Nut-Busting Torque?

The longer the lever arm the less force needed. (move the earth with a long enough lever)
Not sure how this is laid out, using a fulcrum and its location etc.

To lift 300 lb load with a 3 ft lever arm would take 100 lb of force.
A 300 ft lever would take 1 lb of force
Ever put a "cheater bar" on a wrench?

How is this laid out?

 

"Nut busting" is a marketing term not a scientific one,. It is a double entendre.
The straight man marketer's meaning is the tool will break loose a nut that's rusted in place, or is so tight and located such that you simply can't get a tight enough grip on the whole assembly to keep it from turning when you apply torque. Example of latter is the nut on an automobile alternator pulley.... the whole shaft just spins.
The wise guy marketer's second meaning involves a pun, search on 'scrotal hernia' .

The impact wrench applies torque in short impulses so that the inertia of the assembly keeps it from rotating, rather like striking the end of a regular wrench with a hammer.
So - that 1100 ft-lb number is not the constant torque you'll need for lifting.
Nobody could hold a hand tool producing that much constant torque.

How far and how fast do you need to lift that 300 lbs?

around twenty five bucks

 

An impact wrench produces a torque impulse like a hammer does in a straight line. The impact is for a very short period of time. Each impact is capable of breaking the friction between the nut and the thread. Once started the nut spins off rapidly with very little force or impact being required. “Nut busting” is an advertising term that describes the force available to start the nut moving. An impact wrench can turn backwards in the time between impacts, so it won't work to turn a long lever arm.

 

How are you going to hold the impact driver once the load starts to rise. There will be 900 ft.lbs on the handle continuously.
Maybe you need to use a gearbox mounted on a solid base, a boat winch or a chain block. Some small lifting arms for vehicles use a hydraulic ram.
How often will you need to lift it? Why?

 

Unfortunately your design will probably not work for a number of reasons.

(A). The torque / time characteristics of a cordless impact driver will not provide a sustained torque of 3 ft * 300 lbs = 900 ft.lbs.
(B). The impact driver mounting will be torn off the table by the continuous 900 ft.lbs, with or without the added impact.
(C). The device overhangs the edge of the table, the table will probably overturn.

There are many different solutions available. Choice of the best method will depend on why you really need to do this?

 

No.

 

That seems to me like asking a woodpecker to push over a tree.
You need an elephant.

 

That to overcome gravity you need constant torque not just brief pulses of it.

 

You'd do well to try out an impact wrench. It'll give you an intuitive feel for "impulse", and you'll see why i picked the 'woodpecker' analogy.
http://en.wikipedia.org/wiki/Impulse_(physics)
Thanks for the kind words. We all come here to learn.