# Well, this dosen't look safe!



## Finster (Apr 23, 2017)

Side loading a grinding wheel? Bad stuff can happen when you do this. These types of wheels are not designed to be side loaded and here is a tool that is designed to do just that! I found this when I was looking for a cheaper alternative to a drill doctor 750X



I wonder if anyone had had a wheel shatter using this device? Looks like a lawsuit in the making to me.


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## Bob Korves (Apr 23, 2017)

I must admit to using that setup quite a lot, on a  6 x 1" bench grinder.  I still use it, rarely since I got the Drill Doctor 750x.  There are very light side loads on the wheel while grinding the bit, if you are doing it correctly.  A crash might be catastrophic, but there is no reason to ever have one if you are paying attention.  The drill jig mount is also flexible enough to give if there is an accidental heavy feed.  I have ground hundreds of drills that way, with very good results (after the learning curve.)  I used it enough to kill the bearings on the grinder from side loading them, and I have replaced them.  (I have also done heavy hogging on that belt drive grinder.)  That is the worst I can say about it.  The good news with my setup is that I stand completely to the side of the grinder, away from direct hits if it should let go.  The wheel I use is only slightly worn from the hundreds of drills ground with it.


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## pdentrem (Apr 23, 2017)

Used one for years. Never had an issue and it is only sweeping past and does not dig in like from the front with a large gap tool holder will.
Pierre


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## Finster (Apr 23, 2017)

Looks like it may work well and be safe with a carbide grinder if you could make it fit. I'm going to stick with the drill doctor 750X I suppose.


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## wawoodman (Apr 23, 2017)

They've been around for a mighty long time. I suspect they would have faded away, if there was a rash of exploding wheels.


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## brino (Apr 23, 2017)

Those things do get "trashed" here quite regularly by the higher-end machinists.

However I just got one recently, and it works great!
I got it after a bunch of investigation. (I'll post a link if I can find it to a review of Drill Doctor vs. this type of sharpener)
The Drill Doctor was just not in the budget, and I believe this will serve me well.

The only problem I have is that I moved the sharpener base before measuring/marking the location after I found the "sweet spot". Now I need to go thru the "calibration" process again.....

Putting on my flame suit!
-brino


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## Finster (Apr 23, 2017)

I'm sure they work well. I do not doubt that. I also believe that the chances of a wheel exploding is slim when this is used correctly. My point here is that, personally, I'm not going to take the risk. I saw a wheel explode in a shop once. Messed the guy up pretty bad, he had shrapnel in his legs, stomach and lost two fingers.  It was from side loading also. If a wheel does explode, chances are that you're not getting out of it without injury. Just not worth all of that for a sharp drill bit in my mind. To each his own though.


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## mikey (Apr 23, 2017)

brino said:


> Putting on my flame suit!
> 
> -brino



Why, Brino? These drill sharpeners have been around forever and they have worked ever since. Nothing wrong with them if they do the job for you. I know we're told not to side load grinding wheels but I haven't heard of a wheel exploding due to side grinding drills. I have personally had a grinding wheel explode on me while grinding at the front. 

Lot of guys have used the side of the wheel for sharpening. The Brits do it and documented their fine jigs for this very purpose. I think if you are careful not to shock the wheel or take super-heavy cuts, it should be fine.


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## Dinosaur Engineer (Apr 23, 2017)

I'm sure that most of us know about wheel side loading and have used the side of the wheels many many times without any problems. As long as common sense is used and only light loads are applied I've never seen or heard about any problems during the last 50 years of my engineering carreer .


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## brino (Apr 23, 2017)

mikey said:


> Lot of guys have used the side of the wheel for sharpening. The Brits do it and documented their fine jigs for this very purpose. I think if you are careful not to shock the wheel or take super-heavy cuts, it should be fine.



Oh hey, I agree completely! 
I use it and like it.

It's just this topic usually brings out the folks that say it's a death trap and will never be an acceptable way to use a grinder.

The "flame suit" comment is a perhaps a little in jest........I know this site would not put up with real abuse. 

-brino


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## brino (Apr 23, 2017)

Finster said:


> Just not worth all of that for a sharp drill bit in my mind.



Hopefully not literally! 
-brino


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## Rustrp (Apr 23, 2017)

There's a couple of things that happen when a wheel explodes and the first is the quality of the wheel, the second is a wheel that's been abused or not dressed or someone has used the wheel for nonferrous material and not cleaned it up. I don't think sideloading should be ignored because everyone will do it different. I've used the shapener pictured in two different shops and they were set up so the face of the drill was used, not the side. I think the big difference  in how it's used, is how the grinder is mounted. Due to the limitations placed on the grinder when it's mounted on a bench, I mounted mine on a pedestal, so now it's a pedestal grinder. With a bracket or tool rest in front of the wheel to mount the gadget, it works as intended. They work better than I can grind by hand but you don't get split points, and in the larger drill bit category this isn't an issue. When a grinder is mounted on a bench (I know they're bench grinders) there's no alternative for the everyday home shop guy but to use it as it's shown. Make a bracket and mount it so it can be used on the face.  

"I've done it like this for years" he says to the ER doc.


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## JimDawson (Apr 23, 2017)

brino said:


> The "flame suit" comment is a perhaps a little in jest........I know this site would not put up with real abuse.



We'll make an exception in your case.


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## mikey (Apr 23, 2017)

Hmm, Roasted Brino ...


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## Rustrp (Apr 23, 2017)

brino said:


> It's just this topic usually brings out the folks that say it's a death trap and will never be an acceptable way to use a grinder.



I think if someone chose to do so it's all well and good. I think most wheel disintergrations come from cheap, poor quality wheels or abuse, but as an employer I would never allow someone to sideload a wheel. My first choice in using this attachment as it's shown would be a cup wheel designed for the application. I have one I've used so many times it looks new. The are many alternatives to using the side of a wheel. I think more accidents occur caused by the incorrect clearance of the tool rest to the wheel than will ever occur by sideloading.

I think you were looking for a reason to wear the suit.


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## mikey (Apr 23, 2017)

All joking aside, I took another look at this and found out that vitrified grinding wheels have less tensile strength than porcelain or glass. See this: http://en.kuretoishi.com/support/attention/follow.html

I suppose a lot of guys who bear down to grind a HSS tool on a wheel are unaware that even on the rim, the wheel is not intended to take that much load bearing. We KNOW we should let the wheel cut but I think too many of us think this is too slow and we're gonna MAKE that wheel cut faster by bearing down. Big mistake.

If I had to grind tools on a bench grinder I would opt for CBN wheels. No danger of explosion and you can grind on the sides all you want. 

I can tell you that when a grinding wheel lets go, it is truly amazing to realize how powerful your anal sphincters are and how fast they can contract! Same goes for a snapping belt on your belt sander when it lets go with your face just inches from the belt - makes you a true believer in personal safety equipment.


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## ELHEAD (Apr 23, 2017)

Just a thought but wearing the wheel side and weakening the circumference be more  of a problem than than simply the side load. I just recently set up the Craftsman version (US  made by General I think) and placed min in the front. I've only used it on larger bits so far an thought they did a great job.
Dave


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## Bob Korves (Apr 23, 2017)

brino said:


> Those things do get "trashed" here quite regularly by the higher-end machinists.
> 
> However I just got one recently, and it works great!
> I got it after a bunch of investigation. (I'll post a link if I can find it to a review of Drill Doctor vs. this type of sharpener)
> ...


How close the nose of the tool is to the wheel is how you set the back rake and chisel angle, and is different for different helix angles.


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## Terrywerm (Apr 23, 2017)

I used one of those jigs for many, many years, first in my dad's shop, and I now have something similar made by Atlas. They both use the side of the wheel. As others have mentioned, the forces involved are very light, although I must admit that there is always a slight risk of someone trying to use it without a proper education first, but I know that the chances of that in my shop are slim to none. None the less, a full face shield hangs at my grinder and I use it every time I use the grinder. My boys know to use it also, and thus far I've never seen them use the grinder without it.


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## Bob Korves (Apr 23, 2017)

ELHEAD said:


> Just a thought but wearing the wheel side and weakening the circumference be more  of a problem than than simply the side load. I just recently set up the Craftsman version (US  made by General I think) and placed min in the front. I've only used it on larger bits so far an thought they did a great job.
> Dave


I have ground hundreds of drills on the side of one aluminum oxide 100 grit wheel, and if you looked at it you might guess someone tried to grind one drill on it.  There is absolutely no visible 'wasp waist' on the wheel.  It appears barely used.  Cuts are kept light, no hogging, even on heavily damaged drill points.  Hogging on the face of a wheel can also create grooves and explosions.


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## bob308 (Apr 26, 2017)

why not just put a cup wheel on the grinder ?


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## Finster (Apr 27, 2017)

bob308 said:


> why not just put a cup wheel on the grinder ?


If it fit, I don't see why you couldn't as long as the speed was the same or under for the wheel.


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## tq60 (Apr 27, 2017)

Some grinding processes are on sides such as thrust bearings and the wheels are fine.

We have a collection of these that we have picked up over the years at estate sales as people have no clue what they are for.

Get bits by the box so no need to sharpen many...too many other chores like figuring out where to put the stuff we drag home from said sales...;-)

The point is having a suitable Grider with minimal end play and good bearings so side loading works followed by having a suitable and correct wheel.

Best to have a dedicated machine so fixture once in sweet spot stays there.

Sent from my SAMSUNG-SGH-I337Z using Tapatalk


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## Silverbullet (Apr 28, 2017)

Have any of you watched an idiot grind anything on a grinder. I have seen so called mechanics and machinist , jam the piece in so hard it stops the wheel and do it from the side as well. I'm amazed some live , self taught hammer and chisel butcher's. The abuse a grinder gets is just criminal. Have you ever seen a lawnmower blade sharpener, made to rotate both directions, but if there not taught how to be used wheels are destroyed arbors bent motors burnt up. But I've only ever seen surface grinder wheels explode . I think the bonding agents are much stronger in the pedestal type machine wheels.
Now the sharpener in question. If you can put the amount of pressure it would take to break a wheel grinding a drill to sharpen then you need to be on a weight lifting team not a machinist. I own one of these and have it mounted to a 1"x 42" belt grinder, it's been used so often the platen needed to be replaced. At one time I owned and operated a sharpening service . Not for machine tooling but blades, saws , home , farm and garden. When the cheap throw away years started it was no longer worth the time to do sharpening. Circular saw blades up to 6" a big $1.00 each. handsaw filed and set for $5.00 , those were done by hand and took an hour or so. People thought I was robbing them too. Enough tangent if you use the tool as it's supposed to be  you will never explode a good wheel on a grinder.
Don't ever be afraid to tell someone there in danger , it may save your hide and others. So really your right.


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## Silverbullet (Apr 28, 2017)

brino said:


> Those things do get "trashed" here quite regularly by the higher-end machinists.
> 
> However I just got one recently, and it works great!
> I got it after a bunch of investigation. (I'll post a link if I can find it to a review of Drill Doctor vs. this type of sharpener)
> ...


c
Even if you Mark or drill a mounting hole , longer drills will change the sweet spot. I made several tapped holes to mount by length.Every shop I worked in it seemed I was singled out to do the off hand large diameter drills. I guess I had the knack, I also did different angles for different metals also thinned the web , even grinding in chip breakers .


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## blu73 (Apr 29, 2017)

I also have one of these sharpeners.  As far as any lawsuit potential, the instructions that came with mine state that the tool should only be used with a wheel made to certain ANSI standards to withstand side loading.  If the others who market this type of tool include that directive, I would guess they are off the hook if a user blows up a wheel that is usually found on a hobby level bench grinder.  How many of us really go out of our way to find a proper tool for this task?  I know I didn't.  I looked this over and made a conscious choice to disregard what the directions say.  I feel I am able to work within the abilities of the wheel.  After all, it isn't going to blow up just by touching the side with a minimal amount of pressure on a very small contact area.  I have probably hit the side of the wheel harder by mistake when doing other work than I will by sharpening a drill there on purpose.


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## Finster (Apr 29, 2017)

blu73 said:


> I also have one of these sharpeners.  As far as any lawsuit potential, the instructions that came with mine state that the tool should only be used with a wheel made to certain ANSI standards to withstand side loading.  If the others who market this type of tool include that directive, I would guess they are off the hook if a user blows up a wheel that is usually found on a hobby level bench grinder.  How many of us really go out of our way to find a proper tool for this task?  I know I didn't.  I looked this over and made a conscious choice to disregard what the directions say.  I feel I am able to work within the abilities of the wheel.  After all, it isn't going to blow up just by touching the side with a minimal amount of pressure on a very small contact area.  I have probably hit the side of the wheel harder by mistake when doing other work than I will by sharpening a drill there on purpose.


That's interesting, I didn't know they had a "disclaimer". It's not so much the people even on this forum. Most of us know better and have knowledge of grinders. The point is that this is being sold to the masses. People that may not know any better and do something unintended like try to grind an angle on round stock or something. Just theorizing here. My point is that this is a setup for someone that does not know any better to get hurt and I hate to see anyone get hurt. Yea, for people like us, it's one thing but for a complete novice or some kid messing around in dads garage when he's not around, it's something completely different. I guess that's really my point.


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## Norseman C.B. (Apr 29, 2017)

This thread brings to mind the old adage about opinions and anal orifices.
These rigs have been in use longer than I've been breathin, and I'm definitely no puppy.....


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## Downunder Bob (Apr 29, 2017)

Finster said:


> Side loading a grinding wheel? Bad stuff can happen when you do this. These types of wheels are not designed to be side loaded and here is a tool that is designed to do just that! I found this when I was looking for a cheaper alternative to a drill doctor 750X
> View attachment 232047
> 
> 
> I wonder if anyone had had a wheel shatter using this device? Looks like a lawsuit in the making to me.



We had one, actually two of these when I was an apprentice. A small one on a 6"wheel and a larger one on a 10"wheel. they were both permanently mounted and the grinders were dedicated for drill sharpening. Both devices were made in house, and worked perfectly, they also ran on the front face of the wheel not the side.

Both machines they ran on the right hand wheel, which was fairly fine, the left hand wheel was coarser and was for roughing a drill that was damaged.

Never saw a wheel shatter on these machines, in fact I think the only wheel I ever saw shatter was a brand new wheel just fitted. the person who fitted wisely stood to the side while running it up.


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## NortonDommi (Apr 30, 2017)

Any worries just fit a cup wheel or leave the standard wheel in place and make an extention to replace the nut and protrude thought the hole you make on the outside of the safty gaurd and mount a diamond facing disk,(the cheap ones for use on an angle grinder), and then you can sharpen drill bits and carbide tools. So little load that the Diamond  will not dissolve into the iron. It's for sharpening not shapeing.


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## RCWorks (Apr 30, 2017)

There's a tool for drill sharpening? I'm getting one of those.

Thanks!

I was stuck in the dark ages of doing it by hand on the grinder.


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## NortonDommi (Apr 30, 2017)

O.H.S. 
                                NOTHING IS SAFE!!!


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## Joe in Oz (Apr 30, 2017)

I wonder if the 'no side loading' is just a disclaimer by the grinding wheel manufacturers anyway....
I have several cup type wheels (clearly made for side loading only) and I can't see any difference in manufacture or construction of these at all, except that the mounting portion of them is significantly THINNER than most of my grinding wheels.
I have also seen wheels explode, and have a friend who is permanently disabled as a result of getting hit in the forehead by a large fragment. In every case they were either newly mounted  wheels with a fault or a 'crash' where something hit the wheel that was not intended to. In one case a piece of metal getting jammed into the grinding rest gap to the wheel, stopping the wheel in an instant and throwing a piece out.
I still grind things on the side of the wheel regularly, with normal grinding pressure. On both cup wheels and parallel wheels. Have been doing so for around 55 years....
The drill bit sharpener in question is indeed a useful tool I have had from new around 45 years ago. It's pretty well worn out now. The amount of pressure or force on the wheel is near nothing.
Jamming something into the wheel - face or side - is asking for trouble, no matter what kind of wheel.
Just my 2 cents worth....


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## Bob Korves (Apr 30, 2017)

A cup wheel on a bench grinder will also either leave the wheel sticking out beyond the safety guard, or require removing the entire guard or the side cover of the guard.  It would of course be possible to make a new guard for a cup wheel, but how many would actually do so, and with an adequate design, and well built?  Then again, many machinists use cup wheels on tool grinders and surface grinders without any guards at all.  Many thousands of home shop guys have ground drills on the side of the wheel with these grinding jigs for at least five decades that I know of, and I have not heard war stories of problems with doing so.  In the 33 messages so far on this thread, no one has posted a first person account of seeing a wheel explode from using this tool on the side of a bench grinder wheel.  Both Joe in Oz, and I (40 plus years each), and countless others have used them in the same way they are configured on the manufacturer's packaging, without any issues.  Let's spend more time championing safety where there are known, documented, and recurring safety problems that cause injuries.  Machining and metal working have lots of inherent dangers that are simply part of the processes, and we ignore them at our peril.  There are plenty of common injuries occurring daily for us to get the word out on...


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## Finster (Apr 30, 2017)

RCWorks said:


> There's a tool for drill sharpening? I'm getting one of those.
> 
> Thanks!
> 
> *I was stuck in the dark ages of doing it by hand on the grinder*.


 That's how I've always done it. I have a drill doctor coming in the mail now though.


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## Keith Foor (May 1, 2017)

OK, I am not gonna get into the safety discussion. 
Instead I will talk about sharpening drill bits and what you can and can't get away with.

There are 4 basic methods of sharpening twist drills, and each has negatives, I will only discuss the bad here because the good part is you end up with a sharp drill bit if the stars align and you do in either right or as accurate as the method allows.

Now bear in mind that a properly sharpened drill bit will have two cutting faces, of equal angle, size and shape.  They will have a specific amount of rake to keep just the right amount of the face against to work so it will regulate the speed of the cut and not just dig in as a chisel would.

First method is hand sharpening.
This by far is he worst way of sharpening a drill bit.  Only pure luck and planet alignment will get a drill bit properly sharpened with this method.  
There are TOO MANY angles that all have to be controlled, depths that have to be matched and the list goes on.
Figure that a good professionally sharpened twist drill will be accurate flute to flute and cutting face to cutting face to the point that an optical comparator would be needed to see the error in the bit.  Firing up the grinder and free handing the bit until the burs and chips are gone from trying to force the wrong size bit at too fast a speed through metal that is almost as hard as the twist drill is NOT EVER going to be 100% right.

Second is the low grade stuff like pictured.  These are at least an attempt for consistency, but due to quality still fall short and will also generate bits that want to drill triangle shaped holes.

Then you have the drill doctors.  
These are loosely based on the other product the company makes,  being DAREX, which make very high quality and expensive tool bit sharpeners.
These are better than the first two methods but fall short in the fact they use a very small abrasive drum to sharpen with.  The small diameter means that a surface that should technically be flat have a very small radius that is imposed into the bit as it cuts it.  This coupled with plastic parts that flex which leads to errors make them much better but still not great.  

Lastly is the high end high buck stuff.  Now we are talking air bearings, DAREX units similar stuff.  
The biggest drawback to a DAREX is it's 3200 bucks.  But they can sharpen not only the tips of drill bits accurately but also the flutes.  Try freehanding that.
Air bearing end mill fixtures fit into this category as well.  These can be used with a quality bench grinder and proper abrasive wheels to sharpen any round cutting bit.  They can also be used to create odd ball bits from drill rod blanks if you feel the need to do so.  Ultimately price again keeps these out of the hands of most hobbyists.   

Any of them will work to some degree.  And I know I will get flamed by the old guys that have been free handing for years with claims that their bits cut just fine.  But I would still put my air bearing sharpener up against their free hand work any day.


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## NortonDommi (May 3, 2017)

O.K. Keith you've made the point, none of the old guys can sharpen a drill bit like you can with your air bearing sharpener. The real point is that no human is capable of replicating the accuracey of a machine. That is why we humans build machines is it not, to actualy do a job better than we animals can physicly do? CNC is a stark reminder of just how inaccurate humans are.
  Here is something to think about though, a bit that drills a good hole is something that most can learn to grind freehand by several different methods and having been taught by people who started their learning in the early 1900's I believe that the ability to recognise when a bit is not cutting right and the ability to quickly make it good  is a valuable skill.
  Staying in the real world I cannot remember ever needing to sharpen the flutes of a bit. I'm not so old I ever had to make a twisted bit from scratch. 
  We all love the brand new factory sharpened bit but that falls way short of the ideal. In the real world a bit that cuts clean and round and very close to the nominal size works just fine,(reamers were invented for proper round holes). Some of us still hand grind on the job because it expedites the job and also because all that time learning to do the job of sharpening drill bits was not wasted. As a 1st year apprentice I had to collect every bit not in use after Friday arvo smoko and inspect them, sharpen all that needed it and have a tradesman inspect my work. To this day I cannot put a bit back in a rack if I know it is defective. A quick lick,(only if nesacery), after use means it will at least be 'good enough' for the next guy who is in a hurry.
  Just for the record I regulary go through all my bits and every now and then take any I think are sus to a friend with an expensive purpose built commercial grinder and beg ,(wheel),face time.
  - Barry.


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## Keith Foor (May 3, 2017)

NortonDommi said:


> O.K. Keith you've made the point, none of the old guys can sharpen a drill bit like you can with your air bearing sharpener. The real point is that no human is capable of replicating the accuracey of a machine. That is why we humans build machines is it not, to actualy do a job better than we animals can physicly do? CNC is a stark reminder of just how inaccurate humans are.
> Here is something to think about though, a bit that drills a good hole is something that most can learn to grind freehand by several different methods and having been taught by people who started their learning in the early 1900's I believe that the ability to recognise when a bit is not cutting right and the ability to quickly make it good  is a valuable skill.
> Staying in the real world I cannot remember ever needing to sharpen the flutes of a bit. I'm not so old I ever had to make a twisted bit from scratch.
> We all love the brand new factory sharpened bit but that falls way short of the ideal. In the real world a bit that cuts clean and round and very close to the nominal size works just fine,(reamers were invented for proper round holes). Some of us still hand grind on the job because it expedites the job and also because all that time learning to do the job of sharpening drill bits was not wasted. As a 1st year apprentice I had to collect every bit not in use after Friday arvo smoko and inspect them, sharpen all that needed it and have a tradesman inspect my work. To this day I cannot put a bit back in a rack if I know it is defective. A quick lick,(only if nesacery), after use means it will at least be 'good enough' for the next guy who is in a hurry.
> ...


Yes that is all true.  You can get it done free hand and it will work to some degree.  The biggest issue with hand sharpening is the faces not being equal and one cutting harder than the other.  That will bind a bit and break it quick.  As far as sharpening flutes. No sharpening flutes is not common.  One use for it is when you need a .485 bit and you only have a draw full of .500 bits.  An air bearing fixture will allow you to reduce the diameter of the bit to what you need 

Sent from my SPH-L720 using Tapatalk


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## NortonDommi (May 3, 2017)

I know people who break drill bits on a regular basis, reground or new. These same people also have problems with burnt tips, chipped and wiped outer edges ect. This they do with a continual feed of new bits and their problems are to do with no lube when it is needed, wrong speed, using the bit as a punch,(huge axial force),and not having the work or drill secure. Hand drilling is particulary bad.
  On the other hand I know people that very rarely break a bit, most of their bits just get worn out then get used as stub bits,
  You have me envious now of your air bearing sharpner, I had not given thought to the number of times I have needed a particular size and for one reason or another have not had the exact size I've needed. 'Close enough' usually works but never feels good.
  We use Imperial and metrickery here and between whole number, fractions, number and letter sizes and metrickery sizes which come in 0.1mm steps
just about all bases CAN be covered if you have time to obtain the size you need.
  I'll still stick to a reamer when I want an accurate hole though.
  The points summed up  by Bob Korves pretty much says it all about equipment used by the average Joe though. Common sense liberally applied usually gets the job done and done well and that is where knowing how to use machinery in general comes into play. I sometimes hand grind on the side of a wheel, most times the face. Different techniques same result. A drill gauge I made in 1973 still helps with the edge length and watching the swarf lets me know how well the bit is cutting.
   While I am well known for having serious tool envey issues I also have to deal with all the variables that makes life interesting and at the end of the day finding something that works and works well, safely for the individual is the most important thing.


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## Bob Korves (May 3, 2017)

Making a drill bit smaller diameter than original does not require an air bearing.  It can be done on a spindexer on a surface grinder, or on a basic tool and cutter grinder, and perhaps on other setups as well, not quite as accurately, but then drills are not tools for producing precision holes.  Regardless, removing the margins from drill lands will take away any real hope for smooth finished, accurate holes anyway.  I think that is a great idea for a reduced custom sized diameter hole, but it is still a drill, which is a material remover, not a precision hole maker.  Followed by an on size reamer, yes, at the custom size and a smooth and round hole.  Then again, a reamer can do that without the custom size drill...


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## benmychree (May 3, 2017)

Quite agreed, Bob; It would be entirely better to regrind a machine reamer to the desired size than a drill; they are ground with a slight back taper and NO  relief on the flutes, all cutting being done on the chamfer at the end.  a relief may be added on the flutes, leaving a circular land on each flute; this is just done to reduce drag (friction)   I have done this to probably a hundred or so reamers over the years, including a whole set of shell reamers that looked like they had been tumbled in a cement mixer; I ground each one size under, ground the part where the size was stamped and re etched the new diameter on each; they were then reground on the chamfer at the end, which does all the cutting and relieved on the diameter to reduce friction, leaving a narrow circular land.
All this could be done on a lathe with a tool post grinder, taking care to cover all the way surfaces if one does not have a tool & cutter grinder.


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