What is this tool?

[timbertime2]

It's a short straight blade screwdriver with hex head drive. With a knurled collar that spins and is threaded inside. It's an 1 1/4 long 1/2 diameter and the blade is 5/16 wide. No makers mark but is quality made.

 

[rustred]

the photo's are too fuzzy. looks like the ends on the A/C recharge units, but not saying thats what they are.

 

[zuhnc]

Anit-slip driver for an impact driver. The rotating collar one holds against the surface to prevent the bit from slipping out of the screw groove and marring your workpiece. zuhnc

 

[Janicholson]

Anit-slip driver for an impact driver. The rotating collar one holds against the surface to prevent the bit from slipping out of the screw groove and marring your workpiece. zuhnc

Yup. Jim

 

[Goose]

Anit-slip driver for an impact driver. The rotating collar one holds against the surface to prevent the bit from slipping out of the screw groove and marring your workpiece. zuhnc

I was going to say the same thing, except maybe just for a cordless drill.

 

[Keith True]

I have a couple of those I bought in the mid 70's while I was still working on cars.I bought them for adjusting carburators on running engines.Sometimes you could just hold the knurled part and turn it,Or,you could just use a socket and extension to reach under the bosses and protrusions on the carb.

 

[Caryc]

It could be an anti-slip collar or if you own a lawn mower that has carburetor screws that are hard to get at because your screw driver has to go through a hole in the frame before it contacts the screw, you need one of these. I made my own to adjust the screw while the mower is running. The outer collar goes through the hole and steadies the screw driver and holds it in the screw slot. It's almost impossible to get a regular screw driver on that screw while the engine is running. I saw a guy using one of these in his repair shop. The blade is about an eighth inch below the face of that collar.

 

[DoubleO7]

So why is the collar threaded inside if it is to just go over a screw head?