torque wrench will disrupt its accuracy. However, it does not sway my conviction about the invalidity of the "0.8 correction factor." For a beam-style wrench, the indication will not be accurate if you apply force at any place except at the handle. The accuracy of the indication scale near the handle depends on the beam being loaded in simple bending by a force applied at the center of the handle. Most such wrenches have a rocking pivot built into the handle that ensures that the force is applied to the beam only at the correct point. Quote:
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A force is, well, a force, aplied at a point. Forces are measured in units like pounds or Newtons. A pressure is a force applied over an area. The air in your tires applies a pressure something like 30 lbs per square inch to the inner surface of the tire. A torque is the result of a force applied at some distance from an axis that causes bending or rotation. Torques are measured in in-lbs, ft-lbs, Newton-meters, and things like that. An inch-pound is the torque that results from a force of one pound applied at a distance of one inch from the axis. A Newton-meter is a force of one newton (there are nominally 9.8 newtons per kilogram) applied at a distance of one meter from the axis. You might ask, if the Metric system is decimal, why are there 9.8 Newtons per kilogram, and not ten? It's because the Newton is a measurement of force that is independent of the 9.8 meter-per-second^2 acceleration of gravity. But that might be the start of a discussion for a different day. Thanks, Bob K. |
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Thanks, Bob K. |
Totally Agree
Bob
I totally agree about the potential dire consequences, and forgive my poor choice of words, should have said force. I think the point I was trying to make is that there are a lot of opinions and calculations going on here which I suspect would cause more confusion. Also trying to put a light side on the thread. Bottom line is if you search the web there is usually a calculator set up to do the mathematics for you. |
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