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Why Me?

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gr8legs

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#3
I confess I'm not sure what I'm looking at . . . I'm guessing a dovetail cutter with replaceable inserts? What is it really?
 

darkzero

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#4
I see a broken tap also. Looks like there might be enough sticking out the bottom to grab hold of & back it out?
 

ddickey

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#5
I was making a dovetail cutter. Everything lined up nice.
Decided to drill all the way through but my chuck was butting up against the backside of the dovetail cutter. I was using a screw machine drill bit, 3/32". Almost got through, in fact I popped a little hole on the underside. Had to switch to a jobber length. As soon as I drove the bit down it broke. After I realized the y axis had moved .0005". Must've been just enough to cause it to break.
 

Hawkeye

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#6
If you can find a piece of metal that's stiff enough and will fit (even if forced a bit) through the little hole the tip of the bit opened up, you might be able to start the piece moving out. I'm thinking of something like music wire. Hobby shops carry it in small diameters. Cut a short piece and grind the end square. Hold it with a pair of vise-grips (Yes, there are valid uses for them.) and tap it into the hole. Might just pop it out.
 

darkzero

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#7
Well at least a broken drill is a bit better than a broken tap. :)
 

mikey

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#9
Why you? Because it was your turn! :(

Woe is he who thinks this just happens to some other guy. Welcome to the club, Duane!!
 

ddickey

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#10
I got it out with a punch.
Thanks for the suggestions.
 

TRX

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#11
Often if the back side of a through hole is at an angle instead of perpendicular, the drill or tap will break when they break through.

Er, I don't know this personally, you understand. A little bird told me. That's my story and I'm sticking to it. And it's worse with carbide than with HSS. [drops a shop rag casually over a small box on the bench]

You can often avoid broken taps or drills by making a small cut or spotface on the back where the tool will break through, so it come out on a perpendicular surface. Then there aren't any asymmetrical loads on the tool.
 

woodchucker

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#12
Often if the back side of a through hole is at an angle instead of perpendicular, the drill or tap will break when they break through.

Er, I don't know this personally, you understand. A little bird told me. That's my story and I'm sticking to it. And it's worse with carbide than with HSS. [drops a shop rag casually over a small box on the bench]

You can often avoid broken taps or drills by making a small cut or spotface on the back where the tool will break through, so it come out on a perpendicular surface. Then there aren't any asymmetrical loads on the tool.
, that advice is something I didn't know, and is the type of stuff that makes this site great. The experience of others for those of us that have not experienced it, or did not UNDERSTAND the problem when we did experience it. thanks
 

ddickey

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#13
Exactly.
Makes sense now why it broke.
Thanks much.
 
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