Thread: Hand Sharpening Drill Bits

Kody,
I read your article with great interest and admiration.
I then went to collate the parts to print them off for reference in the workshop.
To do that "nicely", I edited the reference to the multiple parts slightly and formatted them into a single pdf document.
It's attached here - hope you don't mind. If you do, let me knwo and I'll remove it.
Cheers,
Joe

everybody wants to be a teacher....I thought Grahame was giving the lesson for us dummies
when he's finsihed is the time for you to step in and tell us how you do it
I will get to be able to sharpen a drill...at last

Originally Posted by mike48

Hi everyone

Best wishes to your wife Dean.

Dean, I am with you in that I use a drill grinding jig, and look forward to your future notes.
I like the repeatability of reasonable accuracy of drills ground in a jig.

For interest, I modified my "Craftsman" guide.
I replaced the square section with 300mm of 8 x 8 mm key steel, secured with a small screw on the forward body, so as to make this and the original bars interchangeable.
This was to enable grinding long shank drills up to 300mm long.
I added a small screw at the end of the square secrion to stop the screw adjusting unit from sliding off the end.
I removed the original sheet steel alignment Lip Rest "thing" at the grinding end of the main body, and just use a visual setup.
I made up several "trays" of various lengths from 20 x 20 thin aluminium angle, so as to hold the drill body centralised more, and to stop the drill top hold down clamp from misaligning the drill when tightened. I filed down two sides of the small metal square which is welded onto the longtitudinal adjusting screw, so as to allow the trays to slide under the square end, and to the edge of the moving casting.
I made up an extra clamp to hold down the shank end of the drill in the tray and guide, so as to improve drill axis alignment during grinding.
I added an extra screw to secure the guide at a grind angle of 59 deg, to back up the wingnut.

I use my jig bolted onto the table of a drill press, and use a slow grinding wheel on a mount in the drill chuck.
This utilises the side of the wheel, and so grinds the drill face concentically with the drill axis, similar to your setup. Thanks for your highlighting this important aspect as well.

The instruction sheets for the various guides of this generic type are a bit confusing.

I find that drill "overhang" past the end is critical for grind back angle and relief, varies with drill diameter, and I now carry out a visual check with an untouched new drill, swinging it to test and optimise the overhang for various drill sizes.

I had the time to learn how to use this guide, and it paid off for me.

I agree with you comments about this forum; very supportive, with lots of experienced people watching and helping.

cheerio, mike

Nice conversion Mike. How have you mounted it?

Ok so far this thread is generally about larger drill bits ones most of us can grab hold and do free hand. No mention of face definition of drill bit as in if it should be rounded back as I was taught for relief area, type of material being drilled or in particular small drill bits. these are the hardest for old blokes to sharpen.
Such as arthritis (even the young get it), can reduce movement.

In another thread some time back I mentioned being clouted for sharpening drill bits on the side of wheels now days it seems the way to go. Never knew I was ahead of my time

Originally Posted by eskimo

everybody wants to be a teacher....I thought Grahame was giving the lesson for us dummies
when he's finsihed is the time for you to step in and tell us how you do it
I will get to be able to sharpen a drill...at last

Grahame,

apologies for my part in steering off course in your thread.

I sometimes just get carried away.

Watching, with keen interest.

mike

I apologize also.

I should have waited until after you had finished your writeup. I hope the info that I (and others) posted doesn't discourage you from writing your tutorial. It's always nice to have several examples to look through when you're trying to learn a skill, so your tutorial is a welcome addition to the forum!

For Joe Hovel and everyone else,
Thank you so much for the great comments about my drill sharpening article, you are all most appreciated. Please feel free to use the information I presented. I only ask that it is not reproduced for profit as it took a lot of personal work to write it and draw the diagrams. When I get time I will peruse it over once more and update the info if/where it's needed. I would love to produce a video of my own technique of drill sharpening but at the moment the time required eludes me. I watched the two videos listed but I am afraid to say that I think a lot of info was left out so I was not very impressed by them. I do all my drill (and tool) sharpening using an 8" x 1" x 60 grit wheel using the normal face of the wheel. The largest drill in my collection that I hand sharpen is 3/4" but I used to also sharpen 1" and up to 1 1/4" dia.
If you read all the comments added to the Sea-Breeze post, you will I hope, find some extra info about High Speed Steel drills relating to the heat produced when they are ground. Please read the info relating to the TiN coated drills. I will do my best this week, to present on this forum, the info on how to shape and sharpen a drill to drill holes safely in shim brass and shim steel. I am hoping that I can take some close up photos to show you all how I do it.
Joe H, I tried to download your combined pages but the article did not load on my computer, feel free to use the info as you wish. I hope the others have had more success.
kind regards to you all
Kody (Joe B)

Does anyone else have troubledownloading my PDF file? I tried it on two computers and it works just fine.
Joe - you might try right-clicking and saving the file. There might be a problem with the association od Adobe with your browser....
Joe(H)

No trouble downloading or reading your pdf here

Originally Posted by jhovel

Does anyone else have troubledownloading my PDF file? I tried it on two computers and it works just fine.
Joe - you might try right-clicking and saving the file. There might be a problem with the association od Adobe with your browser....
Joe(H)

No trouble here Joe, many thanks to you, Kody and also to Grahame for yet another community benefiting effort. The efforts of the members of this forum, to help fellow forum members, is what makes it so enjoyable just hanging out here. It is just like being at a barbecue with your mates on this forum, yet we range in age from young-uns, probably not yet teen-agers, to those of us at the other end of the spectrum, with one foot in the grave and the other on a pile of banana skins. All swapping info and ideas, passing on techniques, and occasionally taking the mickey - We are all most fortunate for this space.
Cheers,
Rob.

Hi,and sorry for the delay, family stuff over the weekend.
Thanks to those that contributed as it reinforces the theory side which is important to the practical.

In order to successfully sharpen our drill bits it is first necessary to understand the basic drill bit geometry. If there is no awareness of how the drill cuts there can be little comprehension of how to sharpen it.

To successfully sharpen a drill bit three things we must recognize that there are equal :
A Cutting Angles
B Cutting edges
C Cutting edge Clearances ( following the cutting edges)

See these in the illustrations below.

Cutting angle –various materials to be drilled respond best to their specific angle for the majority of us,these will not be a concernformost of us and for the purposes of this tutorial can be left out. Those requiring same can find them by googling Drill sharpening angles.We will deal with the basic angle of 118 degrees for steel (A)

As well as being ground to the same angle cutting edges ( B ) must be the same length. One follows the other, as you can't the equal angles without equal cutting edge lengths.

The drill bit cuts in a (very) shallow helix as it slices into the bottom of the hole, so if you didn't grind the non cutting element of the face ( C ) away, it would rub against the bottom of the hole.
In turn this would overheat the drill and cause early failure.


Picture the following in your head.

When drilling ,the cutting edge on a drill bit is the front edge ,logic says it must be the highest point ,the face( the ground area behing the cutting edge ) then tapers away and below the cutting edge .

If the cutting edge not the highest point of your drill ,the bit will be sitting on the part of the drill that’s not the cutting edge , and will not cut.

See the where illustration M has no clearance. It may cut for a few moments but the heat generated will ruin the cutting edge temper very quickly. Illustration N has a clearance and produces a chip.

Now hopefully that we understand the drill geometry we can go on to learn to place and manipulate the drill bit on the grinder wheel as we shape it to obtain the best possible cutting edge .

Grahame

Put me in for lessons too...hit or miss with me!!

Hi,
This safety check list probably seems excessive but it highlights some of the things that can happen when using a bench grinder.
A few checks before start up
RING TEST & RPM MATCH
Inspect the abrasive wheel before mounting it to the equipment. Check the wheel for any visual damage. If damaged, do not use it. Inspect the wheel for internal integrity; this is the "ring test." Tap the wheel "gently with a nonmetallic implement." You can use the handle of a screwdriver or a wooden or plastic mallet for thicker wheels. You should hear a ring. If the sound is more of a thud or dead sound, you likely have a faulty, unusable wheel. Further inspect to make sure the wheel's RPM rating matches the RPM of the bench grinder. • Never operate the wet & dry bench grinder with cracked or damaged wheels.
Always replace cracked or damaged sharpening and grinding wheels immediately.

SPINDLE FIT
Ensure the hole in the grinding wheel fits closely around the spindle.

BALANCE
When a wheel has been newly fitted, rotate it by hand to check the balance before switching on the power

DUST COLLECTION
If the grinder has dust collectors or a exhaust shute , it must be in good working order. Check these before grinding operations begin. Ensure they are clear of clogged waste material and debris that may hinder safe operation.

WHEEL SURFACE IMPACTION
Unless the wheel is ‘dressed’ with a special tool, when pores become blocked or it loses its cutting surface, the operator will have to press harder to achieve the same cutting effect. These additional forces may cause the wheel to shatter. Always use the appropriate type of grinding wheel for the material to be ground. For example, using plastic or aluminium on grinding wheels designed for steel will clog the pores between the abrasive particles.

WHEEL FLANGES
Unless flanges and washers are evenly seated on either side of the wheel before the locking nut is tightened, the wheel can crack and shatter. Always ensure that the wheel has a soft washer on either side to distribute clamping pressure when the nut is tightened. Avoid over-tightening the locking nut as it can exert hazardous forces on the wheel.


TOOL PLATE /WHEEL GAP
The gap between tool plate and wheel should be adjusted to the minimum distance. • The adjustment of the spark arrestor should be made frequently, so as to
compensate the wear of the wheel, keeping the distance between the guard and
the wheel as small as possible, but in any case not greater than 2mm.

GRINDER GUARDS & SHEILDS
Guards should never be removed from a bench grinder. The guards on a bench grinder provide protection in the event of wheel failure, and protect hands and fingers from injury.

EYE PROTECTION
While safety glasses are minimum, a full face shield is always better.

LOOSE CLOTHING
Obviously ,loose clothing has the potential to be grabbed by the wheel.
Gloves are another item which are not safe for grinder use as they have been known to be caught in the rotating wheel.

WORK AREA CLEAN FREE OF SLIP AND TRIP HAZARDS
As with any work area this is a necessary precaution.

RUN UP
Before using the machine, stand aside and allow the wheels to reach operating speed to avoid injury if the wheel explodes during this time. It is the most common time for this to happen.

I now have a bit of work to do a my own grinder needs to be brought up to scratch before I take any pics.

Grahame

I am now back from the big smoke and both my wife and myself have semi recovered from the experience. My wife needs no more treatment, just 6 monthly checks so all looks good for now.

I have thought about the requirements to sharpen drill bits and have determined that there are several important things to consider.

1. The cutting edges of the drill must be set in the jig exactly vertical and the flute stop at the front of the jig should be set to hold this position. Reposition the drill to the stop after setting so drill is in contact with the stop.

2. The Jig must be adjusted so the drill contacts the surface of the grinding wheel in this vertical orientation. Move jig towards grinding wheel while it is not turning, until the drill edge just touches.

3. Grind the drill bit slowly and carefully to prevent overheating etc.

4. Finish both flutes with a small cut, without changing settings, making sure that the drill flute is connecting with the flute stop (A) on each side of the drill. All you do is release the drill clamp, turn the drill around to the other side and clamp again.

The first picture shows my current jig fitted to a slide mechanism I made when I first got this jig. The rear nut on the jig base (B) holds it to the central metal strip which moves. This nut stays tight. The front nut (C) with the rusty steel piece under it locks the slide to stop it moving. This nut is loosened to move the slide. The nut at the right hand end of the threaded rod (D) is turned to move the jig in relation to the grinding wheel. This provides accurate adjustment.

The galv pieces underneath are the current mounting arrangement which will be changed to position the drill sharpening position to 12 oclock on the wheel instead of the recommended 9.00 oclock position which produces a weak drill edge as descibed in previos post.

The rear adjustment wheel (E) on the jig has had an aluminium wheel (F) fitted next to it so it can be locked to prevent movement while grinding. This provides a fixed stop. The front wheel (G) is slowly wound to move the drill into the grinding wheel untill stopped by the rear wheel.

I found that the rear wheel would move causing a difference between each side of the drill.

The second pic is an attachment I made to sharpen larger and longer drills.

While in the big smoke I bought another sharpening jig to replace this one. The instructions with this jig say that the drill bit should protrude about its diameter from the front edge of the jig. It does not say which part of the bit this refers to. It would seem that if this is done using the outer edge of the bit it would work. I haven't had a chance to try it yet.

If you read the woodturning forum you will see I also bought other toys in the Big Smoke. A lot of my info on drill sharpening came from a web sit that I have not been able to find. I have just found it again so for more reading try this page Drill Sharpening

Any questions,feel free to ask.

Dean

Hi,
Apologies to all who may have been waiting with bated breath re the hand drill sharpening info.

I thought iIhad better check and keep you all up to date.
I have had some set backs but and hope to present the info to you to you soon.

One problem was my bench grinder the switch was not to work.Thats just been fixed but another problem I have is my Canon camera in macro is not taking pics of the quality that I can use to illustrate the process. With pics I am taking I can see the cutting edge but the clearance is out of focus badly.

Please bear with me until I get it right.

Until that time I would welcome feedback from those that hand sharpen.
Which is your pivot hand ?

Most of the internet info I can find mentions holding or pivoting the drill between the thumb and forefinger of the left hand and depress and turn the drill with the right hand.

Either this was written by a left hander or I am a bit different ( serious comment please I did not leave the door open there for)..

My drills are held ( pivoted ) in my right hand and the drill end twisted and dipped with the left.

I am am interested in what right handed blokes do in regards to which hand is the pivot while sharpened.

In the mean time I will practice with the camera so my illustrations don't look like they are taken with a cheap mobile phone .

Grahame