Epoxy Kumiko Pendant Light

There's a total of 401 pieces in this lamp, which made it a fun and extremely challenging project. For those who may not know, kumiko is an ancient Japanese technique of assembly strips of wood in geometric patterns without the use of metal fasteners. The grid and infill pieces in this project are 1/2" x 1/8" strips of basswood and you'll need kumiko jigs to cut them to their appropriate angles. Both the jigs and the strips are linked bellow in the 'Tools I used section'.

TotalBoat was kind enough to help out with this project and provide you with a coupon code. Use "JTWOODW10" at check out and receive 10% off all TotalBoat products at www.totalboat.com and also at www.totalboat.com

To help clarify things, for this Instructable, I will refer to the kumiko section as three separate parts. The main grid (consisting of all vertical and horizontal strips), the angled grid (the strips running diagonally in the main grid), the infill (the small strips cut to make the intricate patterns within both grids).

Tools I used:

These are the tools I used for this project, however, similar results can be achieved with similar tools.
Kumiko jigs - https://jtwood.works/collections/plans-jigs

Sawstop table saw - https://amzn.to/2ILhw5L

Chisels - https://amzn.to/2ILhw5L

Japanese handsaw - https://amzn.to/2ILhw5L

Hot glue gun: https://amzn.to/2PydYbU

Dental syringe - https://amzn.to/2VyEhUO

Router - https://amzn.to/2GNeMGU

Drill press - https://amzn.to/2DAtrDo

Random orbit sander - https://amzn.to/2Dypoaz

Materials:

Kumiko strips - https://jtwood.works/collections/plans-jigs/produc...

TotalBoat epoxy - http://www.totalboat.com/product-category/woodwork...

Black diamond pigments - https://amzn.to/2GOOXGy

Sheathing tape - https://amzn.to/2V51bUb

Lamp cord - https://amzn.to/2XSiiWo

Light bulb - https://amzn.to/2XQhy3Z

The main grid is made with three different sized strips. (4 - 17 1/4") (6 - 6 1/4") (6 - 1 3/4") For kuimko, it is very important to be extremely accurate when cutting all your pieces. To make sure all of these are the same length, I tape them together, trim one side of the strips so they're even, and cut the other side to length. I used a table saw with a crosscut sled to achieve this (and many other steps in this project) but it can also be done with a bandsaw or hand saw and the same thing applies for cutting the half laps.

There are a ton of half laps to cut in this project and this is where we start building the pattern we're looking for. All the dimensions I used for this panel are illustrated in the next step. In order to make cutting the half laps easier and to their respective angles, I made this sled for my table saw. The back fence is 90 degrees to the blade and the angled fence is 30 degrees from that fence. The grooves in the sled are 1/2" apart and where meant to put a small piece in to register the previous half laps to but the spacing is off for this panel so I measured the spacing of the half laps for each strip and used a stop block for repeatable cuts.

Once all the half laps are cut, the grid can be assembled.

At the time of writing this, I don't have plans for the sled used in this step. When they are available I will link them in the intro.

The is the first time I've ever incorporated and angled grid in a project and prior to this I made one practice piece. Because of this, I was being very careful to measure out all the half laps accurately so I didn't have surprises (mistakes) later on.

I started by cutting the three half laps on the small angled strips. With those cut I then cut the center half lap in the longer strips. I then used the small strips as a template to mark out the other two half laps on the long strips. I did it this way to make sure all these half laps are spaced out properly so they intersect properly. I also added small angled sections on the ends of this grid and to space those evenly, I measured out from the center half lap of the long strips. With all those half laps cut, this angled gris can be assembled.

Now it's time to combine the two grids together and this is where a couple a things can go wrong. If the half laps aren't spaced properly, the grinds can get distorted when they're assembled and will complicate the future steps. To help prevent that, I'm the using the grids themselves to mark out the half lap locations. I'm cutting the half laps on the main grid first so I centered the angled grid on the main grid and traced around the strips to mark out where I need to make the cuts. I removed the strips I needed to cut from the made grid and cut them with the sled on my table saw. These needed to be cut at 60 degrees so I added another fence to sled.

With those half laps cut, I reassemble the main grid and place the angled in the new half laps slots. I made sure it was centered and marked out and cut these half laps the same way. The grid was then assembled and those are all the half laps needed for these panels.

I glued certain sections at a time and use the glue dried I removed them for the panel to cut the extra lengths of the strips. I used a Japanese pull saw for this and they work great. Removing sections from the panel made it easier to cut the strips and glue made sure the strips stayed exactly where to need to.

If you plan on making this project, think through what sections you need to glue first so you don't paint yourself in a corner. Also, if your half laps are tight enough, you might not need glue. I added it just to be on the cautious side. I'm a belt and suspenders type of person.

This frame is made from African mahogany and I cut the strips at 1/2" x 3/8". After cutting the first miter on one of the ends, I then used the panel to mark where I needed to cut this frame piece to be the right length. With one piece cut to it's proper size, I taped it in place and repeated that process for the rest of the frame referencing off of the first piece. I also marked and cut each piece of the frame for each side of each panel. That way I had extremely accurate fitting frames.

With the frame pieces cut, I tape the corners together around the open up the frame. I add glue in the miters, close up the frame with tape. I also add glue to the inside of the frame and glue the kumiko panel to the frame. I also add tape to close up any gaps between the panel and frame if there are any.

The infill is the fun but challenging part of making kumiko. I covered this process in great detail in another Instrucable linked here. In that Instructable I cover how to make the asanoha pattern for a square grid which I used for the small rectagular sections in the top and bottom of the panels. The process is very similar for diamond sections on the angled grid except the infill pieces are cut with 30 and 60 degree jigs to reflect the angles in that grid.

Next up is the epoxy. I first cover some plywood with sheathing tape which will act as backer boards. The sheathing tape won't stick to the epoxy as it cures and will allow me to easily remove the panels later on. I them secure the panels to these boards with hot glue which will prevent the epoxy from spilling out under the panels. I used a weight on the panels to make sure they were flat on the backer boards. It's important here to also make sure the panels are level. I checked for level in both directions and added shims where needed.

I them started mixing the epoxy and did two separate pours for this project each one about 1/8" deep. The first pour is a clear level and second one is where I added the color pigments. This way more light is able to chine through the sides of the lamp. To get the epoxy into the tight pockets, I used a dental syringe.

Once the first pour enters its gel state, I start mixing more epoxy and added blue and green pigments to get somewhat of a navy turquoise blend. I had to mix a few layers epoxy to I wouldn't have too much in the cup and risk it reaching its exothermic state too quickly and solidifying in the mixing cup. Because of that I knew I would had different shades of blue for each batch. So I mixed enough epoxy to fill the same pockets in each panel and repeated that until all the pockets were filled. When the epoxy is fully cured, I removed the panels from the backer board with a chisel.

Next I cut chamfer on the back of the long sides and one of the short of the panel. That short side will be the bottom of the lamp and the long sides will be glued to the other panels.

I felt it would more accurate to cut these chamfers with a router table but I don't have one. So I flipped my router upside-down and tightened it in my vise very well and installed a 1/4" chamfer bit. I felt confident doing it this way but I wouldn't advise it if it doesn't feel safe to you as you have a very small base to reference off of. With those cut, I held the four panels together to measure out the length of the piece the cord will attach to. I won't provide dimensions for this piece as it depends on how accurate your were cutting in the previous steps and on the lamp cord you plan to you.

I cut this piece to length and used my table saw and cross cut sled with a stop block to accurately cut out the tenons of the ends of this pieces. With those cut I drilled a hole in the center of this piece for the lamp head. The treads on my piece weren't long enough to reach through the entire thickness of the wood so I drilled a slightly longer larger hole half through for the entire lamp to sit into it.

I drilled these holes with a drill press but a regular drill will work fine just make sure to drill as straight as possible. If you're using forstner bits, it helps to drill the larger hole first.

While at the drill press, I set up a fence and drilled out the majority of the mortise in the frame of two of panels. I then cleaned up the mortise with a chisel.

Before assembly I sand the front and back of the panels to clean up any inconstancies in the kumiko pieces and the epoxy. I sanded the epoxy with 120 grit which left a bit of a rough surface. This helps defuse the light through the epoxy.

I start by gluing the cord piece in the mortises first and I use a clamp to make sure it's seated fully. I them add glue to the chamfers and using clamps to hold these pieces together would have been tricky so instead I use rubber bands. I made sure not to add too much glue here as I didn't wan't a lot of squeeze out to clean up later. I also used Gorilla brand wood glue because it dries clear and won't be visible if there's a little bit of squeeze out.

Once the glue dries, I removed all the rubber bands and removed any dust with a brush attachment on a vacuum. I used spray lacquer as a finish mainly focusing on the mahogany to bring out the rich orange color.

And with that, it's all finished. While I was pouring the epoxy, I decided not to add any epoxy in the diamond sections. That way more light can pass through and highlight the warm wood tones against the cold blue epoxy. This kumiko and epoxy process is something I'll be exploring more of in the future so be sure to follow me as well as Instagram (@jtwoodworks) if you want to stay up to date with those projects.

You can watch the video here on how I built this lamp.

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