Thread: Review... the Derek Cohen

Good to hear that you finally got some hands-on with sharpening, Dingo! I'm a bit jealous of your personal tutoring though. Poor Derek'd probably cringe at the sight of my efforts at sharpening hand-planes...I'm a turner, not a darksider and I'm sure it shows in my sharpening technique.

Mind you, I'm becoming pretty anal when it comes to sharpening my carving chisels. I make sure those are capable of circumcising a gnat from 20 paces... too much work pushing 'em through wood without a power assist otherwise.

Originally Posted by Wild Dingo

And so back to the shed... round two... so we were up to the lathe chisels... now these were B L U N T seriously so... I looked over at his watch... mmm times a runnin out here and if hes going to be mucking around at the bench grinder Im in deep doodoos... but The Derek smiled grabbed up the skew waltzed over to the disc sander faces up a quick slice upward flip the skew another quick slice up... The Derek turned and smiled as he handed the skew to me... EH?? WHATHA???... I ran it over what was left of the hair on the back of my hand swish no hair in a line the width of the skew!!! BLOODY ELL!!!... so he smiles again picks up the big gouge and still smiling faces up to the disc again a curling motion a look another curling motion and he turns smiling at me again... BULLBLOODYSHYTE!!! no friggin way could my mind comprehend this I mean 2.4 seconds??... but sharp it was...

Mate, that's all it takes on the bench-grinder, too, unless you're reprofiling or are one of the silly buggers who ran out and bought a wet wheel. (What's the bet I cop flak over that last bit? ) Any longer that that and you're being too fussy... and risking overheating the edge.

The Derek being ever the gentleman that he is smiled again and said quite simply "You wouldnt have believed me if I had... no one does Ive tried to tell the forum on occasion but they dont believe me... maybe they'll believe you?" the grit on the disc was 240 and on the belt 180 but he can go way way up to 1400 if hes in "the zone"

Who doesn't believe him? I don't do it that way mainly 'cos I'll be buggered if I'm gonna go through the hassle of removing/resetting the table on my linisher every time. (Although there are other more "finicky" reasons, too...) A belt-sander works just as well. I'm sure that's also been mentioned one or six times! Hell, on-site I use a belt-sander for sharpening my firmer chisels! I imagine the "purists" are cringing about now...

"What finicky reasons," I hear you ask? I like the convex bevel that a grinder leaves, it leaves more steel back of the tip for the same cutting angle. I find this is important for hard woods, where the cutting edge heats quickly. More steel left means more heat is carried away and the edge doesn't blunt as quickly. Not a problem that's associated with a handplane in normal use.

For the same reason, I prefer a 6" wheel on my grinder, whereas the "accepted general consensus" is that an 8" wheel is better. They can use what they want, but I'll keep on using what I like!

Ding, where are the photo's????


How are you going to explain to your clan, about the mysterious packages from Adelaide/Vancouver/Alstonville

The loss of posts due to the Forums' recent downtime seems means I don't think I saw any answers to a real question I had arising from Ding's visit to Derek Cohen MDA*:

Why did Derek sharpen Shane's first chisel the way he did, rather than using the disc sander? Was it just to show how long it takes to use other sharpening systems (ie he was going to gobsmack Shane after lunch as to how fast it was by showing how slow it is to use the 'traditional' methods)? Or was that first chisel so far gone that it needed special treatment?

Cheers

Jeremy


* Master of Darkside Arts

I agree whole heartedly with you WD. They are both great hosts and Derek's enthusiasm and expertise is inspirational.

I am so glad you had the opportunity to meet him.

Welcome to the Darkside Brother Dingo.

Originally Posted by Wild Dingo

And so back to the shed... round two... so we were up to the lathe chisels... now these were B L U N T seriously so... I looked over at his watch... mmm times a runnin out here and if hes going to be mucking around at the bench grinder Im in deep doodoos... but The Derek smiled grabbed up the skew waltzed over to the disc sander faces up a quick slice upward flip the skew another quick slice up... The Derek turned and smiled as he handed the skew to me... EH?? WHATHA???... I ran it over what was left of the hair on the back of my hand swish no hair in a line the width of the skew!!! BLOODY ELL!!!... so he smiles again picks up the big gouge and still smiling faces up to the disc again a curling motion a look another curling motion and he turns smiling at me again... BULLBLOODYSHYTE!!! no friggin way could my mind comprehend this I mean 2.4 seconds??... but sharp it was... The Derek smiled as he whizzed through the rest of the chisels and handed them back one at a time SHARP... DAMN!!! I was totally gobsmacked dumbfounded and flabbergasted!!.... So looking at him I asked "Why the bloody blue blazes didnt you just tell me that?" The Derek being ever the gentleman that he is smiled again and said quite simply "You wouldnt have believed me if I had... no one does Ive tried to tell the forum on occasion but they dont believe me... maybe they'll believe you?" the grit on the disc was 240 and on the belt 180 but he can go way way up to 1400 if hes in "the zone"

It's one of the great mysteries to me why people can't understand that if you're removing steel from a dull piece of steel it will get sharper. It may not be the most efficient method but dragging a chisel back wards over paper will actually sharpen it. It'll take a hundred years but it will get sharp - and trust me it will be bloody sharp too. Use what ever you have and learn how to use it well. There just happens to be good ways of doing things and not so good ways of doing things. Over enough time you'll develop a method that's good for you. There is only one thing you need to remember about sharpening anything: as you move closer to a sharp edge remove less steel in a more controlled fashion - that's it (bevel angles are a whole topic unto themselves). The more you refine that process the sharper the tool will be. That's the reason why you use progressively finer grits to sharpen. How you get there is your choice.

Now if you want to grind a convex bevel on a lathe chisel that's another story... There's good reason why for the past (at least) 300 years few turners who use the traditional style of chisels use this method. But you'll find out why soon enough

Originally Posted by Pat

Ding, where are the photo's????


How are you going to explain to your clan, about the mysterious packages from Adelaide/Vancouver/Alstonville

yeah right! I would wish

nah seriously it was just a great visit... no photos Im afraid... neither of us gave a thought to pics

Skew he seemed rather convinced that no one believed him how easy it was to do how simple... seems if you think about it most get to believing you need jigs and setups an different things... but see thats what he was showing me... the different methods available

Maybe Ramps will show today maybe not the crash of the forum came at just that moment before he read my second pm you know the one with the time in it? ah well we will see

Originally Posted by Wild Dingo

Skew he seemed rather convinced that no one believed him how easy it was to do how simple... seems if you think about it most get to believing you need jigs and setups an different things... but see thats what he was showing me... the different methods available

Yeah, a lot of blokes like to buy all the new-fangled gizmos. I dunno why... if they don't need a jig to shape the wood with a tool, why do they need a jig to shape the chisel with a tool?

Derek did a good thing in showing you how to freehand 'em. You'll probably want to buy a jig later for the fancier grinds, like the "lady-finger" on some bowl gouges. I wouldn't worry about that just yet though.

Originally Posted by Skew ChiDAMN!!

Yeah, a lot of blokes like to buy all the new-fangled gizmos. I dunno why... if they don't need a jig to shape the wood with a tool, why do they need a jig to shape the chisel with a tool?

Derek did a good thing in showing you how to freehand 'em. You'll probably want to buy a jig later for the fancier grinds, like the "lady-finger" on some bowl gouges. I wouldn't worry about that just yet though.

You WHAT??? a lady finger? NO LADY has ever given me the finger Skewy one!! Im just too nice for them to do that

Okay Im not even going to ask what it is... yet... my noggins still swimming and trying to process all the info that The Derek poured into it!!

Great stuff

If Neil or are reading I think its about time that the powers that be made a new section called say "meet and greet reviews" where we could bung our yarns pics and such of meets with fellow forumites... whaddayareckon?

Gad, now I have to review the reviewer of The Review.

To be honest, from WD's larger-than-life style of writing, I was expecting someone to whom I might have to be extra polite. But Shane turned out to be a good guy. The dogs liked him. Lynndy liked him. We were off to a great start.

Oh, did I mention that he brought along gifts of wood? Several sheets of veneer and some interesting boards of hardwood (that I cannot recognise - Shane remind me please). I am going to have a great time with all of it.

The chisels! You should have seen the chisels he brought along! Nothing really prepares you for this moment. Actually Shane told me that when they were blunt, he'd just buy more! In for a penny, in for a pound, so I bravely reached for the largest chisel in the box. Mistake #1! It was chipped and the bevel was rounded from repeated grinding on the pavement (or so it seemed).

My plan was to introduce Shane to a couple of different methods of sharpening and thereby help him decide which might suit him best. So I took Shane and the chisel over to my 6" bench grinder. This uses a 60 grit white Norton wheel. The Veritas tool rest is a little light weight but excellent value for money, and I can heartedly recommend one.

A confession. I hate sharpening! Really do. There is nothing more frustrating than interrupting what I am busy on to hone an edge. So I take an interest in sharpening - I am always looking for easier, quicker ways to get the damn thing done. But this does not mean that the blades can be anything less than razor sharp. Working with handtools is a pain in the whatsit with blunt tools. So quick and sharp.

One of the quick ways is to maintain edges as one works. Never let the blade get so blunt that you have to regrind. Of course, one has to grind, and I try to make the grind work for me. To this end, for most chisels (except Japanese chisels and mortice chisels) and bevel down plane blades (although I am including some bevel up ones now) I will first grind a hollow. This allows me to freehand the blade. It is a lot easier than it sounds since the hollow acts like a jig - it is easier to balance a narrow edge on two points (the sides of a hollow grind) than to do so on a single point (a flat bevel).

To get the angle of the hollow grind just right, I use a angle setter from Tormek:

Shane's chisel took a while to hollow grind because it was a thick butt firmer type, and it was necessary to remove the rounded, chipped edge. Eventually it was done, and across to my workbench we went.

For many years I have honed on waterstones. At present I am trying something new. The problem with waterstones is that they require a dedicated sharpening area - which I have, but it tends to get dusty and piled with all sorts of "things". I plan to build a mobile sharpening centre (yes, I have everything on wheels - essential when you need to make room in a small area), but for now I am trying out diamond paste. Diamond paste is available in every grit you can imagine. I bought my stock on eBay. Cheap! I am awaiting a full range (down to .25 micron) and I will report on this later. Currently I have a 400 grit (40 micron) diamond stone, 10 micron and 2.5 micron paste. The "pea" sized area of paste is spread like toothpaste on a 8"x3" piece of scrap Jarrah (flattened and smoothed). Instant diamong plate! After the 2.5 micron (which is about the same as a 5000 waterstone), I hone on a leather strop covered in Veritas green rouge (.5 micron). This entire process takes about 5 minutes, at most. The result is a super sharp edge.

Well Shane seemed satisfied with the first chisel. For the second, which was not in a lot better condition, I decided to use the belt sander to regrind the primary bevel.... with a little difference (from my earlier posts on using the belt sander with the honing jig I designed). Shane mentioned that he actually owned an Eclipse honing guide (not that there was any evidence of this on his blades, mind you!). So I thought I would use mine directly on the belt sander. This is a "new" method that I am experimenting with. You can set up the blade in the guide, and take it all the one from rapid grinding to honing on the sharpening media of your choice.

The belt sander belt is 80 grit (not 180 as Shane wrote. I usually use a 120 but this was already on and a bit worn, so I just left it).

When using the guide on the belt, the front hand places pressure on the bevel end and the rear hand uses very light pressure over the guide. As the belt turns, so does the guide's wheel (the Eclipse has a steel wheel) and so it is not worn by the belt (or so the theory goes - I am looking into durable wheels at present).

The process works very well, is quick, and before you know it we are on the diamond paste ... and another sharp edge is done.

Now those lathe chisels. I use the 9" disk sander on the belt sander combo. Caution - this is NOT a method for the heavy handed individual. The belt spins very fast and speed = heat = burned blade = loss of temper. So a gentle hand is required. If you tickle the bevel on a 240 grit disk, you will get a shine like you cannot believe. This is enough to return to the lathe with.

Shane's lathe chisels were easy to do since they still had the original factory hollow grind. This meant that I was honing the edge of the bevel and not possibly rounding the back of the blade (which is what I think Toolin may have been referring to). I might add that I have been honing my lathe chisels this way for the past year and have now omitted the hollow grind stage. The flat grind I do does not create any problems. The edge literally takes a second or two to achieve, and it is very sharp.

Shane, I do hope that this all helped. There are a number of other strategies I could show you - such as microbevels, backbevels, and micro backbevels - but it would be too much to take in. Just let me know when you want to return and we will arrange it. It was fun for me and I really enjoyed our time together. Thanks.

Regards from Perth

Derek

Derek

Using the eclipse jig on the belt sander is a similar thing to the idea of using it on the WASP with a specially made, solid plate support, as described in this article. I use this very happily, and no sign of wheel wear on the one of mine (I have two) with a plastic wheel.

Thanks for explaining the reasons for your different choices in sharpening Ding's chisels. I rather suspected that Shane had been using the first one for scraping mortar off used bricks!

Cheers

Jeremy