# How to Sharpen Twist Drills - A Skill Every Machinist, Every Drill Owner Should Know!



## BladesIIB (Apr 16, 2021)

I am sure every shop has a box of dull twist drills somewhere that need sharpening.  The steel is to good to throw away, but they rarely make it back out of the box.  Time to de mystify the myth, lore and legend to sharpening these critical tools.

When I sharpened my first twist drill some 35 years ago during my machinist apprenticeship my first thought was WOW!  My second thought was that was so easy, why doesn't everyone know how to do this.  Since then I have taught my Dad and many friends how to sharpen their own twist drills and save them money, but mostly save them time when drilling holes. 

In the video you will see how to make a height gauge for larger twist drills, and of course how to sharpen small, medium or large drills.  Starts with the larger ones since they are easier to see what is going on.  Then moves to small ones where I totally flatten a 1/8" drill and get it back in like new drilling condition in just a minute or so on the grinder.

I hope this helps you resurrect a few good drills around your shop.


----------



## Mtnmac (Apr 16, 2021)

One of the first things we had to learn in trade school, long before we were allowed to touch a mill or lathe.  In a production environment, we only sharpened drills in house by hand that were over 1/2".  Drills under 3/16 were tossed when dull, the rest were sent out to a sharpening service when we had a sufficient quantity.  Now that I'm retired, I'm back to sharpening drills under 1/2" again.  Glad I learned how to do it 40 years ago.


----------



## MrWhoopee (Apr 16, 2021)

Before we could pass first semester machine shop, Harry would grind the corners off a 3/8 bit, hand it to us and start his stop-watch. We had 2 minutes to restore it to serviceable (by HIS standards) condition. The idea was that if it took longer it was more economical to throw it away. I thank him almost every day.


----------



## BladesIIB (Apr 16, 2021)

MrWhoopee said:


> Before we could pass first semester machine shop, Harry would grind the corners off a 3/8 bit, hand it to us and start his stop-watch. We had 2 minutes to restore it to serviceable (by HIS standards) condition. The idea was that if it took longer it was more economical to throw it away. I thank him almost every day.


Sounds like a great teacher. I am thankful for mine as well. Learned many life skills in machine shop class that have served me well.


----------



## benmychree (Apr 16, 2021)

I too learned to sharpen drills even before I took machine shop in high school; they worked well enough, and subsequently I got a good deal on a Drill Doctor, leaving it behind when I sold my shop, I got a Weldon drill sharpening attachment for my cutter grinder ---


----------



## BladesIIB (Apr 16, 2021)

benmychree said:


> I too learned to sharpen drills even before I took machine shop in high school; they worked well enough, and subsequently I got a good deal on a Drill Doctor, leaving it behind when I sold my shop, I got a Weldon drill sharpening attachment for my cutter grinder ---


We had a grinding machine where I used to work for about 1 ¼” drills and larger. I don’t recall the brand. Small device that laid on the bench and it worked well. Anything smaller was done by hand and now I just do them all by hand. Worth the few minutes in the home shop for sure.


----------



## projectnut (Apr 17, 2021)

I have a little different take on drill sharpening.  While the skill comes in handy the process itself is a PITA.  Like most I had to learn it early on, and put up with the inconvenience for many years.  I worked in a prototype and experimental design shop for many years.  As in most shops the new guy gets the least desirable jobs.  In my case I drew the short stick when it came to sharpening drills.

The shop would go through anywhere from 25 to 100 drills per month depending on the jobs at hand and the material being used.  We did a lot of food processing and packaging equipment so the majority of the work was with 300 series and 400 series stainless.  The dull drills were thrown in a box and sharpened as time allowed when we were slow.

About once a month I was directed to sharpen whatever was in the box.  Most drills were between 1/1`6" and 1".  Generally anything larger was bored.  Those smaller than 1/8" were discarded since they were literally less expensive to replace than to sharpen.  Most drills only needed a touch up, but there were always a few that were chipped, broken, or overheated to the point they wouldn't hold an edge unless ground back a ways.

I found the job god awful boring and almost mind numbing.  Even at 2 to 3 minutes a drill the job took anywhere from an hour to half a day.  In the late 1980's the boss finally broke down and purchased a drill sharpener.  He also purchased a set of number, letter, and fractional drills up to 1/2" for each machinist.  Rather than go to the store room to get what was needed the smaller ones were at each persons work station.   Now rather than a single person being responsible for sharpening all the drills each machinist was responsible for sharpening their own.

Now that I'd learned to hate sharpening drills I also purchased a Drill Doctor for use at home.  In those days I was far busier than today and would often go through 25 to 50 drills a month.  I used the Drill Doctor in my shop for about 15 years before the plastic began to show signs of wear.  It became increasingly difficult to get a good profile so I retired it in favor of a Black Diamond drill grinder.

The Black Diamond is a higher end machine that makes sharpening drills a pleasure compared to doing them by hand.  When I first got it I sharpened everything I had ignored for the previous 15 years.  In total there were about 500 drills that needed to be sharpened.  It was another one of those mind numbing experiences, but I knew it was a one time shot.

I still break it out about once a month and sharpen whatever I have in the box.  These days it's usually between 15 and 25 drills that need to be sharpened.  While the skill of hand sharpening served me well for years it's something I don't aspire to do on a regular basis.

Here's a couple pictures of the Black Diamond.  It was like new when purchased from a local shop.  The best part is that it didn't cost much more than the Drill Doctor it replaced.


----------



## BladesIIB (Apr 17, 2021)

Nice sharpening machine for sure. Thanks.


----------



## MrWhoopee (Apr 17, 2021)

projectnut said:


> I have a little different take on drill sharpening.  While the skill comes in handy the process itself is a PITA.  Like most I had to learn it early on, and put up with the inconvenience for many years.  I worked in a prototype and experimental design shop for many years.  As in most shops the new guy gets the least desirable jobs.  In my case I drew the short stick when it came to sharpening drills.
> 
> The shop would go through anywhere from 25 to 100 drills per month depending on the jobs at hand and the material being used.  We did a lot of food processing and packaging equipment so the majority of the work was with 300 series and 400 series stainless.  The dull drills were thrown in a box and sharpened as time allowed when we were slow.
> 
> ...


It is for this reason that I never finished the fourth semester of machine shop class. Included in that semester was tool and cutter grinding. I was already working in Fred's shop and had seen my friend Bill spend multiple days sharpening endmills. I decided it was a skill I did not care to possess.


----------



## visenfile (Oct 10, 2021)

The skill can extend to some cost savings.  As shown on youtube a lowly masonry carbide drill can be made to perform surprising feats once drill sharpening skill is learned.   Recently I needed to convert the right side of my pedestal , 8" buffer-grinder for a guarded second grinding wheel.  The Taiwan factory had placed 3 dimples in the nose of the casting where I needed to screw in the shield plate.

After trying my best cobalt drill and only shining the dimple I went to my little HF circular saw sharpening kit.  This thing contains a small circular diamond blade and is set up to only sharpen the "rake" (sides and inside top) of  blades (not to true, or clearance). I found that it is easy to use it as a carbide sharpening center by simple installing a little wooden hand rest. Anyway...

Using offhand technique a person can create a sharp lip, create clearance, and "gash" or "thin web" of the cheap carbide drills  (?$8 for a 5 pak?).  As bought these carbide drills are a blob of carbide and braze material which interferes with the cutting lip area.  The thin , diamond blade is well suited to web thinning by holding the drill vertically (and carefully).

After modification the screw holes were made with heaps of black powder on the floor.  A proper carbide drill for a 1/4-20 hole is about $20.  I did not think  I would prevail because neither the drilling nor tapping could be properly controlled, but I was pleasantly surprised.  I have also used a modified masonry drill on spring steel.   It is fairly easy, also,  to reduce the cutting diameter of these carbide drills on the setup.  Precision...no,   fixing...yes . FYI


----------



## Brento (Oct 10, 2021)

Id love to learn how to sharpen endmills. As a hobby person or even if it were a small business job shop the money save over buying new tools would be well worth it.


----------



## homebrewed (Oct 11, 2021)

Brento said:


> Id love to learn how to sharpen endmills. As a hobby person or even if it were a small business job shop the money save over buying new tools would be well worth it.


Howard Hall has some info on sharpening end mills on his web site, and also has a book on tool sharpening.  I'm partway into making a variation of his end mill sharpening fixture, although it just sharpens the bottom, not the sides.   My version uses a differential screw to advance the end mill in finer increments than his does.  His design doesn't use collets so you have to make holders for all the different shank sizes you've got.

His web site has some updates regarding some of the projects in his book.  One of the better ones is replacing the fixed tool-rest mounting scheme with a pair of magnetic bases.  If going with a mag-base approach, be sure to get a steel plate that's thick enough to produce the full hold-down force.  Using thin steel reduces the force.  Though it might be necessary to occasionally remove swarf "fuzz" from them.

 He also has some comments regarding typos so if you make something from his book, be sure to check his web site first.


----------



## deakin (Oct 11, 2021)

this works well for me. of course you need a surface grinder
aktooling.com


----------



## jwmay (Oct 11, 2021)

homebrewed said:


> Howard Hall has some info on sharpening end mills on his web site, and also has a book on tool sharpening.  I'm partway into making a variation of his end mill sharpening fixture, although it just sharpens the bottom, not the sides.   My version uses a differential screw to advance the end mill in finer increments than his does.  His design doesn't use collets so you have to make holders for all the different shank sizes you've got.
> 
> His web site has some updates regarding some of the projects in his book.  One of the better ones is replacing the fixed tool-rest mounting scheme with a pair of magnetic bases.  If going with a mag-base approach, be sure to get a steel plate that's thick enough to produce the full hold-down force.  Using thin steel reduces the force.  Though it might be necessary to occasionally remove swarf "fuzz" from them.
> 
> He also has some comments regarding typos so if you make something from his book, be sure to check his web site first.


Harold Hall is the name I believe.




__





						Harold Hall's website index. A to C
					

Index of Projects and Processes contained within Harold Hall's web site.




					homews.co.uk


----------



## homebrewed (Oct 12, 2021)

jwmay said:


> Harold Hall is the name I believe.


Right, thanks for the correction.


----------

