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jcaldwell
07-10-2013, 06:17 PM
I've seen a couple articles in HSM about making machines/attachments/jigs for sharpening drill bits and end mills.

I certainly need something better than a Drill Doctor for sharpening my drill bits. And, if I ever get to using my new (to me) milling machine, I'm sure I'll want to try sharpening tooling for it also. I'm sure I'll eventually want to sharpen other things, like maybe boring bars and who-knows-what.

Are there any preferred machines/attachments/jigs/etc for doing these tasks?

Thanks,

JC

Black_Moons
07-10-2013, 06:23 PM
Sharpening drill bits can easily be done by hand with a bench grinder, Or a little more effort with a hand lap to sharpen them up.
Sharpening boring bars can VERY easily be done by hand with just diamond laps or very very simple jigs.
Sharpening end mills... You can kinda do the tip easily enough, but the sides require a special jig/spindle.

DR
07-10-2013, 06:54 PM
Sharpening drill bits can easily be done by hand with a bench grinder, Or a little more effort with a hand lap to sharpen them up.
.................................................. ...................................

.

Yes, but to what degree of accuracy?

It seems when this subject comes up a number of (usually older) guys will tell us they can sharpen to as good or better than a factory grind by hand.

All I have to say to that is, they must be the same guys who can turn on the lathe to +/-.005" by eyeball without the use of measuring instruments.

I do rough grind badly dulled or broken off drill bits by hand to save the expensive CBN wheels in my drill grinder then finish in the machine.

Rich Carlstedt
07-10-2013, 07:18 PM
Lets not get too complicated here.
Tool bit sharpening is a basic tenant of machining and one that should be done by newbies...over and over again !
The reluctance to hand sharpen , and say rely on Factory carbide inserts , only harms the development of what I consider a necessary machinist skill. However I realize I am an old fart and folks today want shortcuts.
The best recommendation I can make is to throw away the pedestal grinder when you are new to machining.
Use a Belt Sander---right !
Use 60,100 and 220 grit belts.
They change very fast, so you can rough and finish with the same machine.
You have a large flat table to use, and a flat grinding surface that does not give you a concave surface (a No No for steel) like a wheel does.
You can draw radial lines on the table for quick angle work, and Vision is much, much easier for seeing applications.
You also can use a angle jig to develop the desire drill angles ( ie 118)
Belts cut cooler than wheels and so the tool bit can be ground longer, and if its sensitive, hold a ice cube against the part at the same time
The only requirement is that you not use old belts !

Rich

PS -Also the belt does not become rounded like a wheel, so dressing is not required, and cut edges are straight !

_Paul_
07-10-2013, 07:49 PM
For most drill sharpening I use one of the Picador type sharpeners for anything over 1/8" up to around 3/4"

http://imagehosting.rodsnsods.co.uk/364d430e63981cf.jpg

Bit of a technique required but not hard to master.

End mills I sharpen the lips with one of Sir John's ER32 blocks from Arceurotrade in the UK and a 1920's Norton T&C grinder.

http://www.arceurotrade.co.uk/imagecache/ca66e8bb-ae43-45a1-ba91-9fb000eac69f_342x249.jpg

Regards

Paul

ncollar
07-10-2013, 10:15 PM
If you are looking to sharpen your own tools, it would be best to buy a Tool Sharpener Grinder. They are not cheap but if you do a lot of work they are worth it. When you use a cutter and you feel it dull put them in a box when you have a few, its time to touch them up. The better the grinder is and what it is able to sharpen will dictate price.
Nelson Collar

Ed P
07-11-2013, 08:16 AM
Are there any preferred machines/attachments/jigs/etc for doing these tasks?


Sure! It's called a "Quorn" tool and cutter grinder. I've got the casting "aging" under my work bench right now.

Ed P

GEP
07-11-2013, 09:27 AM
I never in my life needed a machine to sharpen drill bits. By the time you put a drill bit in the machine i have it sharp free hand

GEP
07-11-2013, 11:10 AM
EdP
If you take the castings for your Quorn and throw them outside let the rain and weater beat on them they would age faster. We did that with engine bolcks and heads left them outside for 2 years or so it seamed to have helped

Jaakko Fagerlund
07-11-2013, 12:45 PM
I never in my life needed a machine to sharpen drill bits. By the time you put a drill bit in the machine i have it sharp free hand
Sure it works, but if you want round, straight and on size holes, then free handing isn't going to cut it (pun intended).

And i think Ed P meant aging as in project-that-waits-for-inspiration.

JohnAlex141r
07-11-2013, 01:46 PM
Sure! It's called a "Quorn" tool and cutter grinder. I've got the casting "aging" under my work bench right now.

Ed P

Or, the Worden from Hemingway over in the UK. Might not be as flexible as a Quorn, but it's a lot easier to build. I have some pics of it on my blog, which should be shown below.

I'm still learning to use it, but so far I really like it.

Still to make - ER25 tool holder (parts arrived last week), and a diamond wheel holder (wheel is here, just need to kick myself in the backside...)

Another JohnS.

GEP
07-11-2013, 02:01 PM
I will go up against your drill grinder sparpening drill free hand any time also my holes are as accurate as a drill bit comming out of a $ 3,000.00 grinder want to put money on it ??????????????

GEP
07-11-2013, 02:10 PM
When i started my apprentice ship in germany the Meister took a about 1 inch drill bit and flattened the end. He handed it to me and told me to sharpen it free hand he said when your done bring it to me. He checked it with a gage. It was not perfect but he was happy. Then we put it in a drill press and drilled a hole after we pree drilled it about a 64th under size the final hole was as accurate as the hole drilled with a drill that was sharpend on a deckel

Black Forest
07-11-2013, 02:25 PM
I will go up against your drill grinder sparpening drill free hand any time also my holes are as accurate as a drill bit comming out of a $ 3,000.00 grinder want to put money on it ??????????????

I'll put money on it! The problem is no one will be willing to be present to verify your results. You might get lucky on one or two but day in day out getting them exact, I don't believe it can be done and done quickly. I sharpen drills all the time by eye on a grinder but when I need an accurate hole I use my machine.

Black_Moons
07-11-2013, 03:19 PM
Sure it works, but if you want round, straight and on size holes, then free handing isn't going to cut it (pun intended).

And i think Ed P meant aging as in project-that-waits-for-inspiration.

Free handing WILL cut it. The trick is not to *measure* it 'free hand' afterwards.

Measure it with a proper drill point gauge and keep sharpening till your drill bit gets too short to chuck or you get it correct.

Black_Moons
07-11-2013, 03:22 PM
When i started my apprentice ship in germany the Meister took a about 1 inch drill bit and flattened the end. He handed it to me and told me to sharpen it free hand he said when your done bring it to me. He checked it with a gage. It was not perfect but he was happy. Then we put it in a drill press and drilled a hole after we pree drilled it about a 64th under size the final hole was as accurate as the hole drilled with a drill that was sharpend on a deckel

This is what gets you the 'better then machine accuracy'
The fact you then check the bit with your gage, and then can keep sharpening it (With hand sharpening tools, if needed) to get it as precise as you want to be.

Puting a drill bit back into a machine sharpener likey won't make it any more accurate then the first time the machine sharpened it. Infact the machine is very much likey to get less accurate with age as bushings/bearings/collets wear out and the wheel gets worn down. Someone who hand sharpens is likey to get more accurate with age (experiance)

Paul Alciatore
07-11-2013, 03:23 PM
When i started my apprentice ship in germany the Meister took a about 1 inch drill bit and flattened the end. He handed it to me and told me to sharpen it free hand he said when your done bring it to me. He checked it with a gage. It was not perfect but he was happy. Then we put it in a drill press and drilled a hole after we pree drilled it about a 64th under size the final hole was as accurate as the hole drilled with a drill that was sharpend on a deckel

This is NOT a good test of the quality of the grind. If you predrill the hole with a smaller one, you remove the material at the axis of the hole. This is the very material that would act to "center" the final drill about it's tip. If the two flutes are sharpened with unequal lengths of the cutting edges, it will drill an oversized hole due to this centering about the drill's own (off center) tip. By removing the central material in the hole, you allow the final drill to center itself using the outer edges of the two cutting edges and it will drill a hole that is very close to the OD of the drill, even if the two flutes are a lot different.

For a fair test, you need to drill the whole hole with only the final, full size drill. Then you will see a larger sized hole when the flutes are not equal.

Paul Alciatore
07-11-2013, 03:30 PM
I am one of the ones who has made the claim about free hand sharpening. I have ONLY made it in relation to drill bits, never about milling cutters. Also, I am careful to say that it is as accurate as "some" factory sharpened bits. I have seen some factory bits that were so bad that I sent them back without even drilling a single hole. I can do a LOT better than that by hand. A LOT BETTER!

Drill sharpening by hand is a skill. It should be learned by everybody who does machining as a profession or as a hobby. If not for it's own sake, then for a general improvement in your skills. Do start with larger diameter drills and work your way down. 1/2" or 3/8" is a good place to start. At some point, it will not be possible to do any smaller ones. I would not try to sharpen a 1/64" bit unless it was a dire emergency.

JohnAlex141r
07-11-2013, 04:04 PM
...Then we put it in a drill press and drilled a hole after we pree drilled it about a 64th under size the final hole was as accurate as the hole drilled with a drill that was sharpend on a deckel

Of course it was. Your "about 1 inch" drill acted as an inexpensive reamer, removing just a shade of material from the sides of the hole.

Now, try sharpening a 1mm drill, or, with the fixture currently in the works, a 4-facet drill jig for drills down to #80 (sorry don't know the metric size for #80).

The small drills I sharpen are expected to drill holes on-size, without wander, and for that, with my skills, I'll use a machine!

(Not to take away from your claim - good for you for hand-sharpening drills. +10 points.

most certainly there are lots of people who sharpen drills by hand, but they have experience, time, and drills large enough to see!)

Another JohnS.

sasquatch
07-11-2013, 04:12 PM
I have only ever sharpened drills by hand.

I'm not an expert by any means,, BUT i do get enjoyment out of the challenge to "Get it Right", and when i do get it right on, get great pleasure watching it drill.

MasterMaker
07-11-2013, 05:09 PM
I've successfully sharpened endmills as well as drills using nothing but a diamond file and magnifying lamp, and they certainly drill close enough to size for me and the endmills cut well.

Good and workable is more often than not what is needed rather than perfect, a tool and cutter grinder is in the work's but I think that the reason they exist is just as much about speed, ease and repeatability with speed and ease as it is about precision.

They are great, give better results with less effort and training, which means that they save money for a commercial shop, I am making one but strictly speaking I don't need one.

As for a quick and easy way of making one that works, a spin indexer on a rotary base and a cheap x/y vice or table will work with a bench grinder(with a cup wheel and some packing under it to get it to the proper height), with a movable post to run in the flutes you can even sharpen the sides.

GEP
07-11-2013, 06:20 PM
Black Forest
I dont know where you are i am in michigan bring all your money you will loose but i will give gas money for the trip home.
Drill sharpening was the first thing we had to learn. Come on i show how its done dont for get your money i will consider your machines as well all of them

Juergenwt
07-11-2013, 07:50 PM
In my whole life as a Tool and Die maker I never needed a machine to sharpen a drill or a tool bit. Cutters are a different ball game. Black_Moons has it right. GEP tells the story of how you learn it. If you do it wrong (the drills and tool bits) than you need to look at it and find out why it is not cutting or not cutting the way it should. It's a learning process. Practice, practice and practice until you know what all the angles are for. We were lucky enough to have a training (apprenticeship) program and someone to show us. For the ones not having such luck it will take time. But once you master it you will have a whole new outlook on your chosen profession as a machinist.
You see - this is like going boating and not knowing how to swim. After all you have a boat and swimming should not be required. Than the boat sinks.
Same with a drill. You have a sharpener and hand sharpening is no longer needed. Than you find yourself somewhere on the factory floor or god knows where, and a drill gets dull or breaks and you have no drill sharpener. You can always find a grinder. Bummer!
As far as using a sand belt - I would stay away from it. The nasty thing about those is that when you apply pressure there is a slight bulge that develops on the belt right on top of the cutting edge on your tool. Your tool no longer has a correct clearance angle.

Jaakko Fagerlund
07-11-2013, 11:48 PM
You see - this is like going boating and not knowing how to swim. After all you have a boat and swimming should not be required. Than the boat sinks.
It is good to know how to swim, but why swim when you have a boat? Makes it much more easier and faster and gives the same result day in day out.

JRouche
07-12-2013, 02:18 AM
Drill sharpening, ERR! Its always been a problem for me. And I have really tried and put some time into it. Not as much as the professional machinist here. But Im just a Home Shop (wanna be) Machinist. But with all the great literature out there guiding us hobbyist with the methods for sharpening the drills its definitely a worthwhile skill to attempt.

But as often as I have attempted to sharpen a nice cutting edge I just cant seem to get it right. And I dont take failure as an option for anything. Thats why I suppose I still give it a go. But with the same results. Im starting to think its a personal issue similar to why I cant draw.

My freehand work is lousy. Drawing, painting, drill sharpening, woodwork, and even my passion, body work on cars. My eye to hand coordination is LOUSY! I could be using the best of tools. I have used every type of grinder, belt sander and other abrasives to get a keen edge but the two edges are either off from each other or the angle overall is off.

I had a great friend, Del Fronteras who even showed me how he did it. He owned a job shop that I used to hang out in and he always hand held his bits (drills and lathe bits) for sharpening. He had a really nice darex sp2500 sharpener that was new unused in his shop for years. He never used it. He didnt have to. He would step up to a really old grinder with bit in hand and after some simple time he would have a good to go bit. Love my friend Del :)

But myself??? Im useless trying to point a drill. Im not giving up though!! I still take a bit to the abrasive in hand. Usually have to come back a few times cause the first few tries the bit would just rub and burn. Its not for lack of trying or knowing what geometry I wanted. Its just that I cant get my hands and eyes to work together to get the drill where it needs to be.

OH!! I do have to say though. Ill use a Golf analogy (I dont golf but have been to the driving range). Once in a while I will HIT the correct geometry and its like when you hit that stupid lil golf ball and it sails far. I have sharpened a drill on occasion where it eats metal like no ones business. That my friends is like connecting with the golf ball or hitting a home run in baseball.

I think thats why I keep trying. I know there is a sweet spot when grinding the bits. I just have to keep at it till I can reproduce a nice profile time after time. I know it can be done cause there are many folks doing it.

NOW :) To "helpers". I say helpers cause thats what I turned to when I couldn't get a good edge with my freehand. I had one of the "Picador" type jigs like what was talked about. Mine was a General or Sears, I forget. Its actually a nice jig. It helped me to get nicer edges than I could get freehand. I moved on to the darex plastic "drill doctor" 750 unit, a 90s model. Really nice lil tool for the price. It is a "cam" type grinder and has some nice features. You could do 118 or 135? degree. Will split a point. It worked pretty good for 1/4" to 1/2". Anything smaller than a 1/4 though and it seemed like it was a lil too loose to hold any tolerance.

And there is something to be said about that. It was designed and sold to be used for small bits as well but IMO it didnt do so well. So that tells me there is enough "slop" in the construction so tolerance will be traded UP as well. So even though I got some usable bits off the machine, it was only in the larger sizes. That tells me there is still a bit of slop on the larger bits and they could be sharpened more precisely. The tolerance of the machine shows up better with smaller bits, meaning the tolerance is pretty low.

Their higher end, read money, machines are very similar in technique. But where the 750 uses plastic the high end, like the 2500 uses all metal. The tolerance factor becomes more favorable. The collet fits like a driving glove VS a catchers mitt :)

And there are too many other machines. I still look for a fully equipped Optima machine. I always wanted one. Then there is the Black Diamond. A well equipped machine is still very expensive.

I have a Cuttermaster machine with all the bells and whistles. Its not a dedicated drill sharpener but I have the accessory for the drill bits. Have I used it to sharpen drill bits? NOPE. What a pain in the butt!!

There are simple jigs to help you. I actually would recommend the simple General drill grinding attachment "Picador" type. They are all day long for 25-30 bucks. They will help to show the correct angles and geometry so that you might say hey? I can hold that angle or I can see the cutting edge like its supposed to be and then freehand the bits.

Free handing the bits will be a joy for you if you hit the sweet spot. You will wonder why folks pay thousands of dollars for machines when you can spend a minute on your grinder or belt sander and get some great drill bits, maybe even better than the original grind. JR

mike4
07-12-2013, 03:36 AM
Often in the field there is no bench grinder just angle grinders and thats what I will use rather than driving to a shop and using a drill sharpener or grinder.
Its called experience, and a need to get the job done .
If the hole is not precise and a bit out of round , it doesnt always matter , have any of you grabbed a commercial bolt and measured how round or square the threads are to the shank or head?
I have not seen many people go around and measure how round a hole is , most are only concerned with being able to put a bolt in and tighten it .
Michael

jcaldwell
07-12-2013, 11:51 AM
I appreciate the comments on hand sharpening versus using a machine.

However, since my close encounter with my table saw and what my neurologist calls an "essential tremor", I think my future as a brain surgeon and hand sharpener of drill bits and other cutters is probably not bright.

That's why I was asking about the machine option. Clearly, I'm too broke and cheap to buy something like a Quorn, which I have only heard about from HSM magazine and have never seen--but have the impression it's pretty expensive. But there is a series of HSM articles on building something that is supposed to be similar/as good. It's still somewhat pricy, if for no other reason than the diamond wheel and the ER collet set. Anyone tried it?

Are there other really good options? I'll check for the inexpensive "Picador" type J Rouche mentions. I've got a Drill Doctor, that, as mentioned, doesn't really seem to do a good job. Has anyone done mods on it to make it more precise??

Thanks for all the posts.

JC

JRouche
07-12-2013, 11:57 AM
I've got a Drill Doctor, that, as mentioned, doesn't really seem to do a good job. Has anyone done mods on it to make it more precise??

Thanks for all the posts.

JC

I swear I remember Forrest writing some good info Re: the drill Doctor. Or maybe it was Tiers :) I forget.... JR

Ziss one.... http://bbs.homeshopmachinist.net/threads/9447-Drill-Doctor-review-Confession-time?

DR
07-12-2013, 12:16 PM
.................................................. .................................................. .................................................. .......

However, since my close encounter with my table saw and what my neurologist calls an "essential tremor", I think my future as a brain surgeon and hand sharpener of drill bits and other cutters is probably not bright.

.................................................. .................................................. .................................................. ..............

Thanks for all the posts.

JC

Don't feel too bad about it. Nobody's future is bright as a hand grinder of drill bits.

As I predicted early on in this thread we would see postings by old guys who claim to be able to accurately hand grind drill bits. It's absolute total nonsense for them to make those claims. And, does a disservice to more impressionable newbies who might believe it.

J Tiers
07-12-2013, 08:15 PM
If you have a gage, you can grind drills fine by hand. Check the point angle, relief, length of each cutting edge, and correct as required.

Or, if you just need to get the ^%$#! thing sharp and cutting again, do it by eye.

You SHOULD be able to do it, absent medical issues that preclude it. And while the others are still shouting and running about figuring out what they can do, you have the drill back and working.

Better than a machine? Better than SOME machines..... you are, if you use some care, unlikely to put a reverse angle on the drill, unlike a popular low cost sharpener, which often does due to messed up alignment jaws, or a different helix angle.

kf2qd
07-12-2013, 08:26 PM
Don't feel too bad about it. Nobody's future is bright as a hand grinder of drill bits.

As I predicted early on in this thread we would see postings by old guys who claim to be able to accurately hand grind drill bits. It's absolute total nonsense for them to make those claims. And, does a disservice to more impressionable newbies who might believe it.

So how in the heck did we ever get ANY of the accurate tools we have today? Someone did a lot of HAND work, they had to take a less accurate machine and make a more accurate machine.

And yes, when I was working in the shop I could grind a drill bit faster and more accurately that the drill grinding machine. From 1/8 to 1-3/4. Not all that hard, started out with my drill gage to check angle and center and soon it was just normal. Later, after I had moved into engineering I had guys coming in to ask me to grind a bit for them.

And as for the new guys here. I think you do them a disservice by constantly insisting that they have to have all the best of everything before they will be able to do good work. I think they have a lot more talent and skills that you give them credit for. Will all of them be able to become expert drill grinders? NO, but they will skills that will help them on the day wneh the drill grinder does die.

Even scraping is a hand operation and we know that is so detrimental to accuracy...

sasquatch
07-12-2013, 08:26 PM
DR, who do you think sharpened drill bits before years back?

OR, do you think they just tossed a dull drill in the garbage?:rolleyes:

mike4
07-12-2013, 08:55 PM
There are a lot of people who will knock something rather than try it , as I said in my earlier post I will often use an angle grinder to touch up a dull drill bit so that I can finish a job , not all holes have to be perfectly round .
As long as the parts fit and can be bolted together is as close as many thing need to be , if high precision is called for the use jigs or machines .

This is beginning to look like another " mines bigger and better than yours" contest.
Michael

JoeFin
07-12-2013, 10:09 PM
Its getting DEEP in here

OK - so a few folks have had occasional success hand forming a drill bit. But milk shot out my nose I laughed so hard at "Hand forming end mills"

Sure in a pinch I've thrown many a drill bit to a pedestal grinder and kept going. Its great when it works but it doesn't dependably work. Yes I have tool scopes, gages, measuring tools, and I've checked them to see where I've gone wrong when a hand job doesn't work out.

But in no way will I ever buy into the "I can hand sharpen better then a T&C grinder" malarkey. Rolling the relief on that drill point to within .001 or .0005 just ain't going to happen with the "Rigidity of your hand".

DR
07-12-2013, 10:21 PM
There are a lot of people who will knock something rather than try it , as I said in my earlier post I will often use an angle grinder to touch up a dull drill bit so that I can finish a job , not all holes have to be perfectly round .
As long as the parts fit and can be bolted together is as close as many thing need to be , if high precision is called for the use jigs or machines .

This is beginning to look like another " mines bigger and better than yours" contest.
Michael

I'm not knocking using an angle grinder to sharpen a drill when necessary. As you say, not all holes have to be round (and presumably not to exact size either). Yes, I've hand ground a number of drills, never when I need an accurate hole.

What I am knocking is those who claim to be able to equal a factory grind by hand grinding. By factory grind I was not referring to a POS Chinese import drill , I mean a quality drill like a Guhring or equivalent.

As to the drill grinding gage, as far as I remember they have a scale to measure the cutting edge. To get equal cutting edges would seem to me to be equivalent to using a machinist scale to measure a turned part (to +/-.005" for instance). I couldn't do it. Then the relief angle has to be equal on both flutes, how do you get that? The point angle may be the easiest to do with the gage. And, I see we have another individual who can do all this faster by hand than by a drill grinding machine.

So who cares if a drill doesn't make holes within .002" of it's nominal size? How about when it's a tap drill for a form tap? For a 10-32 form tap a .002 or .003" oversize could mean the difference between a 60% or 75% thread, a 60% thread might be rejected. Not having to ream to get an accurate tap drill hole could mean an extra available tool station on an automatic machine not to mention the time savings for one less tool change.

DR
07-12-2013, 10:30 PM
DR, who do you think sharpened drill bits before years back?

OR, do you think they just tossed a dull drill in the garbage?:rolleyes:

I imagine small shops, not so well equipped, did it by hand. Larger shops had drill grinders.

About the "before years back", not a good comparison, today we routinely machine to tolerances that could only be achieved by grinding or lapping back then. It's not far off to say I can turn a run of dozen stainless parts easily to all within +/.0005" or better, that would have been unheard of years ago.

DR
07-12-2013, 10:37 PM
.................................................. .................................................. .................................................. ..........


And as for the new guys here. I think you do them a disservice by constantly insisting that they have to have all the best of everything before they will be able to do good work.

.................................................. .................................................. .................................................. ..................
...

I don't recall ever doing that. In this thread I'm trying to explain you hand grinders are blowing smoke when you insist you do equal or better and faster than a quality factory drill grinder.

PixMan
07-12-2013, 10:56 PM
This thread and it's subject is akin to oil change interval and brand choice discussions on an automotive website.

My grinding is better than your machine, my machine grinds better than you can by hand....ad infinitum.

OK, my two cents worth. I have resharpened drills by hand for 30+ years, and now I have a Black Diamond B-2 drill grinder. It does a really nice job on any common drill 1/2" and under, but I have no bushings for metric drills so I still sharpen some by hand and do so just fine. :p

Mike Burdick
07-12-2013, 10:57 PM
Some keep forgetting...

Twist drills are for getting a HOLE punched thru a material and that's all! If one wants an accurate hole then one needs to use a boring bar or a reamer as the next operation. Therefore, sharpening twist drills by hand is more than adequate.

Another thing that seems to be always misunderstood is that bolts are used for CLAMPING only! They are NOT to be used for alignment!

.

11 Bravo
07-12-2013, 11:06 PM
JC,

You didn't say what your budget is, but I would suggest looking for a TDR SRD grinder for your drill bits. Pretty pricey new, but they show up on e-bay pretty regular. You just need to watch for a while and you can likely find one for a reasonable price. I got my model 80M for $250 and it was nearly like new and has an extra chuck with it.

Here is one on e-bay http://www.ebay.com/itm/SRD-DG7M-Drill-Grinder-w-Extra-Wheels-Drill-Holding-Block-/130943569101?pt=LH_DefaultDomain_0&hash=item1e7cd84ccd

And a link to the manufacturers web page http://www.drill-grinder.com/Default.asp

The SRD grinders are excellent little machines, super fast and easy to use, don't take up much space and are light enough that you can store them under the bench or on a shelf when you aren't using it. I have sharpened hundreds of bits on mine and haven't needed to replace the stone yet.

For end mills, I don't mess around trying to sharpen the flutes, although I would like to get a machine for it one day just to do it. Unless you can find a tool and cutter grinder super cheap and have the room for it, new end mills are really not all that expensive unless you are using a lot of larger ones.

To sharpen the ends the generic fixtures like this one from Grizzly work decent enough. http://www.grizzly.com/products/End-Mill-Grinding-Fixture/G9887

You can modify a bench grinder to work with that fixture I guess as I have seen references to guys doing it, but a surface grinder is the better way to go. Fortunately, if you have the room a decent surface grinder can be found for far less than one of those El Cheapo cutter grinders that don't work very well anyway. Besides, a surface grinder is nice to have for lots of other stuff. Surface grinders show up on Craigs List fairly often it seems. For example, a quick search turned up a 6x12 manual machine (looks like one of the generic imports sold by Enco and others) with a magmatic chuck for $450 in North Platte NE.

With some searching and a little patience I think you can get set up to sharpen what you want on decent machines for under a thousand bucks and the machines you end up can easily make your money back for you if you are inclined to use them for paying jobs.

MrFluffy
07-13-2013, 04:59 AM
I freehand drill bits, but then I dont expect them to come out to within 0.01mm of what they are sized at so no claims at how perfect they are. I have one of those picador jigs and a smaller drill sharpener that goes on a twist drill but I can't get along with them. The drill sharpener is too cheaply made and doesnt hold things right, and the picador never seems to make life easier just complicate things.

I've freehanded milling cutters, and while Ive got them back cutting and working, its not as nice as when I take time and set them up in a grinding jig I have and use the surfce grinder. The freehand sharpening never seems as even between flutes, there's always one or two doing more work than the rest.
Having said that, theres a lot also to be said to be able to drop the iso40 toolholder out the spindle complete, touch it up a little freehand and be back cutting straight away.

I think we should all learn all the methods within reason.

SGW
07-13-2013, 06:51 AM
Back around 1978 when I was just getting my shop set up I took a basic machining course at the local trade school. The instructor was a machinist who worked at MIT's Draper Labs. He told a story of him and his co-workers seeing who could most accurately sharpen a drill by hand. They would use a micrometer to measure the chips coming off each flute to see how closely they matched.

In my experience, one can do a perfectly satisfactory job sharpening a drill by hand, at least the larger sizes, especially if you use a drill point gage to check the result. But I seriously doubt whether one can get the point angle (118 degrees, 135 degrees, or whatever) correct strictly by eye alone, or grind a specific relief.

In other words, by hand you can get a drill that works, but it won't be ground to any specific specification. The point angle may end up as 125 degrees, with a more aggressive relief than a machine-sharpened drill. For most jobs it doesn't matter, and experience will guide you in hand grinding so you get drills that work. But if you want a drill that really does have a 118 degree point angle you at least need a gage to measure how you're doing as you grind it, and if you want a specific relief you're likely going to need to use a drill sharpener.

cameron
07-13-2013, 07:06 AM
Sure! It's called a "Quorn" tool and cutter grinder. I've got the casting "aging" under my work bench right now.

Ed P

And if they are like most Quorn castings, they will age for years and years and years.:rolleyes:

cameron
07-13-2013, 07:19 AM
Some keep forgetting...

Twist drills are for getting a HOLE punched thru a material and that's all! If one wants an accurate hole then one needs to use a boring bar or a reamer as the next operation. Therefore, sharpening twist drills by hand is more than adequate.

Another thing that seems to be always misunderstood is that bolts are used for CLAMPING only! They are NOT to be used for alignment!

.

Not really true. Very often what is wanted is the pretty good hole you can get with a well sharpened drill rather than the really bad hole you can get with a badly sharpened drill.

It's nonsense to tell people the only way to get a reasonably accurate hole is to bore or ream.

And, more often than not, bolts and cap screws are more than adequate for alignment. How many parts aligned by dowels in reamed holes do you find in cars, farm machinery, consumer goods etc, etc?

Rustybolt
07-13-2013, 08:06 AM
Moons.

Most of these guys don't have a the experience or the time to learn how to sharpen by hand. When I worked in a screw machine shop when I was in high school the foreman handed me a coffee can full of dull and broken bits. He told me to take my time and sharpen all of them. He then demonstrated what he wanted. By the end of the day I had maybe ten out of 100 that might have been acceptable. By the end of the summer i got to where I could take just about any drill and sharpen it like new.


"As I predicted early on in this thread we would see postings by old guys who claim to be able to accurately hand grind drill bits. It's absolute total nonsense for them to make those claims. And, does a disservice to more impressionable newbies who might believe it."


It isn't nonsense.
If you want to learn get a couple of hundred dull bits and go at it until you can consistantly produce a good cutting edge.


My advice to anybody entering this as a hobby is to get a drill sharpener and learn how to use it well.

Dr Stan
07-13-2013, 08:19 AM
Rustbolt I fully agree with you, especially your advise to get a drill sharpener.

Even though I learned how to hand sharpen drill bits as part of my training in the Navy (even made a drill point gage which I still have) and have sharpened bucket loads of drills, I bought a Drill Doctor and use it on all my 3/4" (19mm) and smaller drill bits. While its certainly not a Deckel (no where close) it does a good job.

Eventually I want to acquire a tool & cutter grinder which I can use to sharpen my larger drill bits, along with other operations of course.

BTW, I 2nd the earlier comment about not using a belt sander to sharpen drill bits, or any other cutting tool as you will not get a clean edge. A belt sander can be quite useful to rough in a badly damaged drill bit, but it really should be finished on a grinder.

J Tiers
07-13-2013, 09:14 AM
Some keep forgetting...

Twist drills are for getting a HOLE punched thru a material and that's all! If one wants an accurate hole then one needs to use a boring bar or a reamer as the next operation. Therefore, sharpening twist drills by hand is more than adequate.



WORD.

The whole thing is crazy...... some optimistic person claimed to sharpen by hand to better tolerances than a machine, and half the world seems to have gone ape-****.

The truth is that unless the machine is a Drill Doctor, or something equally bad, you can't do it better than the machine, except by accident. And there is not one thing wrong with admitting that.

It's all a question of what you want. methods are generally suited to the desired results, and this is no exception. If you can do a decent job of hand grinding, which comes with practice, go for it when appropriate.

If you need the hole as close to perfect as possible, use a machine.

If you want "a hole, to typical drilling tolerances", a good hand grind is probably perfectly good.



Another thing that seems to be always misunderstood is that bolts are used for CLAMPING only! They are NOT to be used for alignment!
.

Unless they are taper bolts, or others made for the purpose of simultaneous alignment and clamping..... but of course you do not "drill" the hole for those.

dalee100
07-13-2013, 11:30 AM
Hi,

Bolts do two things, clamp and locate. It is one of the things they do, they just don't necessarily locate to as close a position as a dowel and bushing can. Fortunately, the vast majority of locational assembly needs don't need that precision.

dalee

Forrest Addy
07-13-2013, 12:05 PM
Yeah I'm an old fart. I sharpen drills by eye alone and over the last 55 years (I was taught be my Dad) I sharpened a couple hundred drills a year from little #58 to 3 1/2". Drills are easy to learn if you have an eye for angles and symmatry. I do, so it was easy for me. I've had hundreds of aprentices in all trades in my clutches and all had to endure my "drill 'lecture" and practice untill they could free hand sharpen drills between 1/4 and 3/4 so the got hole size not over 0.005 of the drill, knew the names of the features to be found on a drill, knew the basic tricks of the driller, thinning the web, backling off the cutting edge, moving the start of a drilled hole, and basin layout.

I encorporated most if it in an HSM article I wrote for the May 2005 issue. The text only version: is too long for the single post limit so I'll break it to four chapters over my next posts. I have a Word document version with illustrations if anyone wishes to email me.

------------ ------------- --------------

Twist Drill Lore
By Forrest Addy
Mar 3, 2005 (for HSM May/Jun issue)

Chapter one

This issue’s topic is twist drills. I doubt if there’s a single tool used more often in industry, construction, and the home shop than the twist drill. They are everywhere. I counted 13 different consumer targeted twist drill sets at the big orange box and quit with more to go so I could move onto my mission. Twist drills remove more metal per unit of spindle HP than any other machining process yet they’re economical to purchase, simple to use, and are available everywhere. Technical evolution has brought us the twist drill from its primitive beginnings in the early 19th century to its present form. The history of twist drills while interesting is beyond the scope of this article but I encourage you readers to research it. Several drill manufacturers have synopsized this history in their catalogs and a few have even posted it on their web-sites. There are drills intended for everyday shop use to production drills used for drilling crankshafts and very deep holes. There are drills for teeth, glass, living bone, and so on up to oil wells, tunnel boring machines, and asteroids. There are long drills, short drills, drills featuring special flute modifications, oil hole drills designed to inject coolant at the bottom of the holes to flush out ships, drills with special shanks for various segments of manufacturing, and on through an endless list.

Today we address only the drills commonly used in the home shop: twist drills. We have so much ground to cover I won’t even mention safety in drilling except to emphasize: work safely!

Construction: A twist drill consists of the shank, the spiral flutes, and the tip or point where the actual cutting takes place. The twist drill has many distinct features that contribute to its function. It’s a good idea to learn the vocabulary of twist drills and drilling operations so you can take active part in a shop floor discussion when it grows dense in technical terms. Drills are hardened for the length of the flutes but the shanks are usually soft or at least machinable. They can be sharpened back almost the full length of the flutes. The soft shank is intended to fail first protecting the chuck or the spindle taper. Look at the sketch and the nomenclature:

Flutes: The spiral part of the drill is called the “flutes.” These provide the metal to form the cutting geometry at the tip and they transmit the torque from the shank to the cutting edges.

Gullets: The spiral grooves are called the “gullets” which gives the chips a path to escape as they are generated. They are spiraled just enough to roll the chips up the gullet from the drill’s rotation.

Margin: The raised edges along the flutes are called the “margins.” This feature reduces the area of contact with the wall of the hole reducing friction.

Web: The central portion of the drill between the flutes is called the “web.” It tapers from the chisel point and thickens as it approaches the shank. This tapered web gives the drill greater strength and stiffness. As the drill is sharpened back the thicker web manifests itself as a thicker chisel edge. Thus the chisel edge has to be thinned as the drill shortens with successive sharpenings.

Chisel edge: Look at the end of a drill. Note how the cutting edges are offset and how the two clearance surfaces intersect to make a little zig-zag called the “chisel edge.” 2/3 of the thrust of the drill is used to force this chisel edge into the work. The chisel edge gets thicker as the drill shortens from successive sharpening consequently the web has to be thinned to keep the feed thrust within reasonable limits.

Clearance: The “clearance” is the angle the lip makes to the shallow cone generated by the cutting edge. The clearance angle is critical to the drill’s performance. Without sufficient clearance the drill can hardly be made to penetrate regardless of the feeding force applied. If the clearance is excessive the cutting edge is fragile and may break or crumble when drilling hard or tough materials.

Back-taper: All twist drills have back-taper. Drills measure to factory size at the point but the size over the margin tapers smaller by several thousandths measured close to the shank. Grab one of your better drills and check this back taper. Taps and reamers are back-tapered as well. The back taper ensures that the friction occurs only at the cutting edges and not all the way up the shank.

Coatings. Many coatings are not only handsome but productive where conditions warrant their use. Gold titanium nitride is very hard and slippery. It’s an almost ideal coating for cutting tools as are many other high tech tool coatings now seen in the market place. It must be remembered that once the tool is sharpened the coating is gone from the ground surface and the tool’s performance decreases by some factor. So don’t expect miracles. You can see the benefit of coated drills in production statistics but the occasional user probably gains little benefit from their use in small scale home shop applications except in a few specific cases.

Coatings are not expensive to apply in production but they do add some cost to the tool if they are to be applied in a way that provides lasting effectiveness. The coatings are handsome and marketers have been quick to push them at the consumer. Plaster “TITANIUM!” on a cheap set of drills that have passed briefly through the coating process and someone will buy it. It’s like “Extra Crispy,” or “Male Enhancement.” Money well spent? I think the jury is still out for the home shop machinist. Some prudent people whose opinions I respect are real partisans for coated drills. I’m not. I may be wrong. Disregard most hype; it’s seldom substantive. Shop skeptically and buy on the merits.

Straight shanks: The “straight shank” drills we most often used in the home shop have shanks the same size as the drill. They’re called “jobber length” and they comply with several US standards in their proportions, materials, and markings. Straight shank drills come in blister packs, envelopes of 10, and larger industrial sized packages. They’re also sold in sets of fractions, letters, metric, and number sizes in a blizzard of packaging options.

Taper shanks: Many of you own a number of taper shank drills that feature an integral Morse taper. They’re designed to insert directly into the socket of a spindle without the need for a chuck. You insert them and firmly seat them with a knock on the chisel edge from a copper or brass hammer. Taper shank drills wedge tighter with drilling thrust preventing slippage between shank and socket.

There’s a misconception about taper shanks. The flat feature sticking out axially from the small end of the taper is called the “driving tang.” “Driving” in this case has nothing to do with torque because the tang has little torque transmitting capacity. The torque for a taper shank drill is transmitted entirely through the taper and the tang plays no part in it. Whenever a taper shank drill is spun in its socket the tang is usually severely damaged. Look over the older drills in the tool room of a busy machine shop and you’ll see the tangs on many that have been weld repaired with varying degrees of success.

The “driving” in driving tang comes from the method of removing the drill from its socket. The feed thrust can seat a drill so strongly that it takes a solid shock to remove it. A tapered drift is inserted in the slot in the side of the socket and positioned to engage the tang. The drift is firmly rapped with a hard hammer (it’s the shock that does the trick.) and the drill is driven out of the socket onto the block of wood you cleverly pre-positioned.

Hex driver: Another shank that’s growing in popularity for smaller drills has a ” hexagon about an inch long with a groove for installing it into a ball retainer driver chuck. These are particularly handy for work in the field and free-hand around the shop.

Contimued in the next post

Forrest Addy
07-13-2013, 12:10 PM
Chapter two

Aircraft drills: One long drill that’s handy to the home shop machinist is the aircraft drill. This drill features shorter than standard flutes and comes in 6” 9” 12” and longer lengths. These are available in common fractional sizes up to ” dia at the home center because they are popular in the construction industry. The long straight shank is much more rigid than a drill that’s fluted over most of its length and is therefore more resistant to abuse and accidental misalignment in awkward drilling conditions. I recommend these for deep hole drilling in lathe projects. The short flute length forces you to withdraw the drill frequently (peck drill) to clear the chips. This is not a hardship because no drill self-clears effectively in holes greater in depth than six to eight times the drill diameter.

Spot drills: These are factory-made short drills designed for making the initial penetration of the work surface in precise locations for subsequent drilling. Since the spot drill is very short and stiff it won’t wander under feeding force as will standard length drills.
Combination center drills: These are used in the lathe for preparing the cone shaped hole in end of the work for the center as well as in the drill press and milling machine for spot drilling holes to accurate location. As with the sport drill the combination center drill is very short and stiff providing accurately located initial penetrations for subsequent drilling.

Selection: While “buying America” is a good thing, most of us have limited funds and need to ensure the maximum bang for the buck drawn from our slim shop tooling budgets. Having said that I would definitely push the home metalworking shop purchaser towards US made drill sets if it will be subject to rigorous use. Import drills can be very satisfactory and many don’t deserve a bad rap from the “buy America” Jingoists. When shopping for import drills it pays to be vigilant for some are truly junk but persistence will lead you to affordable quality. There are many good brands of drills and drill sets on the market. Comparison shop at the home centers, fastener supply houses, construction supply houses, and industrial supply houses. Engage a knowledgeable clerk (that is, if you can find one) in a discussion of your needs. They will have a range for you to choose from. Shop wisely.

Drill sets: Drill sets are popular. You can buy a drill set for about the price of the drills if bought individually. The most common drills used are the tap drills for bolts and machine screws and their clearance drills. So why buy a great big comprehensive 115 piece set containing all number drills, letter drills, and fractions in 1/64” increments to ?” I don’t know. It’s overkill but I do it myself. It must be a testosterone induced primal instinct for acquisition.

Drill materials: Most consumer grade drills are made of high-speed steel (HSS) of some type usually molybdenum HSS. This is a low cost but very effective tool steel that features both hot hardness and toughness. Moly HSS is well suited for general purpose drilling in wood, steel, and non-ferrous alloys. Years ago the home shop machinist had the choice of carbon steel or HSS at much greater cost. Time, good metallurgy, and the economies of production brought us to where only HSS drills are sold. We can’t even buy carbon steel drills anymore.

I’ve used carbon steel drills in days of yore. When drilling steel, they would overheat, self anneal, and go instantly dull at the least provocation. Those of you who haunt yard sales might stumble on a collection of old drills. Beware! They may be plain carbon tool steel.

Cobalt HSS drills are intended for stainless and hardened alloy steels where heat and abrasion are factors in the cutting environment. They feature “red hardness” and hold their edges when drilling the toughest materials. Cobalt HSS drills are intended for severe duty meaning they are made with thick webs and smaller gullets. Consequently, chip clearance will be more of a problem when using cobalt drills especially when drilling deeper holes. Unless you're drilling stainless, very hard bronzes, heat-treated alloy steels, or titanium alloys, so-called "cobalt" drills are overkill. Cobalt HSS offers no advantage in drilling wood, mild steel, and softer non-ferrous metals.

Dispelling myths about cobalt drills: One may be attracted to the cobalt drills sold in sets at the big box stores; some with colorful coatings. The old set at home might be dull or it might be a cheap set purchased on impulse from an import seller. So you buy a set of cobalt drills for about triple the price of an equivalent quality HSS set. What kind of performance improvement can you expect?

Of course new drills work great because they are fresh and sharp from the factory and there is the "placebo effect" associated with every new purchase. The thrill fades after some use and a few hasty free-hand sharpenings. In the end the new cobalt drills perform no better than your beater set. You spent the money and you got… what?

Marketers are quick to pick up popular misconceptions and exploit them ruthlessly. Thus we see "cobalt" HSS drill sets at low-price importers. Whether they actually perform as well as an honestly presented cobalt bearing HSS alloy (M42 or equivalent) we have no way of determining by appearance alone. It's only when we get them to the shop and attempt to sharpen one can we tell by the sparks (sparse red-orange streamers) and abrasion resistance (high) if we bought the genuine article. For the unscrupulous importer “cobalt” drills are just one more gimmick to extract money from the naive home shop purchaser.

It's the metallurgy that makes the difference in drill performance and while budget Asian import tooling is improving with time their metallurgy can be dubious. Therefore I strongly suggest you purchase your M42 drills from a quality supplier, not from knock-off sources - and then only the sizes you need if the purchase of a full set is not clearly indicated. Expect to pay $350+ for a real 115 pc cobalt drill set.

Consider your workload. Make your purchase decision on the basis of your actual need and the materials you usually drill. The performance superiority of M42 cobalt HSS drills over M1 HSS in their recommended application is significant. If conventional HSS drills perform poorly in your particular line of work (stainless steel yacht hardware for example) then moving up to a cobalt bearing HSS drill may be a good idea.

Maintenance: You will spin drills in the chuck and score up the shanks. You will have taper shanks spin in their sockets. Some careful work with a slip stone will take the raised metal down flush with the original diameter or taper and the drill shank will register almost as good as new. Do not go below flush. You use a stone because it will almost quit cutting when the raised metal blends into the diameter. A file will keep cutting and you don’t want that. Use a file to knock off the burrs then use the stone to clean up abused drill shanks.

You will break drills. When it happens and there’s any flute left you re-sharpen them. Use these short drills as spot drills. They work well for “moving” the start of a hole.

Margin wear: The drill’s margin wears over time just above the cutting edge causing the drill’s diameter to be tapered for a short distance. This can pose apparently insoluble problems when drilling tough bronzes and alloy steels. The taper rubs the walls of the drilled hole and crates friction and heat. The drill runs hot and may jam and break – or even fuse to the drilled material. You may stick the drill in the bronze so strongly there’s no extracting it except by drilling from the opposite end and driving the broken drill out with hammer and a big punch. If the operator is on top of his job he’ll look closely at the margins of the drills he selects for critical jobs. He will even mike them at the lip and at several points up their margins. If a drill shows margin wear he’ll drop it in the “sharpen me” box and move on to another. He’ll also stick a piece of masking tape to the drill with the note “crop.” Cropping a drill means to shorten it to remove the worn portion of the drill’s margin - sometime as much as ”. On the occasions I’ve had to crop a drill I used an abrasive shop saw. Once cropped, the drill is sharpened in the normal way.

Sharpening: In the last few years some very effective stand-alone drill sharpening gadgets have come on the market and I sneered at them – until lately. My family gave me a Drill Doctor 750 for Christmas as a gag gift because they were tired of my bellyaching about them (Don’t need no stinkin’ gadgets!) Having used it to sharpen my collection of several hundred (round tuit) dull drills in a few sessions I have to concede it does an excellent job within its range. I especially like the split point feature. There are a few caveats. You do have to “spark out” – twist and twist the drill holder maybe 20 times until the little wheel stops grinding – if you want larger drills to be sharpened properly. Also look closely at the clearance angle. Under some circumstances the clearance angle can finish too shallow or almost nil. You may have to tweak the adjustments to get the machine to grind the clearance properly.

Contimued in the next post

Forrest Addy
07-13-2013, 12:11 PM
Chapter three

The cheap drill sharpening jigs made for bench grinders sold over the years are universally flimsy and awkward to use. They would do a good job sharpening drills if the user tinkered with them long enough but who has the time when a project is burning in the heart of the home shop machinist? Real drill pointers like those made by Oliver, Cincinnati, Sellers, and others over the years are first rate items of production sharpening equipment. One man can keep a twenty man shop in sharp drills by working one of these pointers a couple hours a week.

Hand sharpening: Fancy drill sharpening gadgets aren’t always available. I grind drills free-hand even now as a blurry-eyed old guy.

If you use a common bevel square or a drill gage to get the lip angles equal and a pair of dividers to get the lips symmetrical you can do an excellent job of drill sharpening free-hand. If your skills are well developed you can free-hand sharpen drills by eye alone. All it takes is practice and some experimentation. Here's how:

Dress the grinding wheel straight across so its periphery is a near perfect cylinder.

Assume a firm comfortable stance in front of the bench grinder.

Hold the drill comfortably so the flutes cradle themselves in your fingers of your right hand and with the shank in your left. The fit of the drill in your right hand registers it when you index (rotate the drill precisely revolution).

Present the drill to the wheel and adjust your stance so the lip is parallel to the tool rest and the angle is parallel to the wheel's periphery. If your stance is right your indexing and presentation is almost automatic. If you have to twist or distort your body your drill sharpening will reflect it. Go through a few preliminary sharpening motions to ensure the repeatability of your stance and your grip on the drill.

Touch the drill to the wheel periphery and after a second or two lift up to grind the clearance angle by following the wheel. Make the lift firmly but without haste. Do not rock the drill shank down to grind the clearance. It makes you stoop and throws off your stance, the clearance angle, and often your parallelism to the wheel face. Lift the whole drill up without rocking or rotating it and follow the drill in. If the clearance is excessive don't lift the drill so high. If the drill needs more clearance start the lift sooner.

Index the drill in your fingers to grind the next lip without thinking about it too much. Just give it a quick rotation with the hand and re-cradle it as you resume your grip. Let your senses tell you when the drill is properly indexed. You'll be surprised how accurate and repeatable these neuro-muscular maneuvers are when not interfered with by a worry-wart brain. Check the parallelism of the lip and the angle with the edge of the tool rest then immediately grind.

Grind the drill through several indexes stopping to check the lip angle, symmetry, and clearance. If all is well, good. If not, no harm is done; sharpen it some more until it’s right. Try the drill in the drill press. If you get two equal spiral chips great. If you get two unequal chips maybe not so great but if the hole is less than 0.005" over nominal you did good.

There is no need to slavishly adhere to the 118 degree included drill point angle. You need to be close but it’s more important for the drill point to be centered, symmetrical, and equal angled in its two cutting edges. Different materials might call for special cutting angles and clearances which may be found in appropriate technical references. When the need arises you may wish to grind a special point on the drill. There’s nothing to keep you from doing it except the cost of the drill (low) and the number of sharpenings the drill can endure (many) before it gets to short for use.

Smaller drills – those 3/16” and under – I free-hand sharpen with a hand stone. I might touch them up on a bench grinder but I finish them with a hand stone. It takes but a few minutes and you have much better control over the angles and other features.

Sharpening drills is a manual skill requiring practice and training of the neuro-muscular system. You cannot verbalize free hand-drill sharpening except as a means to get the beginner started. It's like riding a bicycle or catching a ball. The skill lies in the reflex loops you develop not conscious thought. If you don't do sharpen a drill perfectly the first time, don't worry about it. They make drills long so apprentices can practice sharpening them. When you sleep your brain will re-program itself and you'll do better the next day. That's what sleep is for, to rev and mod the brain’s software. Practice! Practice! Practice!

Story: I once was called in to work on a Sunday to drill some big holes to layout in a thick piece of steel plate using a monstrous radial arm drill. There were plenty of suits and white hats present emphasize the job’s urgency. The tool room was locked up but I found a chipped drill the right size (2 5/8" dia as I recall) in a drawer. I free-hand sharpened it on a big Hammond grinder judging the symmetry and the angles by eyeball alone. Some white hats drifted over and talked among themselves as I worked the drill on the grinder - one skeptic making dire predictions.

Well, I was both lucky and well-practiced at the time. When I started drilling, a pair of chips spiraled out the gullets as sweetly as if the drill was machine ground. I cranked up the feed to 0.020" per rev and did my best to slop dirty, horribly contaminated soluble oil on the critics. As senior supervisors they were experienced in the game and danced back, timing things nicely. Drilling the four holes from the solid took a half hour. De-burring and chamfering took another ten minutes. Bada-bing and it was on the pallet.

I got handshakes and congratulations from my panel of judges. I don't know why - I thought success was a lock. I was thirty years old at the time and had the eye of an eagle, was sharp as a tack, and arrogant as a newly hired prosecutor. But I smiled and nodded as I fork-lifted the piece onto a truck for the ship's force to drive it away.

My story goes to show that skills will save your bacon when you least expect them to. What would have happened to my reputation if I sniveled about no sharp drills being available? Thirty people were standing around on overtime and I couldn’t sharpen a drill? What a disgrace! I’d have been sent to the propeller shop to grind and contour blades until I retired with lungs of brass.

Thinning the web: Thinning is necessary as the drill is sharpened back. The slightly rounded corner of a grinding wheel is used to clean out the intersection of the cutting edge and the gullet. The effect is to narrow the chisel edge reducing the thrust necessary to feed the drill. The drill is held at an angle to the wheel and you sight down the corner of the wheel as you bring in the drill into contact. This is another eyeball skill you have to practice. The beauty of this technique of thinning the web is it can be accomplished on a bench grinder whose wheels have been neglected. Some long a the wheel’s corner can tuck into the gullet you can use it to thin the web.

Split points: Thinning the web until the chisel point just disappears to become a sharp intersection is called a “split point.” Do this carefully. Over-grind a split point and its benefit evaporates. It takes a keen eye, a steady hand, and a grinder whose wheel has been properly dressed to a sharp corner,

Contimued in the next post

Forrest Addy
07-13-2013, 12:14 PM
Chapter four

Backing off the cutting edge: The cutting edge angle at the lip is equal to the drill’s helix angle - roughly 25 degrees. This is a very aggressive hook angle and it causes the drill to grab on breakthrough when hand drilling. When drilling some soft, strongly crystalline metals (cast valve bronze for example) the hook can cause the drill to “follow the helix” right into solid metal. Following the helix is a particular problem when step-drilling to enlarge holes. This often results in a broken drill or at least the drill is snatched out of its taper twisting off the driving tang. Backing off the edge of a drill is a means of reducing this “hook” at the lip of the cutting edge making it unlikely to grab.

A slip stone (or on larger drills the side of a grinding wheel) is used to make a narrow land on the cutting edge having either neutral or slightly positive rake. The edge only has to be backed off by roughly double the feed rate to be effective. In small drills where a typical feed rate would be 0.002” per flute only a bright line is actually necessary. However, it’s customary to back off a drill to at least 1/64” land width so the modification is readily visible to the next user - more on larger drills.

Lobing. Drilling spindles are not particularly rigid, drills are usually long and flexible, and the standard drill tip geometry is a compromise at best. The result of these variables is the drill can “lobe,” that is, make three and even five sided holes as easily as round ones. If the material has sufficient thickness the drill will eventually “round up” but the wobbly entry may be unsightly. The solution may be to drill a starter hole a bit smaller than the drill’s chisel edge thickness to give it a center to work from. If the material is thin, use a butterfly drill. You can also clamp a guide bushing on the work – even a piece of plate with the right sized hole in it will serve as a drill guide. If you’re starting the hole with a center drill, next time drill only as deep as the stub. If you’re drilling with the tailstock in a lathe, bore the hole to size for a short distance.

Step drilling: If the hole you need to drill is larger than your drilling equipment’s capacity to feed from the solid you need to “step it out” in stages starting with a smaller drill. 2/3 of the thrust necessary to feed a drill is used to force the chisel point into the work. My rule is to measure the chisel edge of the full sized drill and pre-drill no more than 10% larger than the chisel edge thickness to depth. This will allow the full sized drill to be fed with 1/3 force if drilled from the solid yet it provides sufficient thrust to keep a taper shank firmly seated. Don’t make the step increments too gradual. If circumstances force you to step out in small increments you’ll need to back-off the cutting edge angle to prevent the drill from grabbing and being snatched from the taper socket.

Pilot point drills: There’s a type of drill commonly sold in the tool section of the home center that features a secondary but smaller drill point protruding from the tip like the stub end of combination center drill. This is called among other things a “pilot point” drill. When new and in good shape they work great especially for drilling sheet metal free-hand. But you do have to ask yourself: how do I sharpen them? I don’t know. I’ve touched them up with a slip stone but in my extensive shop I’ve never managed to duplicate the equivalent of a factory ground pilot point on a drill. So for these drills, the home shop user buys them and uses them. When they get dull, they have to be re-sharpened to a conventional drill point. Come to think of it, how could a home shop machinist re-point a pilot point drill? I’ll have to work on that.

Butterfly point: (also known as a brad point) A “butterfly point” features a central spur that stabilizes the drill and has a somewhat concave cutting edge configuration. They are particularly handy for drilling softer thin materials like sheet metal 1/8” thick or less and shim stock. The spur gives them a strong centering action. You use them on the drill press always with a wood or soft metal back-up. You’ll love them. They don’t raise enormous burrs or make lobed holes. On breakthrough they leave a little “washer” that prevents the drill from lunging through and tearing up the delicate shim you’re drilling.

Butterfly drills are readily free-hand ground. The stance and the other aspects of drill grinding are the same regardless of the drill point configuration you wish to grind. Grinding a butterfly drill takes some practice to get the spur centralized. You do need a grinding wheel with a sharp corner. You also need to practice grinding and using them before the actual need arises. Study the sketch of the butterfly drill. Hold the drill shank about 10 degrees away from the plane of rotation. Proceed with care so you don’t round the corner of the grinding wheel. Make the spur so it stands about 1/16” – 3/32” past the plane of the drill’s lips. Grind a tiny chisel point on the spur. The spur should be roughly square (well, parallelogram) in cross section like a pyramid and have about a 20 degree included angle. Don't make it too skinny. Also plunge the clearance angle. Don’t run it up the wheel as you do a conventional drill point.

There’s much I didn’t discuss. Sub-land drills, oil-hole drills, flat bottom drills, spade drills, counter-bore drills, gun drills, oddball grinds, etc. The world of drilling that’s applicable to the home shop is huge. This article is but a start in your education. Go forth and discover.

Here’s a starter. What is a Silver and Deming drill? Look in an industrial supply catalogs like Enco, J&L Industrial Supply, MSC, or Travers Tool. Do you need to drill large holes? No Morse taper drilling capability? Then you may need a series of larger drills whose reduced shanks will fit your drill press chuck. If that’s the case you might find a use for a modest set of Silver and Deming drills.

As for free-hand drill grinding, what was it I said? Practice! Practice! Practice! You’ll never learn any younger.

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Again the complete "twist drill" article is available in MS Word format to any who send me an address.

That's drills. lathe tools and HSS boring bars issimple: free hand grind. If you don't practice and work at developing an eye at lewast use a protractor, learn to gress your wheels, devote time to practice with no other goal than learning what you need to lean.

Endmills I seldom do more than end grind a two flute or champher grind or radius grind, The cutting edges I leage for the tool grinder. I farm out all my endmill sharpening. I can do it but it's a PITA. There is always a local guy who has a side business with a tool and cutter grinder. Find him and if he's any good use him. Do him a favor and get youy cutters sharpened in batches. One-sey two-sey endmill sharpening orders will drive him nuts and he'll have to charge you more per cutter than in batches of a dozen or so.

Endmills 1/4" and smaller are throw-aways. Live with it.

Cuttings
07-13-2013, 12:30 PM
I think you are talking about the grinding rest I built from one of Harold Hall's books. I suggest you get a copy of his book "Tool and Cutter Sharpening"
It is available from the book depository in the UK and the shipping is free.
Try <www.bookdepository.com>

Jaakko Fagerlund
07-13-2013, 12:44 PM
Whatever method is used to sharpen those drills, just remember that the 118 degree angle isn't a must. Bigger angle reduces power needed in drilling and reduces heat generation, which is very nice when drilling work hardening stainless.