"I have never used a drill bit as good as these extreme bits I had to drill 10mm holes in a huge rsj H section girder used a 5mm 8mm then the 10mm took less than 5mins for each hole the steel was 12mm thick."
"Needed to drill a broken/seized 10mm steel bolt (2inch long) out of my car's front hub. (New front hub would have been £100+) 1st thought was to find a local small machine shop to do it for me - but these don't seem to exist any more where I live
Had tried and ruined half a dozen standard black cheap HSS drills, and managed to get in about 1/4 inch and wandered off-center at that.
Bought 2 of these drills and what a difference - It took about 20 minutes going slowly, ( using an old B & D drill and even older drill stand) but hole drilled was clean edged and accurate and followed the line of the rusted-in bolt well. I only needed to use one of the drills, and this only shows a small amount of wear. This product definitely gets my vote"
"These drills cut precision, burr-free holes in steel effortlessly, especially with a pillar drill revolving at the correct speed. However their performance lies partly in their extreme hardness and this comes at the expense of durability - I have broken three of these drills in mild steel without apparent reason. Two broke in half and the other lost its tip. Strangely this has happened only in the 10mm size, all others have been fine."
"I opened the pack, drilled 78 holes in 8mm S275JR plate, and the bit was shot.
That's just over 600mm of drilling from one bit, which, for HSS is pretty darned good. I nursemaided the bit, dipping it in oil twice per hole, so I cut about 4mm per dip and towards the end (last ten holes) performance really dropped off so I do think I pretty neatly nailed the max life you can expect from one of these bits in bog standard structural steel.
So, what's not to like? The tip feature means you can't regrind it. - It's a one way trip from pack to drill to bin. at about 8p a hole, the bit cost more than the screws which went in the holes it made. Of course, my time costs about 10x more than either.
And if I was serious about drilling a lot of holes ( I have a similar job coming up so have got some more of these) I'd buy a Ti coated solid carbide bit (about £180 in this size, but hugely more durable - I just don't have that many holes to drill)
If you're drilling structural steel, these are an okay choice. Get one for each half metre of hole you have to cut, and nanny them. You'll do fine."