# Drill Sharpener



## kiwi2 (Nov 28, 2016)

Hi,
     I splashed out $100 on a drill sharpener as shown in the picture - mainly because I'm hopeless at freehand sharpening. 
I thought there might be some interest in how it performed. 
On the plus side, it does what it says in that the old drills I sharpened were in fact sharpened and cut both aluminium and steel very well.
On the minus side, the holes were 0.5 - 0.8mm bigger than nominal. I noticed this first on an ancient rusty drill I sharpened. It was obvious the drill was a very sloppy fit in the hole it had drilled.
I then drilled a hole with an 8mm drill which was in a reasonably good condition. It made a hole which was 8.1mm dia. I then sharpened the drill and drilled another hole. It made a hole 8.6mm dia.
It seems that these sharpeners are OK if you are drilling say a clearance hole for a bolt and the final diameter doesn't really matter, but if you are drilling a pilot hole for a tap or a reamer then they are definitely not OK.
I think I'll sharpen a set of my worst drills and use them for rough work and keep a good set for finishing work where the diameter matters.
Hope this is useful information.
Regards,
Alan C.


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## Cogsy (Nov 28, 2016)

Good info - thanks. I've considered something similar once or twice but not if it is going to mess up my drill sizes that much.


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## abby (Nov 28, 2016)

If the holes are being drilled oversize then the cutting edges are of uneven lengths i.e the drill is ground off-centre , is there no way to adjust this on the sharpener ?
Dan


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## goldstar31 (Nov 28, 2016)

abby said:


> If the holes are being drilled oversize then the cutting edges are of uneven lengths i.e the drill is ground off-centre , is there no way to adjust this on the sharpener ?
> Dan


 
I sorta agree with Dan but two things arise. The jig is plastic  and probably either oversize or wobbly and the risk of a early replacement of the wheel would preclude me from this.

Sadly, I've been pretty well in such matters.  It is probably cheaper to get a cheap 6" DE grinder , change the wheels from round bits of paving and buy a cheap metal affair. 

Sorry to be a misery but-- but?

Norman


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## vidio1 (Nov 28, 2016)

A drill bit will always drill a hole with clearance. It's the very rare exception when it doesn't. It's simply using the correct tool for the job at hand. If you need to hold a tolerance than you should bore, or ream a hole to size.


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## BaronJ (Nov 28, 2016)

Hi Guys,

I pretty much agree with Norman, I've played around with comercial drill grinders, from the cheap ones to quite expensive and not really found anything under £200 that you could call a precision drill grinder.

I would recomend building one. The two/four facet drill grinder on the Gadget Builder web site is to be recomended.  I wouldn't want to part with mine.


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## purpleknif (Nov 28, 2016)

Uhhh... drills don't cost all that much !


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## goldstar31 (Nov 28, 2016)

purpleknif said:


> Uhhh... drills don't cost all that much !


 
Quite but if a machine is capable of - as Baron intimates, it will do other things with equal capability. 
There isn't a fat lot of difference  between a drill and a slot drill nor an end mill for that matter. 
Again, the average  home grinder is or should be able to 'do' a modest surface grind. 

If one follows John's recommendation to visit John Moran's excellent site and reads the construction and use of the home built tool and cutter grinder, it will grind needles for carbs as well as special tools which would probably be nigh impossible or inordinately expensive otherwise.

A few bits of round, a few bits of steel bar , a tatty Chinese grinder or a redundant wood router plus the inevitable purloining of grandma's best felt hat     - to exclude the grit:thumbup:----- and there you go, laughin' and scratchin'

Regards John B, I thought that you  fliggied the nest:hDe:

Grumpy Norm


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## Brian Rupnow (Nov 28, 2016)

I have a "drill doctor 350x" and it performs very well on drills from 3/16" up to drills 3/8". It too is made of plastic. Does it make the drills give an oversize hole?--I don't know. I never checked. I do know that whenever I have a hole which should be reamed, I don't go one drill size under (0.0156") as recommended. I always drill .030" undersize. If I go 0.0156" undersize, my reamers sometimes are cutting air. I've ruined a few parts doing that. As someone said earlier, drills do not cut "on size" even when brand new. If you drill a hole with a brand new 3/8" drill, a 3/8" piece of tool steel will fall thru the hole you drilled.


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## kiwi2 (Nov 29, 2016)

"If the holes are being drilled oversize then the cutting edges are of  uneven lengths i.e the drill is ground off-centre , is there no way to  adjust this on the sharpener ?"

Hi,
    I thought the same myself but the drill looked symmetrical to me (although that may be why I'm crap at hand grinding them).
I ended up mounting the drill in a collet on the lathe, bringing the sharp point of a tool up to the intersection of the land and the drill circumference with the help of a magnifier, then rotating the drill 180 degrees. The tool seemed to have the same relationship to the land/circumference intersection on both sides, suggesting the grinding is symmetrical. I'm not sure where that leaves me.

"I would recomend building one. The two/four facet drill grinder on the  Gadget Builder web site is to be recomended.  I wouldn't want to part  with mine."

I had a look at the Gadget Builder website. It was a bit clever for me to digest straight away, but I shall return to it.
One interesting thing I found on the website was this:

"
Drilling a hole to accurate size is best done by drilling one size  under and then removing the small amount of material remaining with the  final size drill. Using a drill with SPAs works well for the final pass,  cutting to size and leaving an almost reamed finish.  When hole finish  is important, stop the drill prior to withdrawing it. For really  accurate hole size drill a few thou under and ream to finished size  (assuming you have the needed reamer).
          Drilling to accurate size in one go is possible but tricky.  As  drilling starts the drill isn't constrained by the lands touching the  hole; extra thrust is helpful because it causes the point to stay fully  into the cone. A split point helps by providing more cone area and  encouraging rapid penetration with modest thrust. If thrust is relaxed  the drill often attempts to cut a reuleaux triangle  as first one lip and then the other catches, causing the drill to  ricochet around in the hole. When this is happening, if you stop and  look at the cone in the hole you'll often find 3 or 6 lines radiating  out from the center of the (oversize) hole.  Once depth is greater than  about one diameter things usually settle down but this early rattling  around can cause an oversize or bell mouthed hole.  Accuracy in  sharpening is needed for size accuracy - drill point concentricity and  symmetry are necessary, SPA's and point splitting improve results and  make drilling technique less critical."


Tomorrow I'll try drilling a pilot holes 1/64" and 1/32" less than the nominal to see if I can get the finished hole to be close to nomimal.
I may have unfairly maligned the grinder.
Regards,
Alan C.


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## BaronJ (Nov 29, 2016)

goldstar31 said:


> Regards John B, I thought that you  fliggied the nest:hDe:
> 
> Grumpy Norm



Hi Norman,

Still kicking, but it gets harder to do the things that I used to do without having to think about it.


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## BaronJ (Nov 29, 2016)

Hi Guys,

Getting a hole on size is not at all easy !

Drills are flexible things and become less so as they get bigger,  and become more flexible as they get longer.  Ignoring play and runout in the machine, the more acurately a drill is ground the less the drill point will be inclined to wander about.  You can easily have a drill with very length acurate cutting edges but are several thou away from the true centre line of the drill.  As mentioned this causes the drill to make oversize holes.

As far as four facet grinding is concerned the idea is to make the very tip as small as possible, and extending the cutting edge right to the centre, this reduces the amount of pressure needed to cut and improves the accuracy by reducing the distance that the tip can wander when starting the hole.  Because of this a four facet ground drill can often start to cut without the need for a pop mark, though I confess that I always pop centres.

Having said all that, any drill grinder is better than having none.


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## Hopper (Nov 29, 2016)

Can you post pics of the drill tips that drilled the way oversized holes? It would help to be able to see exactly how they look before we draw conclusions about what the problem with the sharpener is.


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## goldstar31 (Nov 29, 2016)

The old gurus went on and on and into pages of explaining 'Why' and I've read most of it.
One comment has yet to be mentioned and whilst touching on it, the much admired George Thomas  did not elaborate. Probably, GHT expected us to understand Archimedes and the 6th Proposition of Euclid- and so far  here- NADA! The Square Root of Bugger All.

Here's my précis for your delectation. We stick a perfect correctly ground and sized drill in a 3 jaw chuck. Now that's a miracle to have such a thing but let me assume.  With everything chiming merrily, the end result will be probably a hole - plus 6 thous or worse oversize.
Why? The lathe chuck- unless it is one of those fancy Griptru's or similar  will be out by at least 3 thous. Your three jaw was NEVER spot on  and with use or misuse, it will cut a radius of say 3 thous and if we have not been paying attention that day at school , it will cut a diameter of 6 thous. Which we all know is why we are discussing rattling bad fits!
The same holds good ( or bad) for a drill chuck which has much the same alarming characteristics. BUT, but, but,  if the tailstock is out, it will act as another cutting tool and add to the rattles. It may- it may be bad enough to break a lip on the drill.
This is where someone has rushed out and bought a wobbly drill grinder.

And as my testy old maths teacher would add- QED. Quo Erat Demundstrandum  or laughingly 'Quite easily Done.'

That is only part of the Saga. Sorry to take up your time but if you know this already, I'm wasting my time.

Norm


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## SmithDoor (Nov 29, 2016)

Most of the Drill sharpening machines that I have found are for the drilling in wood. For some one that rarely needs the sharpen a drill they work great. 
I do all my sharpening by hand on a 6" grinder . It takes  about  10 min to teach  some to hand grind drill bits.
Note: If you are going to some shop at time they will test on hand sharping
Both ways work (by machine or hand)

Dave



kiwi2 said:


> Hi,
> I splashed out $100 on a drill sharpener as shown in the picture - mainly because I'm hopeless at freehand sharpening.
> I thought there might be some interest in how it performed.
> On the plus side, it does what it says in that the old drills I sharpened were in fact sharpened and cut both aluminium and steel very well.
> ...


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## kiwi2 (Nov 30, 2016)

Well I've had an interesting day. 
John Moran on his site:
http://www.gadgetbuilder.com/DrillSharp.html
says:
"
Drilling a hole to accurate size is best done by drilling one size  under and then removing the small amount of material remaining with the  final size drill. Using a drill with SPAs works well for the final pass,  cutting to size and leaving an almost reamed finish.  When hole finish  is important, stop the drill prior to withdrawing it. For really  accurate hole size drill a few thou under and ream to finished size  (assuming you have the needed reamer).
          Drilling to accurate size in one go is possible but tricky.  As  drilling starts the drill isn't constrained by the lands touching the  hole; extra thrust is helpful because it causes the point to stay fully  into the cone. A split point helps by providing more cone area and  encouraging rapid penetration with modest thrust. If thrust is relaxed  the drill often attempts to cut a reuleaux triangle  as first one lip and then the other catches, causing the drill to  ricochet around in the hole. When this is happening, if you stop and  look at the cone in the hole you'll often find 3 or 6 lines radiating  out from the center of the (oversize) hole.  Once depth is greater than  about one diameter things usually settle down but this early rattling  around can cause an oversize or bell mouthed hole.  Accuracy in  sharpening is needed for size accuracy - drill point concentricity and  symmetry are necessary, SPA's and point splitting improve results and  make drilling technique less critical."
His description of the lips of the drill ricocheting around to produce a bell shaped hole is spot on to what I'm experiencing.
Today, I sharpened a 5/16" (7.9mm) drill and drilled a hole through a 10mm piece of aluminium. The top of the hole had a diameter of 8.7mm which is not acceptable for tapping a thread.
I then sharpened a 1/4", 17/64", 9/32" and 19/64" drills and used them to drill pilot holes for the 5/16" drill.
The diameters at the top of the resulting holes were 8.2mm, 8.1mm, 8.1mm and 8.3mm respectively. Thus it seems that drilling a pilot hole 1/64" smaller than the final hole isn't quite enough while drilling one 1/16" less than the final hole leaves enough meat for the lips of the final drill to start bouncing around again. It seems that the optimum is to drill a pilot hole 2/64" (1/32") less than the desired diameter. The hole thus produced, while still marginally larger (0.2mm = 8thou) than the nominal is acceptable.
I think I will sharpen all my drills and routinely drill pilot holes which are 1/32" undersize for imperial sizes and 1mm undersize for metric drills.
After all this I'm quite glad I got the sharpener which is quick and easy to use.


Regards,
Alan C.


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## goldstar31 (Nov 30, 2016)

Just imagine the task of drilling a hole less than an 1/8th in diameter and say 12" long, perfectly parallel ?

I wonder just how many people could attempt and succeed. And yet it was and is the task of bagpipe makers.
Moreover, said he clearing his throat- I've done it.

I've also done tapered holes.

I'm interested in the technique which others might adopt

Norman


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## Blogwitch (Nov 30, 2016)

Getting away a little from the sharpening side.

I have used for many years bullet tipped drills made for Black & Decker. They are a bit limited in their sizes, but when used in conjunction with a spot drill (not centre drill) then they cut a very precise hole.
They are also very good for thin sheet work as there is no snatch at all when they break through, which is usually a problem with normal drills and the cause of oversized holes as they are snatched to one side as they break through.

I do have a Martek drill sharpener from about 20 years ago, driven rather than by an electric drill but an old model marine motor that was too 'dirty' for radio control work.
It does an almost good job, but on smaller sizes it fails rather badly as you have to set it up by locating the cutting faces in a plastic jig, and that was the major downfall.

If you are going to resharpen drills accurately, then the only way is to buy an industrial sharpener with a cam operation, as used in large workshops. All others sold for the model engineering fraternity are hit or miss, and to my way of thinking are a total dead loss.

John


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## mcostello (Dec 1, 2016)

I worked in a screw machine shop, There was a Guy there that could sharpen 1/8" drills and get Them to cut .001 over diameter. That's counting centering up the bit and all. I was only good to about .003 and could not get any better. It's possible and done in production settings everyday. Used a bench grinder also.


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## BaronJ (Dec 1, 2016)

Hand sharpening drills is a good skill to aquire.
I guess that I'm lazy nowadays, I even use a jig to sharpen small drills less than 3 mm.
However I agree that they are very cheap even though half of the new ones are only fit for the scrap bin.


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## bazmak (Dec 1, 2016)

Been following this post with interest,i used to be able to handsharpen
drills well with the old flick of the wrist to a good std down to say 2mm
but have not done for many years.Large stock of drills and light use
when they stop cutting I throw them away. Having said that yesterday
I broke a 3.2 drill in stainless and my reserve would not cut so I tried grinding
Total failure,eyesight and age.So I had to use a 3.3mm and then tap M4
Don't like stainless at all.Will start a thread shortly on my next project
the  eccentric engineering tool and cutter grinding fixture


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## goldstar31 (Dec 1, 2016)

bazmak said:


> Will start a thread shortly on my next project
> the Eccentric Engineering tool and cutter grinding fixture


 
I bought a 6" 180g CBN wheel at the weekend and today, bought enough plate for two rests, and a lot more and a mile of 25mm square. I found two finer diamond wheels which I thought had been lost through storm damage.

I have the drawings! Metric ugh! I'm Imperious

No post yet??????

Regards

Norm


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## bazmak (Dec 1, 2016)

Just starting a post on making the acute sharpening system Norm
you might find it interesting.Question, I need to buy a better quality grinding wheel similar to the one shown on Utube with the acute grinding system
What and where is best Norm ? diamond?


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## goldstar31 (Dec 2, 2016)

bazmak said:


> Just starting a post on making the acute sharpening system Norm
> you might find it interesting.Question, I need to buy a better quality grinding wheel similar to the one shown on Utube with the acute grinding system
> What and where is best Norm ? diamond?


 
At present, I note that you are far ahead of me. However, As I mentioned elsewhere, I bought a 6"  using the 180 grit CBN wheel which is 1" wide similar to that in the Acute videos.  The local firm was Axminster Tools in North Shields. Confessing to having a Mk1 Clarkson, I have tried the wheel on a lathe tool. I was rather disappointed with the finish despite running at 4000rpm. However, the grit is on the perimeter of the wheel and it came out hollow ground. So my embryo tool was honed brilliantly with bridging the grinds with a 600grit flat diamond.
Then I went out and bought the metal , came home and had to get on with the chores that a recent widower has to attend.
I might add, that the wheel cost £100:wall:
Moreover, I wonder if the 180 grit will improve with use. I mean create finer finish. Perhaps others could chime in here.

Again, I found two diamond wheels 5" diameter but they have no grading information  having been underwater and rusted:wall: They are much finer grits and probably came from a manufacturer of spectacle lenses.

I don't know whether this will help you but that is my 'progress report' to date.

Adding a little idle thought, I got sufficient 150mm square 4mm metal to make THREE bases should I get around to it or them.

Unfortunately, I DO have supply problems and will have to do quite a lot of MIG welding to get anywhere.

So there you have it- back to coffee.:hDe:

Regards

Norm


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## Blogwitch (Dec 2, 2016)

Baz & Norman,

What you have to consider if going for bonded rather than embedded diamond wheels is how to dress them flat again after they become worn and they can do rather rapidly.

Embedded diamonds you just throw away when diamonds get scarce on the plate, but with bonded wheels, you have to use either an ali oxide stone in an attempt to dress it flat or angled by hand, or like myself when I use one on my surface grinder, a brake dresser, which is about one of the only ways you will get them perfectly flat.

http://www.absimporttools.com/diamond-wheel-brake-truing-dresser.html


John


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## Blogwitch (Dec 2, 2016)

Baz,

Just had a look at your grinding rest and for using diamond grinding, it might pay you to move the rest to the side and clamp a diamond lap (embedded diamonds) using the normal mandrel onto the side of the normal wheel instead of fitting a bonded wheel onto your grinder.

Doing it that way you will have the best of both worlds, just by moving the rest through 90 degrees.

Diamond laps

http://richontools.com/index.php?ma...ption=1&keyword=Diamond+coated+laps&x=19&y=14


John


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## goldstar31 (Dec 2, 2016)

Thanks John! I used to make modified resins for abrasive wheels - in the Dark Ages! 
However, I don't really get to 'over use' of diamond wheels because I don't sharpen tools- the present accepted way. 

I rough grind- with any old wheel perhaps from the Great Wall of China so that I get the shape. However, I don't hone the complete cutting face. I simply hone a little more than needed for the depth of cut which leaves the roughed out portion doing nothing but support the real cutting edge and perhaps being an ersatz heat sink.  I find it rather excessive to hone ALL when it is not any use!

The foregoing is what older farts like Ian Bradley described in his ancient but useful 'Shaping Machine and Lathe Tools' dating back to when I bought my first copy as a National Service RAF Corporal in 1949!

Sometimes I get an urge( well?) and I use either an Arkansas stone or the undrilled faceplate from my Myford using one of my syringes of diamond pastes.

So, forgive me, but I'm a non- conformist.

Cheers

Norman


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## bazmak (Dec 2, 2016)

thanks for your replies but I am still non the wiser.I would use a normal
wheel for rough grinding but would like a smoother diamond type wheel
for the light finishing.Wider face just like the one on Utube.Looking on 
ebay what is available then I have a normal wheel or a cup wheel and go at the wheel from the end of the grinder.I bought a diamond cup wheel and it was adequate in the mill for finishing both HSS and Carbide.The problem with the diamond cup and normal wheels are the width of the face is only about 10mm
Could I fit 3 side by side to give me 30mm width ? This is not my area of expertise please treat me as ignorant and put forward suggestions. You know the direction I am heading


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## goldstar31 (Dec 2, 2016)

Barry
It is worth thinking about what 10mm will do. In lathe tool terms, it's quite a big lathe tool- almost 1/2" whereas if this is applied to a milling cutter it grinds/hones almost an inch. If you have a 7" swing lathe, that is quite a lot.
At 100 rpm which I think is the slowest a 7" will drop to, you will be pushing it. My view- perhaps wrong.

Again, using MY way, all one needs to finally hone is a fraction more than the largest depth of cut that you can get with a small lathe.
If you think about it, an insert tool is only capable of cutting its thickness- otherwise you would be including the tool holder as well.
Do you now agree, please? Again, if you have a milling cutter you will find a primary grind of say 15-30 degrees but it is the little bit of 5 degrees that is doing the milling.

At least that is my interpretation of events.

Back after the weekend

Norm


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## texta (Dec 2, 2016)

great , thought i might have a crack at making gadget builders drill sharpener . so off i go to the magazine to order back issues needed for the drawings and yep jan / feb 2012 not available .

johno


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## goldstar31 (Dec 3, 2016)

Barry
Whilst waiting for a taxi, I'm sort of perusing the plans and metal as my request for a kit using my Visa account was refused!
So I have to chop up a large 4mm sheet. So following on, what do you propose to trepan the many discs? 

Cheers

Norm


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## bazmak (Dec 3, 2016)

I don't know if I'm being slow here Norman,but do I understand that you are also making the acute system? I haven't got my drawings yet so haven't
given much thought to manufacture of further parts.Do you have the plans
but not a kit of parts


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## BaronJ (Dec 3, 2016)

bazmak said:


> thanks for your replies but I am still non the wiser.I would use a normal
> wheel for rough grinding but would like a smoother diamond type wheel
> for the light finishing.Wider face just like the one on Utube.Looking on
> ebay what is available then I have a normal wheel or a cup wheel and go at the wheel from the end of the grinder.I bought a diamond cup wheel and it was adequate in the mill for finishing both HSS and Carbide.The problem with the diamond cup and normal wheels are the width of the face is only about 10mm
> Could I fit 3 side by side to give me 30mm width ? This is not my area of expertise please treat me as ignorant and put forward suggestions. You know the direction I am heading




Hello Baz,

The laps that John refered to are thin discs but plated on one side all the way to the hole in the centre. Just fit one of the right size against the side of the existing wheel.  That way you have three surface grades that you can use.


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## BaronJ (Dec 3, 2016)

texta said:


> great , thought i might have a crack at making gadget builders drill sharpener . so off i go to the magazine to order back issues needed for the drawings and yep jan / feb 2012 not available .
> 
> johno




Hi Johno,

All the information is on the http://www.gadgetbuilder.com/ web site, but I do recomend sending an Email to John Moran.  I found him to be very helpfull.

Here is a picture of mine when I was setting up the holder angles.


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## goldstar31 (Dec 3, 2016)

Hi Baz

I will  build one for the Hell of  it
Cheers


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## texta (Dec 3, 2016)

there are no plans on gadgets web site and i dont like to impose with emails to people i dont know . i would of gladly bought the magazine back issues required to obtain the plans but they cant be had .
so i scrap the idea and either buy a drill doctor or i go over to my mates place and use his tool and cutter grinder which is what he has been telling me to do for 12 months but i am not a person that imposes on others and prefer not to use or borrow other peoples gear though some times i have to make an exeption as a last resort .


johno


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## BaronJ (Dec 4, 2016)

Johno,

Believe me John Moran would love to hear from you and would happily supply you with his plans and build notes.  I also know that he likes to put pictures on his web site of work that has been done by his readers.

Whilst I have his plans and notes he does ask that you don't distribute them.  So don't fret about it, drop him a note, his Email details are on his web pages.


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## BaronJ (Dec 4, 2016)

Hi Guys.  Baz, Johno,

I've found some of the missing pictures of my Four - Six Facet Drill Grinder. They turned out to be in an adjacent folder. Anyway Here they are. There are some differences from the original design but it was a matter of using material that I had to hand, though nothing that materially affects the functioning of the grinder.

As can be seen the drill holder is mounted on the left hand side of the wheel. The two holes in the right hand edge are because I followed the wrong line. It makes no difference which edge of the wheel is used. In any case the toggle switch reverses the motor spin direction. The rocker switch turns the power to the motor on/off. I wired the illuminated rocker switch so that it was lit when mains power was available rather than the other way round. The idea was that I would always know if it was plugged in.

I also used a standard IEC three pin mains socket to supply mains power to the grinder. This meant that I could just use a common cheap computer power cable with a 13 Amp fused plug. Saves having to put a fuse inside the casing. It is fitted with a 3 Amp fuse.

The modified arrangement for traversing the table can also be seen here. Again the idea was that a couple of screws and the handle can be reversed and stowed out of the way when the grinder was stored.

Since the motor and hence the grinding wheel surface have to be accurately positioned I made an adjustable stop so that I could move the grinding wheel away from the table by turning the 4BA threaded rod.

Another modification was to mount a false plate on the main table so that I can use the grinder to grind other types of cutters by changing the fixture.

The metal case was made from an old computer case that I cut up and pop riveted together. That colour is supposed to be Myford Green, but its not, its too light.

All in all it was a relatively easy build, nothing particularly difficult. Setting it up was a bit fiddly but once set it doesn't need to be touched unless the wheel is changed.


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