Hollow backs on Japanese chisels

[dh7892]

Fair enough.

Each to his own.

I've not really used them myself so I can't speak for the pros and cons.

Just wanted to make sure that anyone that does have some doesn't grind away the steel!

I don't think you need to reform the Ura very often (perhaps every 10 years or so depending on use) so it's not an everyday task!

The up side is that it should be faster to hone as you don't need to worry about secondary bevels and the back is faster to flatten.

Also, the steel is harder so it might hold an edge better.

Just going on what I've seen on the web. No idea about the reality of daily use.

I do think that they are very nice objects though (if that counts for anything).

 

[dh7892]

I rarely have to touch the backs of my AI's, and they hold an edge as good as anything I've used.

Do you not hone the back of your blade when honing the front?

 

[woodbloke]

......or, just get yourself some decent AI, LN or BS chisels and just get on with your woodworking :shock: :lol: :lol: :lol:

Cheers, Paul

...agreed Paul, but if it's an edge you're after :wink: I don't think there's any way that I'd go back to A2 steel for chisels now - Rob

 

[woodbloke]

The hollow at the back (it's called an Ura or Urasuki when hollow like this) is NOT ground, it's forged.


I hope this helps.

Well... if the Ura is forged, I've got strange grinding marks in the hollows on my chisels - Rob

 

[dh7892]

Strange. Have you got a picture?

EDIT: I just looked on your blog and saw the post about the Jap chisel.
Are those grinding marks in the Ura? I wouldn't know the difference between grinding marks and forging marks. Perhaps they lightly grind them at the end to make a smooth ura at the end?

I might be wrong about them being forged but, unles they are actually made from solid steel (perhaps newer ones are), I hope you agree with me that grinding this hollow out would grind through the steel and render the blade useless once you sharpen it back that far.

The wikipedia page gives a good description on Jap blades:

http://en.wikipedia.org/wiki/Japanese_carpentry

Scroll down for the section on blades.

 

[Harbo]

Toshio Odate does not recommend tapping out a new hollow on chisels less than 2" wide, though he does it himself :?
He does say "So that you will not loose too much hollow at the back, apply more pressure to the front part of the blade (around the edge) when grinding."

And according to Leonard Lee "you do not need to be concerned about the edge reaching the hollow portion - the hollowness will slowly be eliminated as you remove a small amount of metal each time you sharpen."

From this I see there is nothing to worry about?

Rod

 

[woodbloke]

Strange. Have you got a picture?

I might be wrong about them being forged but, unles they are actually made from solid steel (perhaps newer ones are), I hope you agree with me that grinding this hollow out would grind through the steel and render the blade useless once you sharpen it back that far.

The wikipedia page gives a good description on Jap blades:

http://en.wikipedia.org/wiki/Japanese_carpentry

Scroll down for the section on blades.

No...the depth of the ura is only about 1mm or even less. I've just checked. See the Workshop Heaven site of pics of the chisels...you ought to be able to see the grinding marks - Rob

 

[woodbloke]

From this I see there is nothing to worry about?

Rod

Rod - correct - Rob

 

[miles_hot]

I'm confused - does this mean that you would be tapping the blade from the other side (without the hollow) to force the hollow flat? wouldn't that just mean that you've moved the hollow onto the other side of the blade?

Or does it mean that you tap the outer edges of the hollow flat

or....

Help me out here

Miles

 

[dh7892]

Toshio Odate does not recommend tapping out a new hollow on chisels less than 2" wide, though he does it himself :?
He does say "So that you will not loose too much hollow at the back, apply more pressure to the front part of the blade (around the edge) when grinding."

And according to Leonard Lee "you do not need to be concerned about the edge reaching the hollow portion - the hollowness will slowly be eliminated as you remove a small amount of metal each time you sharpen."

From this I see there is nothing to worry about?

Rod

Fair enough. The stuff I've seen on reforming the Ura related to plane blades so that makes sense.

I can see how you can sharpen back into the hollow and still have steel but the geometry will be different won't it? The back (at the cutting edge at least) won't be flat will it? I would have thought that this would be bad.

@ Woodbloke, I edited my above post at the same time you replied.

 

[dh7892]

I'm confused - does this mean that you would be tapping the blade from the other side (without the hollow) to force the hollow flat? wouldn't that just mean that you've moved the hollow onto the other side of the blade?

Or does it mean that you tap the outer edges of the hollow flat

or....

Help me out here

Miles

You tap from the bevel side to flatten the back, then re-grid the bevel side. From what I've been able to tell. It's hard to find a good website on the subject because they're all in Japanese!

 

[ByronBlack]

Ok, so it seems it isn't a real headache after all, but what is the benefit of these chisels over a western set? I had some jap mortice chisels and couldn't get on with them, I much prefer the western style chisel - what am I missing out on? If anything?

Rob - after reading your blog about your see-sawing over the chisel issues - what are you opinions now? How do the Japs compare to your LN's?

 

[woodbloke]

Rob - after reading your blog about your see-sawing over the chisel issues - what are you opinions now? How do the Japs compare to your LN's?

BB...a little too early to tell yet. At the moment the sharpness issue is the main one. The Jap chisels aren't nearly as pretty as the LN's (or BS's for that matter) or indeed as useful as they're chunkier along the side bevel. So if d/t's need to be cut, an additional set is needed which adds to the overall cost Also, unless you've got a decent set up to hone the single bevels repeatedly each time, then I think you're on a hiding to nothing.

Utlimately, I hope [-o< it's the increased precision that the razor sharp edge offers, coupled with the increase in controlling the blade offered by the long handled parers.

I'd think hard about including them in your mobile tool box.

There's nothing wrong in anyway with the A2 LN's as general bench chisels and I'd recommend them every time if within budget, but a side by side test with Mr Fujikawa's finest showed up their principal deficiency - Rob

 

[Paul Chapman]

There's always these http://www.lie-nielsen.com/catalog.php?grp=1494

Cheers :wink:

Paul

 

[woodbloke]

There's always these http://www.lie-nielsen.com/catalog.php?grp=1494

Cheers :wink:

Paul

...so when are you going to buy a set Paul? :lol: - Rob

 

[newt]

Rob I only have 3 Jap chisels one 6mm paring, one 6mm dovetail and a 3mm dovetail. They were from axy £40 each ish. I sharpen them as per normal, 25 on the tormek then 30 using the eclipse guide on the Spiderco stone. I found them easy to sharpen. I would say they are not something I would get over excited about they cut just the same as a freshly sharpened Robert Sorby. I always resharpen cutting tools after each session so I don't know if they last any longer. The long handle on the paring chisel is quite nice. You certainly would not buy them for looks, although the side profile of the dovetails look like an F117 fighter. Also one needs to be careful what you use as a reference when vertical paring. They are expensive but I guess a lot of sweat went into making them.

 

[Paul Chapman]

There's always these http://www.lie-nielsen.com/catalog.php?grp=1494

Cheers :wink:

Paul

...so when are you going to buy a set Paul? :lol: - Rob

I have to manage with cheapo chisels - my last set was about £25 for five :shock: Then there are the best quality Lidl ones which I have re-ground as skews - they were about £10 for five, so I bought two sets and ground them as left-hand and right-hand skews :shock: :lol:

Cheers :wink:

Paul

 

[Harbo]

Homebase had a set of chisels for £2.99 this morning?

Rod

 

[Paul Chapman]

Homebase had a set of chisels for £2.99 this morning?

Bet you were tempted :lol:

Cheers :wink:

Paul

 

[David C]

I have used Japanese chisels for many years. The extra hardness is very beneficial if you work with extremely dense exotic woods.

Mine are all hollow ground on the Tormek.

Paring, grind 23, coarse stone 30 polish 32 (degrees)
Chopping, grind 27 coarse 33 polish 35.

When the edge reaches the hollow I reckon that ten minutes work on a coarse stone "moves the hollow back" about 3mm.

I never get chips and have noticed no disadvantage from the hollow grind. I don't think I would like to grind them on a 6" high speed bench grinder.

(I am well aware that the angles will give Mr.G apoplexy.....)

David Charlesworth