My lathe chuck key broke!

[ARC-170]

Has this ever happened to anyone? The tip of my 1/4" lathe chuck key broke off. I've never abused it, just made it tight by hand. My lathe is 80 years old, so maybe the chuck key is as well and was at the end of its life?

 

[CJ5Dave]

Grind new flats, use it another 80 years.

 

[Dhal22]

 

[ARC-170]

Grind new flats, use it another 80 years.

That's the plan. I thought it might be interesting to post and see if this is common and if anyone had any insight as to why this might happen.

 

[mksj]

Not unexpected after many years of use, looks like the steel fractured, was pretty worn. Easy enough to make a new one. I have made a couple, most recently for a 10" chuck that needed a larger key for the scroll. Used some O1 rod, pretty simple to turn four flats and I turned down some O1 rod the T handle. The body was heat treated. The T handle is pinned with an allen set screw in the head in addition I knurl the T handle section that fits into the body, and then press it in (gives a nice rigid fit). Then blacken and oil.

 

[Ultradog MN]

Mine is 1/2".
It took about 12 minutes to weld a T on a no name socket extension.
Your 1/4" would be just as easy.

 

[fixit]

use a 1/4 inch drive tee handle and extension

 

[Ulma Doctor]

Thread 'Playtime With 304 Stainless'

Oct 20, 2017

I had an itch to scratch. a simple task but one that i wanted to do for awhile.
i wanted to make an extended lathe chuck wrench for my Hercus ARH Lathe.
the 3 jaw chuck is beautiful, but if the jaws are extended out,
you can bust a knuckle because of a short chuck wrench.
don't ask how i know this.....

i have lots of scrap 16mm 304 stainless steel axles, that i cut down and repurpose for projects like this

here is the perptrator,
a beautifully seductive 1976 Hercus ARH, named Shiela...

• Ulma Doctor
• 304 chuck wrench chuck wrench playtime with stainless ss chuck wrench ulma doctor
• Replies: 5
• Forum: ULMA DOCTOR

• 

 

[Chipper5783]

Has this ever happened to anyone? The tip of my 1/4" lathe chuck key broke off. I've never abused it, just made it tight by hand. My lathe is 80 years old, so maybe the chuck key is as well and was at the end of its life?

Kind of an old thread. To answer the two questions the OP asked - no and no. Metal does not break because it got old. Like the “steel became crystallized” remarks (yes, the day it was made). It broke because there was some sort of a flaw, whether the originally, due to abuse in the past 80 years (the OP has not owned it the whole time) or combination of issues. As the OP implied, a chuck does not need to be cranked down hard (like “tighter is better” - not in this case). Chuck keys are a pet peeve of mine - I hate seeing chuck keys with bent handles. I get most of my equipment as used (auctions and other usual sources) - chucks rarely come with the correct chuck key, if any at all. I think I have made ~15 keys, the type of material doesn’t really matter (not brass, not cast iron - most any steel), having it fit well is more to the point. My factory made chuck keys look like they are heat treated - probably a good thing, but the non-heat treated home made ones work great (in regular use for many years).

 

[Jake M]

Look at the damage- That's a hardened piece, it's fractured. Odds are it got damaged long ago, and the crack has been developing for some time, waiting for just the right time to do that.

With a key that small, I'm picturing a threaded chuck and a hammer.... But depending on how hardened it is or isn't, it couldda just been dropped on the floor the wrong way at some previous time.