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View Full Version : Drll bit sharpening question...people w/out drill bits need not read.



Your Old Dog
04-11-2010, 08:01 AM
I have a Drill Doctor and I know how to use it ;)

I have a set of 118 degree drill bits. After reading a thread on the topic a week or so ago I wanted to sharpen one to 135 degrees and split the point... all of which I know how to do on the Drill Doctor.

My question is this, after meeting with meeting with no success I'm suspecting the web on a store bought 135 might be thinner then on a 118 bit. Is that right? Sharpening a 118 to 135 leaves a web to wide to split in my opinion? Anyone have experience with this?

John Stevenson
04-11-2010, 08:09 AM
Sorry can't help because I don't have any drill bits :D :D all mine are in one piece.

Your Old Dog
04-11-2010, 08:24 AM
Sorry can't help because I don't have any drill bits :D :D all mine are in one piece.


You got brown eyes? :D

John Stevenson
04-11-2010, 08:26 AM
Dunno, can't see them .

Peter.
04-11-2010, 08:48 AM
Dunno, can't see them .

THe correct answer is: just the one :)

Duffy
04-11-2010, 09:57 AM
YOD:_ Obviously Your question is too trivial to rate an answer! It seems to me that somewhere in China factory #19B, there are a bunch ogf machines fed on bar stock, (rod stock?) that spit out different sizes of spiral-grooved little rods. These then go to the pointing machines for either a 118* or 135* point. If that is how drills are actually made, it makes no sense to have differing web thickness. Perhaps for different MAKES, or DESIGNS, but I dont think that is what you meant.
Just my thoughts after rolling around on the floor over all that INCREDIBLE wit! Duffy

Rustybolt
04-11-2010, 10:09 AM
The web thickens the further down you go. On most drill bits. There were some early deep fluke drill bits that were pretty consistant most of the way down.
If your drill bits are from different manufacturers there will be a difference.

sidneyt
04-11-2010, 10:15 AM
I have a Drill Doctor and I know how to use it ;)

I have a set of 118 degree drill bits. After reading a thread on the topic a week or so ago I wanted to sharpen one to 135 degrees and split the point... all of which I know how to do on the Drill Doctor.

My question is this, after meeting with meeting with no success I'm suspecting the web on a store bought 135 might be thinner then on a 118 bit. Is that right? Sharpening a 118 to 135 leaves a web to wide to split in my opinion? Anyone have experience with this?

I have reground drills that were originally 118 degrees to 135 degrees more to see if I could do it with a "pit bull" type drill sharpener as shown here on gadgetbuilders web page:
http://www.gadgetbuilder.com/DrillSharp.html (scroll down towards the bottom of the web page)

You can thin the web of a drill bit by hand if the drill is large enough like James Harvey shows on page 154 of his book Machine Shop Trade Secrets. I tried this with a ~ 1/2" drill bit and I was fairly successful getting it right. I just eyeballed the angle and tried to get the same amount ground off each side. Gadgetbuilder discusses the Honedrill fixture which can be used to thin the web of smaller drill bits. I have not built one of these fixtures, but I can see how it would be useful.

I sharpen drill bits using the above mentioned pit bull drill sharpener on a surface grinder using a cup wheel.

moldmonkey
04-11-2010, 10:39 AM
I have always seen it the other way around. 135* having a thicker web with them needing to be split-point. Going from 118* to 135* I'm not sure on the geometry.

I personally put split-points on rather than just web thinning. Easy to do freehand with a well dressed stone.

By the way, what Sir John is refering to is that in the trades they are called drills and the handheld things they go in are drill motors. Lots of different trades, apparently both sides of the pond.

J Tiers
04-11-2010, 10:57 AM
maybe your problem is the inherent suckiness of the Drill Doctor......

I have one (headed for recycling) and I know how to use it, but it never did do a good split point, it is apparently seriously misaligned and leaves a square area around the point on the drill for any smaller drills under about 0.312".....

it has also got other problems, like requiring the drills to be hand=alined by trial and error until, they sharpen with positive relief, since using the alinement tool in the DD they come out with reverse relief if under around 0.312".

Worked really well for about 50 drills, has sucked bigtime ever since, but wheel is NOT worn. The drill tip can move around at least 0.125 inch, since the collets are that loose in the tube....which just can't be right or good.

websterz
04-11-2010, 11:40 AM
The best time a machinist can spend IMHO is learning how to sharpen a drill bit freehand. I worked for several years in a shop where we had machines for sharpening everything from a #60 thru a 3" diameter drill. They were way across the shop from me, but the 12" disc sander was right there. It took me about an hour to get the feel for it and I have been sharpening by hand ever since. It's a good thing I learned when I did too. Now that I am no longer working for a machine shop I have to sharpen all my own drills. :rolleyes:

J Tiers
04-11-2010, 12:01 PM
DISC sander works

A belt may not, because it tends to round over the edge. So if you have a combo unit, use the disc side

lazlo
04-11-2010, 12:09 PM
I have one (headed for recycling) and I know how to use it, but it never did do a good split point, it is apparently seriously misaligned and leaves a square area around the point on the drill for any smaller drills under about 0.312"....

People either love or hate the Drill Doctor :)

I have the 750x, and it works great, but the point splitter does suck. It seems like it goes too deep:

http://i164.photobucket.com/albums/u15/rtgeorge_album/split.jpg

Compare my picture to the Drill Doctor video (that comes with the unit). I'm doing something wrong:

http://i164.photobucket.com/albums/u15/rtgeorge_album/vlcsnap-3049245.png

J Tiers
04-11-2010, 12:18 PM
Well, the collet is filthy............might that be a problem???

The problem with the point splitter, apart from alignment, is that there is no "stop".... you can go too far easily and quickly. or at least you could on mine.

Carld
04-11-2010, 12:24 PM
Learn to do sharpening and split point freehand and your problem is solved.

rode2rouen
04-11-2010, 12:29 PM
maybe your problem is the inherent suckiness of the Drill Doctor......





FTFW!!!!!!!!!!!!!!!! :p


Rex

wierdscience
04-11-2010, 12:41 PM
Standard jobber drills have consistent web thickness over the whole usable length,taper length drills get thicker as they get shorter.

Either type the web is thicker on bits intended to be ground 135 and split.

That said,split point drills have thicker webs,because well,they are intended to be split.

I never buy 135* split points,118* does everything they will.

Drill Doctor?What's a drill doctor?:D

BobWarfield
04-11-2010, 12:49 PM
The drill doctor (I am using lowercaps advisedly) can't take too much pressure. Push on it too hard and the plastic bends. Then again if you push too little it doesn't do much of anything.

This is a precision device, accurate to microns. It's just that they're not the microns you want. It has its own idea of where all those little microns are.

With all that said, it beats not having any sharpener at all for small bits. For bigger ones, it starts to be questionable. Seems like "big" starts at 1/4". YMMV.

Cheers,

BW

lazlo
04-11-2010, 01:06 PM
Well, the collet is filthy............might that be a problem???

It's actually pretty clean. I took that picture when I first got the Drill Doctor, so that's one drill's worth of grinding grit. :) It's just tough to take a macro picture of a 1/4" drill bit on a point-and-shoot camera, so the grit is reflecting a lot.


The problem with the point splitter, apart from alignment, is that there is no "stop".... you can go too far easily and quickly.

My thoughts too -- a stop might fix a lot of that...


With all that said, it beats not having any sharpener at all for small bits. For bigger ones, it starts to be questionable. Seems like "big" starts at 1/4". YMMV.

Very true. A good friend here sent me a real drill sharpener, but I need to learn how to use it :o

JoeLee
04-11-2010, 01:18 PM
I have a drill Dr. as well and have noticed the same thing on some bits when I split the point, not all. My guess was that it was related to the web thickness of various manufacturers of bits. Hoever as far as the stop goes, there is none as was mentioned in one of the previous post. You just have to peck away at each side until it looks good. All in all it works fine and I'm very pleased with the results it gives.

JL....................

GadgetBuilder
04-11-2010, 01:50 PM
I suspect the thicker web isn't related to the point angle; the thick web makes the drill a bit :) stronger at the cost of slightly less room for chip evacuation.

I split the point on an old 118 degree HF bit and found the web was much thinner than a bit purchased as a split point:
http://www.gadgetbuilder.com/PointSplit%20004.jpg

Generally points are split on bits with thick webs to reduce drilling pressure required and the thick webs are chosen by the manufacturer to make bits stronger so they can take more abuse.

I prefer using sharp bits so I've tried lots of ways to sharpen them. Point splitting on small bits is difficult because I don't know how to sharpen the corner on the Brooks' CBN wheel and it takes a very sharp corner for this. So I use small bits with a 4 facet point to drill pilot holes; small bits drill well with modest pressure. Larger bits drill with modest pressure without a split point when the pilot hole is about the size of its web. So this non-solution means I seldom split points but always drill pilot holes.

John

Willy
04-11-2010, 02:59 PM
First of all I'd like to second what GadgetBuilder said. My experience almost mirrors what he said.
When I do need to split points I use a method loosely based on this method:
http://its.fvtc.edu/machshop1/bench/Webthinning.htm

Second point I'd like to make will only be appreciated by some of the older boys here.
I don't need no doctor (http://www.youtube.com/watch?v=LZMmV6xXYFw).
Sorry Tiffie, but I too would like to add a couple of irrelevant links that nobody bothers to link to anymore.:D

Third point...you got some pretty big cajones mister, posting a thread title like that. Some of us don't even believe in drill bits and would rather use a punch press or an edm, or even a, (god forbid, oh damn I did it again!) a torch, but we don't have a choice. So don't come to us with that hole-ier than thou attitude telling us how to deal with drill bits, when some here don't even want the darn things in our shops. Most of us only use the darn things cause we have no other economical choice.
A part of society that has fallen through the cracks, too poor to buy an edm...forced into a lifetime of dealing with dull drills and the people that sharpen them. :D

Alistair Hosie
04-11-2010, 03:45 PM
It's like when they ask me
*IS THERE ANYTHING WORN UNDER YOUR KILT* and I reply *CERTAINLY NOT* IT'S ALL IN GOOD WORKING ORDER.:D

Oldbrock
04-11-2010, 05:50 PM
I'm with Websterz, been at this for too many years and have always sharpened my drills freehand. Bought 100 3/8 cheap drills when I was teaching and the students all had to grind an acceptable drill point - two even curls from the drill and hole size not more than a few thou oversize. Took some of them a week to master it but master it they did then went home and sharpened dad's drills for him. Taught in a farming community so most of the students had shops at home.
Did use one once I remember when I was an apprentice to grind a 2 1/16" drill but that's the only time. Peter

J Tiers
04-11-2010, 06:13 PM
All you folks who sharpen by hand...... I do it too....

But I'm NOT going to claim that I can do it better than a decent drill sharpener.... When I am done it is sharp, and the two edges cut reasonably evenly... But even the DD, with its faults (back when it really worked for the first 50 drills), did a more consistent job, faster, than hand sharpening.

BobWarfield
04-11-2010, 07:54 PM
It's like when they ask me
*IS THERE ANYTHING WORN UNDER YOUR KILT* and I reply *CERTAINLY NOT* IT'S ALL IN GOOD WORKING ORDER.:D

Go ahead and wear it out Alistair, we're only here a short time...

Cheers,

BW

Your Old Dog
04-11-2010, 09:20 PM
All you folks who sharpen by hand...... I do it too....

But I'm NOT going to claim that I can do it better than a decent drill sharpener.... When I am done it is sharp, and the two edges cut reasonably evenly... But even the DD, with its faults (back when it really worked for the first 50 drills), did a more consistent job, faster, than hand sharpening.

BINGO, it takes a real man to handle a drill doctor and it's not for whimps :D

I can, have and do sharpen by hand on my grinder. I've done it that way until I wized up and bought a drill doctor 750DX as it does a better job then I can by hand. When I use the Drill Doctor (note I'm using caps!) I find I get equal size chips out of both flutes. Occasionally, when I sharpened by hand only one flute did all the work. I have the feel for the Drill Dr now and only need a second to use it.

Thanks gadget builder, I saved off your link and will read it over more carefully but the example you showed is what I've been getting.

I'm contemplating buying a few more Drill Doctors just to spot around the shop!

oldtiffie
04-11-2010, 10:48 PM
I have non real problem with hand-grinding drills - even though I have two perfectly good industrial level drill-sharpeners - which are a bit of a PITA to set up and pull down on the T&C or surface grinder/s - but they really do work very well.

I "web thin" by hand either with a good wheel with a sharp edge on my T&CF or surface grinders - and if bigger - on my pedestal grinder.

I also use my "Proxxon" high-speed grinder and well - a truly good machine. My air-driven die grinders went straight into the *hit tin as soon as I realised just how good that "Proxxon" was.

Web thinning is only needed if a pilot drill is not used. If the pilot is larger than the core/web and all cutting is done on the cutting edges, there is no need for "thinning" nor is there any need to try and force the chisel point either.

I start off with a 1/8" or 1/4" drill - "thinned if necessary" and then follow up with larger drills in succession. Its easier on the drills, the machine and the operator - and its pretty quick too.

I centre-punch every hole unless there are compelling reasons why I should not.

If I am drilling a part on the mill, I will just "spot" or "start" the drill (or use a centre drill) there and then take it off the mill and finish drilling it on the pedestal drill - and only change each drill once.

BadDog
04-11-2010, 11:35 PM
I've got 2 drill sharpeners, and have owned several others, including a DD750. The best I've ever seen for day to day use with little or no hassle is the SRD/TRD grinder.

NzOldun
04-12-2010, 02:31 AM
Way, way back when I was a green 15 yr old apprentice, the shop where I started had a dedicated drill grinding machine. I can't remember the name or much in the way of detail, but the mode of operation was, with the bit held at the lip angle (59deg?) the bit was power rotated about its own axis and at the same time oscillated back and forth slightly, again on the principal axis. Thinking about it, clearly the oscillations must have been twice per rev and there must have been a reference point to set the drill bit lip to, before starting.

The grinding wheel was about 10-12" dia. x 1" wide (approx) and grinding was done with the periphery of the wheel, more or less on center. I can't recall whether the bit was horizontal, or slightly lower, or if there was any slight sideways oscillation.

Ring a bell with anyone??

beanbag
04-12-2010, 06:41 AM
For general purpose drilling of metals, is there any reason NOT to have a split point?

And if I have a stub length split point, is there still a need to spot/center drill first?

krutch
04-12-2010, 05:44 PM
I have two Darex drill sharpeners, one for HSS and one for carbide drills. Also have accessory for left hand drills,as I use them for broken stud/bolt removal. I split point 118s along with 135s. Seem to work OK for what I do, so far. I don't regret getting them (sharpeners), but I also hand sharpen. I especially hand touch broken drills before taking them to the Darexs'. Used a drill doc. at a place I once worked and was not too impressed with it. But it was used by lots of 'machinists' there, and I use the word machinist very loosly. The DD was quite abused by the time I got involved with it. I wound up hand sharpening as it was much quicker and better finish. Did I say it was abused? I had a Black & Decker sharpener some years ago, but it was hard to use. The wheel had an angle on the face and the drill chuck seemed too sensitive to pressure when useing it, making it take too long to get both lips to the same angle/length.
Krutch


MCAPTWandering

JimMin
04-12-2010, 06:15 PM
I have a Drill Doctor and I know how to use it ;)

I have a set of 118 degree drill bits. After reading a thread on the topic a week or so ago I wanted to sharpen one to 135 degrees and split the point... all of which I know how to do on the Drill Doctor.

My question is this, after meeting with meeting with no success I'm suspecting the web on a store bought 135 might be thinner then on a 118 bit. Is that right? Sharpening a 118 to 135 leaves a web to wide to split in my opinion? Anyone have experience with this?

From my apprenticeship days many years ago we were taught how to sharpen drills to perform many functions, the greater the drill angle the less effort is required to drill as there is a smaller cutting surface but it has a possible tendency to wander the greater the angle, the web thickness can be reduced by keeping the cutting face parallel (or the outside edge of the drill land slightly away from the wheel) to the side of the wheel and reducing the web as it touches the outer rim of the wheel.
You can effectively reduce the web to zero if you wish buy having the drill land area further away from the wheel.
You are effectively extending the cutting surface but it has a negative rake, not a problem unless you are drilling cobalt or something exotic.
There used to be some interesting drill sharpening techniques, including spiral point, put out in booklet form by Cleveland I believe many years ago, maybe something on the net by now.