Making a Kanna from a Paper Cutter Blade

Craftsmen often create custom mameganna (small “bean” plane) for small wood projects requiring a custom radius or access to tight spaces. In this case a large post kanna was made from a section of industrial paper cutting blade as part of a timber framing project.

Materials for this large kanna are a scrap block of hardwood and a length of industrial paper cutting blade that has passed its usefulness. The wood is usually shiragashi, Japanese white oak, but some type of oak or similar wood that has been seasoned sufficiently should provide the strength and tension required for a kanna. Among the few remaining pieces of wood here, this block of unknown tropical hardwood was the closest candidate with about the right dimensions for the width of the blade.

The paper cutting blade has some good characteristics in that it is very hard 18% tungsten alloy steel inlaid into very soft iron or steel. Because it is hss, however, it cannot be heated and forged or the complex industrial temper will be lost. Therefore it was necessary to shape it entirely by grinding and filing, keeping it cool while working. It also has the drawback of being somewhat narrow and will not protrude very far above the dai.

Island Blacksmith: Hand crafted tools made from reclaimed and natural materials using traditional techniques
The blade is an 18% tungsten high speed steel edge inlaid into a very soft mild steel body.
Island Blacksmith: Hand crafted tools made from reclaimed and natural materials using traditional techniques
The inlaid steel hagane area can be seen along the edge.
Island Blacksmith: Hand crafted tools made from reclaimed and natural materials using traditional techniques
The bevel is a bit too acute for a handplane and the body needs a slight taper from spine to bevel.

To make the paper cutter blade into a kanna blade the profile was cut out (most of it can be sawn but the hagane must be snapped or cut with a grinder) and then a slight taper added from the spine to the beginning of the bevel. This kanna will be of the flat ura type for now and have no chip breaker, though it could be modified at a later time.

Tools used to plan and make the dai include a saw, drill, kanna, chisel, hammer, thin coarse file, protractor, and sashigane. The blade is 123mm (4 7/8″) wide, 10mm (~3/8″) thick at the spine, and the cutting edge is 112mm (~4 3/8″) wide. The dai is 263mm x 156mm (~10.25″ x 6″).

Island Blacksmith: Hand crafted tools made from reclaimed and natural materials using traditional techniques
The blade width in relation to the block of wood for the dai. The edge comes out at the 4:6 point proportional to the length of the dai.
Island Blacksmith: Hand crafted tools made from reclaimed and natural materials using traditional techniques
Some sketching and the final layout marked on the top, bottom, and side. More on the theory of kanna layout in a future article but the top surface of this blade is about 8/10 or 38 degrees up from the sole.
Island Blacksmith: Hand crafted tools made from reclaimed and natural materials using traditional techniques
The first cuts are made on the sole, to protect the mouth area and provide a target to aim for when carving.
Island Blacksmith: Hand crafted tools made from reclaimed and natural materials using traditional techniques
Working towards the lines, turning the chisel over can prevent digging in on the blade bed.
Island Blacksmith: Hand crafted tools made from reclaimed and natural materials using traditional techniques
Ready to cut the 4mm slots for the blade on each side.
Island Blacksmith: Hand crafted tools made from reclaimed and natural materials using traditional techniques
Using a saw and then narrow chisel to remove the slots for the blade. Fine adjustments can be made with a coarse file.
Island Blacksmith: Hand crafted tools made from reclaimed and natural materials using traditional techniques
The dai trimmed, planed, and chamfered.
Island Blacksmith: Hand crafted tools made from reclaimed and natural materials using traditional techniques
Due to some careless chipping around the mouth the opening is much larger than necessary and will be filled with a block of hardwood to close and protect the mouth.
Island Blacksmith: Hand crafted tools made from reclaimed and natural materials using traditional techniques
This is still quite wide but it will be used on rough-sawn beams.
Island Blacksmith: Hand crafted tools made from reclaimed and natural materials using traditional techniques
The sole is smoothed and adjusted for two contact points, and a light coat of tung oil applied to the dai.
Island Blacksmith: Hand crafted tools made from reclaimed and natural materials using traditional techniques
Large and thick shavings coming from rough sawn 100x150mm (4×6″) Red Cedar beams.
Island Blacksmith: Hand crafted tools made from reclaimed and natural materials using traditional techniques
The cut cells of this Fir post reflect light nicely.
Island Blacksmith: Hand crafted tools made from reclaimed and natural materials using traditional techniques
A comparison of the rough mill sawn surface of red cedar with the surface after a few passes with the plane.

Island Blacksmith: Hand crafted tools made from reclaimed and natural materials using traditional techniques

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