What's this groove for on my chuck key?

[PaulR]

I'm making another key for the 4-jaw to speed up centering and I'm wondering what this groove is for? It's miles from the chuck when in use and I doubt it's decorative (it's made in China after all!).

Most likely irrelevant and I don't intend to duplicate it unless there's a good reason but it's really bugging me!

[Charles Lamont]

Might be intended to take the Annoying Spring. The one that means you absolutely can't leave the key in the chuck - or do anything else much.

[cnr6400]

Some chuck keys are supplied with a spring and collar as a safety device. The sprung collar prevents the chuck key being left engaged in the jaw screws, to prevent launching the key into low earth orbit (or the user) if the lathe was started with key in place. The collar is usually retained by a spring clip of some sort. The groove on your dark-coloured key may have been included so the makers could offer the key with or without the spring and collar. Hope this helps. 

[PaulR]

Might be intended to take the Annoying Spring. The one that means you absolutely can't leave the key in the chuck - or do anything else much.

Hmmm, it didn't come with a spring although the 3-jaw key did.

[PaulR]

Some chuck keys are supplied with a spring and collar as a safety device. The sprung collar prevents the chuck key being left engaged in the jaw screws, to prevent launching the key into low earth orbit (or the user) if the lathe was started with key in place. The collar is usually retained by a spring clip of some sort. The groove on your dark-coloured key may have been included so the makers could offer the key with or without the spring and collar. Hope this helps. 

Seems reasonable especially as Charles has the same idea. I definitely won't be replicating it then, those springs are as irritating as the plastic chuck guard (was)!

[redhouseluv]

I think you're right, I have a collecction of those 'Annoying Springs'

I bought a longer key and modified it to size as I found the short ones especially annoying when trying to use chucks mounted on a rotary table

[PaulR]

Finished this and considering it was all done by eye it's not bad - probably as much jiggle when it's in the chuck as the one I've copied.

Made a little widget to hold it in the vice to file opposite flats, hardened and tempered except the handle.

[redhouseluv]

Very nice, I like the widget, very simple, but functional!