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[Nick W]

the cobalt bits  have a split point and a 135 degree point angle compared to normal 118 degrees.  they require less pressure.  i would always use a cobalt on a bolt but they can snap if abused even a little.

Whats the forum term?  Dangle Berries or something.  A drill bit is a drill bit.  That's all you need to know.

As a twist drill-bit is a complex cutting tool, that's a very rash thing to say. What I think you mean is that using a handheld drill motor to hack out a broken bolt negates a lot of the careful engineering that went into a good quality bit.

[omega2018]

the cobalt bits  have a split point and a 135 degree point angle compared to normal 118 degrees.  they require less pressure.  i would always use a cobalt on a bolt but they can snap if abused even a little.

Whats the forum term?  Dangle Berries or something.  A drill bit is a drill bit.  That's all you need to know.

Next we'll be having threads on buying Chrome Vandium spanners.   

you've obviously never used a cobalt drill bit

[aaronjb]

As a twist drill-bit is a complex cutting tool, that's a very rash thing to say. What I think you mean is that using a handheld drill motor to hack out a broken bolt negates a lot of the careful engineering that went into a good quality bit.

I never gave drills any thought until I started reading & learning about turning (as in lathes, but you knew that already).. when it's a little 1/4" drill spinning a ninety-billionty RPM in a hand held drill it looks very simple, but scale it up to a 1" or bigger drill bit in the tailstock and you stop and think about how it actually works, it's a miracle it ever works at all in that hand held drill

[ronnyd]

It,s always easier if it,s in either a pillar drill or the tailstock of a lathe. Hand held drilling is always likely to wander off. Well, mine is anyway.

[Marks DTM Calib]

I use a centre drill followed by various sizes working upwards, the key thing is reasonable pressure and make sure it keeps cutting so the metal does not work harden.

For me, I have to say that decent drills are much better, I have a few Dormers which are 10-15 years old and still going strong