View Full Version : Sharpening Drillbits

04-25-2003, 01:27 PM
I do quite a bit of CNC drilling with 1/8" drillbits, and I'm wanting to try sharpening my own. I work mainly in aluminum and copper. Does anyone have a good tutorial on drill bit sharpening? Also, what rake angles and such should I use for aluminum and copper?

04-25-2003, 02:09 PM
Try to Google "twist drill sharp*". You'll find plenty.

05-09-2003, 05:42 PM
Some customers have been getting good results with the Drill Doctor. Others not so good. Most of my customers just throw away anything under 1/4".

Your rake is built into the drill, so you really can't change that by any means other than trying different brands of drills. I recommend a good quality 'brite' finish drill for aluminum. A parabolic cobalt drill has been our savior in copper. Keep the RPM's down and the feed up. The chip needs to be thick enough that it takes all the heat out of the hole for you. The end relief for both mat'l should be 11 - 12 degrees.

05-09-2003, 09:01 PM
I have a Drill Doctor. With a little pratice they work great! Hold the toolholder firmly against the cams and don't stop in the middle of a cut. Keep all cuts equal on each flute.

05-10-2003, 02:34 AM
We use a Darex drill sharpener, the predecessor of the Drill Doctor. It was quite the invention, and is actually as good as they say so far as being handy enough to actually use on the spur of the moment.

The trick to sharpening drills is to not give them too much or too little clearance. Too much clearance usually can be suspected whenever you hear the drill bit make a snapping sound while drilling. Sometimes the snap is really due to the fracturing of the edge, but often it is due to hogging in and releasing in soft materials. Proper clearance helps control the feed in.

As a rule of thumb, I always check that the angle of the "chisel edge web" to the cutting lips is 135 degrees ( commonly referred to as a 45 degree angle). This tells you that the clearance is about right. Parabolic drills do not follow this rule, and I find them more difficult to get the proper clearance for. I guess it is because the cutting edge is curved, it makes it hard to tell what the average angle is.

One thing about the Darex drill sharpener, is that it is very convenient to change the clearance angle by a few degrees after you have made an initial sharpening. Just loosen the chuck, put the chuck and drill back into the setting fixture and advance or retard the chuck body a few degrees (on a scale) and reclamp. I do not know if the drill doctor allows this.

High helix drills position differently on the finger stop when chucking, so it is necessary to be able to allow for this (or else the clearance will be way out of wack), and the Drill sharpener does allow it.

05-10-2003, 01:44 PM
Both of those sharpeners will do quite a nice job with a little practice. I thiink both are worth the money in a small or home shop.

05-10-2003, 02:02 PM
I use a darex M5 which I guess is now the horse and buggy version of drill sharpening.

go to http://www.darex.com/xps/movie.html for the newest toy.

And if you buy now, you'll save $2000.00 (!!!!)

Thats a lot of 1/8 drill bits.

05-10-2003, 11:06 PM
Zounds, $16,000!! That is pricey.

Because of my Scottish genes though, I simply cannot throw away a dull drill. Darex's old sales literature challenged me with the question: you wouldn't throw away a dull pencil would you?
Why would you throw away a drill that costs 10 or 20 times as much? :)

05-11-2003, 02:01 AM
Darex has always been good to me;)

03-06-2007, 02:04 AM
I was given a Darex M-4 that had been sitting on a shelf since it was purchased in 2001.Cleaned it up and tried it out.Works really well.I would love to find a point splitter and the #4846 and #4851 grinding wheels for an M-5.Darex still sells the point splitter but,it costs $279.They no longer sell the #4846 and #4851 grinding wheels.They now only offer diamond or borazon wheels at a cost of $209 each........ouch!!!!!Anyone know of a source for these items?

03-06-2007, 08:35 AM
Buy a second hand manual tool and cutter grinder with an indexing head. Slap a cup wheel on it and have fun. (Note, this'll enable you to do facet points, but not rolled. If you wanna do a rolled point on a T&C, you'll need a tricky workhead.)

Suggested point angles;

ALU - 118deg included
Cu - 100deg included (45-110 brinell)

When you're drilling the alu, you'll need to ramp up the cutting speed or even increase the clearance angles when sharpening if it has a particuarly high silicon content, to counter the chewing gum effect of the silicone on your cutting edges.

04-13-2007, 07:20 PM
Hi Newbie here ,very thick when it comes to drill bits.Can some one tell me, what is meant by point spliter.
i was going to invest in a Drill doctor.Not sure if I would have the skills to opperate it .I have collected hundreds of good quality bits over the years that are in good need of a sharpen.Are the drill doctors for people with limited knowledge of drill sharpening ? would I be wasting my hard earned cash.I do use the drill bits quite frequently.It becomes very expensive replacing the large ones each time they become blunt.
I watched a person sharpen them on a bench grinder and it looked , OH, so easy, I thought I can do that,WRONG the bits I tried to sharpen are flat out going through butter.
I supose what I am asking will the drill doctor rescue me. ?
Thanks Rod

04-13-2007, 07:25 PM
Here are a few more opinions on sharpening drill bits.


04-13-2007, 07:43 PM
I was given a Darex M-4 that had been sitting on a shelf since it was purchased in 2001.Cleaned it up and tried it out.Works really well.I would love to find a point splitter and the #4846 and #4851 grinding wheels for an M-5.Darex still sells the point splitter but,it costs $279.They no longer sell the #4846 and #4851 grinding wheels.They now only offer diamond or borazon wheels at a cost of $209 each........ouch!!!!!Anyone know of a source for these items?

Actually, those wheel prices are not bad, considering that they could easily be the last 6" wheel you will ever have to buy. If you are careful, reserve rough offhand grinding for another grinder, then these expensive wheels last and last.

Not only do they last, but they also maintain their shape very well, ie, the face stays flat, and the corners stay sharp, both of which are essential to getting a good grind every time. Use diamond for carbide and borazon (CBN) for steel tools to preserve the wheels for maximum life.

You could also check www.shars.com for certain types of diamond and cbn wheels at budget prices For the occasional user, they might be good enough to outlast you, depends on how well you can mount them on your grinder. I'd say a diamond wheel deserves a nice machined flange with a long bore to ensure running accuracy.

04-18-2007, 09:53 PM
Some of our wheels run well over $800 for tool grinding. Some are less than $100. It really is determined on the wheel type and availability. Borazon and diamond wheels can last dozens of times more than a vitrified (sand) wheel so the cost is worth the extra when using.

BTW: We have several drill sharpeners. The one I use has a 5 axis CNC control:rainfro: . We only use it for the really expensive drills though. In reality it is a full tool and cutter grinder and Sandvik uses them to manufacture those high performance drills and steptools.

Take a look and see on the manufacturer's sight www.jungner.se

04-19-2007, 01:16 AM
I ended up buying a 440 Drill Doctor,this was one of the best investments I have ever purchased for my home workshop.I sat down and sharpened about 200 drill bits that were destined for the rubbish.I estimated, by re-sharpening the bits I have just about paided for the machine.
Over the years I have thrown my hard earned cash at so called drill sharpeners,this is a tool that actually does what they say it will do.
OK Mr Drill doctor where is my commision ? just kidding.
I note that the price here in Australia is approx 3 time that of the USA .
My experience , I also found it very easy and simple to use.

10-26-2008, 01:36 PM
Sorry this is raking up an old thread. I have just bought a Drill Doctor 750X. While it does put a sharp edge on a sad looking drill bit, it is far from the standard on a new drill bit. The split point is being cut so it is overlapping the centre because the wheel mounting collet is incorrectly positioned on the motor shaft. The wheels have run out because the mounting collet has runout. This and the slender shaft give a poor surface finish, and consequently a rough cutting edge. Though bear in mind the wheel is 180 grit. IMO this is way too coarse for a tool edge.

I am about to discuss this with Drill Dotor, so I will let you know the outcome.

12-03-2008, 03:12 AM
That's sorted. I contacted Drill Doctor who initially supplied some parts FOC, but this did not cure the problem. A few phone calls and a chat with their design engineering department resulted in an impressive solution, and a vast improvement in performance. So if anyone has a problem with their Drill Doctor not performing, talk to them and discuss the problem. They really do try to help, in fact I have never had better customer service.

The Drill Doctor will not produce the results given by the machine shop grinders, but then they cost 500 times as much, however, they do give a consistent result quickly and accurately.

12-03-2008, 05:49 AM
Ok boilerman you've got me wondering what the impressive solution was? Care to elaborate?

12-04-2008, 06:09 PM
Not really, that takes all the wonder out of Christmas. If any one gets a Drill Doctor for Christmas and they find it disappointing, just get in touch with customer service.:cheers:

Drill Sharpener
01-08-2009, 05:50 PM
Me and my father have come up with a new product.. its a drill sharpening arm that pivots against a bench grinder.the result is a beautifully sharpened bit. it will sharpen bits up to 50 mm in diameter and as low as a 5 mm bit.
we are going to start manufacturing the product soon.
is this of any interest to anyone?
please check back for video demonstration and photos.

01-12-2009, 04:59 PM
Some pictures would be interesting.

Drill Sharpener
01-12-2009, 08:10 PM
hi boilerman..heres a few photos of the drill sharpener..
it will do a minimum of 5mm and a max of 50mm.we have a video on youtube.its under drill sharpener bielo. if you search that it should come up..