Category Archives: Kobiki

Roubo Frame Saw Eat Your Heart Out

There is an alternative for woodworkers to the Roubo style frame saw for medium scale resawing and sawing of smaller boards. Introducing the Woodmizer -1, haha. Its a 450mm rip saw with about 3tpi, made by MIG welding a tang to a western panel saw.

I’ve felt the need for a smaller saw for ripping boards. Especially as the piece of timber that you’re milling becomes lighter, a full scale maebiki-oga becomes very hard to use, simply too much saw for the cut. While I would love to have a frame saw I feel that a pull saw offers several advantages in comparison.

First, a pull saw is much lighter and easier to use when the orientation of the cut is less than perfectly plumb. Second, the tooth line is shorter, faster to sharpen, and fits the natural length of stroke for a single sawyer. Frame saws have a definite advantage of allowing two person use, which creates good efficiencies, but most of us are working alone, and three feet of saw blade is a stretch to use evenly.  Third, there is no problem running a pull saw through a wide cant, where a frame saw can only cut material that fits between the frame. The wider the frame the more skill would be required to make sawing smooth and comfortable.

As it turns out I cut  ridiculously aggressive tooth geometry on this saw. Over the course of trying it out I’ve basically tuned it back to a neutral rake angle by back beveling the teeth with a micro bevel. Any saw will need tuning to the specific species and quality of wood you are sawing. In my case the limiting factor in milling pine is the knots. The fastest saw is not the most aggressive saw, its the smoothest saw that you can keep running with ease and rhythm in the cut. If you waste a lot of time hung up pulling through knots in tortured jerking fashion its not a fast saw. I had to push the tooth set way way out, but the kerf is still about 1/16″.

MIG welding butt edged sheet steel is not easy. My first try at the tang weld quickly failed. Forge welding would be much preferable, but using MIG meant that I didn’t spoil the saw plate temper and it didn’t need much correction of plate flatness.

Somebody asked about my preference for an ink line over a chalk line. An ink line serves as more than just a snap line, its the pot you dip sumisashi in for layout. Plus, its not that hard to make your own.

The ink throws off the line better than chalk, and sumi ink is a rich and satisfying black colour, without worry of it fading or rubbing off.

The sumitsubo is a fiddly tool, I’m still learning to keep the ink the right consistency and the wadding just the right degree of wet. Sometimes I find the sumisashi quite difficult to give a good line, especially when marking with the grain. In the end the ink pot, bamboo brush, and Japanese carpenters square have been designed to work really well together and its worth the difficulties to learn their use.

My latest Japanese franken-saw greatly exceeded expectations. I know just enough about saws now to be dangerous. The handle is a little low to the tooth line but I wanted to keep the tang weld as long as possible for strength. But if you’re looking for a cheap way to put a saw together that can handle material out to about 12″ (although fletch cut at 12″ might make a bitch out of your kerf, quartersawing is more stable), its a viable option. The perfect saw in this range for green timber in my mind is a bit larger with a thicker plate, but for such an ugly saw it does still work, and at a fraction of the cost for putting a Roubo style frame saw together. What do you think?

 

Heavy Trestles for Log and Beam Work

I felled a tree the other day and needed some low heavy trestles to bring the saw logs up to a height that’s comfortable to saw horizontally with maebiki-oga saw.

I didn’t want to worry about carefully preparing the lumber for joinery. Working from a center line allows you to use lumber that is twisted or bowed, but joints need to be housed.

How about a nice big log for the top of the trestle, plenty of space for driving dogs and not likely to walk around  when pulling on the saw.  I’m a fan of draw boring for pegging mortise and tenon joints.

Good work holding makes me a happy sawyer, and creates the most efficient conversion of human energy to the saw.

Height for the trestles are an inch or two below my knee, about 20″. Sawing being such a simple activity, one would assume that it is easier than in practice. In reality you will find that small details make a big difference, getting the log to a good height for sawing is one such detail.

Now if I could keep my ink line from freezing in this cold, haha.

The Mini Sawyer

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A friend showed up today and dropped off a chunk of birds eye maple that had split on him when he felled the tree. I’m not sure what happened to the rest of the tree, boy would I like to know! In any case I found myself in possession of a small piece of wood, and for sure it would make some fine bowls turned on the lathe, but I don’t have access to a lathe at the moment. Being highly figured wood, and a small piece at that, I figured the best use would be to saw into thin boards, either for veneer on drawer fronts or small presentation boxes. With birds eye grain the best figure is gained from flat sawing, not quarter sawing, which also happened to work out to give me the widest pieces.

The problem is, how does one saw an oddly shaped piece of wood like this without a large bench vise as I am accustomed to? I started by planing down the outside face until I had established a flat land worth converting into the first board.

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A bit of the figure shows in the bark, as well as being quite obvious in the freshly planed surface, quite beautiful!

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With one flat face I knew I could use a marking gauge to mark for the cut, but my end wheel gauge doesn’t have a large enough fence to register against, especially when the surface to be marked is sloping heavily away. Luckily the wooden straight edge I made a couple of days ago was at hand, and already had a hole big enough to pass the bar of the gauge through, now the first board could be marked.

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I’ve thought of using a technique analogous to this for marking highly irregular logs, akin to the sled that an Alaskan chainsaw mill uses for aligning the first slab cut.

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After marking with the wheel gauge I darkened the line in with a soft pencil.

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And clamped the chunk of wood to the closest near vertical thing at hand, a ladder to the loft above. You have to move the clamps around a bit as you cut, and keep the kerf open where its clamped with some wedges, but it obviates the need for a large bench clamp. The same function would be served quite nicely by a 4×4 timber, and it could even be made free standing in the shop if you were to add some cross pieces at the bottom for feet.

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The figure became more pronounced as I sawed through.

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I titled this post “The Mini Sawyer” because this is basically the miniature version of what I go through sawing a proper sized log, same orientation, same dynamics of the saw at various angles to the grain. The crossing grain of the birds eye was quite noticeable when sawing, a bit like small pin knots but softer.

For those unfamiliar, the saw that I’m using is a home made Japanese style rip saw, re-purposed from an old western panel saw. The steel is nothing special, but I’ve done a lot of sawing with it at this point, and it does a good job because the blade is flat and I sharpen it frequently. If you’re into Japanese saws you may have run across mention of saws that hold their edge for forty hours, almost mythical stuff, I had to sharpen for every board I cut, sometimes it went dull a couple inches before the cut finished. You know its time to sharpen when the middle of the tooth line is dull and you start snagging on the outside teeth because of the increased pressure of using a slightly dull saw.

I started having problems with cupping in the cut and became increasingly frustrated until I noticed that I had sharpened most of the set out of the teeth, hadn’t been keeping track of that even though you’d think I know what I’m doing by now. Carrying enough set in the saw is seriously important for wide rip cuts in green wood, which as you can see from the photo above tends to cup when flat sawn, especially if the outside surface has had some time to dry and introduce some stresses in the wood. Sawing like this is fundamentally quite different from how a joinery saw is tuned for minimal set. Even the most skillful hand sawyer wouldn’t be able to track a straight line ripping boards in green wood if the saw was under set. How much set is enough? That depends, but generally its towards the maximum that the saw can handle for the thickness of the plate, I tend to run this saw at about 2/3 of maximum set because I also use this saw for seasoned lumber. Don’t feel bad about the wider kerf, its peanuts compared to the extra wood you’d have to plane off if the plate gets pushed around as the wood warps in the cut.

I stickered the boards as I cut them to keep the drying even, and stacked a couple of really heavy slabs on the hole affair to keep things flat as they dry. My stickers aren’t even in the photo below, they should be directly over each other or you could end up introducing warps into the slabs as they dry.

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No band saw involved, no great fuss, just time, effort, and paying attention to the saw. Its your best teacher.

Making a Saw Setting Spider

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Time for working with a new saw! This time its a 5-1/2′  two man cross-cut for felling and bucking, cuts on the push and the pull, with four cutter teeth to every raker. I’d been needing the use of a larger capacity saw for bucking logs prior to ripping with my whale noko, because my madonoko isn’t really meant for cuts over about half a meter. Now, I’ve made some pretty epic cuts larger than that with time and patience, but even after careful straightening by metate Mark my madonoko still wanted to wander on the opposing side of the cut, and it gets to be a real struggle to layout for boards on the end of the log when the surface of the end grain is concave.

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I’ve resisted the idea of two man saws for the simple reason that its damn hard to find another guy to get on the other side of the saw. If you do, damn, that’s a good friend, I tell you!

But a saw like the one in the picture above can be used by one person quite effectively as long as the cut is plumb.

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And! There’s some very interesting tools used in dressing these large saws accurately. The jig at the top of the picture above does three things. First, it can hold a file in a curved shape for jointing the tops of the saw teeth to the same level. Second is a pin gauge for setting the height of the raker teeth when peening over the hook. Lastly is another height gauge for finish filing the rakers to a consistent height, accurate to the thousandth of an inch. The tool at the bottom left is the setting spider, the subject of today’s post. How about some instructions?

Simmons Saw Sharpening Guide

And learn from the master filer I learned from, a fantastic set of videos that include a bit of hammer straightening of saws.

The spider is used as a gauge to accurately determine the degree of set in each tooth. Simple and brilliant, it immediately struck me that such a tool could be easily made and used on maebiki-oga.

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You’ll catch this if you watch through the videos above, but basically the spider has a small difference in height between the long arms. Placed on the saw you see how it rocks back and forth. If the long arms rock the tooth needs more set, if the short arms rock the tooth is over set. Its important to note that this tool only works if the plate of the saw is quite straight, flat, and even of thickness.

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I started by cutting a cross out of some mild steel a bit thicker than 1/8″.

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I stuck it in a vise to bend the edges over, filed a flat land on all the feet, and leveled them to the same height on my diamond stone.

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Then one leg could be lowered by grinding with part of the spider off the stone, checking how much material had been removed with a feeler gauge.  For the large cross cut saw the spider was set at about .012″, for my maebiki-oga I adjusted the spider to gauge .010″ of set, which with a plate thickness of .085″ gives me a kerf just under 1/8″.

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Luckily the plate on my saw is pretty consistent and flat, so I got right to work checking my set. Up to this point I’ve been setting by eye by sighting along the plate held flat. If you have an oga saw with a rough hammered surface you’ll have to depend upon setting by eye. I still don’t completely trust the spider, but it is a great analytical tool to gauge how well I’m setting, and weather I’m actually seeing the degree of set correctly. As it turns out, I had over set one side and under set the other, probably due to the change in orientation of the saw when flipping it to peen the teeth over.

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For setting teeth you need a small anvil, mild steel is okay, as long as it has a rounded edge that allows the tooth to make contact in the right spot. The teeth of a whale noko are hard enough that if you were to strike the tooth while unsupported you run the risk of breaking it.

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With the plate held in your lap at a lowered angle to the flat  you can place the tooth line on the anvil and strike the upper third of the tooth.

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I’m using a new hammer for setting, a cross peen with a ‘v’ shaped edge, not rounded, that is basically a large single edge version of a Japanese setting hammer. If you use too light of a hammer you find yourself whacking the tooth with a rather random amount of force. Adjusting the set within a thousandth of an inch requires control. Also, bending teeth back that have been over set on such hard steel is not an option, they just break off, so get it right or you’re stuck with an over set tooth until you sharpen it down a bit.

Happy sawing! I hope more people now are getting these big saws ready for the cut and avoiding the hassle of a chain-saw.

The Pain and Pleasure of Sawing While Seated

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Continuing from my last post, the rotten heart of this pretty little piece of Black Locust. There was a knot that healed over and decayed into the heartwood, something I didn’t think could happen with Black Locust given its reputation as exceptionally rot resistant.

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So now I have slabs that are exceptionally…artistic. What would Nakashima have done?

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And when you don’t sharpen your saw the cut can cup in the middle and binding, chaos, and pain in your arms ensue as you curse the very existence of the tree you’re sawing.

Mark Grable is fond of saying, “Know when to stop”.

And, “Sharpen your saw, its so easy, its a rip saw”.

Okay, okay, I’ll sharpen the damn saw when it needs it.

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You may find yourself in a pickle needing to snap a line off the end of the cosmic void…I mean off the end of the butt of the log. Get creative with a level batten and some marks and you’ll be fine.

And finally, some video of sawing horizontally, sorry it took so long to the guy who asked.