Cobalt drill bits??

[EricP]

Just flicked through QVC and found "Cobalt" drill bits.

Drill anything including glass and with a 10 year guarantee. (Worthless)

Pro opinion on them for a laugh?

[John Rumm]

Next step up the hardness ladder from HSS, so not in the solid carbide league, but will still hack things that HSS won't

Some info here:

[The Medway Handyman]

Only thing I've found that are effective on stainless steel. Those gold coloured titanium coated jobbys won't hack stainless.

I carry a set on the van for those 'difficult' jobs.

[Sylvain VAN DER WALDE]

I'm glad that you didn't get a laugh, as I bought the very ones. I haven't used them yet, though.

Sylvain.

>

[fred]

In article , EricP writes

They're the bee's pyjamas.

Had lots of deep 6mm drilling to do in steel and they were the only ones that could hack it, continuous waste spirals all the way.

[EricP]

[EricP]

When you do, a report would be interesting. Having been bitten by QVC in the past, I treat their claims with some caution. :)

[EricP]

As good a recommendation as comes. :))

[EricP]

reinforced concrete and having yet another masonry drill bit tip drop off. :)

[Owain]

The Zilo smellkiller didn't?

I've always been happy with QVC. A friend was very pleased with her rosebush as a housewarming present.

Owain

[The Medway Handyman]

Not at all sure cobalt are suitable for reinforced concrete, unless you mean drilling just through the rebar with the cobalt drills?

If the plan is to drill concrete & rebar try these

fantastic drill bits, work well without hammer action on masonry & cope with steel, wood, concrete etc.

[meow2222]

I'm wondering exactly what youre after. For each app a different type of bit is best, and co-steel isnt the best for any app that I know of. Its harder than hss, but there are much tougher bits for drilling stainless than co-steel.

Maybe you coul clarify what you want a bit more. If its just a general purpose drill bit, there isnt really any such thing. If its for steel reinforced crete, there are multimaterial tct bits for that.

NT

[EricP]

Cheers Fred, :))

[Chris Hodges]

Ever tried them on glass? I can't find anything smaller than a 5mm in a glass/tile spade bit.

[The Medway Handyman]

No not at all. Me & glass don't get on to be fair, I use a local glasier for everything glass related.

[Peter Ashby]

Not exactly the same but I have drilled glazed tiles with a masonry bit (no hammer setting of course), when I needed a small diameter. A careful starter and/or masking tape is advised to stop them wandering though. Oh and go carefully.

Peter

[Andy Dingley]

There are two sorts:

Blueish variegated "cobalt" coating, from Northern Tools and QVC - cheap, worthless.

M42 HSS, an alloy with cobalt in it. Expensive (but not insanely so), available from Axminster, really do drill (almost) anything. Worth having a set around for "best".

[Andy Dingley]

Wrong shape.

Axminster. Buy their indivdual carbide leaf bits though, their cheaper quality in sets aren't ground to be accurately concentric.

[Chris Hodges]

fair enough - I was refrring to the claims the OP quoted.

I'll have a lok at that tomorrow (that counts as work related!). Thanks.

Chris

[EricP]

In the next few weeks I have to drill several reinforced concrete items, inside and outside.

I was flicking channels and found a bloke apparently drilling a glass block with a HSS looking drill bit.

Watcing it, revealed it was a "cobalt plated bit that would last a lifetime and was guaranteed ten years for sharpness".

He used the same bit to drill hardened steel, (a metal file), glass, ceramics, a house brick, wood, carbon steel and so on and on.

As they have a 30 day returns policy I thought the first thing anybody would do would be to get a bit and try to wreck it. Having wrecked it, return the whole set for refund. Hence it would appear to really do what they were claiming.

I had never seen anything like it so I dragged it in here for the brains to comment on, as it seemed too good to be true, particularly at their price.