Sharpening twist drill bits freehand

[Derek Cohen]

For many years I have used a Drill Doctor to sharpen drill bits, always feeling a little guilty as I have prided myself in sharpening just about anything freehand. This is excusable for very small bits, but 1/8" and up should be doable by hand ... well, I have seen these demonstrated for some years. Anyway, recently I decided that it was time to learn, and especially with bits 3/8" and up since these were time-consuming on the Drill Doctor.


For woodworking, twist drill bits have a 30 degree slope to each side. One cannot, however, simply grind the side slopes square and expect them to work. The cutting edge requires a relief angle otherwise it will not cut. In other words, sharpening a drill bit is not like sharpening a chisel or plane blade - the drill bit cutting edge needs to be both square (at the face) and rounded (from the face back).


To train my hand, I came up with a guide (or jig). This presents the bit to a bench grinder wheel at 30 degrees, and then holds this constant as the bit is lifted against the wheel to create the relief. Here is the guide ...


https://i.postimg.cc/wxbHrjyX/2.jpg



The fence lies at 60 degrees to the front, and there is a 19mm (3/4") dowel to rest the bit on.


https://i.postimg.cc/rsbkRfXn/1.jpg



The jig is clamped to the platform on my bench grinder (which uses an 80 grit CBN wheel here).


https://i.postimg.cc/Gh8rnnGZ/3.jpg



The drill bit is pushed along the fence and against the wheel, with the cutting edge on the horizontal ...


https://i.postimg.cc/FsMv9Cx1/4.jpg



Once the cutting face is ground, rotate the drill bit upwards so the the back is ground at an angle (actually, it should be rounded). That is the relief edge ...


https://i.postimg.cc/JhmWXyvL/5.jpg



The result is like so ...


https://i.postimg.cc/Px5s6gdV/6.jpg



Proof of the pudding ...


https://i.postimg.cc/g0DbHzb6/7.jpg



Regards from Perth


Derek

[Frank Pratt]

Great idea! I sharpen them by hand as well and this will help.

[Edward Weber]

Title is a bit misleading IMO
Using a grinder platform and a guide jig is not what I would consider "freehand"
Your results look good, glad it works for you

[Cameron Wood]

Aren't you showing that backwards? Lower the bit to create the relief angle.
Do you have a drill gauge?

[Tom M King]

I like the jig. The relief angle is nothing like as critical for drilling wood as it is for metal. As long as there is plenty of clearance cutting wood is easy for it, but having the least bit too much for drilling metal shortens the cutting life noticeably.

[andy bessette]

Aren't you showing that backwards? Lower the bit to create the relief angle...

This.

Though I have a Drill Doctor and other aids, I now usually just sharpen freehand. Easiest to learn using the side or the wheel, no support. But I'm usually drilling stainless.

[william walton]

Glad you're getting better results. I'm getting old now and eyesight isn't what it was, but still remember the way i learned in machinist apprenticeship. This was one of the first things we were taught, along with memorizing all decimal equivalents.

[Bill Dufour]

Looks like a little web thinning is in order.
Bill D

[andy bessette]

...memorizing all decimal equivalents.

That memorization has stood me in good stead. Though I have to think about the 64'ths in the larger sizes. Especially since my 80'th birthday. :)

[Derek Cohen]

Aren't you showing that backwards? Lower the bit to create the relief angle.
Do you have a drill gauge?

Cameron, you're correct! I took these photos a few weeks back, and lost the memory of what was happening at the sharp end.

Also .. Edward, note that the jig is to train the hand. I could have stated that in the title - more accurate, but not as direct.

Regards from Perth

Derek

[Tom M King]

In the pile of machinist tools that a dear friend left me when he passed is an old yellow Darex drill shapener. It has a bunch of collets that go with it, and probably has everything that came with them. I used it once but don't have anywhere to set it up. Drill bits come out just like they are new. I just freehand mostly.

This is a newer and I'm sure better model, but the old one does a fine job. This is the bottom of the line. I'm not sure which model the old one is comparable to, but I doubt the bottom of the line.

https://darex.com/shop/sharpeners/v-390-drill-sharpener/

[andy bessette]

...
https://darex.com/shop/sharpeners/v-390-drill-sharpener/

Looks like quite a nice piece of gear.

[Tom M King]

The old ones, like the one I have, is more like a regular bench grinder with an attachment on one side for drill bits. There is a collet for every size bit instead of a chuck, but there also is a chuck I guess for oddball things. I haven't spent much time messing around with it. My friend was a welder for NASA and when they stopped the Apollo program he spent another career teaching welding and machining. They closed the program when he retired, and he ended up with all the equipment. We became good friends while he was building a house for himself next to one of my spec houses while I was building it. He left me all his tools. That's the second shop I need to build.

Here's one like the one I have. It does a perfect job with a drill bit. https://www.ebay.com/itm/266347472034?hash=item3e038be4a2:g:1l8AAOSwafZkwBh e&amdata=enc%3AAQAIAAAA0O0qIIMbgjnMEIFSIZD6Ly2MG872M 6jz8zx1Z%2BEx4JmA433PFU25sR6O5Vh5IVvYnM1CjJ9QEcPPP ooUvB%2FZKnER2mufuD61w1aq7368VgavC5jHkthu3uy%2FifB WCiROxfRCRTt3kp%2FjrOHqEZd37cN8URgYFqN%2FWK1pyVmrv 4nRdTNOF29gyXbzqFPlFgFiZpp1DhtJkDy8rblLMyJmLk%2BYB vUxmWg%2Bum1Vr1koE0UQMmRasnAElMfvy5770qVSODi64lalp p%2BWd1qHFXMlO%2Fw%3D%7Ctkp%3ABk9SR7bLkJT4Yg

[Cameron Wood]

Brad points are easily made.

510224

[Edward Weber]

Cameron, you're correct! I took these photos a few weeks back, and lost the memory of what was happening at the sharp end.

Also .. Edward, note that the jig is to train the hand. I could have stated that in the title - more accurate, but not as direct.

Regards from Perth

Derek

Derek, I believe you and I have a slight difference in the english language we use.

To me, "freehand" means without the aide of jigs, reference surfaces or measurements.
Seems like a bit of clickbait to me.

[Tom Bussey]

If you buy a jobber drill out of a hardware store the drill point angle is a 118 degree included angle not 120. It is a 59 degree angle and not a 60. The other normal angle that it can come in is 135 included angle. I am sure one can get them in about any angle for special applications. Having said all that any angle close to that will work. The main points a to look out for are is that they are as close to the same angle as possible and the flute lengths are as equal as possible. I sharpen free hand but it does include a drill gauge. I like to stay at 59 degrees as closely as possible. It is easy to change angles when grinding and it is also easy to get one flute longer than the other. Hence the gauge which also has lines on it and I veneer the lines. Just so you know if drilling copper ,copper likes a single cutting edge not 2 so the drill point is drilled odd center with one flute longer that the other. Copper conducts heat very well and it can heat up and actually cease the drill bit.

Having said that steel on the other hand likes flutes of equal length. Also a drill of one flute being longer than the other will also drill a larger hole than the drill size That is where probable hole size comes into play

Now to sharpening. First of all you have to train your mussels so do not expect preface points right out of the gate. Place the drill onto the wheel ( eyeballing the angle of the point parallel to the grinding wheels face). I use 2 hands one top close to the wheel for support ad the other closer to the body . one closest to the body is dropped down and there is a twisting motion at the same time. Do not ride the drill point up the wheel but the grinding should be dun when the point is dropped. You can move it up and down the wheel but do not let it ride up always down. You will know when you are at the cutting edge because you should be see sparks come over the the cutting edge than drop the body hand and slight twist the drill at the same tine.

I bench grinder works best for this operation and the stones that come on the grinder will work but for me a 180 CBN wheel is ideal. Fine enough to get a good sharp edge but course enough to remove metal without heating the wheel. I find it easier to feel than a regular stone.. Some will argue a belt sander works great but the sanding belt comes away from the platen and actually make the cutting edge duller and I think the using of a belt sander is the stupidest idea I have eve heard. But what do I know I only taught Machine shop for 10 years at a community college.

[Cameron Wood]

If you buy a jobber drill out of a hardware store the drill point angle is a 118 degree included angle not 120. It is a 59 degree angle and not a 60. The other normal angle that it can come in is 135 included angle. I am sure one can get them in about any angle for special applications. Having said all that any angle close to that will work. The main points a to look out for are is that they are as close to the same angle as possible and the flute lengths are as equal as possible. I sharpen free hand but it does include a drill gauge. I like to stay at 59 degrees as closely as possible. It is easy to change angles when grinding and it is also easy to get one flute longer than the other. Hence the gauge which also has lines on it and I veneer the lines. Just so you know if drilling copper ,copper likes a single cutting edge not 2 so the drill point is drilled odd center with one flute longer that the other. Copper conducts heat very well and it can heat up and actually cease the drill bit.

Having said that steel on the other hand likes flutes of equal length. Also a drill of one flute being longer than the other will also drill a larger hole than the drill size That is where probable hole size comes into play

Now to sharpening. First of all you have to train your mussels so do not expect preface points right out of the gate. Place the drill onto the wheel ( eyeballing the angle of the point parallel to the grinding wheels face). I use 2 hands one top close to the wheel for support ad the other closer to the body . one closest to the body is dropped down and there is a twisting motion at the same time. Do not ride the drill point up the wheel but the grinding should be dun when the point is dropped. You can move it up and down the wheel but do not let it ride up always down. You will know when you are at the cutting edge because you should be see sparks come over the the cutting edge than drop the body hand and slight twist the drill at the same tine.

I bench grinder works best for this operation and the stones that come on the grinder will work but for me a 180 CBN wheel is ideal. Fine enough to get a good sharp edge but course enough to remove metal without heating the wheel. I find it easier to feel than a regular stone.. Some will argue a belt sander works great but the sanding belt comes away from the platen and actually make the cutting edge duller and I think the using of a belt sander is the stupidest idea I have eve heard. But what do I know I only taught Machine shop for 10 years at a community college.



Good info- I didn't know that about drilling copper. That's where I learned- community college machine shop. Didn't think highly of the instructor, 'tho- he spent almost all his time with the advanced students.
I think mussels would be very hard to train. :rolleyes:

[Derek Cohen]

If you buy a jobber drill out of a hardware store the drill point angle is a 118 degree included angle not 120. It is a 59 degree angle and not a 60. The other normal angle that it can come in is 135 included angle. I am sure one can get them in about any angle for special applications. Having said all that any angle close to that will work. The main points a to look out for are is that they are as close to the same angle as possible and the flute lengths are as equal as possible. I sharpen free hand but it does include a drill gauge. I like to stay at 59 degrees as closely as possible. It is easy to change angles when grinding and it is also easy to get one flute longer than the other. Hence the gauge which also has lines on it and I veneer the lines. Just so you know if drilling copper ,copper likes a single cutting edge not 2 so the drill point is drilled odd center with one flute longer that the other. Copper conducts heat very well and it can heat up and actually cease the drill bit.

Having said that steel on the other hand likes flutes of equal length. Also a drill of one flute being longer than the other will also drill a larger hole than the drill size That is where probable hole size comes into play

Now to sharpening. First of all you have to train your mussels so do not expect preface points right out of the gate. Place the drill onto the wheel ( eyeballing the angle of the point parallel to the grinding wheels face). I use 2 hands one top close to the wheel for support ad the other closer to the body . one closest to the body is dropped down and there is a twisting motion at the same time. Do not ride the drill point up the wheel but the grinding should be dun when the point is dropped. You can move it up and down the wheel but do not let it ride up always down. You will know when you are at the cutting edge because you should be see sparks come over the the cutting edge than drop the body hand and slight twist the drill at the same tine.

I bench grinder works best for this operation and the stones that come on the grinder will work but for me a 180 CBN wheel is ideal. Fine enough to get a good sharp edge but course enough to remove metal without heating the wheel. I find it easier to feel than a regular stone.. Some will argue a belt sander works great but the sanding belt comes away from the platen and actually make the cutting edge duller and I think the using of a belt sander is the stupidest idea I have eve heard. But what do I know I only taught Machine shop for 10 years at a community college.


Thanks Tom. As you have written, 59 degrees is the angle when supplied. I chose 60 degrees for the jig as this is easier to measure. Plus, the wood cannot tell the difference. I am sure that when freehanding the drill but face on the grinder wheel, the angle will change slightly anyway.

I think the easy way to remember what to do when grinding (I trust my earlier correction of the photos did not confuse this) is to start with the cutting edge and then rotate the bit to grind the relief.

To repeat what I wrote at the outset ... this jig is to train the hand.

Regards from Perth

Derek

[Derek Cohen]

Years ago I was advised to increase the cutting angle (with a micro bevel) when cutting brass and copper. I do this with a diamond hone. It seems to stop the grabbing.

Tom, can you comment on this?

Regards from Perth

Derek

[Tom Bender]

A long time ago, as a young engineer working in a large manufacturing facility I saw a note offering a drill bit sharpening class. It was given by an old machinist on the midnight shift which meant coming in an hour early. I was the only student. We started with a 2" bit which made it easy to see and understand. It's been a lesson more useful than hundreds of calculus classes I've sat thru. Same with the welding class.

[Tom Trees]

I think I found AvE's video the most helpful, in regards to successfully showing the technique clearly, even with the comical angle grinder bodgery,
whilst also the most entertaining to boot.
Plenty of obscenities in this one, so some might want headphones.
https://youtu.be/FgcESWoJ3CU?si=C7l-2F96D9ZPs9Fh

[Tom M King]

I have one unusual circumstance for hand sharpening a drill bit. The blades I like for my mower don't come with a 3/4" hole that it requires. I buy them with 5/8" holes and drill out the hole. The Gator blades are hardened, which I found out the first time means the whole blade. I bought some 3/4" cobalt bits.

I put a 5/8 bit in the drill press, put it down through the blade hole, and clamp the blade to the drill press table. That leaves the enlarged hole centered, and the blade doesn't require much balancing.

I might get one hole until it breaks off the corners of the 3/4 bit even with plenty of lube. I probably have to stop 4 or 5 times to resharpen the bit to do three blades. I don't care about the angle, since I'm only using the outside 1/16 anyway. As the angle gets sharper, the better it cuts for this job. I guess I'm getting it closer to being a car reamer.

I have a 3/4" car reamer, but I'm afraid to use it on this hardened steel as it's much more valuable than a drill bit. Comments are welcome. I'm sure the other Tom knows about this. It's just guesswork for me.

I not only like these blades better, but they last at least twice as long and are $45 cheaper for a set of three mower brand blades. The $35 dollar bit is paid for in one set, and so far I've gotten three sets done with one bit.

[Steven O Smith]

Have you tried heating just the area you're drilling? Clean the metal so it is bright, heat until it turns blue, quench to keep the heat from getting to the blade edge.
It should be *lots* easier to drill.

[Tom M King]

That might work, but this only takes a few minutes including any bit grinding. Once in a while I can drill all the way through without having to sharpen the bit. My torch would require longer than that to dig it out from behind other stuff crowded in that shop. Right now, my mechanic shop is serving multiple purposes with the main purpose being tool storage. Into too many other jobs to build the other shops I need right now.

There are a number of things I could do to make this job quicker, but all take longer than the time to get it done like this. One set of blades lasts me a whole season here, which is about 50 hours with that mower.

[George Yetka]

Now you have to sell them.

[Steven O Smith]

Tom, have you tried heating just the area you're drilling? Clean the metal so it is bright, heat until it turns blue, quench to keep the heat from getting to the blade edge.
It should be *lots* easier to drill.

[Tom M King]

Steven, please read my last post. It's not hardened a lot, just enough to be more work than A36. It's only a few minute job as it is, and I only have three of them to do a year.

[Steve Demuth]

Brilliant.

[Paul Saffold]

Tom, have you tried heating just the area you're drilling? Clean the metal so it is bright, heat until it turns blue, quench to keep the heat from getting to the blade edge.
It should be *lots* easier to drill.

Quenching it will harden it.

[Steven O Smith]

Tom, sorry about the repost. My settings were wrong, which kept me from seeing my first post. I wrote it again--still couldn't see it and went over to the Tech Support forum. Now I see both!
Sounds like you have a working solution.

Steve

[Steven O Smith]

Paul, quenching will only harden it if it gets hot enough to glow. If you stop at the point where the oxide colors are blue and quench, the steel is nicely machinable. Varies a bit depending on alloy, you won't soften air hardening steels this way.

[Paul Saffold]

Paul, quenching will only harden it if it gets hot enough to glow. If you stop at the point where the oxide colors are blue and quench, the steel is nicely machinable. Varies a bit depending on alloy, you won't soften air hardening steels this way.

Steven, thanks for explaining.

[Wes Grass]

Brass = zero rake. The tiniest little bit of 'blunting' the edge parallel to the axis of the drill will do it. Not really a huge deal, until you're breaking through the off side. IOW, blind holes, don't bother.

Muscle memory is what I use. And eyeball the 'chisel' at the center for ... 'center'.

It's just a drill. Yeah, for wood it's more likely for a finished size than for metal work ... clearance holes for screws aside. Split point stub 'screw machine' drills outnumber 'jobbers' in my cabinet by at least 3x. Something important gets a new one ... pretty hard to regrind them properly with the split. I've free-handed a few large ones, just to reduce the thrust required. It's kinda hard on the quill feed of a mill.