Dual diameter HSS bit.

If they do, these people will have them. If they don't, they can make one to your specifications:

De Walt "extreme" bits are like this (I have a set) and work very well in a drill press but are slightly aggressive in a hand-held drill

Very interesting. Have you tried them in thin (0.5mm and 0.7mm) sheet metal?

Nice but £Ouch!

Probably. When I first got them I used them all the time but found they were a bit too aggressive for general handheld use so, now, only tend to use them when their virtues are needed - they should be fine for your application. Although, TBH, for non-critical drilling in thin material I would use an auto centre punch and then go straight to a 4-facet drill of the right size. Whichever technique, I would have a piece of wood at the back if at all possible. If this is for cladding/roofing panels then use self-drilling Tek screws, they're the dogs danglies when driven with an impact driver.

You do get what you pay for though, which is quite important when drilling holes as part of a manufacturing business.

Two drills (one for each size drill you need)?

A bit tedious when doing 200 holes.

I might try one:

Chris Bacon snipped-for-privacy@maildrop.cc wrote in news:sglnof$19h7$ snipped-for-privacy@gioia.aioe.org:

If truly cobalt then they could prove brittle, the Bosch extreme range (also avail at Sfx) with a similar profile may work out better.

Thank you. I had a look, could not find them. Got an URL? I might buy both...

It says they are cobalt high speed steel (HSS). That is a steel with up to about 5% cobalt in the alloy mix.

Chris Bacon snipped-for-privacy@maildrop.cc wrote in news:sgm3f0$skp$1 @gioia.aioe.org:

Sorry it is the _DeWalt_ Extreme 2 Metal range, same tip as your linked product but no mention of cobalt in the description at DeWalt:

Huge potential for confusion as they have applied the 'Extreme' name to many drilling material ranges so finding "Extreme 2 Metal" is key. Many suppliers are showing stock photos of non-stepped drills too so more room for doubt.

One stockist here:

or

nightjar snipped-for-privacy@bignell.me.uk> wrote in news:ibKdnSLE9dLbJ7P8nZ2dnUU78W- snipped-for-privacy@giganews.com:

I think mine are about the same and I suffered a few breakages before I realised how fragile they were and learned to handle them care. I now only use them carefully in a drill press and on materials or thicknesses where they give a real advantage.

That sounds like M42 cobalt steel, which has a higher percentage of cobalt than the more common M35 grade. For really brittle drills, which only work with machine feeds, try solid carbide drills.