Brian Reay wrote in news:558999594430351400.971108no.sp-
:

They tend to be fine for thin steal (eg car panels if you are fitting an
antenna)

Good point. I don't drive or own any large boatanchors so I'm not used to
thinking of non-portable or unsupported surfaces. It may even be easier to
improvise with a slightly wrong hole punch (or aim small and file
outwards) and some large washers than to attempt the way I usually do things.

For small round holes of unspecified size I have never beaten an M3 pilot
hole followed by a tapered reamer, deburring the result with a Stanley blade.
That is VERY cheap, I started out that way and it was a couple of years
before I needed anything better.

Lordgnome wrote in :

Someone once said to me, that precision engineering was the easiest
thing in the world - far easier than having to 'adjust' holes to fit
things and used a lot less material!


They were right. Measure thrice, cut once... I'm about to spend 300 quid on a
small pillar drill, something I avoided doing for years, but I am tired of
seeing the good results of hand work and most of my tools beignj ruined by
the use of one really bad one. I know what peopole say about bad workmen and
tools, but there are bad tools too. Pistol-grip drills are the worst...
Never rely on a pilot hole for centring with those, far too many ways chaotic
oscillations can get in to screw things up royally.. I mean, a 2mm hole in
acetal was fine for a subsequent widening to 3.7 for tapping with a fluteless
tap, but try the same methods, no matter how carefully the speed ajuster is
used, and a 5mm bit rips into it with a pattern that resembles a tornado!

Can't beat precision and secure methods. The expense increase is always lower
than the avoided loss.