Sharpening Drill Bits - The Long Way Round

so I've had to order a few parts for the cart care specifically a handful of small bearings and while I wait for those I thought I'd do a quick video I've gotten quite a few requests for drill bit sharpening that and today is international drill sharpening day so you know it feels appropriate the cart is more or less how we left off in part one though I did make a little bit of progress on the control system but I need to get enough footage together to make an interesting second part think of drill sharpening like treading water now I know I know there are a lot of great videos out there on this topic already nonetheless you asked I obliged this will be drill bit sharpening by hands but with a twist sorry let's do what we did in the high speed steel lathe tool sharpening video we'll start from scratch make our own drill bit and see why when where how and who we need to grind which effectively is how you sharpen them when they're dull I mean there's a little more work and making your own drill bit from scratch of course but once we get to sharpening it it'll be how you sharpen them when they're dull in our case we'll be starting from extremely dull so on the right you're looking at a dull drill bit my trick for sharpening something I've never sharpened before something I don't know how to sharpen is to just simply look at a new sharp thing and copy what you see onto the dull thing grind your dull one until it matches now mind you all drills aren't created equal you can get some real winners right out of the box with dull or even backwards grinds as with anything else you get what you pay for make sure you're copying something good now the problem with copying geometry from a sharp tool onto a dull tool although you'll likely get your dull tool sharp it doesn't necessarily tell you why they're sharpened the way they are and if for example you needed to make changes in the case of drill bit say for a different material or if you wanted to drill an oversize or an undersized hole well you wouldn't have much insight into how to do that you probably won't have that insight after watching this video either but we'll try I'm going to do this with a piece of round stock some cold rolled steel in this case this is just a cut off from a piece of the drive shaft I'm using for the go-kart let's not get into why we're starting off the rounds knock and not say square stock but if you think you know leave a comment down below now cold rolled steel does not make for a good drill bit it's too soft but for the amount of grinding I'll need to do to actually make this into something that drills well it's easier to show you with this stuff than it would be with a solid ground piece of high speed steel this is just for demonstration though it should be hard enough to drill a clean hole and say some wood or maybe we even try some aluminum in the lathe tool sharpening video before we did anything we tried to take a cut with just the blank I'm not going to do that hopefully it's self-evident that just a round piece of steel won't do anything at all other than maybe burn itself up if it's not self evident you might want to stick to just buying new drills when your old ones get dull to state the obvious this has no cutting edges the first thing I'm going to do is put two cutting edges on this thing since we're making a two flute drill your classic twist or job or drill it could take a look at this back at the bench since we'd like this to drill a hole while it spins and the round face is what's touching our work you might expect the cutting lip to live somewhere across that face somewhere near the center line now in order to leave a sharp edge we'll have to cut away some material removing that material also results in our first flute basically in empty spot where the material we're cutting can go out and exit the work what you're looking at on the screen would be the start of a single flute drill drills with only one flute do exist and they're really quite interesting but they have a different geometry altogether so we'll skip those and jump right to the classic two flute er you probably have at home or if you're anything like me you might have one in your pocket right now okay so anyway two flutes will need two grinds if we make those two grinds so they meet in the center well you'd essentially cut your drill in half lengthwise and it would fall apart two pieces will need to separate those grinds a bit and doing so leaves behind a bit of material called the web we'll get to that later but the web is what gives the drill its strength the larger or thicker that web is the more torque it can take the downside of course is that we have no cutting edges in the middle that's problematic while the flutes are trying to cut the center is just sort of spinning they're getting all hot and bothered making it hard to push the drill into the work I don't remember exactly but I think the web thickness is usually somewhere around 15 or 20 percent of the drill diameter actually let me check my three-quarter inch drill this looks to be a smidge over or a hundred thousand ten I've got this stock in a square Kollek block just so it's easier to flip 180 degrees I think I'm going to go with 150,000 as' because I think it'd be easier to see a little bit later in the video I'll mill these two flutes in and then we'll take a look okay so now we have two flutes on that front face ideally this would have been done with a big ball or bullnose end mill just so the inside corners wouldn't be sharp stress risers but let's take a closer look at the flutes and the cutting edges we just made if you recall from the lathe tool video if the angle that the tool and the material make is 90 degrees it has zero rake basically it's not very sharp yet the way i milled this resulted in a 90-degree edge it's a very strong edge but not very useful for what we needed to do I'm going to recut these flutes at this time I'm going to use a 30-degree angle block just to tip the bit up and give some more of an acute angle to the cutting edge I'm going to try not to lose that sharp corner we established with the first cut just because it's sort of at the right location all right well I managed to blow hole through the part but now we have some backward lean to that face we have some positive rate our cutting edge is one step closer to being useful I wonder if this is how they make through-hole coolant drills I'm a little bummed out about having broken through I've never tried this before I hope it still works anyway allow me a quick analogy would you imagine these two chisels are the two cutting edges of our two flute drill bit it'd be arranged something like this perhaps technically I suppose it an angle like the tip of the drill bit and they'd be spinning around trying to drill a hole now I think we can all relate to the fact that chisels don't cut very well standing up like this it might make great scrapers but they wouldn't move a lot of material you'd want to give them a little bit of lean something like that now as they come around they actually have a shot at cutting material and this lean is exactly what we just cut on the mill so if I spun these up say in the drill press and tried to drill a hole I'd probably get smacked across the face with a chisel handle now imagine we could somehow twist these chisels around each other kind of like a giant twizzler we'd end up with like a spiral staircase looking thing one might say perhaps like a drill bit the twist rate of that spiral of that helix would depend on how far back we leaned the chisels right the steeper the chisels the steeper the helix let's go back to the twist drills own consequently the primary and secondary bevels that you find on the chisel that's what we'll be grinding in next will the parallels never okay so we're talking about how the positive rake was created when we leaned the twisted up chisels back of it I'll take a closer look at these two drills it's a little subtle in this case but this is what I got one has a steeper helix angle usually called slower and the other one has a shallower or faster helix angle the one on the left has the star helix angle it's got sort of more twists in it that means that one has more rake than the other now the more positive the rake the sharper the tool but the weaker the edge you could get me on the technicality here because these are really two different types of drills but in general that means the drill with the faster helix would be more suited to softer materials in this case that drill is very good in aluminum and you'll find that drills made for drilling harder metals have a slower helix to give them a stronger cutting edge our 30-degree helix is a bit of a compromise not fast not slow it's your standard drill angle now I can't cut a helix on my milling machine and believe you me not a day goes by I don't feel terrible about that so this is all your get but hopefully you can imagine that these cuts would continue all the way up to the back of the drill creating the flutes on the same page now can I move on next we'll need some relief on the face behind the cutting edges we may have a sharper edge but there's still no clearance there for the edge to actually move into the work the trailing part of this edge would just rub and make one heck of a racket keeping our sharp cutting lip from biting in and removing material to create a hole before we do that there is one thing we should take care of now that will save some time later this drill has no point as is this drill would try to walk all over the place like it's taken a Sunday stroll different parts of the face of the drill would likely touch the work at different times and places as its spinning causing it to move off its mark so let's cut a point in the end and for now I'm going to cut that point on in the lathe we'll come back to drill point angle a little bit later and to be honest will be more important when we're sharpening drills at the grinder but for now I'm going to do it here I'm going to pick an arbitrary point angle of I don't know 118 degrees okay I'm just messing with you 118 degrees is the standard drill Point angle for general purpose drills for now you're just going to have to take my word for it trust me I'm an amateur to get 118 degree included angle my compound is set to 59 degrees off the lathe axis well it's actually starting to look like a drill as you can see it's starting to look more like a drill now look closely and you'll notice that the cutting edge is still sort of square to the trailing edge there's still no relief back there this drill would rub just as much as it would have before you know just be better at doing it in one place instead of walking around will cut that material away over at the grinder this next step would probably make more sense at a belt grinder like up against the flat platen but I'm going to wager more people out of bench grinders than belt grinders if I didn't say it out loud we'll be going through all of this again but faster when we sharpen an adult drill bit with a dull drill all the work we've done till now will already have been done for you by the drill manufacturer all this futzing around we're doing now is hopefully to give you some insight on what will come later okay so cutting edge relief we have two cutting edges and we saw back on the lathe that the material behind that edge is Square to that cutting edge it's not giving it any clearance to actually cut so we're going to remove some of this material immediately behind that edge on bench grinders the tool rest is set at the grinding wheel centerline since the wheel is round anything we pushed up against the wheel will end up with a bit of an angle to it so if you look at it this way it's touching at the bottom but there's a gap at the top so it's going to end up cutting a an angle in the front it's a hollow ground technically but it's small enough in this case that it might as well be flat now I don't personally use the tool rest and I recommend against you doing it but feel free if it makes you more comfortable you'll get a lot more feedback and control if you're holding the drill in your hands then if it's leaning up against a vibrating grinder now I don't want to lose that nice angle we put on the end of this drill I just want to relieve the back of it so there's two things to sort of keep track of while we're grinding first I want to keep the drill to that same 59 degree angle that's built into the tip so as I'm grinding I'm going to be paying attention to make sure that cutting edge is sort of parallel to the wheel and as part of that I also want to make sure that that edge is level meaning rotation of the drill is sort of in line with the wheel we have to keep track of both that angle and sort of the rotation while we're grinding so with the body of the drill at 59 degrees in this case and that flute sort of parallel with the ground I'm going to start to remove some material until I get up to that edge check your progress while you're grinding and just dunk it in some water when it starts to get too hot to hold when you start to see the sparks break across the cutting edge sort of consistently from one side to the other you know you've reached that edge okay so hopefully you can see this there's a nice consistent grind all the way up to the cutting edge I haven't broken that edge so my angle should still be correct we're so close to having a sharp drill bit I can almost taste it no wait sorry that might be the grit from my grinder now if you look closely there's still a bit of material we didn't get by just relieving up to that cutting edge basically this part back here you might even still see some of the blue this needs to be taken away again if you just look at the geometry when you're holding it and you think of that cutting edge trying to move into the work you'll notice that this should sort of continue down and away that's what we're going to grind now and I'm going to try to grind it until it's about in line with the opposing flue I'm going to take it up to about this line here this is more or less just like the first grind except in order to get to that material you're going to have to climb up your wheel a little bit and just grind and check your work as you're going it'll be a combination of kind of adjusting the angle and rolling the drill until you get this material out up to that line all right I think that looks like about it I went back on the hill probably a little further than I needed to this cold rolled seal is soft it's a little bit more grabby than your standard high speed steel drill bit that you know I'm doing it on camera performance anxiety but we now have a sharp edge the primary relief and then sort of I guess the secondary relief now some people like to do this in facets instead of like rolling the drill up against the grinding wheel it sort of grind the first sort of a second grind and then the third grind would just sort of take off this the highest of the back edge the back of the heel so look more like a prismatic grind Reed have three angles creating the full clearance around the wrap of the cutting edge now what we've done here is basically the same thing you would do to sharpen a chisel you've got the primary and secondary bevel providing clearance for the cutting edge the only really tricky part is that this is sort of round or conical and so you've got to be a little bit lighter on your feet up at the grinding wheel you know while you're moving the material around is trying to get the geometry that you want let's go give this a try as is this is a piece of hard wood I mean it's not hard wood like scientifically I don't know if it is not it's not pine I'm not exactly sure what to expect here I haven't tried this but theoretically it should drill a nice clean hole so I'm no expert here but I don't know those chips don't look too unreasonable there's a lot of sawdust I don't know if that's the drill or my speeds weren't right that feed did seem a little bit slow let's try it in a piece of aluminum well I didn't work so that there is why you don't make drill bits out of mild steel but now I'm curious we said earlier that the point of the drill sort of the web thickness can't actually do any cutting because there aren't cutting edges there I wonder if we were to try this with a pilot hole bigger than that smooshed area if it might not have better luck certainly made a drill bit looking tip but maybe you can see the aluminum is sort of bonded to the cutting edge there and you heard slow down so this seems like a good time to talk about web thinning or splitting the point as in split point drills they're sort of similar but they're different let's have a look at this one and a half inch drill this is somewhat of an extreme example but it's easier to see now I wouldn't usually split the point or thin the web on a drill this big because I wouldn't use it without a pre-drilled pilot hole let me explain by the way this is usually how I sharpen drills this is more typical of the kind of grinding that I do personally it's more of a sort of a long continuous grind you know I'll set up the angle make sure the point is in centre balanced and then just sort of blend out the relief in the back the web on this particular drill is a little over two hundred thousandths that's a smidge over five millimetres the point on the end of this web as sharpened is called a chisel point we said that part doesn't do any cutting the centre really just kind of pushes material out of the way until it's picked up and cut by well the next part of the drill that would actually do any cutting if you think about just what the web is trying to do while this drill is spinning it would be like trying to make a hole with an equivalent size drill only maybe imagine it spinning backwards so it couldn't really cut it would try to bulldoze material out from underneath it to make big holes like this you'd pre-drill the work first in this case with a drill maybe one or one and a half times the size of the web that way when you go in with this drill the web is in pushing against anything alternatively since it's the thickness of this web that is causing high drilling forces the other way to get those forces down is to make the web thinner at the tip basically do some local grinding in those areas effectively making the chisel tip a smaller size a thinner chisel point will have an easier time getting into the material trying to drill now usually you do this on the edge of your grinding wheel on smaller drills you could use say a dremel tool now this here is a split point drill now split points don't always look the same every brand sort of has their own take on it it might be a mix of split pointing and web thinning but take a look at how they've done it here the primary bevel is ground a bit steep and long the second bevel or secondary relief grind is also pretty steep it clips the heel off the primary grind and also splits the point they ground pretty much to where the center of the drill is to where the center of the chisel tip was splitting it into this drill doesn't have much trouble at all cutting through a mild steel and that point geometry also does a great job of keeping it on center or in a center punch mark okay so I was going to sharpen this drill that we saw earlier in the video on with the chipped off corners this actually has enough damage where it needs quite a bit of reconstruction I'd probably grind the end off and then start from scratch that is a little more challenging than just sharpening a dull drill bit I mean the steps are exactly the same but if you're just learning how to do this you know don't make it too hard on yourself from the get-go so I dug through an old box of drills I've probably got 20 pounds of old drills and I found this thing this is a 7/16 about 11 millimeter the tips been kind of burnt up the angles are all goofy the thing is even quite magnetic I wish I could tell you I bought this had some kind of flea market but I'm pretty sure this damage is all my fault it's got almost no clearance in the back the angles don't look right the two lips of the drill are different sizes I'm kind of embarrassed to be honest I think it might look closer to a dull drill bit you might try to sharpen at home so this might be I don't know an easier place to start the other thing you'll want to have is a drill gauge a drill gauge is really nothing more than a broken protractor like it's stuck on 59 degrees you'd use one of these to set your drill Point angle for a 118 degree bit and you'd use little graduations on the scale to make sure both flutes are the same length both cutting edges are equal that means your point is on center now in reality 118 isn't really written in stone it just happens to be the drill point angle that works you know reasonably well on most materials all-purpose one-size-fits-all if you do more work with harder or softer materials plastic or aluminum or brass that kind of stuff you may want to look into drill plant angles and just sharpen all your drills to the appropriate angle they'll perform a lot better in the majority of the work that you might do have to use one of the easy just simply put the drill up against the gauge and you kind of sight in at the top there hopefully you can see that the angle is pretty close but the two cutting edges are different links that looks like it's almost at the thirty two mark that's the wrong angle and it's a little bit longer now drill gauges are pretty inexpensive but if you don't have one of course you could use a protractor and a scale to do the same thing use the protractor to keep track of your drill point angle and use your scale to make sure the cutting edges are the same length if you don't have a protractor I have seen people use a pair of hex nuts that included angle there is a hundred and twenty degrees but like I said earlier it's close enough and if you don't have a drill well I can't help you there in my case the first thing I want to take care of is this magnetism there's nothing worse than trying to sharpen or even use a drill bit that kind of accumulates fuzzies on the end you could use one of these things magnetizer demagnetizer you can get them pretty much anywhere I don't even how much they cost more than what they're worth for sure all about maybe they're really good for is small screwdrivers I guess technically in this case this drill would fit in one of those openings what I have and what I prefer to use though is a proper demagnetizer it's a little bit small but for what I do it's priceless I bought this soon after I got the surface grinder as any parts you take off the surface grinder highly magnetic which again gets annoying very quickly okay that should be a lot less hassle to deal with often bench grinder now if you like you could mark a line with like a sharpie marker across the rest on your grinder just to help you keep track of the point angle but I'm just going to start grinding and keep track with the drill gauge anyway as we noted on the bench one cutting edge is long than the other and it's at the wrong angle the other one is pretty close but it's a little bit short I'm going to keep the drill parallel to the ground again the round grinding wheel is going to add that I don't know five or seven or eight degree clearance on the backside and I'll just keep alternating sides until it comes in according to my drill gauge I'll dunk every now and again to keep it from getting too hot now hopefully you can see this both the cutting edges are the same length and at the same angle that means the included angle is correct and the point is on Center the other thing to note maybe I can show you here the cutting edges are parallel to each other now that's how sorta they'll just come out in the wash if you're just freshening up a dull drill if you're doing complete facial reconstruction you'll want to keep an eye on that the other thing we haven't talked about is the chisel point angle you see the angle that connects sort of the two flutes across the center that should be at about 120 degrees I don't know how much that is but it looks about right now I'm going to relieve the back of those grinds again cut this material off here I'm going to blue sharpie these just so we can keep track how far that grind goes up that primary bevel and just like we did earlier i ground that secondary relief or secondary clearance up until sort of the opposing cutting edge trying to keep everything as parallel as possible in fact if I look close I think I can even see some wear on my grinding wheel because the grinds are a little bit bowed so although not strictly necessary in my case I'm going to be using this mostly in machine tools in the lathe and in the mill let's try to split this point just for the sheer thrill of being alive [Music] [Music] all right I lose that looks a lot more like web thinning maybe than split pointing you can see the chiseled point is still sort of continuous across the top I bet that thing looks absolutely huge in the camera compared to what I'm looking at but anyway there's not really like a single point there to catch like a center punch yeah give it a try this might have been one of those should have stopped while I was ahead moments a piece of cold-rolled steel let's see how this thing does I'll try it here first I want to see what the chips look like under a constant feed rate and if the cutting edges hold up we'll try it in the hand drill and see how it feels there well it certainly drilled a hole cutting edges are still intact let's try it with a pilot hole okay so I intentionally let that run at a constant feed rate into the material that's why you saw get all birds nesting usually bump the handle or ease up on the quill to break these chips but this is more what I was looking for both flutes are creating this pretty much it's the same identical chip so the initial grinds were good but my split pointing sucks consequently this was running at 600 rpm and a little over 2 inches per minute 50 millimeters per minute feed rate let's try in the hand drill alright this is a piece of mild steel just some hot-rolled it's I don't know quarter-inch thick six millimeters use the same pre-drill because I don't feel like pushing a half-inch bit through hot rolled steel and here's our 7/16 bit same bit the cutting edges are still there so it's a good first sign see how it feels all right so I mean it's a half inch hole sucks to drill by hand but other than that split point I'm happy with how that comes so just one last thing I wanted to mention what we've just kind of walked through for better for worse applies to really any kind of drill bit or cutting tool hopefully you see the parallels between what we did on the drill and what we did back in the lathe tool sharpening video again if you've never done it before just look at another equivalent drill and try to copy that geometry onto your dull one each drill will have slightly different geometry based on the job that's intended to do as a last example let's take a look at a masonry bit looks very similar to our bit for drilling metal but the actual sharpening geometry is a little simpler and it still has flutes they don't do as much as the other bit do they're really just there to move away the material that the tip of the tool the carbide insert in this case is breaking away and it's really only got that primary bevel on both cutting flutes in the secondary asserted that's just support material in the steel shank that's braised to the cutting tip certainly if you grind this back far enough where you're running into that you'll need to clearance that to now to sharpen one of these it's really just a matter of hitting the two primary cutting edges I mean you'd want to do this with like a diamond wheel on your grinder or a green stone meant for carbide you'll go crazy trying to do it with a hand file but if you have masonry bits and you've never sharp on them give it a try and I'm sure you'll see it makes quite a difference I don't know how my 10 minute video is always tend to turn into half an hour as always hope you enjoyed that thanks for watching and I guess I'll see you in go-kart part 2

Channel: This Old Tony

Views: 988,791

Rating: 4.8796654 out of 5

Keywords: sharpening drill bits, bench grinder, split point drills, thin web drills, drill relief angle, drill point angle, home shop machining, metal drills, sharpening masonry bits, sharpening bits, another synonym for drill sharpening

Id: r8oORR6jyh8

Length: 29min 39sec (1779 seconds)

Published: Mon Jun 12 2017

Reddit Comments

[u/daedalusalpha]

Trust me, I'm an amateur.

[u/RegencyAndCo]

I mean, I absolutely love ThisOldTony's channel, but that was just super standard drill bit knowledge. What really makes the video for me is the production, analogies and delivery.

[u/paulcam]

For a less thorough and more hilarious take, check out AvE's video. See also, /r/skookum

[u/TheLilyHammer]

Kind of reminds me of Chef John from Food Wishes, but with tools!

[u/eric1rr]

His camera is never focusing on the correct thing.