Drill Sharpeners Compared.

[PlasmaParticipant @plasma]

I have just bought the Warco drill sharpener. Very reasonable price and looks robust.

initial results are encouraging so it looks worth the outlay

[Bill PhinnParticipant @billphinn90025]

Does the sharpener do split points?

Also, if it does, can it sharpen existing split point drills, or is it only able to do split-point grinds on standard-grind drills?

[SteviegtrParticipant @steviegtr]

I also have a picador. But many years ago while working as a maintenance electrician at Yorkshire vehicles in Leeds, Hunslet. Who built fire engines & road sweepers. I became friendly with Cyril. Same as my dad’s name. He was a toolroom engineer. He taught my how to sharpen drills by hand. To this day some 47year on I still have the skill he taught me. It is all about the twist of the wrist on the wheel. Once taught never forgotten. A bit like swimming i guess, or riding a bike.

Steve.

[PlasmaParticipant @plasma]

Bill,   it does point thinning which is similar to a split point I’m guessing.

The first operation is to set the blunt dril in the collet chuck so that the webs are properly oriented and the protrusion is right, this is a simple thing using the jig on the left hand side of the machine.

Next operation is to grind each Web in the port on the right hand front of the machine.

Finally the collet is lowered in to the port on top of the right hand side to thin the point each side of the drill.

The diamond d wheel is shaped so that it can achieve this, it’s not just a plain stone as I thought it would be.

[Steviegtr]

On Steviegtr Said:

I also have a picador. But many years ago while working as a maintenance electrician at Yorkshire vehicles in Leeds, Hunslet. Who built fire engines & road sweepers. I became friendly with Cyril. Same as my dad’s name. He was a toolroom engineer. He taught my how to sharpen drills by hand. To this day some 47year on I still have the skill he taught me. It is all about the twist of the wrist on the wheel. Once taught never forgotten. A bit like swimming i guess, or riding a bike.

Steve.

I can still sharpen drills by hand but my eyes let me down.

Tony

[noel shelleyParticipant @noelshelley55608]

Point thinning is the reduction of the web and so shortening the length of the chisel edge and less scraping . To generate a split point or four facet drill requires very careful grinding of a second pair of cutting edges with almost no chisel. It will now be self centring !

Why has no one tried to copy the rotating cam action of the Brierley ? Admittedly complex but once done the job is so simple, quick and different cams give different drill forms. Noel.

[Michael GilliganParticipant @michaelgilligan61133]

I had not seen a Brierley in action … but found this:

https://youtu.be/aLPZcvb1zwk?feature=shared

Half an hour well spent.

MichaelG.

[noel shelley]

On noel shelley Said:

[…] Why has no one tried to copy the rotating cam action of the Brierley ? […]

Imagine what a waste of space it would be if built to “Hobby Market” standards !

MichaelG.

[noel shelleyParticipant @noelshelley55608]

Hi Michael, now you see why I say quick and easy. Once you know how to use it, it takes about 1 minute to sharpen a drill. Noel.

[Tony Pratt 1]

On Tony Pratt 1 Said:

On Steviegtr Said:

I also have a picador. But many years ago while working as a maintenance electrician at Yorkshire vehicles in Leeds, Hunslet. Who built fire engines & road sweepers. I became friendly with Cyril. Same as my dad’s name. He was a toolroom engineer. He taught my how to sharpen drills by hand. To this day some 47year on I still have the skill he taught me. It is all about the twist of the wrist on the wheel. Once taught never forgotten. A bit like swimming i guess, or riding a bike.

Steve.

I can still sharpen drills by hand but my eyes let me down.

Tony

Well Tony I have to admit, the small drills are now a challenge. I think I need to get some new glasses.

Steve.

[bernard towersParticipant @bernardtowers37738]

Having seen Noel sharpen drills on his Brierly I cannot compete with the speed but the results from my setup on the stent are quite good and definitely slower.

[noel shelleyParticipant @noelshelley55608]

That’s a neat job Bernard. You don’t often see the brierley point splitter ! You need a separate bush for every size you do. Easy enough to make but still a pain. There are 14 cams in a full set to do all the various point forms and at about £100 each I was lucky to get 10 of them. Noel.

[Plasma]

On Plasma Said:

Bill,   it does point thinning which is similar to a split point I’m guessing.

 

 

Thanks for your reply.

I’m going over some of the same ground covered by Neil Lickfold and Noel Shelley here, but, as far as I understand it, there are four potential treatments a shop-sharpened twist drill can have undergone:

1. standard grind

2. split point

3. web thinned

4. four facet grind

I don’t think these dedicated bench-top collet-type drill grinders of the type you have there typically do the four facet grind. Some, such as Stefan Gotteswinter’s Motom BSM 13 Duo, will do the first three, but, from what I can see, most, if not all, of the machines with only a single port on the top right of the machine will either do options 1 and 2 or options 1 and 3.

If anyone knows of a machine that is available in the UK with the capacity to do options 1, 2 and 3, like the BSM Duo in Stefan’s video, I’d be interested to hear about it.

[bernard towersParticipant @bernardtowers37738]

I’m quite surprised that none of you seem to put a secondary point angle on drills, it makes the drill more useable for longer.

[Bill PhinnParticipant @billphinn90025]

What do you mean by a secondary point angle, Bernard?

[bernard towersParticipant @bernardtowers37738]

Sorry Phil don’t have library photo but will post one tomorrow. Basically halving the angle on the outer tip of the drill which travels fastest and furthest, this slows down tip burn.

[Clive FosterParticipant @clivefoster55965]

Although the lifetime before a drill becomes unacceptably blunt is greatly improved when a secondary point angle is ground I’m unconvinced of the overall benefit in the home shop if your drill sharpener is quick and reliable. I estimate effectively more than doubles the sharpening time due to requireng second set up. Of course a Brierly or similar is fast enough that its not objectively much extra time but the more common machines aren’t such speed demons.

My Clarkson does a really sharp standard grind in about a minute or so between walking up with an unsatisfactory drill and coming away with really sharp one so i routinely re-sharpen at the first hint of bluntness. Mk1 eyeball and finger test being much more sensitive than drilling performance. I doubt if I use more than 1/4 of the real life from sharp to blunt enough to noticeably reduce performance.

Maximising life is very important in production shops where the economic life between sharpenings of a drill was expected to be hundreds of holes but few model engineer of home shop types get anywhere near that in a year or three. Generally i’m dealing with damage close to the full diameter of the drill where the cutting edge has been damaged by unexpectedly obdurate materials and similar issues. But I do fair bit of repair work as being the local “old fart with machines in the shed” so its easy to get caught out by incorrectly assessing the material being pierced.

Concerning the four facet point my understanding is that it requires machine guidance as in pillar drill, milling machine or lathe. Hand held drills being insufficiently stable. I keep a separate set of drills for hand held use so could easily use the four face system of my machine use only set. Indeed before the Clarkson arrived I looked into fitting an ordinary grinder with variant of the simple flip system used on surface or T&C grinders where a base with two angles produces the facets. Abandoned the idea due to a bad case of devils in the details. Sort of works looked easy enough. Right first time every time without the controlled motions built into a proper grinder being a whole n’other thing. Folk smarter than I may well disagree.

Clive

[noel shelleyParticipant @noelshelley55608]

Point thinning simply reduces the chisel edge, point splitting, 4 facet, prismatic and truax Etc all seem to be variations on a theme ? Noel.

[bernard towersParticipant @bernardtowers37738]

Sorry about the typo Bill but here are the images as promised. as you can see in the 3rd image the angle is halved reducing the tendency to tip burn because as we know most people use drills 10mm and over at speeds that are too fast.

[Robert ButlerParticipant @robertbutler92161]

Good afternoon Plasma

Will the Warco machine restore damaged points without excessive wear on the stone or is it only suitable for sharpening a blunted drill.

Robert Butler

 

[PlasmaParticipant @plasma]

Hi Rob.

It’s really only a point dresser I would say. It’s only a fine diamond wheel.

If I had a broken drill I would hand grind it as best I could and finish it on the Warco.

Found this drill gauge in my box of bits. I would not fancy trying to sharpen a No. 80 bit….

[bernard towers]

On bernard towers Said:

as you can see in the 3rd image the angle is halved reducing the tendency to tip burn because as we know most people use drills 10mm and over at speeds that are too fast.

Now I get it, Bernard.

I wonder why drill manufacturers don’t do this to their drills.

Are there any functional disadvantages to it, e.g. slower drilling?

[Mark RandParticipant @markrand96270]

That form of secondary grind is used for cast iron on conventionally ground drills.

In the case of four facet grinds it’s useful because the grind produces excessive clearance at the tip of the drill and the secondary grind helps to control the tendency to feed too fast into the work.

[bernard towersParticipant @bernardtowers37738]

yes from the information I found it seems to come from the american motor industry in the middle of the last century, they claimed nearly 5 times the life between grinds and straighter holes. You can see by the last image how well the angle is halved, presumably sharing the heat generation to two points instead of one. Who knows?. The results i get from the larger drills is quite encouraging especially the finish on the inside of the hole.

[bernard towers]

On bernard towers Said:

yes from the information I found it seems to come from the american motor industry in the middle of the last century, they claimed nearly 5 times the life between grinds and straighter holes. You can see by the last image how well the angle is halved, presumably sharing the heat generation to two points instead of one. Who knows?. The results i get from the larger drills is quite encouraging especially the finish on the inside of the hole.

If you have a look here, at the top right hand side, there is a pdf link to download Mazoff’s article in a more readable paper document format (A4 ish)

https://www.newmantools.com/machines/drillpoint.html

Bill

[Author]

Posts