Why do I keep breaking flexible drill bits?

Old 05-10-17, 12:37 PM
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Why do I keep breaking flexible drill bits?

Hi, I have a tool that I think is called a flexible drill bit, of flexible drill/chuck extender. It's used to screw or drill using a power drill in difficult spots where the drill itself won't reach. It can bend and get around corners.

This is the second one I've purchased that I've ended up irreparably bending. What am I doing wrong? I was using this to screw into a piece of wood, and I guess I applied so much torque that it's now bent into a new shape, and I can't fix it!

It looks like it's made of a flexible spring that's wrapped in a thick metal coil. I guess I somehow over-twisted it.

Can it be fixed? I've tried to just twist it this way and that, to rotate it while holding one end or the other. But I can't get it straight again. And in this twisted state, it doesn't rotate very well anymore.

Any advice?

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Old 05-10-17, 01:53 PM
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The flexible shaft is 2 concentric pieces of metal where the inner metal piece rotates within the fixed outer metal piece while the shaft is being positioned from a straight line If the positioning from a straight line is too severe the inner or outer or both metal pieces stretch and won’t go back to a straight line. I would think the manufacturer would state a minimum bend radius or maximum bend angle on the packaging. If not, you have to figure it out on your own. Since this is your second device. You have some experience to call upon.
Old 05-10-17, 02:08 PM
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If it's any help, I do all kinds of drilling and have never owned a flexible bit.
For tight spots I use a right angle drill and various stubby bits and various length bit holders.

I especially like to use spade bits with a locking holder/extension.
Old 05-10-17, 03:20 PM
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I have found that they only work for light duty stuff, Anything heavy they end up like yours.
Old 05-10-17, 03:27 PM
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Also Milwaukee makes a right angle driver bit that is more durable than your flexible one. It obviously has a limit to how much torque it can handle.
Old 05-10-17, 03:40 PM
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I too have had those and they are very light duty and can not take the forces a drill can generate.
It is only a small flexible cable inside it like a speedometer cable or a cable on a curved string trimmer.
Old 05-11-17, 11:59 AM
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Thank you for the detailed info and suggestions. It does seem like I applied too much torque at too sharp an angle. If it did come with documentation, I've long since lost it. There's probably no way to fix it now, eh?
I'll look into some bit extenders and right angle equipment for next time.

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