Correct way to use an impact driver?

I engage mine into the screw, twist it the direction I want it to go and use a 2lb hammer.

Me too...

Do not bottom out the spring, the cylinder needs to compress to work. Giving it a bit of pretension to get it seated and set in the direction it needs to move is OK.

Thomas Prufer

So its related to inertia. If there was no rotational movement after hammer impact , if the torsion spring had been precompressed, there would be less impulsive energy built up in a rotational sense to wang into the bolt head.

Umm. Internally the device is a male/female triangular shape. Engaging contact by the initial manual rotation, you determine which direction the rotational force imparts to your nut/bolt head. The force from your hammer blow is converted to rotational torque mostly felt by the nut/bolt although some must be lost at your hand/tool body contact.

I should have said momentum rather than inertia. Looks like I've been erroneously pushing and rotating impact drivers, doh! I suppose if a carpenters hammer fails and heating has failed and then its all or nothing, ie risking graunching the slot, then try a lump hammer. Then drilling with left hand drill and LH drill bit and so-called easy-out as next to last option.

Weld a nut on, pound a torx bit into a hex hole, EDM erode the easy-out you broke off, ...

or "Screw Doctor": "The original! The patented screwing aid for better screwing. Gives the tool "grip" and hold. All screws quickly solved - one drop is enough - for all screw types, even for bits."

It is also "Ecologically unconcerned"...*

Thomas Prufer

You may need to bottom out the sprint to place it in the "undo" position whilst applying anticlockwise tension.

But, yes, the spring should be extended whilst applying some anticlockwise tension before striking it with a hammer.