self centring drill bits

Yeah, I've got some cheap'n'nasty ones, clog very easily, maybe for branded ones, try Bosch or Trend?

Not sure in what respect you mean. Once a drill bit is sharpened it's never quite the same again. The most noticable thing is the holes you drill are slightly larger than when the bit is new (assuming it's been made to a decent standard in the first place!) Are you saying the apex point of the drill is not central wrt the shank? Or that it is central but the chuck can't centre it up as it should for whatever reason?

I assume he meant 'vix bits'

It may be soi for you, but people who did this regaularly could often make them as good as, or better, than original.

However these days the labour cost is many times the cost of a new drill so one doesn't sharpen.

They look an excellent invention, and one which is very simple in design and concept. I presume the conical tip means that they will work with a range of sizes of holes in hinges: the cone finds its own level and is then centred.

Now we need a device which prevents a masonry drill wandering all over the place. I measure accurately and drill a pilot hole with a small drill whose tip is on the mark I've made. Then I use a drill that is the size of the Rawlplug. But the resulting hole, once the Rawlplug is in place, may be a couple of mm adrift, which makes it very difficult to get two holes that are at the same height so the object that I am attaching may not be level.

I take the lazy way out and attach a thin wooden batten and then drill the accurate holes in the wood and fasten the object to that rather than the wall.

they're the same if you grind them the same, better if you grind them better, worse if you don't do it right. Drill bit grinding is odd in that some people have no trouble doing it, some never can.

IME I can grind a whole pile in 5-10 minutes, and make them better then new.

With small bits, 3mm & under, geometry ceases to be of much importance for wood drilling, almost anything works. Anyone who's no good at regrinding could start on small ones.

NT

That's quite a claim. How have you checked them? You would need to be able to establish that the hole you have drilled with your sharpened bit is no larger than that made by a new drill and has clean edges for which some 30x magnification would be required. Decades ago in aircraft and spacecraft construction, the manufacturers would never sharpen worn drills; they'd all be flogged off wholesale purely for the fact that once sharpened, the holes they made were often no longer within the tight spec demanded. And I'm talking about very expensive made-in-England HSS twist drills, none of your Chinese rubbish. ;)

By looking at the tips & using them.

Lol, for drilling holes in wood I need no such checks. You only get oversize holes if you haven't centred the grind or have majorly messed up the geometry.

Sure, but I'm not building aircraft or spaceships, I'm making holes in wood. Steel is fussier but still pretty straightforwadrd. With wood you can take huge liberties if you wish.

NT

Oh for wood? Sure, no probs.

A tip for starting an sds drill is to start the hole while in normal drill mode, When an indent has been made switch to sds mode

I use the rotationstop position to start in plaster.