I had a bit of bamboo lying around the shop and decided to make a small 3-legged accent table. With a couple isosceles (equilateral) triangles jigs, you can easily make this type of table using many different materials. You could also use metal tubing, pipe, wooden dowels or rustic tree branches, but I used bamboo cuz that's what I had lying around. And bamboo looks pretty cool. So first let's build the 2 triangles you'll need to assemble this type of table. In the 2nd picture, you get an idea of how the triangles anchor the legs while you secure them at the middle crossing. For my table, I only used the bottom triangle as I decided "mid-project" to use a slightly larger top which meant the triangle was too small. Ideally you should build a larger triangle at the point, but I simply leveled the table top and it worked out fine. I'm planning to build multiple sized triangles so I can make a variety of tables. It is easier to do with 2 triangles.
Rip pieces of 3/8" or 1/2" plywood 1 1/4" and 2 1/4" wide. You'll need 6 pieces of each width roughly 20" long. Later we'll cut them down to 19 1/2" after they are fastened together. Take a 2 1/4" piece, apply wood glue to one edge, and nail an 1 1/4" wide piece to it (pic 3). This creates the six 20" angled side pieces which are 1 1/4" x 2 5/8" (pic 4). Trim the ends even and to a length or 19 1/2". To make an isosceles triangle we need to trim 15° off the ends to create 30° angles. On my miter saw, I use an auxiliary fence which is basically a large 90° angle (pic 5). This fence allows me to accurately make this cut with my miter saw set at 30°. To cut the other end of the side piece, use a 2x4 under it for support. You could also make this cut on a table saw, hand saw, etc. Don't forget the ends are cut in opposite directions.
Next you'll need band clamps to hold the triangles together after gluing the edges (pic 6). To support the corners, glue and nail a small triangle across the bottom of the corners. Picture 7 shows the finished triangles ready for use. You can imagine how the edges of the frames hold the table legs in the correct position.
Step 1: Preparing the Bamboo
Next you need to prepare the bamboo unless you chose another material to use. You'll need 3 culms or sticks 36" long. Bamboo is stronger if it is heat treated to caramelize the sugars in the bamboo which increases strength. Picture 1 shows the before and after. It also shows a hole drilled through all of the diaphragms inside the bamboo so air can escape during heat treating. If you don't drill these holes the bamboo will explode as the air has no place to expand. Exploding bamboo is a bad thing. I use a 36" long drill bit that electricians use to run wire in walls. Alternatively, you can simply punch holes through the nodes using a metal rod.
Bamboo is covered by wax which must be removed by heating with a propane torch (plumber's torch). Picture 2 shows dull unheated bamboo on the left , shiny melted wax in the middle and heat treated bamboo on the right. When the bamboo wax melts and looks shiny, you simply wipe it off with a rag. Once the wax is removed, continue moving the torch over a small area until you get the shape of brown you prefer. Once you have 3 heat treated piece, you're ready to cut (pic 3).
Step 2: Cutting the Bamboo Culms
For these legs, you'll need to cut each end at a 30° angle with both cuts in the same direction relative to the bamboo. To do this I like to hot glue small blocks to the side of the culm to make the cuts parallel to each other. Since the blocks only have to stay in place a very short time, first apply some painters tape to the bamboo where you intend to glue the block. This saves a little time by not having to clean the bamboo later. Place the blocks against a fence, apply the hot glue and then press the bamboo into the glue.
Next wrap the bamboo with more painter's tape where you will make your cut. Bamboo splinters badly on the back side of a miter cut and the tape is all it takes to prevent this happening (pic 2). Now set your miter saw to 30° and make your cuts. These 3 pieces have a finished length of 36". Remember the ends are cut in the same direction, unlike the sides of a picture frame where the ends are cut in opposite directions. It's also helpful to clamp a block to your miter fence so you're pieces are even in length (pic 3). The last picture shows the cut ends.
Step 3: Cut and Drill the Table Tops
This accent table has a 2 "shelves" which are 9 1/2" and 8" radius circles cut from 3/4" plywood. The holes for the bamboo legs are drilled along smaller circles of 8" and 6 1/2" respectively (pic 1). The easiest way to cut circles this large is with router circle jig. Alternatively, you could also cut these circles with a bandsaw circle jig which some find easier. Certainly less dusty. Set the circle jig of your choice to the larger radius of each circle and cut away.
You'll need to cut 3 circles in each top at 30° angles for the legs to pass through. Picture 2 shows how to draw an isosceles triangle inside a circle. After drawing the circle, keep your compass at the same setting and place the point anywhere on the circle you've just drawn. Swing your compass left and make a mark where it intersects the circle. Next swing the compass right and make another mark on the circle. Now move your compass point to one of the marks you just made and make a right and left mark again. Continue around the circle moving mark to mark and you should end up with six circle segments of equal length. Draw a straight line between every other mark and you have an isosceles triangle (pic 2). Remember you will be making your triangles inside the 8" and 6 1/2" radius circles.
Next you'll need to find someway to drill holes large enough for your bamboo at a 30° angle. My bamboo measured roughly 1 1/2" so I used an 1 5/8" hole saw. Since bamboo tapers a bit, isn't truly round, and has nodes, it's very difficult to attain the precision of an exact fit. The loose fit will be solved later in the process. To saw the holes it will first be necessary to make a small angled jig to position the table tops under a drill press. You will need some blocks cut at 15° which is convenient since we have 15° scrap pieces from cutting the triangle frames. Glue these little blocks together to form 2 blocks of equal width (pic 3). Once they are dry, attach a small board with glue and nails to the blocks to complete the jig.
With the angle jig attached to the drill press table, I find it easier to simply drill a 1/4" pilot hole for the hole saw (pic 5). This avoids having to clamp the table tops to the drill press table. Drill your holes as perpendicular as possible to the straight line on the opposite side of the circle. Since these holes don't have to be exact, there's a little fudge factor, but it's still best to be as precise as possible. Once your pilot holes are drilled at the points of the isosceles triangle, use the appropriate hole saw and your handheld drill to finish the holes (pics 6&7).
Step 4: Round the Table Edges
Using a handheld rotor or a rotor table, round the edges of both tops with a 1/4" round over bit. The second pic shows the difference between the rounded edges on the bottom and the unrounded edges on the top. Alternatively, you could sand or plain the edges or simply leave them square.
Step 5: Wrapping the Bamboo Legs
With all the pieces now cut and drilled, temporarily assemble your table using a triangle frame on the base and make adjustments as needed. The table is held together at the intersection of the 3 legs and you will need to temporarily tie or tape them together. Electrician's tape or rope both work well. Because the holes and bamboo are very loose, you'll need to block or clamp them in place. For the bottom shelf, I cut small blocks 4 1/4" tall and placed them underneath (pic 1). If you're assembly table is level, you can use a level on the shelf to double check it. For the top, I used long 22" pieces between the 2 shelves to level the top. Once I found the sweet spots, I placed small clamps on the bamboo under the upper shelf (pic 2).
Using a Sharpie, make a mark on all 3 legs where they touch the leg next to it. This is where we will be wrapping twine and ultimately tying all 3 legs together. You should also color code your table legs and the triangle frame so you get your legs reassembled in the correct orientation. This is especially true if your bamboo is not exactly straight (you may have noticed;). Picture 3 shows colored tape on the bamboo and the frame. Now disassemble your table and prep the tops by sanding and then painting or staining. For paint, 150 grit sandpaper is usually sufficient on plywood. For stain, continue up to 220 grit. (Somehow my shelves were already magically painted) It's also a good time to sand and varnish the bamboo legs. I recommend 220 grit paper and a coat of spar varnish.
When your varnish is dry (24 hours), it's time to wrap the legs. Place a piece of tape 3" on either side of your center marks (pic 4). These "center" marks aren't actually in the center of the bamboo's length since our tops are not the same size. The marks will also move depending on how far apart your shelves are located so just trust your marks! I begin wrapping the bamboo with a constrictor knot at my tape mark (pic 5).
Here's an instructable on tying a constrictor knot:
After tying the knot, lay the short end of your rope along the length of your bamboo and wrap over the top of it. It's not a bad idea to put a dab of hot glue under the rope in a couple places. Keep wrapping tightly until you reach the "center mark" and hot glue or tie the rope to the bamboo. Don't worry about the glue showing as we'll be wrapping over it later. It's best to make this a uniform single layer of twine. Repeat this step 5 more times until you have covered all 3 of the legs in twine (pic 6).
Step 6: Assemble the Table
Now that your tops are painted and your legs are wrapped (sounds like a personal problem), it's time for final assembly. Once everything is back to it's rightful place and you're happy, squirt some hot glue where the legs contact each other. This will be covered by the final wrap so you can be pretty liberal. Place a piece of paper on the bottom shelf in case some glue runs out from above. I did most of the gluing on the inside from above as it's not really possible to do the bottom side without turning it over. Once the glue is set, wrap the 3 legs together with the wrap of your choice. There's probably a minimum your should use, but the max amount is up to your artistic impression. I tried several different types and colors of rope, but settled on a basic look by using the same 7 lb twine. Try and tie your knot on the bottom of the twine band as much inside as possible. I also considered soaking the twine in epoxy resin but that seemed a bit messy and not really necessary.
I don't have a picture of the last step as I was stuck to some epoxy, but it's very basic. Test your table top and bottom shelf to see if they slide up or down. There may be a little movement depending on how tight the bamboo fits into the holes. For my table, I needed to place clamps on 2 of the bamboo legs on the top side of the shelves so I could turn the table over. The idea is to keep the tops level when you turn it upside down. Next turn the table over and lock the legs into the holes by applying 2 part epoxy paste to the bottom side within the holes. You want to fill the space between the bamboo and the top without it being visible from the top. It really doesn't take very much so go slowly. Let the epoxy dry for 24 hours. That's it! All done.
As I usually do, I found a way to make this simple accent table difficult by making the top shelf larger and having the bamboo penetrate the tops. I think that's the beauty of this little table. For a simple first table, use the 2 triangle frames to make a 3 legged base (pic 2 of intro) and then place a table top on it. Using different sized triangle frames and various materials for the legs the possibilities are endless.
I hope you found this instructable insightful and this table something you might enjoy making. It was a fun and relatively quick project and I love my little table. If you like it, give me vote in the Furniture Challenge. I look forward to hearing your comments!