I admit an affinity for Japanese tools. I started using Japanese saws in the early 90’s. I finally lost my mind and spent way too much money on a full set of chisels produced by a well known Japanese blacksmith. I love them and they sharpen beautifully.
Whenever I use these chisels to chop mortises/dovetails/etc, they chip … significantly. I have never had that experience with my marples chisels. Is this just something I should expect from chisels made from such hard steel? It’s distressing to “damage” my tools through routine use.
Replies
Mortise chisels are build "stout" for a reason - the forces going through the cutting edge are large, especially in the harder or more "difficult" timbers. Are your Japanese chisels really intended for such a task? It seems unlikely if they're, effectively, the equivalent of Wester bench or even paring chisels.
Chopping out dovetail waste is one technique ...... But it does require the large forces of a mallet. Perhaps your Japans would be happier just paring out the remnant of DT waste following a coping saw removal of the bulk?
I second this opinion. If you can, measure the bevel angle and make sure it is acceptable.
Japanese woodworking tools are more suited to fine carpentry tasks in softer woods than say mortising white oak. Not that they aren't capable, but definitely not ideal. Would take very strategic chops.
Try removing the waste with a brace and bit or drill press. Then paring or hammering out the waste with the nice chisel is a joy.
The mortise chisels I use have never been sharpened. They're 100+ year old tools I got from a flea market in West Cork. They're just beefy chunks of steel for bulk removal well inside a line. Too slow for my taste though so I drill and pare.
The art is in the tempering. Harder isn't always better. Every chisel is not a parer.
I am not chopping mortises. Additionally, when I am chopping I don’t believe the forces are “extreme”. I use a small blue spruce mallet and perhaps take a 1/8 of material. I am just wondering, is the Japanese metal just too brittle? Chips on the edge of the chisel approach 1/32. I think that is crazy.
"I am not chopping mortises."
But you said that you were:
"Whenever I use these chisels to chop mortises/dovetails/etc, they chip … significantly."
Is it possible to ask the maker of your chisels for a list of intended and perhaps also not-recommended uses?
You’re right, I miss spoke. I only chop the side of mortises. I drill out the majority of the waste.
Yes, it's crazy. They're poorly tempered. They're too hard. Famous maker or not, somebody F'd up. Use a different set of chisels.
Ha ha!
I too get an occasional chip in the cutting edge of my Japanese chisels. I attribute that to the very hard and brittle steel on the cutting edge side of the chisel (why it holds an edge so well), and me doing something a bit rough with it.
If this is a recurring problem, next time you sharpen try picking a steeper angle. If you're at a 25 degree angle, try 30. This will give more steel to support the cutting edge, and it'll be ever so slightly harder to do fine pairing cuts. That's really the trade off, and why mortise chisels have a more blunt angle.
My two cents.
I have never owned Japanese chisels and have never felt the need.
I have no such problems with standard chisels.
I do chop mortises - I prefer to use the mortise chisel to do the work rather than drilling - I know it is inefficient, but as I get older I find slowing down more satisfying.
Ditto - although I like the Narex compromise of their dovetail chisels, made with hollowed backs to quicken/ease back-flattening; but also made of standard Western steel with a hardness of 59-60.
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I too find it best to go slower as I age. This compensates for the fact that, as the years accumulate, time speeds up. It seems only a few months since six years ago! :-)
Mind, I try to stay fast when on the bicycles as it makes me frown if a 150llb sprog passes me going up a hill. Bluddy yoofs.
Well the edges are fabulous. Paring with them is a dream. They get sooo very sharp.
I have started to try and chop mortises. I have been using Paul Sellers video as a guided
Chopped mortises are such a mess though. I like the smooth sides paring produces.
Other than drilling mortises and dimensioning lumber, all I do is hand work. I find it very fulfilling/frustrating.
fattboyy, I have used Japanese chisels for decades and never once chipped an edge. I work with hard woods. Either the steel is too hard (and brittle) or it is incorrect technique.
The amount if waste to remove each strike depends on the hardness of the wood. The great the thickness (e.g. 1/8"), the greater the stress on the edge. Perhaps you need to only take 1/16" slivers? Ħeavier blows also add stress, especially when working hard woods. All pretty obvious, and you are being sensible here, it points to the steel.
Next step is determining the bevel angle. It should be around 30 degrees for chopping. 25 degrees is only for paring.
Lastly, the width of the blade will also determine how must stress is placed on an edge. A 1/2" wide blade will encur much greater stress than a narrower 1/4" chisel.
Regards from Perth
Derek
Actually, with the same force applied the 1/2 wide edge will be subject to half the stress the 1/4 inch will.
But one will double (or more) the force to achieve the same penetration as with the narrower chisel. Regrds from Perth, Derek
It's been my experience that it's the levering action applied to the chisel end that tends to cause the ends to chip when chopping out mortises, not so much the actual striking forces. Taking more and lighter passes could reduce the need to lever out chunks of waste.
The chisels may also just be too fragile for the job either due to steel hardness or bevel angle.
I’m not intentionally levering but I’ll pay more attention. I just need to save my Jap chisels for paring.
I have a similar issue with my Jap saws. They are pretty fragile. Occasionally a tooth will disappear. I am migrating back to western saws. I just prefer cutting on the pull stroke
Your answer is in your post... do your heavy rough work with the marples and finish up with the JCs. Same results over time suggest the need for a new approach.
Obviously but I am perplexed by damaging a quality tool with routine use. Clearly no point in questioning what is happening, just adjust accordingly
Add a secondary bevel 2 degrees steeper, try the chisel. Add another 2 degrees until you find out what it takes for the chisel to not chip.
If the angle is above about 33, any number of things could be wrong, but most likely would be the chisel maker chasing some arbitrary hardness spec because people want it. the solution to figuring out what's going on beyond that - presumably we're assuming chopping straight in here, and not levering the tip in something that needs to be broken loose.
At any rate, it's pointless to have really expensive chisels you can't use, but they'll be unsellable of you improve the temper, and someone with no wit would probably be proud to give you 1/3rd or 1/2 of what they cost new if they found out they were "really hard".
25 degrees more tempering temperature may have been all that's needed.
Which leads to what can you do yourself - you can designate one as a test chisel, take handle off, put it in a pan with a top on it and put an oven thermometer in the pan or figure out some way to rig it and start at 350F temper and work up from there 25 degrees at a time. don't assume the oven is right, and don't leave the chisel laying out on a rack- you'll just temper the tip or overheat it when the oven cycles and the rest will be relatively unaffected.
But try adding angle at first. You may be two degrees away from bliss.
Oh yeah, love this response.
If "You may be two degrees away from bliss" doesn't motivate, I don't know what would.