Best metal for a chuck wrench?

[MrWhoopee]

Aren't Grade 8 bolts surface hardened?

No, grade 8 bolts are equivalent to 4140HT at 150 ksi tensile strength.

 

[MikeInOr]

No, grade 8 bolts are equivalent to 4140HT at 150 ksi tensile strength.

It still seems to me like hardening the nub on the end of the chuck key would be a good idea considering all the broken and messed up home made chuck keys. No?

 

[MrWhoopee]

It still seems to me like hardening the nub on the end of the chuck key would be a good idea considering all the broken and messed up home made chuck keys. No?

Depends on what the next weakest link is and whether you want it to fail.
I'm shocked by the failure of that Grade 8 chuck key, particularly without the use of a cheater. Makes me think it may not have been up to spec. It was twisted quite a bit before it failed, some Armstrong going on there.

 

[benmychree]

4140 HT is heat treated to about 32 Rockwell C, and holds up well for chuck wrenches. Grade 8 bolts are through hardened; I was going to test one for hardness, but was not able to find one ---

 

[jmkasunich]

Surprised no one has mentioned drill rod. I've made chuck keys from drill rod and hardened them with propane torch and a quick quench.

 

[KevinM]

Surprised no one has mentioned drill rod. I've made chuck keys from drill rod and hardened them with propane torch and a quick quench.

That is my go-to metal for tools. Harden then temper in the oven, sometimes hardening just the "tip". O1 is pretty tough stuff without hardening.

 

[Ultradog MN]

Compared to some of you I don't know whether to be ashamed of mine or proud of being resourceful.
When I got my lathe it came with 3 chucks and 3 chuck wrenches - none of which fit the chucks or cam lock.
So when I got the machine installed and powered up I wanted SOMETHING to chuck up a piece of metal. I discovered a 1/2" socket extension fit just right.
So I knocked the handle out of one the three that didn't fit and welded it onto a China Maid extension I had in a junk drawer.
One of these days I will mill down the flats on one of the other chuck wrenches and make a nicer one. Till then this one is doing the job.

 

[main_cogg]

Compared to some of you I don't know whether to be ashamed of mine or proud of being resourceful.
When I got my lathe it came with 3 chucks and 3 chuck wrenches - none of which fit the chucks or cam lock.
So when I got the machine installed and powered up I wanted SOMETHING to chuck up a piece of metal. I discovered a 1/2" socket extension fit just right.
So I knocked the handle out of one the three that didn't fit and welded it onto a China Maid extension I had in a junk drawer.
One of these days I will mill down the flats on one of the other chuck wrenches and make a nicer one. Till then this one is doing the job.

I wish mine were a standard extension size, I would have done the same thing and called it a day.

 

[Tozguy]

Compared to some of you I don't know whether to be ashamed of mine or proud of being resourceful.

The latter.

 

[Shotgun]

So I knocked the handle out of one the three that didn't fit and welded it onto a China Maid extension I had in a junk drawer.

I've done the same, except for using a 1/4" extension on my Craftsman 12x36. Instead of welding on a handle, I just use the ratchet. I keep thinking about welding on a handle. If ever do, I'll weld on hex stock that fits my carriage lock bolt, and broach a square hole in the other end that will fit the compound slides rotation lock down bolts.