Phil Addison wrote:

http://www.diyfaq.org.uk/testing/pow...s/drillfaq.htm

A trivial style/readability point he

"This FAQ is not about Electric Hand-held Drills (for those look here),
but is about different types of drill-bits and the actual process of
drilling"

I'd remove '(for those look here)' and make 'Drills' the hyperlink
instead.


I keep wondering about this:

'Drilling can be very loud and create loads of dust, so ear defenders
and a mask are often essential'

Rarely I find, unless its a particularly mean job. I'd say 'sometimes
essential'


IME masonry drills work fine when theyre blunt. Its only the hardest of
workpieces that need a sharp one to work.


"Many metals need to be drilled at relatively low speeds in the 300 -
900 rpm range, so many standard mains drills are too fast, the result
being an overheated drill-bit"

yse, I'd add: the workaround for this is to drill for 10 or 20 seconds,
rest to allow cooling, repeat.


" point but a flat cutting edge and look a little like a small spade. A
sharp flat bit will rapidly cut a pretty clean hole"

I've never seen that, always been messy, even with a new drill bit. I'd
say: 'Flat bits make messy holes, can be unstable, and can't be used to
widen existing holes. Theyre suited to drilling large holes, where
other bit types get expensive.'


More cut n paste offerings:


Blunt bits:

Some new bits are so badly ground they wont work, and all bits lose
their edge in time. Blunt and broken bits can be reground if you pay
sufficient attention to the angles. Regrinding attachments are not
needed, and not that helpful.

If you want bits for wood and plastic use only, sharper steeper angles
will make them perform much better. Just dont use these to drill steel.

If you dont succeed at sharpening bits, and not everyone does, its very
easy to grind a flattened point on them. They'll then work again,
though the performance wont be as good as a sharp twist drill.

If you have no sharpening equipment, even an angle grinder can do it,
provided you use very light pressure only, and take frequent rests to
avoid overheating the bit. With practice a bit can be reground in a
minute this way.


"Then there are those you find in DIY sheds. these are thin bendy
spring steel things that do not quite form a complete circle, and you
get a whole set of them mounted on a single wide arbour.These thin
floppy ones can cut holes through sheet materials, though not much
else. The arbour is always bigger than the cutter so you can drill no
deeper than the exposed depth of the blade. The set comes with all the
blades mounted on the arbour, but in use they should all be removed
except the one required, remembering to do the securing grub-screw up
tight"

They will drill twice that depth, just tackle the hole from both sides.
They will also drill big lumps of wood, eg solid doors, but one must
treat them as somewhat fragile. If you push, they buckle and break.


"Lubrication: Drilling in metal needs lubrication of the drill-bit,
ideally with proper lubricating fluid, but failing that 3-in1 oil is a
lot better than nothing. No, it won't just make the drill-bit slip!"

suggest: '3 in one or vegetable oil are'

I wont mention that margerine, chocolate, and presumably earwax also
work.


NT

PS I wonder about a secondary drill bit FAQ for those that want more
depth of information? There are lots of extra tips could go in, but
would be time wasting for many readers.