Adam Savage's Guide to Drill Bits!

this video has been made possible by support from kiwico and i'm going to be telling you why they're

awesome later on but right now let's get into the video hey everybody adam savage here in my cave

with a deep drive into drill bits into drills and making holes uh making uh of the physical

manifestation type uh as a jamie heinemann once said is about taking large chunks of things and

making them smaller in precise ways uh and the drill bit is probably the most common way we

do that i know you don't think of using a drill bit as making this smaller but you are

but we're talking about making holes which is again one of the most common maker activities

and there can be a dizzying array of drill bits to utilize and i have some favorites but

i thought i'd just give you a kind of basic overview of what i understand about drills

i'm probably not going to get all my terms correct i i'm only giving you my experience of each of

these things not an expert's opinion on them so you're both your boast your most basic kind

of drill is a twist drill and this is the one you've probably encountered these uh this is an

index full of twist drills in english sizes and they're a pretty standard type these are

uh i'm trying to remember what they're called these are specifically short hardened drill bits

i use them in my mill because i can actually drill without pilot drilling all the time

but i'm getting ahead of myself already let's talk about how drill bit works a drill bit works and

is a little bit uh a little bit of a chisel uh a little bit of a hone and a little bit of a reamer

uh and the structure of a drill bit is the same of a twist drill it's the same whether it's a 16th of

an inch or an inch and a half so we're gonna talk about it here using this inch and a half

deming bit it's very fun to show people these in the shop because about one in every ten persons

will say wow what is that used for and i'll say drilling big holes next ridiculous question

i know it's a softball um these are called deming bits and yeah they're for making large holes

in hard materials you don't ever really want to take one of these just right to a piece of

metal you want to pre-drill you don't want to put too much energy specifically because when

you're thinking about a drill bit the action's all happening here out at this outer corner in

here there's this chisel point and it's mostly scraping and if you think about this as if this

is moving at like 1 rpm right this is moving a certain speed whatever's going on in the

center is moving at a much slower speed because it's a much shallower uh shallower lever arm

all that is a way of saying uh these drill bits can well let me just show you how this

one operates i've got a piece of uh machining engineering urethane here and i'm going to

drill a hole in it to demonstrate to you how the drill bit does its work there we go

this by the way is guaranteed way to get in lots of trouble and you should be very scared

of this kind of arrangement like you've i have seen these uh i saw someone drilling a piece of

half inch steel on one of jamie heinemann's drill presses using a bit like this and it

grabbed the steel and bent this shaft at about a 20 degree angle all of us just hit the deck

all of us like hit the floor because this thing was like vibrating the whole drill press and it

was gonna like crack and shoot a piece of hot steel across the shop we literally like

what do you call that we like army crawled across the floor to the plug of the drill press

to take away its power so don't do this but i'm doing it with some engineering resin just because

um i almost exclusively use these in machines never in a handheld thing but

it will show you how the drill bit operates so as you start to as you move slowly

you can see here right it's it's starting to make a bit of a dent but it's not like a

it's not like a perfectly accurate dent right so if i had a pilot hole here if i took a um

if i took a sharpie and i made a hole and then i really want to make sure i hit that

hole it's not going to be perfect this is going to wander a bit this is one of the

limitations of a twist drill yeah you can see that but as it as it starts to move out

you can see that it's starting to chisel up material and again

it's not a perfect cone this isn't like well we'll get to this so it starts to peel up materially

and you can see the amount of work that it's got to do right each time each time this edge

turns around it's like peeling up a thin slice of the material that it's cutting through and

even now you can look at this and see that it's almost triangular rather than circular

what does this mean this is simply the irregularity of this hole is

probably just a cautionary tale right now not probably it's a cautionary tale for

why you shouldn't be using these like this you should use these in machines but it also is a

reasonable way to show you uh how much twist drills can move here and there um

for uh let's see so uh yes that's scraping that scraping in that chiseling

is a terrific primer right there for how your basic twist drill works and to be fair that's

not that different from the very first drill bits which were effectively uh a round rod with the

triangle cut at the tip at a specific angle that allowed it to drill this here is a glass drill

but it has basically the exact same structure as the earliest drills and you can use you can watch

uh chris at clickspring both making filing and utilizing these twist drills uh in his

antikythera mechanism and he is able to achieve superiorly accurate hole drilling with that

okay now that i've given a little bit of a primer in what i understand about drill bits let's talk

about some of the various ways to make holes that are available to you i've covered these before

unibits they are fabulous because they can cut any size hole along the cone these are smooth bores

uh i use these for probably weird applications depending on props and stuff like that they're

more commonly released like this with steps on them and people refer to these as step drills

each step is a different measurement and they come in english standard and metric and

really you should always have a set of these in your shop these are fantastic

really really useful i have burned out expensive ones and cheap ones i have in

my life rarely encountered a significant difference between the super cheap and the

super expensive versions of these um i'm i'm sure there are differences but

i have not encountered them so just go get yourself a an inexpensive set of unibits

the ones that harbor freight are absolutely fine in my opinion uh but your results may vary

for masonry uh it looks like the body of a twist drill but masonry bits have this extra hardened

chisel point out on the end and i believe that is a braised piece of carbide right in the end

of the bit here and again its tip is a really good illustration of the very first drill bit design

which is you know these two angles meeting under very specific rules for moving metal out of a hole

in drilling of acrylic oh okay so one of the things that a twist drill also does is

after it's peeling out i'll use the bigger bit after it's peeling out with this chisel point

the flutes here are pulling the material up that's why they they exist as a kind of an elevator for

the material to pull it out of the hole and this is great until it's not great and where it's not

great is if you're drilling something brittle like acrylic and you're scraping out the hole and then

all of a sudden you break through and this flute now wants to go all the way into the acrylic

because the first hole that it makes is like this little figure eight hole it's not a round hole

right the moment this bites through the other end now it wants to pull the drill bit in and it can

shatter the hole and this happens with a lot of brittle materials so when you're drilling

acrylic an acrylic drill bit has been ground in a very specific way to have a different mechanical

relationship with a hole it is not chiseling out it's more scraping out and when it scrapes through

when it scrapes through the hole with this long long shallow angle it actually provides

a much better uh better finished surface on the inside of the hole and it doesn't want to pull

the drill bit into it um i have in a pinch when i needed a really specific sized acrylic hole

i have in a pinch taken one of a regular twist drill like this onto my belt sander and simply

elongated its angle and i was able to make it work i think i pre-drilled it with another acrylic bit

um yeah i did pre-drill it with another acrylic but you don't have to get this

angle exact to get it to work um now now let's move on to bigger holes because most people

aren't going to spend 50 bucks on a drill bit like this and that's the cheap one the first

large hole drill bit that you probably encountered is one of these a spade bit and these things are

both fantastic because they're really inexpensive they've been around for like 150 years or more

they can get you in a lot of trouble because they're levered way out at the end they don't

make super accurate holes they can wander but you can basically see their function

uh they've got this uh this chisel triangle way out at the end that keeps it centered in the hole

and then these two outside chisels which are flared slightly out from the body of this are

doing the carving now there's no mechanism in the spade bit for pulling material out of the hole so

you're going to have to do that yourself as you go i don't use these very much

i find them to be sloppy they break through wood easily they can do a lot of damage i don't love

them and i don't even think i have a complete set here in the cave now this sharp point for

centering the drill bit in the hole does have a utility in a woodworkers bit which i think

is called a brad point bit i'm not sure it's got this super sharpened point that allows you to get

into a really nice center marked hole and it's got these long edged flutes which are

quite sharp and well sharpened and these woodworker bits make beautiful smooth bore holes

in wood uh and they go up to about this big this is about a half inch one so if you want

to get bigger you have to go to something else um the predecessor for these the early early

predecessor which you can still get in various applications is this it's called an auger bit and

this is a beautiful piece of engineering as you can see it it uses the same spiral flutes uh these

are shallower and this has a chisel way down here a nice shallow chisel angle compared to the um

compared to the steep chisel angle of the of the twist drill there and that shallow angle

means that this thing bores really nice round holes these are great this is an ancient one

it's got a square back for an old brace like one of these drills i've got a couple of them around

here and this makes really nice smooth bore holes unfortunately i think if you can if you can buy

these they're quite expensive um and uh they're the perfect lead in to my all-time favorite of all

the drill bits and the one that i am was really surprised how much it improved my life when i got

it and that is the forstner bit and that's what we're going to talk about next summer is here and

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it might be peculiar to have a favorite drill bit but these are my favorite drill bits um

so many people make different forstner bit sets again like the unibits i haven't found

a significant difference between the cheap forstner bits and the expensive forstner bits

and the reason i haven't detected much of a difference is because i don't use them all

the time if i was doing production level work i'd probably invest in a really high-end pair

of forstner high-end set of forstner bits but because the work i do here is all very piecemeal

and i might use one particular dribble only a couple times a year the inexpensive ones work

just fine and when young makers ask me about esoteric tools they might not normally find out

about in the average hardware store walkthrough forstner bits are at the top of my list

your basic set can run you right around 30 bucks so if you have a young maker in your

life this is a fantastic birthday or christmas present or shopwarming present um 30 bucks 30

bucks to go all the way from one quarter inch up to two inches and i'm here to explain that

forester bits go even bigger this is the biggest one i could find i think this is a three inch wait

uh no it's two and a half is that two and a half yeah it's two and a half um i thought i had a

three inch somewhere maybe not okay why do i love forstner bits how do i count the ways okay let's

chuck in this big bad boy and give you a demo of why i love forstner bits okay this guy out

i've never looked into who forstner actually is um okay so uh i'm gonna drill next to

the same hole i had and you could oh right and the forstner bit let's talk about the

parts of a forstner bit before i do this getting ahead of myself forster bit has this

uh you can see this outside machined surface which is on a very slight taper it tapers from

the outside from the bottom up so it's a tapers that way and there are two breaks in this barrel

some forstner bits have teeth like this others have just one or two big teeth but the two breaks

are where our chisel points are and as you can see from this angle of attack it is uh it is not

dissimilar from the chisel action of your twist drill um but these are mounted to these very like

you can see this piece of steel there's a lot more support for it than across a spade bit even though

their actions are somewhat or quite similar plus the fact that this is round and precisely round

means that it self-centers itself in its whole it's got this nice brad point uh to get yourself

on your mark like that but then once it breaks the surface it holds itself really nice and tightly

into the hole and i'll show you a practical example of the kind of hole that it drills

there we go

now oh yeah take a look at these two holes right there i think it's pretty obvious you can see

that this one is not as not perfectly round and i told you it wasn't going to be

um but look how beautifully round this is and look at the sides that is like

the the the sides of a forstner drill bit hole are really nice and smooth

and actually um if you have a piece of like one inch pipe of real true one inch

pipe and sorry one inch tubing and you use a one inch forstner bit those fitments together will be

perfect and i use forstner bits like that all the time if i have a precise radius that has to go

into a material the forstner bit is my weapon of choice for making sure i've got a hole that is

highly accurate to the piece that i am putting in it but that is not drilling these big

like nice smooth bore round holes is only part of what makes forstner bits totally amazing

um and i want to talk about a safety issue here um one of the worst injuries i got on my hand

before i messed it up on the lathe last year i was using a forstner bit probably probably about like

this and i was drilling into a piece like this and i had a backing piece behind it but the forstner

bit went through the piece through the backing piece and carved up the inside of my index finger

yeah it was a dumb mistake uh and you can get in a lot of trouble with these so you want to

be careful don't don't don't be like me you want to be clamping your work uh and using these mostly

with a drill press uh if you if precision is in your interest um but here is something that i

truly love about forstner bits is that they can do something that almost no other drill bit can

do which is they can drill into material when they're not completely surrounded by the material

example

what yeah that basically kept itself self-centered now i'm not gonna pretend that this is like a

perfectly linear hole i'd use a drill bit if i had to do this but basically you can kind of

use one of these for doing rudimentary machining in soft materials and i have actually way back

way back in the time before mythbusters i was uh i was teaching myself the rudiments of digital

filmmaking and it was the early part of 2002 and i bought a sony trv10 handycam i bought a macintosh

pismo laptop devoted to digital video editing and i started shooting and i started thinking about

extra ways to get better shots out of my camera so i decided to build a little handheld steadicam and

this is the cam that i built uh i had an xy table up here that held my camera for balancing but this

allowed me to do the kind of like holding on to a gimbal and not having my camera move around

and i built this entire thing using only forstner bits i didn't have a milling machine at the time

um that is the kind of stuff you can do with the forstner bit right so i had these

highly precise uh uh uh bearings that were what is that probably an inch and a half two inches

uh and i used a two inch forstner bit and was able just to sock two of these down plus or

minus about a thousand able to use an arbor press to press these into this uhmw plastic

and get a fantastic bearing surface and now this whole thing sat beautifully uh on the on the post

um i did disc i will tell you that this was not a uh uh uh this device never properly worked and it

never properly worked because of uh one issue i had which is because i did this on a drill press

how do i say this okay if you want a gimbal like this to work all of your lines this line

and this line have to travel precisely through the center of the center post if they don't

you kind of can never get this thing properly balanced and vertical

you just can't no matter how hard you try and i tried uh that is a failing of you know i didn't

basically i learned a really important lesson by screwing this up and i'm grateful for learning

that lesson um but forstner bits were how i did much of my machining in the early days of having

a shop um and they uh like you see the possibility here like this thing wants to stay centered you

can actually do some really interesting work with these i've done flutes of columns using these uh

i've removed huge amounts of material actually if i have a plastic casting and i want it to be

hollow but i can't really grab onto it i can loosely clamp it between a couple of pieces

of soft wood and use a forstner bit to kind of just gently remove material because you don't

need a high amount of pressure for the chisel action to start working you can actually do it

at a at a quite low pressure that can keep you from getting your hand all twisted up as well

and like i said under light use conditions i have not encountered much of a difference between the

hundred dollar set of forstner bits and the thirty dollar set of forstner bits so my advice to you is

go get yourself a thirty dollar set of forstner bits and if you burn one out

just buy another one of that one uh if that turns out to be a common size that you love you may

notice when you use the replacement one that it's way better for you under certain circumstances and

in that case then it's time to go buy yourself the nice hundred dollar set but until then

uh yeah this is a great great addition to any beginning maker shop or experience

makers and this falls into the category of tools that aren't in common uh that aren't

common knowledge everyone knows what a spade bit is i mean really i feel

like everybody knows what a spade bit is but this is a bit of a mystery to most people um

it's one of those tools that someone has to tell you about so i'm telling you about it thank you

guys for joining me for this tool tip i'm adam savage and i will see you next time cheers you