I do wonder why I keep the blunt ones (as I do for some klepto reason with duff sparkling plugs). How many blunt drills of the same size does a chap need for goodness sake?
I did buy a drill bit sharpener some years ago but since I doubted that re-sharpening drill bits at home was feasible I bought a cheap one. Like all cheap stuff it wasn't any good.
I've been trying to drill 4mm holes in angle iron this morning and all I've managed to do is work-harden the previously blunted tips of 7 different bits. Yes I do use oil and the appropriate drill speed. Having just paid £18 for three 'quality' bits I've decided to spend a day sharpening my existing ones but only if there's a good sharpener available.
I'll wager that I'm not alone in having boxes of blunt drill bits and duff sparkling plugs.