Making Wooden Combs

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Tonight, something a bit different.

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I’ve been planing out the White Ash for the piece of cabinet work I’m building, but the exigencies of modern reality have me hustling to make a buck, traveling for work. So I’ll save the talk around planing out big hardwood panels for another time, today I work on something small and precious.

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How about making a wooden comb?

So, I needed a comb to be able to trim my beard recently. I had given my normal comb to my mother in an emergency that involved her combing stinging honey bees out of her hair, bless the woman. She had gone and swept up a swarm of bees this spring from our hives that I was too frustrated to deal with, in a difficult spot on a bush close to the ground. Would you believe I’ve yet to be stung by a honey bee? But my mother was stung a bunch in the face, and needed a comb to get the bees out of her hair, for some reason long hair easily tangles them up (and they were trapped inside her veil).

Now that its winter again I need a comb for the all important facial hair, but she kept my comb, and what is a woodworker to do? Go out and buy a comb? Hell no! I’m a twenty first century kind of guy, I like to think could make you anything from a house to a tooth brush, so here goes.

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Layout on Boxwood with ink, nice on the eyes. Beautifully dense wood by the way, I lust after larger pieces of Boxwood.

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I used a really cheap ryoba pull saw to cut the teeth of the comb, needing a health width of kerf. I used a spacing between cuts of 3/32″. If I was making a larger comb for hair I might go for 1/8″ between cuts.

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Then the teeth of the comb were tapered to a point with the help of abrasives. I actually used a belt sander with a 36 grit belt to quickly shape the profile, hand sanding is slow and meticulous work.

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The teeth of the comb after sanding, each and every one! Finished out to 220 grit.

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And then given a couple of coats of paste wax to make them shiny, people like stuff that’s shiny.

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Of course, I couldn’t leave it at that. After all, there are possibilities inherent, design possibilities that must be explored. I have a bunch of thin pieces of different tropical hardwood lying around, time to put it to work!

Here’s one of them, with a strikingly red dust from sanding. Looks like the color oxidizes to an almost deep purple hue, I don’t suppose anyone knows what this is? I’m afraid to hazard a guess, I didn’t buy this lumber, someone gave it to me.

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But it makes a nice looking comb, that’s for sure.

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Well shit, that’s not good enough, I’m a joiner after all, how about a comb with some joinery? Lets solve the fundamental problem of grain direction in a comb.

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I had to make the comb a bit thicker than I want to, at 5/16″, for the sake of the joinery. I’m limited because my smallest chisels are 1/8″ for cutting a mortise or dado. So lets join this up with a tiny sliding dovetail! I’m not sure, again, what the wood on the left is, but the comb teeth I made out of boxwood, very smooth stuff.

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Cutting such small joinery is a good challenge.

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But the results are satisfying. Time to open an Etsy store? I have lots of ideas for quick craft items like this. I’ve made plans to travel to Vermont for a couple months this coming January and cut a frame with Mark Grable for his forge. To that end my focus has to be working enough to be in the sound financial position to get out there and back. So its a hustle, everything counts. I have lots of the stuff I’ve made up for sale in my local market, fiber tools, shoji, even my fuigo, time to see what sells!

Layout for Simple Japanese Hip Roof

Hello! Tonight we go further down the rabbit hole that is Japanese hip roof joinery. Where might it lead? To building of course! I’m not sitting here in my shop obsessively building joinery models as an attempt at some kind of mental masturbatory self indulgence. This is about a little corner of structure, a fundamental of human existence. It is then, as they say, an existential topic to speak of timber joinery.

I think most peoples experience with structure has been entirely sub-optimal. Except, maybe if you’ve lived on a boat. But for most of us we don’t even know what we’re missing. If you have the misfortune to live less than a comfortable first world existence then necessity becomes the drive that creates the idea of a better circumstance, and often a better structure.

Tonight I had the good fortune to speak with Mark Grable for a bit on the telephone, I found it galvanizing. You have to understand the potential out there for people that are willing to get shit done. How bad do you want it, how badly? Now go find out.

So, to get back to the topic at hand, I’m giving it another try with the simple Japanese hip roof model. This is walking step by step towards structure by understanding one small piece of it at a time.

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We have our two keta beams joined together with a wedged mortise and tenon. By the way, my model is about half scale to what is listed in the book. My keta measure 60mm by 80mm. I feel awkward trying to explain this because my own understanding is so rudimentary, but here goes.

You can see that the layout starts quite simply with the hip centerline drawn on the top surface of the joined beams. Then the width of the hip rafter can be added in parallel to the centerline. Lucky for me this is a normal hip roof, symmetrical between the wall edges at 45 degrees.

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Next I added the lines parallel to the top centerlines that represent  the top and bottom edge of the common rafter notches. Because there is a jack rafter projecting out from the end of the centerline of either beam the kogaeri line must extend into the layout for the hip rafter notch.  Then the cut lines for the rafter notches can fall in place. It does make things look a bit crowded in there.

I remember the first time I looked at these hip roof models and the layout for it. Mush! Unless your a genius its hard to work out what’s going on. Give things a name, order appears, and structure commences.

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From there we can draw a series of lines perpendicular to the hip rafter, they all seem to have their own names too. You can see I’ve made a nice little series of squares by intersecting at the centerlines of the keta. There’s almost a hip rafter notch, but I’ll have to do a bit of layout on the hip rafter to find out where to place one of the cut lines on the keta.

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I started the hip rafter layout with the middle honchu line. Where as the common pitch of the roof (rise/run) is 5/10, the hip rafter uses its own pitch, 5/14.14, based on the relationship of the normal hip rafter being the hypoteneuse of a right triangle whose two sides are equal.

With our hip rafter pitch we can mark both a level line and a plumb line. In this case I saved myself some time by grabbing the plumb line with my bevel gauge and referencing to the edge and not the centerline. In practice I wonder if that would be possible. This whole endeavor does seem to depend on quite carefully dimensioned and squared material. I wonder what acceptable tolerances are for beam cross section and squareness?

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I made a mistake yesterday in the spacing of these lines, because I was measuring along the edge of the hip rafter and converting the distance between lines on the keta mathematically to the distance along the hip edge. I cut that out entirely this time, measuring equal distances along the level line of the hip rafter run.

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I used the same method to transfer the distance to the back face of the keta beams. The distance between nyuchu line and the back face of the keta beam is equal to the distance between honchu line and the tip of the notch on the back. This ensures that we get a triangle that will be 45 degrees to plan when the hip rafter is at the proper slope. Remember how those three intersecting lines helped form a series of squares on the keta? Now they’re a bit stretched out on the bottom of the hip rafter.

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Next I added the level baseline that intersects with the bottom rafter line and nyuchu. Because the baseline for this model is above the keta centerline 5mm I had to mark a line below the baseline that represents the top of the keta beams. This new line, “top of keta” extends to a new point where it hits the bottom of rafter line.

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Last for the hip rafter was marking the front of the notch where it intersects with the side of the keta beam.

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I’ve drawn some stars to help point out the new line derived from the hip rafter that is the start of the notch on the keta. All that was left from there was dropping the hip rafter notch lines down the side of the keta beam to the correct depth. I made a mistake there yesterday, hit the wrong numbers in the calculator or something. So I decided to get the numbers both mathematically and graphically.

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This time apparently I did things okay. It wasn’t a perfect fit, but most of my marks lined up pretty well.

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Pretty cool looking!

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I did make one mistake, my jack rafters are not meeting the hip rafter in plane, but that was another simple mistake with how I marked the depth of the jack rafter line on the hip rafter, and I’m getting too tired to explain it properly. Sebastian and I will be cutting a slightly more complicated model next week some time, we’ll try to explain it together and I look forward to continue exploring this aspect of house joinery. Its quite challenging, but fun!

Hip Roof Model Fail

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From “Wood Joints in Classical  Japanese Architecture” we have this wonderful little hip roof model, of the intersection between the wall sill plates, or keta, and the hip rafter/adjoining jack rafters. The model has a pitch of 5/10. So, how the hell to go about building this thing? Its a murky depth to probe at first. There’s something really important about having the pieces in your hand as you mark for cuts, looking at the orientation. I’m also working (almost) entirely in metric, the time saved converting decimals to inches is appreciated. I still want a sashigane with square root scale, even if it means working in shaku.

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Ahh, the good old compound miter for the jack rafter. Top face marked 45 degrees to plan, side faces marked with common rafter 5/10 pitch using the carpenters square. Bread and butter stuff if you’re cutting a stick framed roof.

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The top edge of the hip rafter is beveled to stay in the plane of the roof, and the jack rafter has to meet that plane evenly. So how do you find the angle for beveling the top of the hip rafter? It gets more interesting than that, there’s a common “pivot point”, or toge that represents where the bottom face of the rafter meets the base line of the top of the sill plate. Usually it would seem toge is often an imaginary point a little above the center line of the keta beams. It matters because the joinery has to be cut on the hip rafter such that the top planes that form the roof slope lie in the same plane as the common rafters, there’s a relationship there that is not immediately clear how to apply in layout for the cutting of the joint.

For the purposes of my model I made toge 5mm above the centerline.

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The sashigane is the most important tool in this awesome adventure. Can you say, hip rafter pitch?

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Finding the bevel angle for the top of the hip rafter involved measuring along a  level line on the side face representing the 5/14.14 pitch for a distance half the width of the hip rafter.

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The same use of the sashigane gives the plumb line as well, along which you can measure the distance to the bottom line of the jack rafters. I realized at this point that I made my hip rafter too deep, not sure about the proper proportioning yet.

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On the keta, we have the center line above which is our imaginary pivot point. Based on the common rise/run of 5/10 I know that the bottom of the jack rafters will contact the top of the beam 10mm away from the center line. On the side face of the beam we have the all important kuchiwaki line, representing the bottom of the jack rafter notch.

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“The Complete Japanese Joinery” was my main reference for understanding the process of layout. But I’ve already made a terminal error in my marking here, not to be found until I started cutting.

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The downward slope of the jack rafter notching continues from the kuchiwaki line where it intersects the perpendicular keta beam. From there I measured up to find the slope cut on the nose of the beam. I couldn’t tell from the model if it was supposed to be flush with the top of the beam or slightly below.

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At least I did a bang on job with the wedged tenon. This is the first time I’ve tried the technique of drilling small stress relief holes at the bottom of the saw kerfs on the tenon.

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It should have been a simple matter to measure the notch depth, somehow it became way lower on the left side and I didn’t notice the twist until I started chiseling out the waste.

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My second and more serious error was in the joinery for the hip rafter. The cuts on the side were properly marked at 5/14.14 pitch, but the spacing between marks for the bottom I multiplied from the keta beam using the square root of two, effectively marking for a 10/10 pitch roof…

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At least I’ve reached an understanding of my mistakes, and know how to mark correctly for the next try. But that is for tomorrow, all this thinking of angles and hypotenuse makes for a night dreaming of triangles.

Isuka Tsugi

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A little warm up joinery? Looks simple enough. This is a simple form of isuka tsugi, or halved rabbeted oblique scarf splice. I’m hosting a Japanese carpentry study group meetup this Saturday to study these joints, so I wanted to get in a bit of practice such that I’ll be useful explaining what I’ve learned.

This joint is mainly used on cosmetic applications, like the interior ceiling rafters on a drop ceiling in traditional Japanese construction. Its also used as a ware-away on the top of batter posts when laying out a foundation, not a friendly surface to sit on and throw off the layout, haha.

I’ve never seen a western carpenter cut spikes on the top of a foundation layout posts for stretching string lines, I wonder why. OSHA may have a fit! When I recently layed out the foundation post holes for the greenhouse I built I actually ran in to the problem of people wanting to sit or lean on my batter posts.  Hell, I wanted to sit on them, or grab the top to stand myself from a seated position. Good idea, and good practice for apprentices new to the saw.

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What you notice right away is that the central rip shares a cut line on the end face. At first I assumed that I’m missing something important in cutting this joint. But consider, if you first cut half way down the end grain face for either side, most of the joint is well defined on its face grain cheek surfaces. I tried my best to ride the edge of the adjacent kerf without slipping into it, but its all but impossible. The saw slips into the kerf and undercuts the cheek surface a bit.

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Surfaces from the saw, marking with sumisashi and ink on 1-1/2″ square stock, using 210mm ryoba saw.

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For such small cross section material it made more sense to use a marking knife and kebiki for the joint layout. I also used my dozuki saw and a piece of kumiko as a cutting guide. I’m slow with my sashigane, I know that from watching better carpenters than I at work via Youtube. It took me longer to lay out the joint than to cut it.

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On to a more complicated variation. Here’s what it looks like when you draw it incorrectly, haha.  While in the midst of this useless layout a small bird flew into my shop and slammed into some window glass trying to chase a fly. The poor little fellow was so dazed I was able to pick him up and find a tree nook for him to recuperate. It wasn’t a great moment, the bird might have had a broken neck. Thankfully a little fresh air and he took back to the skies. And I was able to draw the joint correctly, well sort of.

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I scaled up the lumber a bit to 2″ square. This variation has a cool parallelogram key to lock the joint, sachi-sen. I didn’t get the ratio of length to cross section correct, and I’m actually missing a bunch of cut lines, but I started cutting to find out. Made a bunch of cuts actually, all over the place.

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With not much wood removed as a result.

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Most of the material removal came down to being chopped away with a 1″ bench chisel. This blue stain pine is very soft, the chisel work was fast.

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The mating joint is identical in all respects. I wised up a bit and added more cut lines. I shouldn’t have taken out the waste portion of the ‘v’ in this photo, it removed my cut lines for the central rip before I had a chance to saw to the line! Still not much of a problem though.

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Looks like the subject of an Escher print.

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The assembled joint, planed out and keyed with a tapered oak wedge. The joint showed a tendency for the two halves to assemble with twist if there was any proud surfaces. Getting the joint to come together in plane seems to be the major challenge of doing an acceptable job.

Feeling warmed up? Time for hip roof joinery.

Killing a Tenon and Upside down Mortise

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I’m down at my Grandfather’s house hanging some security doors on his deck. And, being the optimistic fellow that I am, was able to explain the benefits of using a bit of honest joinery to add a post for the hinge rail of the door. The main sill beam of the wall had been cantilevered out to support the eave beam at the edge of the roof, but it was a bit under sized to the task and managed to noticeably sag over a couple of decades. So, time to jack the beam up and slip a post in!

I had to cut the mortise upside down, very different experience. All the swarf wanted to drop right out of the mortise, which was nice, but then most of it managed to head for my eyes.

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Beam with centerlines drawn, and tenon cut and killed with a hammer.  I read recently in “The Complete Japanese Joinery” about the joinery for shikii and kamoi, the grooved sill and header boards which serve as the track for fusuma and shoji in traditional Japanese homes. Because they are installed after the posts are erected they must use some creative joinery to allow their secure installation. The most simple joinery involves a mortise on one side and toe nailing the other, which is basically what was employed here.

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Assembly was easy, the compression from hammering the tenon surfaces coupled with the sheer weight of the roof made seating the tenon a breeze. Plus it was only really a stub tenon. I put two screws through to lock the tenon, but its not like the roof is going anywhere that it hasn’t in the past fifty years. Could hold up a beer bottle!

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Ok, setting a post is not a big deal, but is really out of the norm for the work I’ve done professionally as a carpenter. Normal would be butt joints and you screw that sum b**ch in there and get on with it. It made a work day very fun!

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My plane iron did this on the stone, very cool! Couldn’t get it to stick twice though. It really looks like it shouldn’t be able to stick like that.

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I’ve done a fair amount of work on this house in the past, including cutting the scallops on the beam edges with a chainsaw. Cutting one beam end up on a ladder with a power tool like that is fun, but thirty? That just starts to feel like work.

I like hanging doors though, it takes a lot of consideration for all of the plumb surfaces involved to do it well. All this needs is a bit of paint for the post and the corner boards and it’ll be on to the next one.

Hip roof joinery, here I come!