I think that Neil's comments are very valid, particularly with the thinner versions of the drills which as he says can be difficult to centre on the blank even when using a pillar drill. The DeWalt Extreme 2 with the bullet tip, or even a lip and spur bit being much better in that respect.
I don't however want to give the impression that I think they are total rubbish because the flutes do clear more quickly than most other drill bits and they do a good job if you need to drill longer blanks. All I am saying is that they are not the miracle tool that the manufacturer's make them out to be and their own promotional video demonstrates this admirably. No matter how you design the flute or the cutting edge, cutting generates friction generates heat and drilling too fast or failing to clear the flutes will cause one or the other of breakout at the exit point, a split blank or with acrylics, the drill bit melting the plastic and jamming.
As an experiment I tried drilling a couple of corian blanks that Neil very kindly sent me so that I can experiment with burnishing cream as discussed somewhere earlier. (Thank you Neil, they arrived safely.) They are quite thin at about 12 or 13mm so I though they would make a good subject. Using a 7mm Colt pen drill in my pillar drill I drilled one at 750rpm withdrawing regularly to clear the flutes and another at 1500 rpm without clearing the flutes. The first method produced a perfect clean hole with no breakout at the exit point, the second had so much breakout at the end that it will probably not be usable. So yes they are good drills but they are not a wonder tool that allows normal sensible drilling practice established over centuries to be ignored.
If you want real quality drill bits, with high tech fast clearing flute design and a centring spur, then you can't get better than the Famag 1594 series or their longer stable mates the 1599 long series but, before Brian says it, why would you spend that much when the DeWalts will do the job well enough?
