Tool suggestions



    O.K. I was thinking that it was like a jeweler's screwdriver sharpening fixture which I had in the past -- a pair of bearings which rolled on the stone while holding the screwdriver in one of two positions to remove from one or the other side of the tip.

    Understood.
    That is why I *prefer* split points. You don't need to preach their benefits to *me*. :-)
    I've even managed to drill a 1/16" hole through a 1/4" shaft mounted in an awkward position using a hand-held electric drill motor with no problems using a split point bit.

    Those are the split points which I am familiar with. I've got examples from 1/2" down to something like #50 (I think -- without going down to look at the number size index's contents. :-)
    I think that form gives greater chip relief for the chips made by the near-center area of the split point.
    Enjoy,         DoN.
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Yep Don, I didn't expect that I was telling you something that you didn't know.
I found quite a bit of interesting technical info by searching for "twist drill geometry" (with quotes). This site covers grinding for production use, and includes the Winslow-Helical point (S-shaped chisel edge/web line), which has been brought up here in RCM in the past. http://www.mmsonline.com/articles/099805.html
This site shows several sharpening fixtures, including one that has a fixture that sits on ball bearing "wheels" http://www.gadgetbuilder.com/DrillSharp.html
The main hurdle (time consuming) in building precision grinding/sharpening fixtures (particularly for small drills), would be the number of small collets usually required for holding various sizes of drills.
WB metalworking projects http://www.kwagmire.com/metal_proj.html ...........
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    That one is *nice*.

    Although he needs only four collets for the range of his version.
    I was also interested in the mention of the problem of the direction of the grinding scratches in the General drill sharpener attachment -- and on thinking about it, the Dumore drill grinder puts the scratches in the proper direction.
    In case you are interested in what the DuMore looked like, I put up a web page when I was restoring it to proper function.
    http://www.d-and-d.com/interesting-tools/DuMore-Drill-Grinder/index.html
or
    http://www2.d-and-d.com/interesting-tools/DuMore-Drill-Grinder/index.html
I lucked into an almost complete set of collets later on, and (still) have not photographed them for the web site.
    Enjoy,         DoN.
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Thanks Don, for the link to your grinder restoration page. That's an interesting machine, and the chuck/bushings (collets) combination looks like a good system.
WB metalworking projects http://www.kwagmire.com/metal_proj.html ...........
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Steve B wrote:

Beware the Harbor Freight drill sets. The bits I got were bent, dull, brittle, or all three. Even the case was shit. I bought a fractional set from my hardware supplier for around $85. Been good so far, but I need to sharpen.
Hope this helps.
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John L. Weatherly
Nashville, TN
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for
quality?
Learn to sharpen your drills by hand. You'll have a new skill that fixes "bad" drills anyplace there's a bench grinder.
Of course if you buy junk drills, no amount of sharpening will fix them. Stick with name brands. It's going to cost you, but if you opt for the cheap ones you'll be buying the good ones before long anyway.
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Can you explain or point to some links that explain how to sharpen drill bits?
TIA
miguel
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wrote:

Help me out here guys.
I'm a little new here, but there used to be a guy, I think they called T-nut that wrote a great description of how to sharpen a drill bit by hand. He may be the only guy in all of UseNet that is remembered after his passing. I wish I would have been here to converse with him. :(
If somebody can't point you to it, I'll bet you can google it.
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http://yarchive.net/metal/drill_grinding.html
Jim, You are dead right about not being able to grind a drill without mechanical help! Well here's how you create your own "6 Million Dollar Bionic Darex" ;^)
Let's assume we are going to sharpen a 3/8" diameter, 2MT shank drill..it is about 8" long (these figures are arbitrary..I just want every one to have the same mental picture of what I am describing.) We approach the wheel, which has been dressed on its face, dead straight across with no grooves..(Ve SHOOT anyone ve catch putting grooves in ze drill wheel!!..No Pity..No Prisoners..Ya! Verdampt!)
(Sorry)...
The drill shank is held firmly in the RIGHT hand...ALL the movement and control is imparted by the RIGHT hand. For the purposes of drill grinding, the left hand could be...with benefit..a LUMP OF CLAY!!
It is from this "lump of clay" that we fashion the Bionic Darex".
Place your left hand thumb and finger tips LIGHTLY together..Relax the other three fingers aand let them naturally curl against the palm of your hand. Let the drill flute drop into the vee between thumb and fore finger and let the tip of the finger "Find" the curve of the flute where it fits comfortably. The tip of the thumb rests on the sharp junction ot the land and the flute, about an inch back from the drill tip.
Now...SQUEEZE HARD!!! YOUCH!...I said it would be easier if it were clay! 8^) Lift the drill from your fingers...see the GROOVE?...Drop the drill back in..it locates within a thou or two! Magic?..Bionic at least! Squeeze again to set the groove. You have created a customised drill guide that fits better that that on any machine ever built! You can relax your grip now..feel how smoothly the drill will ride back and forth, guided by the groove you have created for it.
Place the knuckles of your left hand, LIGHTLY on the ginding wheel tool rest, and swing the drill shank, from left to right (using ONLY your right hand) and push the drill lengthways though that groove in your fingers back or forth using the groove to make the drill twist or "rifle" in your fingers. Do NOT move your left hand in any way..it is made of clay remember!
UNTIL....
A) The drill axis is "eyeballed" to be at half the required point angle to the wheel face...You can scribe or chalk reference lines on your grinder benchtop to help you line this up..at least untill it become almost second nature.
B) The drill axis is dropped JUUUst below horizontal. This will ensure that your soon to be ground drill lip will start with a "smidgin" of cutting clearance.
(Ideally, and certainly for a beginner, the grinder rest should be set dead radially to the wheel center and about half the drill diameter below the true center of the wheel)
C) The two cutting edges of the drill..the straight, sharp bits, formed by the junction of the flute and the back face (the only bit you grind), should be horizontally disposed..with the edge uppermost on the side closest to your left hand..the othe sharp bit of course, pointing downwards (Jeeze this would be a lot easier with a sketch pad)
This I will call the SET or START position!
NOW, move your left hand for the first, last, and ONLY time during th is whole exercise. GENTLY ease the cutting edge towards the spinning wheel, carefully maintaining all the angles and orientations of the SET position..until the cutting edge is JUST shy of touching the wheel. If you listen carefully you will hear the tone of the entrained air, whistling through the narrowing gap. You will hear a subtle but distinct change of tone JUST, I mean Just...a couple tenths of a thou BEFORE the edge touches the wheel. STOP!!! FREEZE!! DO NOT MOVE!!
Now, press the knuckles of your lump of clay..sorry, your left hand FIRMLY down onto, into and around the grinding rest..establish a "Groove" on the back of your hand as well as between your fingers.
We are now ready to grind, Your left hand locked to the drill and grinding rest is otherwise quite relaxed..letting the drill slide, twist and tilt wherever your right hand and the groove in your fingers tell it to go.
The actual grinding is a bit of an anticlimax.
You have previously studied a new drill point, you have read about clearance, and cutting angles, and rakes and......
With the RIGHT hand in control, gently, kinda, lean forward... bending or squeezing your arms hands and body..rather than actually moving them..untill you take up that last couple of tenths and the wheel begins to cut. Let it cut..don't force it, and dont' rush it..it really won't hurt anything if you take a full minute Per pass per face. YOU and your "Bionic Darex" are totally in control of that drill and the wheel..Forget the times when, close to panic, you swung the drill wildly past the wheel, hoping to get "the dirty deed" over with as quickly as possible.
Take your time, enjoy the moment, THINK about the shape you are trying to generate. Just the one face is left to "Interpretation"...every other aspect,angle, facet, what have you...Has ALREADY BEEN TAKEN CARE OF!! and is locked in place under your control!
The right hand should perform a "Lower Quadrant sweep" for want of a better term..An observer behind you would see your hand move from about 17 minutes past the hour on a clock face, to roughly 25 minutes past. But it isn't a smooth arc of a circle, more a sector of an elipse..You see, as your hand starts to drop slowly, you are also rotating the drill in "the groove"..the first third of the turn needs to maintain that very slight clearance angle on the cutting edge, and not increase it too rapidly.
You need the clearance to cut..But too much at that point will WEAKEN the edge, and cause the drill to snatch and chip...So the first part of the rotation is ALMOST but not quite, just as though you were grinding a straight cone point on the end of your drill. Only as you approach the second third, does your right hand start to noticably drop..kinda "Catching Up" on the rotary motion...increasing the clearance as it does.
In the last third of the rotaion the right hand drops quite rapidly..Thogh not enough to catch the OTHER drill lip on the wheel..that lip is coming around quite rapidly by now.
Above all, take your time, if it helps, move the drill one degree at a time, and think ahead what shape or angle the next degree of cutting face needs...Remember, you have control, and IT ain't going nowhere 'til you decide.
After a pass on one face, flip the drill in your "Bionic Darex" DO NOT MOVE THAT LEFT HAND!!, return to SET position and repeat, the pass on the other face.
Having done a couple of passes on each face..it is now time to check the results on our homemade "Optical Comparator"
(Sorry Jim I couldn't resist!!) ;^)
Rest the center hole in back end of the drill shank, on the center point of the "Comparator" and use, first one and then the other drill lip to scribe a light line on your whitewashed (OK Blue or red dyed) surface.
You will readily see if the lines coincide..if the lips are even..or not, as the case may be.
Lets assume they are..Now look directly DOWN on the end of the drill to check the clearances. HUH? How can you check radial clearance by looking it staight in the face? Surely you need to look at it sideways?
Well no you don't...for once all thos interacting and confusing angle and faces and clearances are going to work together in YOUR favor and make what could be a tricky bit of metrology..quite simple. While we are looking at the end of the drill, we will also check that the POINT ANGLE is correct too!!!
(Ok guys, leave quietly..teenut has finally lost it!!)
No really, trust me. IF you look straight down on the point of a well sharpened, standard drill, you will see the two cutting edges, joined by the CHISEL edge which crosses over the web of the drill The angle fromed by the chisel edge to each cutting edge, should be ABOUT 50 deg...anywhere between 40 and sixty is ok for a first attempt. (I can hear the purists and theorists screaming and lighting up their flame throwers) But believe me, get it in that ball park and your drill will CUT. If the angle is too steep..you don't have enough clearance...negative clearance will give you an angle event greater than 90 deg. Too MUCH clerance and the angle will appear too shallow!
While looking at the end, check the point angle, How? Look down the axis of the drill at the cutting edges. Are they straight? If so, your point is pretty close to the right angle (As designed for that drill, by its manufacturer when he set the helix angle and the cross section of the flute) If the edges appear CONCAVE the point is too flat and if they appear CONVEX, the point is too "Pointy"
If your drill passes all these tests, which take but a second or two to perform, THEN IT WILL CUT..pretty close to size, without chattering, chipping, overheating, wandering or seizing. I guarantee it!
Hey, thats a pretty good start for the first drill you ever ground! All it takes now is a bit of practice for it to become second nature and almost as easy with a little 'un or a big 'un!
Hey guys!
My apologies for "goin'on" but If it helps just one person to pluck up the couragre and go hand sharpen his (or Her) first drill, by hand...
Then I hope you will bear with me.
It is late, I am tired and I am not even going to proof or spell check this,
'night all
teenut
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Yep, that's what I said to do :{) Patrick

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On Wed, 21 Mar 2007 12:05:10 -0700, miguel wrote:

Only 2 angles to worry about, the point and chip clearance, they vary slightly with the material you are cutting (drilling is cutting) with a twist drill. How to on a bench grinder: start with a big (3/8 or bigger) so you can see what you're doing. On the fine wheel (dressed flat) hold your bit so the 50% of the point your are going to grind lines up parallel to the face of the wheel (I'm assuming that the bit is still beveled) now as you slowly roll the bit into the wheel face give it a little movement into the twist "shoulder" to create 2 to 3 degrees of chip clearance. Remember that the leading edge of twist is the cutting edge and the whole thing is pretty easy to understand. I've taught some pretty backwards guys to put a pair of sharp cutting edges on some badly burned bits.
Experiment, it ain't hard.
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Steve B wrote:

Hertel is also a good name. A full 3-in-1 drill index (fractional 1/16-1/2, lettered A-Z, numbered 1-60) is $185 at J&L Industrial in either bright or black oxide finish, but today through Friday they have a 25% off sale if you buy any 5 items, so once you throw in some taps and dies you can get the drill index for just under $140. A smaller 29-piece 1/16-1/2 fractional-only set is $70, or $53 on sale. They have these 25% off sales every month or so. www.jlindustrial.com
Mike
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Guhring, Titex, Emuge
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Anthony

You can't 'idiot proof' anything....every time you try, they just make
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Drill doctor? what's that????
In High School metal shop the FIRST project was to make a drill sharpening guide...
the SECOND project was to learn how to use and hand sharpen drill bits...
40 years later that skill is STILL valuable... (and I still have the guide)
Best story was when I was in the service, (USCG 1973) working A2N (Aids to Navigation), stuck on 'Mile Rock' in the outer SF bay when the 1'st class BM rips the web of a 1/2 bit and the Chief BM figures were screwed for the day. Funky old E3 me says 'aww no prob'... as I clamp the fricken die grinder we have in a vise and hand sharpen the thing better than when we got there... took about a minute (had to take quite a bit off to get it centered)... Jaws drop... I shrug and hand it back...Uh needless to say THEY bought the beer that day and ever after I was the guy they wanted on the team...
--.- Dave (403-029 one more number I'll remember for the rest of my life)
[snip]

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I learned onboard the USCGC Burton Island on the way to Antarctica in 1973 as an EN3
Patrick Hill USCGC Ret CWO4 Eng
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