Altoids Inro

A new method for making Inro

September 2008

Explanation

I've made a few inro in the past, but I was growing increasingly unhappy with that design. The resulting inro are very flat and rectangular, and the process relies too heavily on specialty wood. Also, drilling out the channels for the cords was still more of a pain than it should have been, even if the inro was a multi-chamber one.

This inro uses a new design. Instead of multiple layers in a sandwich, this design only uses two layers. There is a front and a back, and that's it.

This particular one was made to hold an Altoids tin. The Altoids tin is kind of an Internet standard for volume. Nobody knows how big a breadbox is any more, anyway. If you can make something fit in an Altoids tin (a camera, an emergency kit, a piece of art), it's probably small enough to carry around easily. So, if you can make an inro just big enough to hold an Altoids tin, that's as big as it really needs to be.

The outside of the inro is finished with 13 coats of tinted polyurethane, to approximate a lacquered exterior. This isn't as much work as it sounds like. A dirty brush can be stored in a bag in the freezer overnight. Every morning I would pull the brush out of the freezer, sand the inro lightly, give it a light coat of polyurethane, and put the brush back in the freezer. I'd do the same 12 hours later in the evening. So, 13 coats is only about 30 minutes of work a day, for a week. This would be a bigger deal if the item were large, or more complex, but a small simple item like this is not a big deal to finish this way.

Materials

The body of the inro is made from some scrap pine board that I had in the basement. It doesn't take much wood to make an inro, and if you're going to finish it heavily, it doesn't have to be nice wood.

The coating is Minwax "Polyshades" tinted polyurethane. This stuff is kind of a pain to work with, but it yields nice results if work at it. Since it's tinted, every layer deepens and darkens the color.

In the above photo, the inro is appointed with the 8-strand Braid #3 and a resin reproduction of an ivory netsuke.

The Process

1. The first thing I did was to disassemble an Altoids box. The edge of the lid is the widest and longest so I needed to use an unencumbered lid as my template.
2. Next, I cut my piece of pine into two pieces. I suppose I could have started with two smaller pieces, but it was all reclaimed scrap anyway.
3. Then, I traced around the lid on both pieces. Here's where I made a little mistake. I should have traced around the lid, then shifted the lid a bit in the long dimension to account for some wood that would be lost later.
4. With a 1/2 inch straight router bit, I routed a 1/2 inch deep mortise inside the traced outline. Altoids tins are about 1 inch thick, so you want to go just a touch deeper than that.
5. After cutting, I used this opportunity to smooth the inside of the mortise with sandpaper and sanding drums on the Dremel.
6. For the cord channels, I drew a line 1/4 inch away from each long edge of the mortise. This line must extend past the ends of the mortise by at least an inch in either direction.
7. Then I used a 1/8 inch round-end bit in a Dremel tool to cut a semicircular channel 1/16 inch deep along the drawn lines.
8. Now that all of the cavities were cut, I could begin looking forward to the outside. I started by drawing a rectangle around the mortise and channels that would represent the outside of the uncarved inro.
9. I cut this rectangle on the band saw.
10. Then, I placed an Altoids tin in the mortise of the cut piece, and placed it on the uncut piece. The tin helped make sure that the front and back were properly lined up.
11. Next, I cut the other piece to match the first piece. Now, the outside edges of the two pieces matched up as well as the insides. Remove the Altoids tin now, before you forget.
12. Being careful not to use too much glue, I spread glue on all the uncut surfaces of the cut sides of one piece.
13. Then, I clamped the two sides together and let it dry. I almost left the tin inside, which would have made it difficult to cut open later. Make sure you don't do this. The outsides should be enough to line up the front and back before clamping.
14. Once the glue was dry it was time to shape the outside. First, I used a band saw to trim about 1/8 inch off the front and back of the inro so it wouldn't be so thick.
15. Then, I used a 1/4 inch roundvoer bit to cut down the parts of the inro that contain the cord channels. This gave them that "tube on the outside" look that seems to be common in inro I've seen.
16. I used the band saw to cut the larger diameter curves around the top and bottom corners of the inro.
17. Then, I went back to the 1/4 inch roundover bit to round all the remaining edges and corners of the inro.
18. Since it was still a solid block, this was the best time to sand the whole thing as smooth as possible. I even used abrasive cord to sand the inside of the cord channels.
19. Finally,I measured down from the top of the inro about 1.5 inches and cut open the inro along that line using the band saw.
20. Construction of the inro was now complete, and it was all over but for the finishing.
21. To finish both sides of the inro at once, I padded a couple pieces of 1/4 inch wood, and jammed them inside the inro pieces. I could then uses thes pieces as handles while brushing finish on the inro, and clamp these handles while the finish dried.