Ever See A Drill Break?

[TommyD]

I saw the damnest thing the other day, a group in school here were making a project using heim joints. The school doesn't have drills over 1/2" dia and they needed, not remembering exactly, a 11/16ish drill to tap threads. A student has his dad borrow said drill from, I guess, work. They placed it on our Do-all saw table where it promptly rolled off, hit the floor.... AND BROKE IN HALF! I have dropped larger drills all my life and all they ever did was bounce with a nice, metallic DIIING! My jaw dropped, how brittle was this thing? I didn't see the name on it but reading the file thread got me wondering.

Anyone?

 

[John Hasler]

Carbide?

 

[kd4gij]

Sounds like it was a carbide drill. Check it with a magnet Or some one tried to harden it and got it to hot and didn't draw it back.

 

[TommyD]

Nah, it wasn't carbide. I know carbide and for it's size and if it were carbide it would have been a LOT heavier.

 

[kd4gij]

Some one probably tried to harden it and didn't draw it back then. Where I used to work we used a lot of A2 tool steel and had an oven to harden it. I have seen parts shatter when dropped before they where put back in the oven to draw them back.

 

[TommyD]

It just amazed me, I have NEVER seen a drill break like that. I felt bad for the kid, not the 'owner', who put it on the table, I told him it was a freak but he bought the kid another drill bit to replace it.

 

[Ulma Doctor]

i haven't seen a drill bit break like that,
but i had one of my grandfather's old school cold chisels fall from the bench one co;d morning and break in the same fashion.
i loved that chisel ,
it held an edge forever even in rough duty. it was very hard tool steel.

 

[Silverbullet]

With me it's always a tap , yupp pull it out of the box new no less and old fumble fingers thinks it in the tap wrench tight . Nope pick it up turn it put the tap in the hole and twang on the floor in two or three pieces.

 

[Andre]

Probably a preexisting stress fracture. Taps so the same thing, as stated above.

 

[cascao]

This happened with me once.
I was a relatively new 13mm Dormer MT02 drill.