Category Archives: Hand Tools

Twin Mortise Chisel: Nihon-Mukomachi-Nomi

Ever since reading the description of a twin mortising chisel in Odate’s book “Japanese Woodworking Tools” I’ve hoped to some day acquire one.   Its a truism that you can’t always get what you want, and because generally there is more than one way to make mortises a chisel like this definitely isn’t the first thing to go after if you’re trying to build a tool set. But it sure is nice.

I found this one through Yahoo Japan auctions, using Buyee to handle getting it out of the country. Usually I see these chisels half used up and part of a set of other chisels, but at the time I was looking this one popped up, a new chisel from old stock that had sat somewhere for a long time and offered as a single item.

The chisel widths are 6mm, with about a 4mm gap in between.

Up to now I’ve ben cutting twin mortises, but with a single 6mm chisel. Here they are side by side for comparison. The twin mortise chisel is a bit thicker, but it may be just the slightly larger size of chisel you can find between a cabinetmaker’s bench chisels and the larger timber chisels.

So I set about eagerly sharpening, hungry for that first try of a new tool.

For a first rough stone to take the steel to I’ve been using a Beston 400 grit, a nice affordable option. Its been wearing down quickly though, so I’ve lined up a Shapton Pro 320 grit stone to replace it when the time comes.

My 6000 grit Shapton on gass polishing stone is down to a thin little whisp of stone left. They are harder wearing stones but they won’t last forever. A synthetic Kitayama polishing stone is waiting behind it. I’m quite interested to see how it compares, I usually don’t bother with polishing the edge beyond 6000 grit except for sharpening my straight razor or seeing how fine a shaving I can pull with my kanna.

I did run into a disappointing observation with this chisel. The fork of this chisel was spread slightly apart, about 25 thou from the bottom of the slot to the cutting edge.

I gave this a lot of thought, tried cutting a few mortises, and decided the tolerances actually needed addressing for this tool to work properly. I don’t know if this is just something that happened in quenching or poor quality control, but without a fix the chisel would be hard to control and cut tapered mortise walls on the inside. It was disappointing to say the least.

But I didn’t start whacking it with a hammer right away. I have a habit of getting new tools and thinking something is wrong and then correcting it in error. For instance, have you gotten a kanna blade that wasn’t sharpened square to the sides in a new block? I’ve erroneously “fixed” that only to find that it was sharpened that way to match the block. Same thing with a double bladed marking knife…cutting edges that came from the factory at different lengths. Figuring that had to be wrong I “fixed” it and only then realized that it was supposed to be like that for a good reason. The blade has to tilt over a bit when marking so that the back bevel rides plumb against the straight edge, thus the different length of blade so the two cutting edges contact the wood evenly.

So definitely sleep on it before deciding to fix something you think is wrong, give it some real consideration and see how it works in the cut before making twice as much work putting the tool back to right.

Here’s another example, a two inch timber framing chisel I picked up at a small mountain antique store for $20 bucks. For comparison I’ve placed a 30mm timber chisel next to it, makes it look tiny, haha, but its not. I thought it was the most amazing deal until I got it home and noticed that the bottom of the chisel was way convex. Honestly I beat the hell out of this thing with a 3lb sledge hammer trying every technique I possess to get some of the bend out.

The marks on the side weren’t from my straightening attempts, some body had stuck this chisel in a knurled vise jaw and cranked down really hard. Can’t imagine why. It has a thick cutting steel forge laminated in there, wouldn’t budge no matter how I nudged the mild steel around it, and didn’t break even with me hammering the cutting steel directly, which I can’t recommend. Sometimes you need to just set the hammer down and leave it be, the chisel still works, just held at a different angle when chopping down.

So now duly considered of the dangers of ignorant hizumi I stuck my new chisel in a vise and tightened it where I needed to get a bit of deformation to bring the blades back in line. I did this slowly, by degrees of measurement with my dial guage, and thank god it worked. I had to bend the forks in 75 thousandths past where I wanted it to end up, which doesn’t sound like much when you’re measuring by the thou, but it was clear and visible just how much I was straining the chisel to the naked eye. The tool steel lamination on this chisel extends past the slot all the way to the heel of the chisel. I’d really love to see how one of these is forged, because they still manage to get the lamination to wrap the sides of each blade.

A chisel like this needs its own marking guage, one of my favorite little birdie things to make. Its real important to get a good fit of the beam to the guage block, make sure it comes through nice and square, just snug enough not to move when the keyed wedge is loose.

Nice and comfortable in the hand, easy to adjust, and it doesn’t hurt if it looks nice too.

I use tempered finish nails for the pins, sharpened to a chisel point with a file. The thickness of the nails gives you some adjustment room for getting it to exactly fit the chisel.

Now I really need to make some shoji, this thing is begging to be put to use. The appeal of this tool…double the mortises in the same time. Twice the glue area compared to a single mortise, or I imagine you can cut shorter tenons and shallower mortises and have the same joint strength compared to a single mortise. I love it and its  a classic tategu-shi tool.

Don’t despair if this isn’t a tool you can lay your hands on. How about making your own by slotting a stock bench chisel? I know I’ve seen chisels modified like that. You wouldn’t have to grind the slot to the full length of the chisel, just to the depth that you expect to be cutting mortises, probably no more than 1.5″. It would be a good little challenge to make accurate tool surfaces in hardened steel. When I was first starting out I definitely didn’t have money for all the specialty chisels and made my own 1/4″ dovetail chisel and fishtail chisel, even a little 1/8″ mortise chisel. They’re cheapo Harbor Freight steel, but I still use them and carry them in my chisel roll. They’re the mutts of my collection but give good service, so I take pride in using them and my work is the better for it.

Rescuing an Old Dresser

Do you recall the first time being asked to restore a piece of furniture? For me it was not really that long ago. I help re-seal a customers concrete patio, lo and behold there’s an old dresser that this lady had re-finished with her grandfather when she was a little girl, and she’d like it to be fixed up.

I take a look at it, its a bit rickety. But somehow I’m thinking, fix a few drawers, strip and spray some poly, blah, blah, yah I can do that for $400. As I’m loading the dresser into the back of my pickup I tell the lady’s husband in a most sincere tone, “I’ll take good care of it.”

He replies, “Oh, that thing is a piece of junk.”

Ah, so it is, so it is.

It should come as no surprise then that once the dresser was back in my shop I realized that it needed to be disassembled and all the joints re-glued. And hey, why not French polish the thing while its in pieces? Maybe I blew my work budget right at the get go because I knew I would enjoy the work only if I could do it to my own standard of quality. When its done, its done.

Not to lie, it was a piece of junk in terms of joinery. The panels sat in the same groove as the tiny wimpy stub tenons for the rails. By the time it got to me the only thing holding it together was the nails used to get it out of clamps on the production line.

That said, taking apart a piece of furniture you didn’t make is really fun and interesting. You get to be part detective, brushing the dust off of a past place and time, exposing wood that hasn’t seen the light of a workshop in a long time.

And gosh, pulling rusty nails is just excruciating. It makes you think of all the times you’ve read “disassemble the joint with as little damage as possible”. Well, just how much damage is possible, lets not find out. The drawer stops were little pieces of dowel glued in to the front drawer dividing rails, what a joke. They got replaced with proper dovetail stops mortised into the front dividing rail.

 

And worn drawer bottoms.

Which are  a simple fix.

I made up some finishing samples for the customer to look over. As it turns out the fewer choices you present the better. I’ve seen a dozen samples put in from of someone that pretty well melts their decision making ability, in the end they of course pick something not even shown, i.e. “match this color from this different species of wood on the other side of my house” kind of thing, ugh.

French polished shellac is a rabbet hole, but try it, its a beautiful finish, truly. Soon you’ll be convinced that everything, including the phase of the moon needs be considered when applying shellac with a rubber and spirits.

The front faces of the drawers were warped, which had to be corrected on the newly glued runner strips. I don’t care if the drawer face doesn’t sit perfectly flush with the frame, the drawer needs to run flat on the runners.

Now lets see how many specialized tools I can use repairing a drawer.

Marking the drawer bottom for a sliding dovetail batten.

Azebiki saw for cutting the sides of the dado. As an aside, if you pay $40 dollars for a saw like this expect to get a $40 dollar saw. Or be happy and practice your saw doctoring skills!

Routering out the waste. The drawer bottoms were badly warped. Normally I might have just flipped them upside down and called it a day, but the drawer stops had carved grooves in the drawer bottoms from sagging so much. Consequently the panels had to be held flat with battens for all the marking and cutting.

White Ash tools pleasantly by hand, including a little dovetail plane.

Cut too loose and the joint is pointless, too tight a fit and you warp the panel. Maybe there’s something to be said for always cutting tapered sliding dovetails?

Whew! One drawer down, four more to go.

But something fixed with care, it adds a charm all its own.

The shellac finish convinced me to buy a proper cabinet scraper, I spent way too long sanding out tiny digs from using a hand scraping card.  The wood was red oak, filled. Stained with a brown mahogany gel, body coats of amber shellac and then clear followed by a dark paste finishing wax. And to skip over all the tedious bits, it turned out quite well. Just in time for Christmas, and passed on to its next generation of owners.

 

Videos of Japanese Blacksmith Forging Kanna

This is a follow up to my previous post on ura. I’ve had these videos for a while, every time I watch them I spot something new, great stuff! I’ll keep the comments brief and let the videos speak for themselves. If the footage seems strange its because it was shot with a cell phone inside the Takanaka carpentry museum.

The tool steel for the lamination has to be tapered on the back end so that the forge weld line is neat.

The forge weld.

Here is using sen to carve the ura, among other amazing things. It looks like the ura shape is pre-forged.

This video has an interesting shot of honing the ura on the edge of a stone, as well as coating the blade pre-quench with clay slip.

To finishing things off today, more final shaping and straightening.

If you liked this stuff I made all the various videos I have from Takanaka CM public, enjoy!

 

Making a Dovetail Kanna

Here is a Japanese dovetail plane, a simple style for cutting the male part of a sliding dovetail joint. Its a nice little plane, about eight inches long, great for one handed use cross grain or long grain. I had the chance to fall for this little guy up in Vermont and have wanted one ever since. With that in mind I took the time to make tracings of all the parts in my design notebook. Well worth the effort!

I’m short on good dai wood, quartersawn white oak is the best I have and it works okay for planes, not the best but ok.

All the various lines were marked out. If you’ve never cut a dai before this is not the first one that you want to start with. Having learned about western style side escapement planes helped me a good deal. You don’t need plane makers floats for something like this though.

The effective cutting angle for the blade is right around 45 degrees. Marking the wedging angle for the blade across its width was simple because I cut a practice dai in pine first, stuck the blade in there, and set my bevel gauge.

The shaving escapement line is cut after the sole of the plane is cut to the angle of the dovetail you want. I’m pointing to the angle with the pencil in the photo above. Let the wood find the angle for you. If you were to cut it before the sole angle the mouth of the plane would be too open on the inside.

Here is a shot of the kanna I modeled after showing a critical detail. The knicker iron is not set evenly into the block, its shallower at the cutting edge and lays in progressively towards the top of the plane block to provide a cutting relief angle. Its also not even side to side, the blade skews outward just like how a marking guage blade is set up so that it pulls into the work a bit and helps keep the fence tight to the work. Its an easy to miss detail!

Here’s the cut for the shaving escapement, and a 1/4″ starter hole for the conical shaving escapement.

I lack carving gouges for this sort of thing, but do have a conical carving thingy, what are these called? I don’t know but it worked a treat.

With all the major cuts made I match drilled the body and fence for the fence adjustment hardware.

Lots of fine tuning to get a simple looking plane like this to work properly. There’s no lateral adjustment of the blade, just sharpen it properly for an even projection from the sole. Getting the knicker iron lined up with the outside edge of the cutting iron is also critical, they both sit very slightly outside the edge of the block.

Really simple fence hardware, some long machine screws and whatnot. The little adjustment knobs that hold the fence took a while to cut, file, and tap.

Works great! I could not be happier with the blade quality after cutting with it a bit, the edge holding is there. It was easily a week of work to make this guy starting with chopping the charcoal, it makes the antique one you can find for sale online look like a really good deal!

If anyone is interested in making one of these I can post the rest of the image set I took of the original I copied and some dimensions.

There’s easy sliding dovetails in my future.

Grinding the Ura and Why

So you want to make some Japanese cutting tools, kanna, whatever, and you get past the hurdle of forge laminating tool steel to something softer. Then comes flattening the back and there is a wide ocean of very hard steel to waste away your expensive sharpening stones. How about hollowing out the back (Ura) and greatly easing all of the subsequent work?

The old school approach would be using sen on the annealed blade prior to hardening, but a quick look at most of my own tools from japan show a ground finish. Sen, well, are nice, but it takes the time and charcoal to make them and even full process annealed tool steel is hard stuff compared to the buttery/gummy consistency of lower carbon steel. Sen are also near impossible to use without a rock solid sen-dai.

Apparently I’m writing a blog post about something almost no one on the internet cares about. If I was writing about katana it would be a different story, plenty of interest there. Certainly there are many talented modern swordsmiths outside of Japan who could do a good job making tools, you know, stuff not made for killing people. Why don’t they give it a try (nudge, nudge). If you care to search for methods of hollowing ura dear Jason Thomas pops up, but he’s to busy swinging in his hammock daydreaming in Hawaii to help us poor uneducated blokes out. Just kidding, I’m sure he’s hard to work at something, which we all would like to know!

Back more to the point, how does one hollow the ura without a lot of fuss? I use the edge of my 8″ grinding wheel, which is just about perfect for backs 1/2″-1″. You can even make a little jig consisting of a board with a fence hinged at one end to keep the grind radius centered on the tool.

Take as an example this little kanna blade for a dovetail plane I made from some 0-1 steel forge laminated to mild steel. You get it all dimensioned and pretty in the annealed state and then quench it and it warps. So you temper and some of the warp comes out, then you can hammer straighten it at the anvil to the best of your ability, hopefully without cracking the tool steel. If you already had the ura shaped it wouldn’t be even by the time the back was flattened on a bench stone. And everyone wants that nice aesthetically pleasing ura.

Grinding the ura after tempering saves a ton of work. If you’re making narrow tools you’ll want a stone smaller in radius than 8″, if you’re forging kanna you’ll find yourself lusting after the really large Japanese water cooled grinding stones.  Some ura are elliptical, some a more true radius, let your eye be the judge of the progress.

I’m trying to save wear on my sharpening stones, they wear down fast with work like this. In the above photo the back was still low at the cutting edge, so I took the blade back to the grinding wheel several times and ground the ura back completely to the outside edges of the blade.

Here’s the finished ura, done freehand. Its not perfect, but you wont hear me complain.  The grinding gets shallower towards the cutting edge, the shape produced naturally by the radius of the grinding wheel, easy right?

Two blades, my best forging work by far, ready for a dovetail kanna dai to be made.

The bevel on the kanna looks weird because it tapers across its width. A dovetail kanna is a side escapement plane, there being no wedge, it is held into the body by said wedging shape. The knicker iron is also a tapered sliding dovetail. I quenched the knicker iron a bit too hot and its coarse grained, you can feel it when sharpening. The blade though, maybe good enough for me to sign.

I need to get my hands on some wrought iron.