should i avoid using a grinding wheel on Japanese chisels

[Trafalgar]

We'll never know for sure but I'd bet there are at least a dozen other locations on that stone where the cutter would not stand. And a long cutter wouldn't stand anywhere and it could dead flat to the last angstrom. It's meaningless, perhaps as meaningless as it standing on the spot it is. Might be flat, might not be flat.

Again, the only relevant and objective test would be registering a straight edge against the bevel and enhancing the view with a small bit of magnification, maybe a light behind the cutter, etc.

Find a photo of this and then you'd have something. All extraneous items are out of the analysis - capillary action/surface tension of water, the condition of the stone, whether or not the shop fan was running in a certain direction, the length of the cutter, etc. Too many variables!

I think you're just having a problem admitting that you were wrong Charles... (hammer)

Cheers, Vann.

I absolutely think that the photo of BugBear's shows a cutter as flat as one can get it. That said, I'd like to see a straightedge applied to one.

Why not? What's to lose?

 

[G S Haydon]

Honey Badger don't give a s%4t! Now you know how to reduce the tools Toby, all you need is a claw hammer for everything!

 

[Trafalgar]

...
Not to mention you can clearly see him rounding the bevel under as he moves it on the stone. =D>

You have to ask - why would anybody not do a rounded (under) bevel? I've never heard a good answer to this. There isn't one.

Agree.

There isn't a good answer because anybody doing freehand honing at all to anything other than a hollow ground tool (and maybe then, too) is rounding under to some degree.

 

[Trafalgar]

They only pick the finest cinder block but it must be followed by a rub on the pavement/sidewalk too

I like to see a hammer used with control and skill, just 'cos it's not a nice hammer don't mean it's not going to work.

Funny, and words of wisdom, too.

 

[James-1986]

I'e never experienced any problems hollow grinding chisels, I use an 8" dry grinder and used to have a 6". Grinding is a skill and it takes practice to gdo accurately without overheating the steel.

Square block cutters for spindles, moulders tenoners etc are the same setup as one of those Japanese chisels, HSS laminated on the back of soft steel. Wadkin often specified that they needed to be hollow ground, the grinding machines ran dry.

 

[woodbrains]

I'e never experienced any problems hollow grinding chisels, I use an 8" dry grinder and used to have a 6". Grinding is a skill and it takes practice to gdo accurately without overheating the steel.

Square block cutters for spindles, moulders tenoners etc are the same setup as one of those Japanese chisels, HSS laminated on the back of soft steel. Wadkin often specified that they needed to be hollow ground, the grinding machines ran dry.

Hello,

Japanese chisels and plane irons are not HSS (there are a few modern and not particularly good exceptions) and the steel is much harder and more brittle than spindle knives etc. so the comparison does not hold up. The softer back of Japanese tools is meant to support the very hard steel cutting edge and should be honed with a flat single bevel to maximise strength. Purposely making a convex edge removes too much soft steel back so is not done. A little inadvertent convexity probably won't be worth worrying about. Hollow grinding on a large diameter wheel, and a secondary honed bevel that incorporates a certain amount of supporting steel should be fine also. It is widely documented that Japanese tools are honed with single flat bevels. Discussing anything else is Western expediency, or just plain nonsense.

Mike.

 

[Jacob]

.... Purposely making a convex edge removes too much soft steel back so is not done.

Nobody suggests "purposely making a convex bevel"

A little inadvertent convexity probably won't be worth worrying about.

Exactly - you've got it! It also makes sharpening easier and faster as you can relax and put more effort into it.
This is why so many old (inc jap) tools have a convex bevel - old users hadn't picked up on the new sharpening obsession with flatness, which is mainly a byproduct of using jigs, and a misunderstanding of the the universal advice to avoid rounding over (rounding under is fine).

 

[Phil Pascoe]

I think Mike meant "concave" and "concavity".

 

[Jacob]

I think he means convex.

 

[Phil Pascoe]

You don't remove too much steel by making it convex, you leave it there.

 

[Jacob]

You don't remove too much steel by making it convex, you leave it there.

You remove more than you would if you left it as one flat bevel, assuming the same edge angle.

 

[bugbear]

This is why so many old (inc jap) tools have a convex bevel

A repeated assertion, which I continue to believe to be false.

The Japanese, (as discussed, with evidence, in this very thread, as well as previously) want flat bevels, and
go to some lengths to achieve them. Plenty of website, blogs, videos in support.

So I'll repeat my request for any evidence at all for your assertion that the Japanese have tools with convex bevels.

BugBear (expecting more assertions, sweeping generalisations, ad homs, and no evidence, as usual, but ever optimistic)

 

[Jacob]

....
So I'll repeat my request for any evidence at all for your assertion that the Japanese have tools with convex bevels.

BugBear

Have seen them, live and on forums - ISTR it was woodbloke complaining about the awful way the previous owner (jap?) had sharpened his jap chisel, some years ago. There are lots of references on the net. Do your own research!
The weird thing about this endless discussion is that no one has ever given a reason for a convex bevel being disadvantageous, likewise a reason for sticking so religiously to flat (and or hollow ground). Until they do, they have nothing interesting to say on the matter. They are just arbitrarily sticking to a rule which someone made up from thin air. I think they like rules for their own sake!

PS there was a Jap demo at one of the shows a few years back. All his chisels and planes had convex bevels. This was drawn to my attention on this forum. You should be able to find it BB!
I'm not saying they all do it - no doubt some of them take pleasure in arbitrary rules and procedures, as you do yourself BB. Others take the easy way.

 

[bugbear]

....
So I'll repeat my request for any evidence at all for your assertion that the Japanese have tools with convex bevels.

BugBear

Have seen them, live and on forums. .

A Link? Book citation? Photograph? Since they're so common (*) you should easily be able to find one or two examples.

I've already shown flat ones, and the pride taken in same, and we have Odate's clear statement on the subject.

Evidence thus far presented says flat.

BugBear

(*) I don't think so

 

[Phil Pascoe]

You don't remove too much steel by making it convex, you leave it there.

You remove more than you would if you left it as one flat bevel, assuming the same edge angle.

Precisely - making it concave, not convex. The OP's question was whether the concavity left from grinding on a wheel caused a problem.

 

[Corneel]

Well, I will probably go to tool hell and all that. But I tested it thourougly for you all. My Japanese chisels (Koyamachi's) don't self destruct after being ground on a high speed 6" grinder. I use them for all chopping jobs I can think of, except mortising. I keep a close watch on the temperature while grinding because these chisels are tempered at a low temperature.

The hollow from a grinder is so small that it is very hard to imagine a negative effect.

 

[Sgian Dubh]

Over the decades I've had to regrind and sharpen quite a number of Japanese chisels, usually a tool a learner or inexperienced woodworker had damaged in some way - dropped on the floor, or being a bit hairy chested excavating a mortice, or some other such carelessness.

I've never thought too much about the method for fixing them, and sharpening. I just take (or took) the chisel and use(d) whatever is or was to hand for grinding and sharpening. I've reground on standard vertical running high speed grindstones, hand held belt sanders, linishers, coarse oilstones, a horizontal running grindstone with an oil drip, diamond plates, and so on. This is, or was, followed by honing on, again, whatever was to hand - oilstone, ceramic stone, a bit of abrasive paper, diamond stone, etc, always freehand in my case because I'm not a fan of jigs and guides. The honing angle is a touch steeper than the grinding angle.

The result has always been a tool that cuts satisfactorily. That's all that seems to matter. It may be that over time and successive honing the honing angle merges into the grinding angle, and may even develop a convexity. It seems to me that on the whole it isn't particularly important how a keen edge is achieved. I don't think the metal in a Japanese chisel cares much one way or another any more than a western style chisel how it's sharpened. Freehand the job, jig the job, use whatever suits you, the user: in the end, sharp is sharp, although I suppose we could debate 'appropriate' sharpness. Sharp enough to do the job in hand has always been sharp enough for me. Slainte.

 

[Jacob]

You don't remove too much steel by making it convex, you leave it there.

You remove more than you would if you left it as one flat bevel, assuming the same edge angle.

Precisely - making it concave, not convex. ....

Er, no. Could be either - leave the edge untouched but grind the bevel concave on a wheel, or ditto but grind the heel of the bevel flattish or rounded to make it a double or a convex bevel

 

[Phil Pascoe]

Struggling a bit?

 

[Jacob]

Struggling a bit

Are you? I'm not sure which bit you don't get.