Sharpening Drillbits

[NeoMoses]

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?

[keithorr]

Try to Google "twist drill sharp*". You'll find plenty.

[Durkee]

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.

[HomeCNC]

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.

[HuFlungDung]

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.

[Durkee]

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.

[keithorr]

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.

[HuFlungDung]

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?

[hardmill]

Darex has always been good to me

[tool_man]

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?

[Article99]

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.

[rod1947]

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