Tanto Letter Opener

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John Z Zhu

Project by

John Z Zhu
USA

General Information

Combine technology with hand work for the fusion maker. The majority of the cutting is done on the X-Carve. This project is a balance between design, X-Carve, and hand-to-hand tool work. Many thanks for the professional photographer at Inventables for 4 of the 5 cover photos.

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tanto sheath.svg

sheath ebony piece

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tanto_handle.svg

handle ebony piece

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tanto_leather4.svg

sheath leather pieces

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tanto1_16_design.svg

tanto ebony piece

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from Inventables

1

cutting out the pieces on the X Carve

120 minutes

1. The ebony I am using is about 1/8” thick. It is cut at a rate of 10”/min and a depth of 0.1”/pass (1a & 1c). The clamps secured the ebony, but the ebony was slightly cupped, so that is something to be aware of when cutting (1b). A 1/16” bit was used to do the cutting on the X-Carve.

The vegetable tanned leather was about ¼” thick, but it is inconsistent in it’s thickness (1d). There needs to be abundant clamps to ensure the leather does not flop around when cutting (1e). I did not put a back board under the leather. I would advise in putting a back board under the leather, and set the depth of the X-Carve to make sure it cuts into the back board. The leather is cut from the suede side (cutting from the top grain side will cause the leather to tear. Leather is easy for the X-carve to cut, so set the speed and depth to one of the presets for any of the softer wood.

The lack of a back board left with some of the details on the leather and ebony pieces uncut. The Braille details on the leather pieces were poked out with an awl (1f) and a drill. The uncut ebony parts where cleaned out with a knife and chisel (1g).

2

epoxy acrylic inlay

10 minutes

2. After the X-Carve has completed its cutting there are tabs left holding the pieces together. Leave the tabs, the bigger surface is easier to hold. Tape one side of the design with masking tape (2c), and dam up areas where the epoxy may run (2a). The epoxy inlay is made by mixing 2 parts epoxy with an equal volume of titanium white acrylic paint (1 part A: 1 part B: 2 parts acrylic paint) (2b); once cured (24 – 48h) this mixture is easy to work with. Remove the masking tape once the inlay has cured (2d). A chisel was used to remove the excess acrylic/epoxy mixture to reveal the decorated blade (2f & 2g). Free each part with a coping saw (2e) and clean up edges as needed.

3

ebony pins braille low relief

180 minutes

3. The braille low relief in the handle and sheath is made with a thin ebony dowel; the dowel started as a 1/8” square and 6-8” long piece of scrap. The piece of ebony is chucked into the drill while pinched with 60 grit sand paper (3a). The dowel is then smoothed to the diameter of the hole on the leather pieces, then cut to ~3/8” in length (3b). Insert the dowel/pin into the leather (3c) and epoxy the suede side (3d), cure for 24 – 48h.

4

rough forming the handle and sheath

60 minutes

4. Grind most of the epoxy off the suede side of the leather (a), if you grind too much the ebony pins will be freed, I know this from experience. I also changed the design here; the handle ebony piece was moved backwards to expose some ebony behind leather. The leather pieces of the handle are trimmed with a chisel (4b) just passed where the two holes are located (4c). The handle (4d & 4e) and sheath (4f) pieces are then glued together using epoxy, be prepared with lots of clamps (4g).

5

blade collar and hand guard

90 minutes

5. The blade collar is made from a piece of maple. A V-groove (5a) is made so that the drill would not drift (5b). A series of holes were drilled and a mortise is cleared (5c) to fit the blade using a knife and a chisel (5d). The hand guard is the same as the collar, except with a piece of ~1/8” thick ebony. The collar and guard were roughly shaped on the grinding wheel (5e & 5f) and finely shaped with a chisel and sand paper.

6

fitting all the pieces

5 minutes

6. The pieces are fitted by hand then glued together using epoxy (6a & 6b). The sheath is extremely tight at this point use to distribute clamping pressure (6c). In the picture the blade has already been 90% shaped (see step 9 for blade shaping). The pieces are now assembled; it looks ugly but it is an ugly duckling (6d).

7

trimming the parts

90 minutes

7. The leather pieces were designed to be larger than the ebony pieces so that the leather can be trimmed to fit tightly to the ebony (7a & 7b). A chisel is used trim the leather to the ebony (7c). A file is used to shape ebony pieces as needed (7d).

8

finishing all the leather parts

30 minutes

8. I found the top grain surface of the leather to be too smooth; so 180 grit sand paper was used to give the top grain a texture (8a). Neats foot oil was then applied to the sanded surface and allowed to dry for 4-6h (8b). Natural bee’s wax was applied to the edge (8c) the leather and an edge iron was heated to ~220 degree’s F and smoothed the wax (8d). A small hammer can be substituted for an edge iron. The iron was heated on a electrical stove at low heat until desired temperature was reached.

Three coats of shellac were applied onto the top grain side and edge of the leather (8e). The shellac was allowed to dry 5h between coats and 24h after the last coat.

9

finishing the ebony blade

30 minutes

9. The blade was rough shaped on the grinding stone (9a) at the same time as the blade collar and hand guard (step 6). Sand paper was used to finely shape the blade. While sanding the ebony deposited a layer of blackish dust on the white inlay. A chisel was to scrap the ebony deposit from the blade (9b); this also provided the final smooth finish for the blade (9c). The last step is to apply 3 layers of shellac (9d); allow the shellac to dry 24h between coats, and 48h after the last coat.