# Drill Bits



## djg (Dec 24, 2009)

This may be in the wrong section, so feel free to move.


Does anyone sharpen their own drill bits? If so, how or what do you use? I'm specifically talking about twist drill bits.
I've got several sets, some good, some cheapos. The other day I had to drill four 5/16" holes in low carbon (mild) steel and all of my 5/16" bits were dull and would not cut. I do use cutting fluid always when drilling/cutting metal but the bits would just sit and burn. One (HF) actually melted. So I had to drill a small hole first and then step up to a larger size.... until I could finish the size with a dull bit. I won't tell you how long it took.


Also, is there an optimum speed to turn metal twist drills under 1/2". The used 5/8" chuck bench-top drill press I bought from a machinist who rebuilt engines. So I never adjusted the belts for speed.


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## woodnthings (Jan 24, 2009)

*learn how to sharpen them!*

There are You Tubes on sharpen drill bits either by hand or with a low cost jig. I have the jig and I also can sharpen them by hand. There is a learning curve, but not all that complicated IF you start with a large one first and observe the cutting edges and relief angles.

I've had one of these for 30 years and it works best on a belt sander with the belt vertical:
https://www.amazon.com/General-Tool...D=41rF%2BH3BokL&preST=_SY300_QL70_&dpSrc=srch

As the size increases from 1/8" to 1/4" and up the speed slows down from 1500 RPM to around 500 RPM or less. A pilot hole is aways a good idea for bit 1/2" and up. A drill press allows you to put increased pressure for easier penetration. Do plan on changing the belt position for different speeds. It only takes a second and will keep your bits from overheating, losing their temper and going dull too quickly.

I've probably drilled more holes in metal than wood over the years and it's a whole different process other than having the bit spin. Feeding pressure, coolants, and RPMs all combine for success or failure.


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## Terry Q (Jul 28, 2016)

There is a company called drill doctor that makes sharpening drill bits easy and precise. There is a small learning curve, but once you get it figured out it only takes a minute or two to sharpen a bit.

I think one important thing to keep in mind is you can get by with inexpensive twist bits to drill into wood, but quality drill bits make a big difference when drilling through metal.


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## djg (Dec 24, 2009)

Thanks, I did try to sharpen one my trying to follow the curve. But as you said, practice. And I'm probably spinning too fast. I'll check.
Yes, when I drill a 3/8" hole and up I do drill a pilot first.


As for price, I do have a decent set and the cheap I reserve for wood.


I'll check into a jig.


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## Tree Hugger (Sep 1, 2011)

Terry Q said:


> There is a company called drill doctor that makes sharpening drill bits easy and precise. There is a small learning curve, but once you get it figured out it only takes a minute or two to sharpen a bit.
> 
> I think one important thing to keep in mind is you can get by with inexpensive twist bits to drill into wood, but quality drill bits make a big difference when drilling through metal.


Exactly !
I have a drill doctor at home , eyes aren't good enough to sharpen by hand anymore ( at least to my satisfaction).
Darex makes the Drill Doctor and also industrial drill sharpeners.
We have a CNC controlled Darex sharpener at work that is really awesome in it's capabilities ...so is the price $40,000.


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## Tool Agnostic (Aug 13, 2017)

I question the value of special drill sharpeners. You gotta sharpen a LOT of drill bits before the savings pays for the machine. 

I have sharpened drill bits by hand on an ordinary bench grinder. I marked the tool rest with parallel lines at the correct angle and learned to press, twist, and lift the bits against the grinding wheel with the right "flair". YouTube videos were very helpful for me to learn the technique.

I had mixed results from my drill bit sharpening. The larger the bit diameter, the easier it was to sharpen the bit well. Small drill bits did not sharpen well. They're small, which makes it difficult to get a good grind. 

That's the rub. The larger bits are easier to sharpen, but they rarely get dull for me. The smaller bits are the ones that wear out the most. Even when I use larger bits, I drill small pilot holes first, which means that there is wear-n-tear on those small bits even when I use the large ones.

I will probably keep at it, but the economics don't seem to be in favor for me as a hobby woodworker. Perhaps those special drill bit sharpeners are economical if you are a large shop and you use lots of large drill bits.


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## Terry Q (Jul 28, 2016)

You can get started with a drill doctor for $50. If you buy good bits and spend a couple dollars for a bit, a drill doctor doesn’t take long to pay for itself.

When I first bought one I went through piles of dull drill bits and it probably paid for itself in the first 24 hours after buying it.

Small bits sharpen just as easy if not easier then big bits.





In woodworking there is always more then one way to accomplish something.


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## MaintenanceMan (Jun 25, 2010)

The Drill Dr. works great, is easy to learn, and is worth every penny. 



Now sharpening hole saws... That's something I need to figure out....


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## Alchymist (Jan 2, 2011)

I hand sharpen all mine from 1/16" up. Use a magnifying headset for small sizes. A good wheel on a grinder, a little practice, and one of these.


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## Steve Neul (Sep 2, 2011)

A lot of grinders come with a groove in tool rest. This groove is made to lay a drill bit in to give you the right angle to sharpen a drill bit. For bits to drill wood it's better to use brad point drill bits and that takes a different procedure. I put a metal cut off wheel on the bench grinder.


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## FrankC (Aug 24, 2012)

When you are practicing sharpening bits put two large bolts in your vice sitting side by side, this is your 120 degree guide for a standard use bit.


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## woodnthings (Jan 24, 2009)

*I have a new in the box drill doctor ....*

I've never used it. Never had to. Bought it on a whim. Both adaptors. 
Over $100.00. :|

I use the $25.00 General Tools drill grinding jig (mine was a Craftsman from the '70's) and the smaller bits by hand. 
My largest twist drill is a 1 1/2" diameter and I have all the sizes below and many duplicates of the common sizes. I rarely buy new ones any longer since sharpening takes just seconds and the lips are at the correct angle AND the lengths are equal. If you don't get the lips equal in length, the drill won't cut accurately or just one lip will do all the cutting.

I can't imagine the Drill Doctor being any better than my setup. This You Tube proves my point:


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## epicfail48 (Mar 27, 2014)

Another vote for the drill doctor. Theyre one-trick ponys for sure, but its hard to beat 'insert bit, twist, sharp'. Ive tried the free hand route, ive tried the basic guides that you can clamp on a bench grinder, drill doctors beats them all for ease of use and speed. Larger bits are easy enough to do by hand, but smaller ones are a colossal pain. 

As far as speeds go, a 5/16 bit should be spinning about 1300rpm for mild steel. Decent feed pressure, bit of cutting oil, youll be through in no time at all with a sharp bit. Going slower wont hurt anything, but it wont help either. As for pilot holes, most of the time they arent necessary unless whatever youre using is flat-out incapable making the hole otherwise, i.e trying to drill a 1 inch hole in a benchtop drill press. Then step drilling may be needed. Any other time a pilot is used, it should only be about the size of the web, the point in the center of the drill, of the drill its piloting for. An example is a roughly 1/8" pilot for a 1/2" final drill. 

Reason being for this is standard twist drills dont like enlarging holes, the corners can grab in the material and either snap the bit or turn the workpiece into a frisbee. People are going to raise a ruckus about me saying this because "ive been doing that way all my life without issue", to which id like to respond that just because youve got lucky doing it wrong, doesnt make it the proper way of doing things.


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## NoThankyou (Mar 21, 2018)

I have a drill doctor. I don't remember what I paid for it but it is worth every penny. 

If I know that I'm going to drill a lot of holes, I'll sharpen the drill bits before I start the job. It is so nice to have the bits sharp when I start.

If you watch the video, learning is a very simple process.


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## GeorgeC (Jul 30, 2008)

My father was able to hand sharpen any drill bit as well as or maybe even better than using a jog. I used to be fair, but have not done any in so long that now I probably would be a complete failure.


George


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## FrankC (Aug 24, 2012)

I have a drill doctor and use it manly because I have been too lazy to set up the drill jig since I moved some years ago. I do prefer the drill jig because it sharpens the point differently than the Drill Doctor. 

There was a time when I could sharpen the bits by hand, I am now out of practice and the eyes aren't what they used to be.

Twist drills are not really the best for woodworking anyway and if one is only occasionally drilling metal it is probably cheaper to just buy a new bit when necessary rather than putting money out for a Drill Doctor. Fortunately most of my metal drilling is in brass so dull bits work best anyway.


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## FrankC (Aug 24, 2012)

We blame old age stopping us from sharpening bits by hand, yet the best drill sharpener my Dad had was his mother-in-law's ninety year old partner. He would throw all his dull bits in a box and when George came for a visit he would hand sharpen them for him.


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## GeorgeC (Jul 30, 2008)

There is old age and then there is OLD age. For the last few years my arthritis is to the point that it is difficult to even hold a small drill bit. 



My golf clubs have jumbo grips so that they do not slip out of my hand and hurt someone.


George


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## FrankC (Aug 24, 2012)

GeorgeC said:


> There is old age and then there is OLD age. For the last few years my arthritis is to the point that it is difficult to even hold a small drill bit.
> 
> 
> 
> ...


Tell me about it, I go to a healthy heart exercise program through the YMCA, there is a guy that plays in an over ninety softball league among us.


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## EdH (Nov 20, 2017)

Tool Agnostic said:


> I question the value of special drill sharpeners. You gotta sharpen a LOT of drill bits before the savings pays for the machine.
> 
> I agree but it seems that every time I want to drill a hole the bit is dull so Drill Dr to the rescue.


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## Brian T (Nov 3, 2018)

I was gifted a Machinist's Handbook. I discovered that the book shows 5 different tip angles 

for effective drilling in everything from Plexiglas to stainless steel.
They work.


I bought some nice s/s pots. The lids fit so well that they would airlock on cooling.
Learned that 90* for woods was inadequate but 110* goes through s/s like cheese.
Just a 1/8" steam/gas vent was all the pots needed.


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## woodnthings (Jan 24, 2009)

*Let's clarify this ....*



Brian T said:


> I was gifted a Machinist's Handbook. I discovered that the book shows 5 different tip angles
> 
> for effective drilling in everything from Plexiglas to stainless steel.
> They work.
> ...


Typical over the counter drill bits come with a 118 degree grind. None are ground to 90 degrees that I've ever seen. The 118* grind is an all purpose, middle of the road grind for metal, not meant for wood, but it will work. Here's the tip grinds for various materials:









I have drilled a fair amount of stainless steel and find that a 135* angle works best, but a Cobalt drill is best. You also need a heavy feed pressure, once it starts to cut and lubrication helps keep it cool. 

https://sppusa.com/stainlesssteel_overview.php

When the stainless steel "work hardens" from the heat and lack of feed pressure, you really have a problem and that's when a Cobalt drill will help. Those cheap Titianium Nitride "coated" bits will work, but may require several sharpenings per hole. Stainless steel comes in different "flavors", 304 being most commonly available. I used that grade on the ss parts on my "Restoration Project" a complete frame off, rebuild of a Chevy 4 X 4 pickup. 
https://www.woodworkingtalk.com/f15/restoration-project-109305/

Drilling metals is a whole 'nother topic and production drilling is different that home shop methods. Constant flow coolant changes everything when drilling metal an few, if any home shops have that system. 

Notice the various drill point angles on this drill grind gauge:


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## Alchymist (Jan 2, 2011)

Rule of thumb - the harder the material she sharper the point angle, and both sides of the lip must be of equal length, properly relieved.


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## johnep (Apr 12, 2007)

That B&D angle checker is a neat gadget. Must get one.
johnep


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## woodnthings (Jan 24, 2009)

*Not in my experience OR by the chart above...*



Alchymist said:


> Rule of thumb - the harder the material she *sharper the point angle*, and both sides of the lip must be of equal length, properly relieved.


The 135 degree angle is shown for hard metals like stainless. The 118 degree angle works for cold rolled and other softer metals. Unless you and I have different meanings of the word "sharper" ?


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## Alchymist (Jan 2, 2011)

woodnthings said:


> The 135 degree angle is shown for hard metals like stainless. The 118 degree angle works for cold rolled and other softer metals. Unless you and I have different meanings of the word "sharper" ?


My bad, should have said "flatter" rather than sharper. As the point becomes more "pointed " it is easier to penetrate harder materials.


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## Brian T (Nov 3, 2018)

About as I expected. As you can imagine(?), pot lids are not very thick, unlike pot bottoms.
My difficulty as I recall, we getting the hole started without the bit skating around.
It did not have a useful tip angle so I changed that for 100% success.
My Machinist's Handbook was a useful reference.


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