Those are actually tapered drifts,
NOT punches. Note the
flat ends. Parallel drifts (often called parallel pin punches) and tapered drifts are designed for maintenance tasks such as drifting out pins (e.g. hinge pins where appropriate, clevis pins holding your van's brake shoes in place, etc) where you
don't want to mark things. Tapered drifts are stronger and less likely to bend than parallel ones, but they can only go a limited distance down a hole. In order to avoid confusion between different tools the guy who taught us metalwork (ex-Royal Engineers) was always fussy to differentiate between drifts, punches and sets. More than 50 years on that sticks with me
Punches, or more correctly centre and marking punches, are designed to put a visible mark in a piece of metal. Marking punches only leave a very shallow mark but can be very accurately positioned. They should be followed up with a marking punch which leaves a much deaper, heavier hole in the material - deep enough to start a twist drill off (bearing in mind that a twist drill actually has a flat point on the end of it). The problem is that they aren't easy to position acurately onto smooth, flat material, especially if you need extreme accuracy (think aircraft)
These punches are to mark a starting point to drill in metal ? How about knocking nails below the surface? Different tool?
Look carefully at the ends. Do they look hollow? (then look at the picture below which shows the hollow top of a Stanley nail set) So they aren't
nail sets either (and in any case you don't get nail sets as big as the left hand one) - they are engineer's tapered drifts. You do know that you asked the self same question about nail sets and punches a while back, and I answered it then, don't you? I sometimes think I'm addressing the wall
I'm "old school" (whatever that's suppose to mean) - but that means I differentiate between different tools and their uses. So, to recap:-
Nail sets - (see above) are tapered and have slightly
concave ends (not flat, see left hand picture) so they won't slip off nail or pin heads when driven with a hammer. They come in up to 5 or 6 sizes to accommodate different size nail/pin heads and they have very hard heads. They are use to "set" (or punch, if you insist, I'd rather you didn't) nail and pin heads below the surface of timber, etc. They cannot be used as centre punches as they have no point. In a jam they can be used as drifts providing you don't mind the risk of damage (to whatever it is you are trying to shift). The
ignoranti selling them these days tend call them nail
punches (presumably because they don't know any better having never actually used a tool - there's a lot of it about). Best general purpose ones are the sets of 3 or 4 with coloured plastic or rubber grips that Stanley sell. The absolute
best quality ones are made by Starrett, with a price to match. Bahco ones are somewhere in between the two. Don't talk to me about cheap Chinese carp, though! You get what you pay for...
I know that there are web sites out there which state that nail punches
(sic!) can be concave, flat or pointed (mostly American sites) but it simply isn't true. If a nail set isn't concave how will it ever locate properly on, say, a convex pin head and what stops it from skidding off the first time you smack (actually, tap) it with a hammer?
Marking punches (sometimes called
dot punches) - are lighter than centre punches and ground to a relatively fine point which makes it easier to see the point. They are designed to allow accurate marking of a drilling centre point but don't leave a deep enough impression to start drilling from except for the very smallest drill bits. The advantage of using them is that if you mark the point in the wrong place it is possible to correct the position of the point (more difficult with a centre punch). Automatic and manual sprung versions are available. Normally only of use with engineering work, so I doubt very much that a chippy or handyman would ever need one
Centre punches - are ground to a blunter point than marking punches and can be more awkward to position accurately - a big issue in precision engineering, but much less of a problem in general work where a discrepancy of 0.5mm is neither here nor there and you can therefore dispense with the oreliminary marking punch. That's why you "dot " the drilling centre first, then you make it bigger with the centre punch. So they are used to enlarge a "dot" to produce a deeper indentation which you can start a twist drill in (bearing in mind that twist drills all have a flat end and that they cut on the sides of the flutes). Should never be used to drift components out of holes as they can mark or damage the thing you are trying to drift out. Equally can be downright dangerous if you attempt to set nails or pins with them
Drifts (tapered and parallel) - also referred to as "tapered pin punches" and "parallel pin punches" (note the full names). These have flat ends and are specifically designed to knock-out items in holes such as gudgeon pins, etc without marking or damaging them. Cannot be used for marking as they have no point on the end. Shouldn't ever be used to set nails or pins in wood as they can slide off, potentially damaging the work and possibly injuring the idiot attempting to use one to drive a nail...
Regarding small metal drill bits i guess the brand matters, what's the best brand for 2- 3.5 million bits?
Yes, brand does matter. But so does availability. Because so many of the steel box section and RSJs I deal with these days seem to be as hard as hell I tend to stick to HSS-G (also called "M42 HSS" and "HSS Cobalt") drill bits. Milwaukee ShockWave are remarkably good, Heller are also good (although the ShockWave bits are better on electro steel). Buy them in boxes of ten off eBay (milions are maybe a bit more than PayPal could cope with), then you'll always have some on hand.
