Repairing a Japanese Chisel

[Zuye Zheng]

Just got beautiful 3mm Koyamaichi chisel in a dovetail pattern. However went a little hard peening the ends and ended up bending and delaminating the chisel blade...

Any ideas to try to fix it? Do you guys even bother peening such a delicate blade?

uWJgOEU.jpg

[Andrew Hughes]

You must return it to the fires Isengard.
Or it's pretty much done.

[Pat Barry]

I wouldn't call that delaminated

[Brian Holcombe]

Ouch, something went wrong in the peening process. What is your process? Mine involves lightly tapping the edge of the end grain over the hoop after fitting the hoop.

[Kees Heiden]

The elves of Rivendell were into reparing broken blades like that. Otherwise I would write it off.

[Zuye Zheng]

Ya, seems like a loss, good excuse to put in another order though... Giving JB weld a go and seeing if I can at least salvage as a paring chisel.

I wouldn't call that delaminated

Haha ya, the part that bent was the softer steel on top, the harder steel for the blade kinda just separated from the softer.

Ouch, something went wrong in the peening process. What is your process? Mine involves lightly tapping the edge of the end grain over the hoop after fitting the hoop.

I think mine might have been 2 fold, I was pounding decently hard to set the hoop which might have drove the chisel pretty deep into the block and bent it a little. I think peening it off center might have done it in especially with the chisel driven into the block...

On my first set of chisels, I soaked it in water and then peened. I recently read to just go for it instead so tried that which was a little stubborn so probably went with too much force.

The elves of Rivendell were into reparing broken blades like that. Otherwise I would write it off.

How's shipping costs there?

[Allan Speers]

Wow.


Maybe silver solder? JB Weld?

I'd try anything, before tossing a nice piece like that.


If all fails, maybe you could grind a new bevel, and turn it into a mini router plane.

[Mel Fulks]

I think Allan has it right. I recently broke a 1/4 inch beginner priced Japanese chisel. No good for demolition work!

[Jebediah Eckert]

You must return it to the fires Isengard.
Or it's pretty much done.

That is the best solution, but USPS won't ship to Mordor, too many problems with the Orks.

[David Wong]

I think mine might have been 2 fold, I was pounding decently hard to set the hoop which might have drove the chisel pretty deep into the block and bent it a little. I think peening it off center might have done it in especially with the chisel driven into the block...

On my first set of chisels, I soaked it in water and then peened. I recently read to just go for it instead so tried that which was a little stubborn so probably went with too much force.

I use to wet the ends of the chisel before setting the hoops, but after some internet "discussions", I decided that setting the hoops dry would work just fine. I do not set the chisel on a block when I set the hoops. I simply hold it in the air with my left hand, and hit the edge of the protruding wood with a hammer in my right. I try to have between 1 and 2mm of wood proud of the hoops. I lightly hammer the handle on an anvil to compress the wood before placing the hoop. Hoops generally have a thick and thin end. The thin end goes in first. If there are any burrs or rough edges inside the hoop, file them smooth. I use a hoop setting tool to pound the hoop onto the handle before preening.

[Brian Holcombe]

The hard steel is ahead of the break, so there is no way a bevel is going to hold on that stub.

Peening from the side with the chisel knocked into a block of wood is definetly what did it.

I don't hammer them into a block, I fit the hoop so that about 1-2mm of handle is exposed than I just peen around the edge of the wood to lock it in.

I have a cone shaped tool for knocking the hoops on.

File the inside of the hoop to remove any burrs that may prevent the hoop from installing smoothly. The shape of the hoop is made so that it compresses the wood as it sinks down onto the handle and naturally the wood should partially return to size after it exits the handle. If it won't drive onto the handle, some wood must be removed. I do this very carefully, takin slight shavings and testing the hoop as I go.


edit, looks like David beat me to the punch with near identical advice, hah.

[Chris Fournier]

As mentioned silver solder or brazing, I'd even consider TIG in my shop. Then of course you need to reharden and temper. Plenty of work...

[Stanley Covington]

Defective chisel. Return to retailer for replacement.

[Matthew Hills]

Defective chisel. Return to retailer for replacement.

Not sure that this was "defective".
When I got my Koyamaichi chisels some years ago, I set the hoops following the instructions on TFWW site.
https://www.toolsforworkingwood.com/...oop_guide.html


They explicitly cautioned about the risk of cracking the chisel on 1.5 and 3mm chisels when setting the hoop. (they recommended holding in hand or making a hole in wood and supporting the bolster, rather than putting the blade into a block and whacking away. They also recommended against putting the handle into a vise (potentially knocking the blade off and onto the floor)

I will say that the Witchhazel handles on my chisels did not mush very well at all.

Matt

[Kees Heiden]

I always wondered if my Koyamaichi chisels were made with wrought iron or not. Well, this break certainly looks like wrought iron, the grainy structure is visible as far as I can see.