View Single Post
  #6   Report Post  
Posted to uk.d-i-y
Andy Dingley Andy Dingley is offline
external usenet poster
 
Posts: 5,175
Default Drill all drills

On 20 Dec, 19:09, Tim W wrote:
Dave


Has anyone come across them before?


Cobalt-unobtainium alloy drill bits have been around for decades, but
are a very niche market. Locksmithing is one user of them, for
drilling hardplate in safes. Certainly the chap demonstrating drilling
through files was at the model engineer exhibition 30 years ago.

They're less useful than you'd think. Just how often do you need to
drill something that won't respond to a carbide masonry bit, or decent
HSS ? I've used mine a few times (every couple of years), but always
for demolishing stuff, not for fabrication. As always when drilling
out broken drill stubs etc., wandering sideways into the softer metal
is a huge problem.


http://www.screwfix.com/prods/95958


Those aren't.

The usual "cobalt" drills these days have a "cobalt" (sic) coating on
them, giving a bluish rainbow look. They're cheap, Chinese, and made
of a secret alloy of rubber and bananas. No earthly use for anything.