How to Hand Sharpen a Twist Drill

a skill every machinist should possess is the ability to hand shop in a twist drill I know you can buy tools to do it automatically but unless you want to spend a ton of money you'll find they're pretty cumbersome and time-consuming to use you're a lot better off just learning how to do it by hand think you can do a few bass master a few basic skills you'll you'll do as good of a job and a lot faster than you can with a purchase tool not only that but once you you master some of these skills you can apply them toward grinding lathe bits as well Oh basically I need a couple tools to sharpen twist drill obviously you'll need a bench grinder this is just a simple craftsman grinder no big deal you'll also need a protractor so you can check the point angle angle with a point on the drill and you'll need a six-inch ruler check the length of the cutting edges on the ruler or on the drill so to start with the first thing we want to do this is a this is a drill that I purposely mangled because all my drills are sharp I couldn't find a dull one to use so I kind of ruined it on the grinder here now we'll I'll show you how by step procedure how to take it back to its original condition first thing we want to do let's talk about point angles there's basically two different point angles on undrilled that you can buy one of us one hundred thirty five degree included angle that's intended for harder Steel's like tool steel and high carbon steel and another option is a hundred and eighteen degree included angle that's more of a general purpose drill can use it on mild steel or non-ferrous metals I like to grind all mine to 118 degrees seems to be a good all-around angle so the first thing we need to do only sharpen a drill is to establish the angle of one of the flutes since I'm going to use 118 degree included angle we're only grad in one side so that's 59 degrees we'll set our protractor for 59 degrees and then that's the angle we'll grind the first cutting edge basically just say this this is in before we going farther this is a tool rest that I don't use it as a tool rest and neither should you just rest your hands on this use that as a consider that isn't a hand rest while you're grinding is going to take place above the rest up on the wheel if you hold it up in here like this you have lots of control over it all the axes you know you have to rely on setting your rest place to get the angle hold it up in the air gives it complete freedom to move the tool around and correct for different angles coolest start grant starts establishing this 59 degree angle just kind of hold it above center a little bit above the center of the wheel take a guess at the initial angle use the full face of the wheel and grind a nice straight edge on that first first lip what you get something looks fairly good we'll check the check the angle here and see where we stand we're a little bit little bit flat so I bring crater one more on the outside of correct some we're getting pretty close now one thing I want to point out another thing I want to point out is you not only have to get that point angle correct you also have to get a little bit of clearance angle when they're cutting it in other words you want looking at it from the side you want that cutting edge to angle back a little bit you don't do that if you just make it square to the axis to the drill the cutting edge will rub behind back here and it won't cut you got a rock that burns and go back a little bit so three to five degrees is generally pretty good I'd say just just hold your girl above the centerline of the wheel you kind of you're kind of get that angle it's probably the biggest mistake people make when they try to drain grills is they don't get enough clearance behind the cutting edge just check our 59 degrees here again yep that's right on got a pretty good pretty good clearance angle going here and if we look at the cutting edge we just ground you see it goes past Center a little bit that's a good thing this first one we don't care about the length what I want to do is establish those two basic angles so we'll call that good no foot Brown the other side we'll do the same thing to the other side establish our 50 90 and gopher and before we get too far picture that's right here yeah it looks good before we get too far we want to keep track of the length of this one want to make it the same length is the first one we ground that's important because if we get one cutting edge longer than the other the drill will will wobble and that when it wobbles it will drill an oversized hole which is generally not a good thing so we'll just take our sixteenth rule here and we'll just measure the length of each cutting edge yeah about nine thirty seconds this is about quarter-inch so we got a little more to go [Music] they know didn't close to strip that 59 gree angle again make sure picture we're good there still looking good all right we will check the link make sure the length is the same we got about kids to hear over quarter inch on this one and about same on this one okay so now we got both of these cutting edges the same way which is a good thing but this drill still not ready to drill because if you look at it from the side you see if you tried tried to drill this thing it would rub back here and this is the heel of this fruit okay we have to take a secondary clearance angle to leave this back area and that's what we're gonna do next so fly it up again just as you were going to do here you're 59 angle and then raise it up a little higher on the wheel yet take a secondary [Music] [Applause] okay you can see we got started there and we want to kind of walk keep this line parallel with the cutting edge and kind of walk it up to it's just about even with the cutting edge on the opposite fruit here get pretty close here a little bit more [Music] all right here we go felt like that now flip around do the same thing to the other side you see him just rest of my my fingers on this rest so you just use the whole face of the wheel trying to work your way up to it yep the trick to learning how to grind by hand is to be able to learn how to put the tool back on the wheel on the same position and take it off to look at it long as you don't change your hand position you can set it right back down and we'll be in the same position [Music] okay looking away over it's a little bit more [Music] you alright now we got both of those really be looking at from the side you'll see that a nice secondary relief here okay larger drills like this sometimes it's a good thing even add a third angle just take a third just knock this back heel off here just to make sure nothing drags behind the cutting edge that's there's nothing critical about that just hold it up even higher on the wheel take a little more off like that okay now we have a drill that will cut it will cut a nice hole little drill nice hole to be round concise but if you look at the center here you'll see this heat they call a chisel point okay that's the web of the drill this part does not cut this just kind of pushes the metal of the side it doesn't cut so what we want to do is want to reduce the size of this chisel point as much as possible and the way to do that is to let's call thin the web all right there's lots of ways to do that sometimes we can people grind up in this area take some of that out kind of up into the point a little bit on both sides I like to use what's called a high tensile notch gave it to do that it's basically just kind of an a little angled match up in the very point here but I do what I do to to get that like that happen as I use the side of the wheel kind of speed to grow up into the corner so it's touching all around and I rotate the drill a little bit so it just puts a little notch right up in the in the corner here these same thing on the other side rotate it now you can see we have very little chisel point left this makes the drill that only easier but it makes it so much self centering and that's pretty much it I mean this drills done it took me a couple minutes here if I wasn't doing the demonstration it would have been done in under a minute I said it's just basic skills a little bit of knowledge to get started you can be sharpening your own drill that's pretty much it

Channel: Toms Techniques

Views: 6,090,810

Rating: 4.5007005 out of 5

Keywords: sharpen, drill, grinder, grind, twist drill, hand, grinding section, machining, machinist, processes, techniques, how to, turning, milling, lathe, mill, threading, thread cutting, South Bend, Logan, Clausing, Delta, Sheldon, Atlas, Bridgeport, Starrett, Lufkin, Mitutoyo, instructional, tutorial, educational, metal, metalworking, shop, machinery, tubalcain, millwork, facing, drilling, grinding, Harrison, hardinge

Id: y0SQkzScQk0

Length: 11min 27sec (687 seconds)

Published: Mon Dec 17 2012