A beginner's guide to drills and bits


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Apropos of drilling, ‘swarf’ has got to be one of the more endearing terms for a material processing byproduct.


Gurren Lagann covers everything you need to know, but with mechas.

What the article calls “Drill Bits” are actually called “Drills”. Twist Drills, Spade Bits, etc.
That the article calls the “Drill” is actually the “Drill Driver”. Hand-held, Reversible, Drill Press, etc.

Let the tool do most of the work, applying steady pressure directly parallel to the bit.

I think you mean “perpendicular,” but I guess if you don’t know where to put pressure when you’re drilling something you’ve got larger problems than this piece can address.

One good way to avoid ragged blowouts on the back of the hole you’re drilling is to affix a piece of scrap material against the back side. For example if you’re drilling wood, and the piece you’re drilling can fit on a workbench, put a piece of scrap wood directly below where you’re drilling. Just make sure the scrap wood is thick enough that you don’t drill straight through it into your workbench!


[Edit. I can’t read apparently]

On another subject, metal can be a weird material to work with, and cutting speed and feed (i.e. how fast the tool penetrates the work) can be much more important than with other materials. Certain metals (stainless steel for example) may also work harden if you stop drilling or if you vary the feed too much. This can harden the work piece to the point where you’ll just burn bits trying to get through it.

i made this drill bit out of 24k gold. it’s soft and buttery so probably doesn’t work very well but it sure is beautiful. it feels nice to hold. has a good heft. oh. new users can’t upload images. a picture of it was the whole point. i’ll try again later i suppose.

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Called by whom? If I told someone to hand me that drill over there, I’d be pretty surprised if I got a bit instead, even if some dictionary somewhere says otherwise.


Nice, basic article, but while sharpening is mentioned, not a word on exactly how to sharpen the various drill bits, which is something I’ve never done and was curious about.

Yeah, it’s pretty standard (at least in the US) that the tool is the “drill” and the bits are the… “bits”.

For anyone reading that might have a tiling job in their future; take it from me and invest in diamond-tipped hole saws. I had to cut a few holes in some floor tiles for pipes coming up to the sink and toilet. Masonry bits were KIND of getting the job done, but I had to use so much pressure I broke a ton of tiles. Once I bought proper diamond-tipped bits, though… smooth cuts, like a warm knife through butter, perfect cuts. Worth every penny.

Materials like that, you’re going to want to use a lubricating oil of some kind to make the drill work easier (reduce the friction) and to help dissipate the heat.

curiously drill bits cutting square holes were left out of the article.
Althought rare, (I have yet to see one out of youtube) seem awesome!

They need a special drill and a lot of stabilization. Reminds me more of a sewing machine. Neat.

Bunch’o’stuff here…

A ‘drill’ is the whole gadget, and a ‘drill bit’ is the bit that also does the munching in the UK, as in the US. However, ‘drill’ is an acceptable abbreviation for ‘drill bit’ so if you asked for a 4mm ‘drill’, this would not cause confusion.

However, before you cart making holes in something, learn the difference between a masonry bit, a metal bit, or a wood bit. I would have stuck that into the video.

Masonry bits are easy. These often have a lumpy bit that makes the cutting edge, made from some harder stuff. These are used for making holes in bricks and plaster and stuff with the drill on hammer action. They don’t so much drill as smack stuff out of the way.

Some wood bits have a spike in the centre and a flat end - this is good for cutting square-ended holes for pegging stuff together. This is a trick that doesn’t work as well with metal: if you see something that looks like a metal drill with a square end it is probably for a milling machine. If your bit has a gold finish, then you probably have a fancy metal drill. Then there are some that dull, round ones with pointy ends like, well, normal drills. I can tell the difference in the UK but I am to sure if the visual guides will work in the US. Maybe the box will tell you. Metal drills will work on wood if they are sharp, not not vice-versa.

If you are drilling metal, then you will probably need a better guide than this, and if you slide yourself something horrid, well it isn’t my fault. However, if you are cutting some metal that cuts, do use oil or an oil-water emulsion - it seems mad but it makes a lit of difference. Also a hint that you are getting it right is you have long, spiral bits of swarf rather than little flakes, but you don’t always get that. Or, if you are cutting steel, you have to go at huge speeds with ceramic tools, which can get a bit hairy.

Sharpening drills is more complicated, and I would not presume to advise. It depends on what you are cutting, and some sorts of drills can’t be sharpened with regular tools. If you are handy with a grinder, and the drill doesn’t seem to have a fancy end made of different stuff, try making it into the same shape as one drill from the same set that hasn’t worn.

Oh, and welcome, brother or sister, whichever you are, to the wonderful world of power tools - may your appendages survive the learning process!

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I have a Drill Doctor for twist bits which works great. Highly recommended.

In my (wholly North American) experience, the bit is usually called a ‘drill’ in machine/metal-working shops (which distinguishes it from other kinds of ‘bits’ that can be used in milling machines etc).

Confusingly, in the same shops, a hand drill (the tool, not the bit) was also called a drill. Apparently we got a lot of mileage out of context :smile:.

However you go about sharpening it, don’t get the bit hot. Easier to in a jig type device.

Awesome post! Makes boingboing feel a bit more like old “popular mechanics” mags. Old tech makes new tech even better in my opinion.


Yes, it’s important to be decisive with work-hardening materials - low speed and high feed (i.e. apply heavy pressure with hand-fed machines).
That said, free-cutting stainless steel e.g. 303, is pretty forgiving.

With regard to sharpening, it takes a lot of practise to hand sharpen drill bits (I prefer that name to avoid confusion).
For small sizes, it’s probably not worth the trouble. For larger, more expensive ones, read up about the correct shape they should be, and concentrate on making the two cutting edges equal lengths and angles - the actual angle is not quite so critical for most purposes.