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[grifter]

Hi what's the best drill bits anyone can recommend for drilling out threads. Is cobalt the name of the game for this?

[Andy B]

cobalt are harder drill, but if it's just AN Other bolt on your car, a reasonable HSS drill (not a set of 100 from the £ Shop  ) is good enough

[Kevin Wood]

Indeed. Remember, the harder it is, the worse it is to sort out if when it breaks off in the hole.

[omega2018]

bolt extractor/left handed drill bit, something like this www.ebay.co.uk/itm/311734242947

cobalt is the best for drilling any hardened steel but as mentioned more brittle so more likely to break

[Andy H]

Is it a bolt on an Omega?

[Broomies Mate]

Drilling is bit of an art.  You can't go in heavy handed, especially with hardened steel, or steel which has been hardened due to high temperatures.

Slow and steady.  Use less force than you would expect, let the bit do the work.

Start off small and work up.  It's easier to cut material away once a pilot has been drilled.


The amount of times I've seen 'mechanics' trying to drill out a 8mm threaded bolt with a 7mm drill bit in an air gun, leaning on the drill while it spins at 324348 gazillion RPM.  Just Dont Do It.

There really is no need to spend a fortune on drill-bits.  Even the cheapers end of the scale will perform just fine IF they are used correctly.

[grifter]

Is it a bolt on an Omega?

Nope, I'd been meaning to find out as it's something I come up against here and there.

[grifter]

Is it a bolt on an Omega?

Nope, I'd been meaning to find out as it's something I come up against here and there.

Usually give the drill tip a scoosh of oil now and again and don't lean on the drill permanently, let it off and on in short bursts.

[Viral_Jim]

Drilling is bit of an art.  You can't go in heavy handed, especially with hardened steel, or steel which has been hardened due to high temperatures.

Slow and steady.  Use less force than you would expect, let the bit do the work.

Start off small and work up.  It's easier to cut material away once a pilot has been drilled.


The amount of times I've seen 'mechanics' trying to drill out a 8mm threaded bolt with a 7mm drill bit in an air gun, leaning on the drill while it spins at 324348 gazillion RPM.  Just Dont Do It.

There really is no need to spend a fortune on drill-bits.  Even the cheapers end of the scale will perform just fine IF they are used correctly.

+1 to all of this. Top advice. I buy all my bits from toolstation and have never had a problem drilling out any bolts I've had to on cars. Usually do mine in 3-5 stages depending on the size of the bolt.

[Doctor Gollum]

Well that's summat learnt today... 

[Andy B]

Well that's summat learnt today... 

So have I 

...... some people buy their own drills 

[henryd]

Well that's summat learnt today... 

So have I 

...... some people buy their own drills 

Lol

[Andy B]

Well that's summat learnt today... 

So have I 

...... some people buy their own drills 

Lol

 

[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.

[Broomies Mate]

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.   

[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