Sharpening stepped drills

[andrew]

We've been using DeWalt 10mm Extreme 2 HSS Drill bits ( Screwfix 32213), they're 10mm drills with the points thinned to a pilot of about 4mm and the hole then cut to full size by chisels on the flanks of theses, like a pilot drill and plug drill combined into one. They are hard but brittle and not cheap. I'm going to have to try sharpening them but wondered if the hardness is likely to be a small depth such that they won't stand much sharpening? The flanks have become chipped rather than worn blunt, from drilling palisade fensing on site.

I'm guessing I'll need an ordinary drill guide to sharpen the pilot and a dremel to do the chisel edges or are there better suggestions?

AJH

[NT]

I still use an angle grinder to do drill bits. People cringe when I say it, but the results vastly outperform new bits.

[Andy Dingley]

You need a real tool and cutter grinder (searching for "Quorn" might show pictures of a simple one).

You can make a useful lashup from a Picador drill sharpening jig (fairly common at the better car boot sales) and a proper cup wheel, mounted on a spindle (again, you're looking at metalbashing fleamarkets). This gives you a grinding wheel with a flat end face and, more importantly in this case, a sharp outer corner.

OTOH, just go at it with an angle grinder and a brand new rigid disk (to give that sharp corner). You'll end up with a wonky drill that shakes and drills oversize, but then if you're drilling poorly supported stuff on-site and don't care about exact diameters, that's probably good enough. You're going to get away with a lot because the pilot holds it central.

I wouldn't expect a decent HSS drill to show a "skin" problem.

[NT]

complete nonsense - if we assume the reusltant bit is drilling wood. If youre going to drill steel its another story.