Summary of this instructable: how to shape a strip of bamboo then heat bend it over a shaping form, glueing it and smoothing it out leaving you with an unique bamboo bracelet.
Looking at the fantastic properties of bamboo getting inspired by split cane bamboo fly rods ( yes, I know I am a fishaholic) I decided to see what I can do with it. I dediced to make something for my girl since she is so fond of bracelets. The end result is a lightweight, super though and aestheticly pleasing bamboo bracelet that really surprised me and my girl as well.
Go check it out!
Bamboo, any thickness you can get at the garden shop or DIY shop, being at least 2 cm in thickness
Bolts and nuts, screws
Piece of thick plywood
Workbench, vice or clamps
Fretsaw or scrollsaw or jewlers' saw
Sandpaper, grit 100, 200,400
Files , rough and fine
Masking tape and regular sticky tape
Pipe clamp or string
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Step 1: Splitting the Bamboo Into Strips
Summary of this step:
Choosing the right part of the bamboo and making them into strips
Selecting the right part: Bamboo is a funny material. Opposite to trees, bamboo has its strongest fibers lying closest to the surface, just under the hard and protecting film layer called enamel. See picture. The density of the fibers decrease from the outside towards the inside. (See picture) In this instrucable I've been using cheap bamboo stalks from the garden center used for agricultural goals such as bean stakes. The don't cost much so get a few and select the ones that are dry but look fresh. ( bend it, let it bounce on the floor) Get the straightest stalks.
Splitting the bamboo: For the bracelet you need a strip of bamboo around 120 cm. To get this strip you have to split the bamboo in half. Splitting the bamboo is really simple but they don't always split the way you like it. Choose where you want to split the bamboo. Look across the culm from the bottom to the tip. Rotate the bamboo untill you find the side where the bamboo appears to be the straightest. The nodes, thickened cross sections, need to be in line as much as possible. Find this line and put a blunt kitchen knive at the bottom across this line. With a small hammer you force your knive towards the tip splitting it in half. You only need one strip, make several and choose the best one.
Step 2: Making the Strip Ready for Heat Bending
Summary of this step: Cutting, scraping and filing:
When you are left with a nice straight strip you need work your way through a number of steps to end up with a straight and even strip. Remember that you want the highest density of fibers but you don't need the enamel top layer. You scrape this off. With a sharp knive you start cutting away the parts you don't need. With the strip clamped down on a working surface you remove all the soft material with a rough file. See pictures. Notice that the density in fibers also differ in colour and the outer layer is noticeable more work. Check thickness for an even result. Thickness of the strip should be no more than 2mm. Thinner strips bend but also burn more easy.
Tip: keep some of the bamboo sawdust, you can use this later to restore some imperfections.
Step 3: Making the Bending Form
Summary of this step : Made a round bending form in the right diameter (wrist diameter).
Creating a notch for securing the bamboo strip in place.
Make a stable fit for placing it in a vice or work bench.
The idea is that you wind a strip of bamboo around a round form to create your bracelet. A laminated bracelet you could say. To get the diameter right I borrowed a bracelet that just fitted my girls wrist and traced it onto a piece of thick leftover piece of plywood. The diameter in this example is 62mm. If you have a hole saw in the right diameter it is easy. I haven't so I used a fret saw instead. (Hard work)
In the first picture you see that I have cut a notch with my fret saw. This is the place where you squeeze your strip of bamboo when you start bending.
In the middle of the bending form I created a hole where the bolts and nuts go in place. The only purpose of these nuts and bolts is that you have some surface area to clamp it in a vice or workbench. Beacuse when you start bending you need to apply some pressure and you don't want it to spin around. So I used what I had around and that explains the peculiar barrel shaped nut (probably from Ikea)
The nut in the middle of the hole is more interesting. It's a T-nut. This nut has an inner thread and teeth that you force into the wood so that you can tigthen things up easily.
Other ways to do it:
Use what you have around. For the nuts you can go with wing nuts and washers. The other idea is to screw the form onto a piece of wood like shown in the other picture then using screw clamps to fasten it to a working space.
Step 4: Bending the Bamboo Using a Heat Gun
Summury of this step: Placing the strip in the form and heat gently while bending the strip around the round form.
One of the amazing properties of bamboo is that you can bend it using a heat source, in this case a heat gun. After is has cooled off the bamboo will keep the curved shape. The bending form has a notch to keep the strip in its place. Make sure it stays there during this process. You can use stickytape or masking tape or even hammering a small peg in the notch. The process is really straight forward. Be sure to apply a little tension while bending it around the form. Since you are using heat you should be wearing gloves at this point. At the pictures you can see aluminum foil. That's for protecting my wooden work bench. Note: When bending it is best to have the outside part of your strip on the outside. Check out the video!
Note: when the bamboo starts to crack to often it usually is to old and to dry.
Step 5: Glueing
Summary of this step: using the bending form, wood glue and sticky tape to combine all the layers together leaving it to dry
I'm using white wood glue. Plenty of it actually. Because it's a messy job I advice you to wear disposable gloves. Apply the glue evenly by spreading the coil a bit. Because there is some tension on the coil you need turn and twist in such a way that the layers lay completely flat. If you let go know you need to do it over again. Have your masking tape ready. Once the coil is thight you lash plenty layers of tape around it. Before you place the bending form back in its place you make sure the bamboo doesn't get stuck to it by giving the bending form a few layers of sticky tape. To tighten things up I've been using a pipe clamp in a large diameter which you can tighten with a screwdriver. However this is an easy way to do it I also found out that It left a dent in the final product. Another way to do it is to lash it all together with synthetic string. This work fine too and won't leave a dent. Note that the bending form has a longer bolt to hold the string in place. Don't use sticky tape for this or your glue won't dry.
Step 6: Rough Finish
Summary of this step: shaping the bracelet using files, sandpaper or power tools
After 24 hours the glue should be set and it's now time to see the result. Doesn't look attractive now so from here there is still a lot of work to be done. Check the dent on the left I was writing about earlier. Now it's time to make it as smooth as you can starting with a file and sandpaper. You're welcome to use power tools. I used a round file most of the times but it also depends on the shape you'd like it to have. Happy with the result? Well, I made some errors, let's clean them up in the next step.
Step 7: Smooth Finish and Decorating
Summary of this step: making a decorative pattern and filling up unwanted grooves or gaps using homemade filler made from wood dust
Since I already made a plain natural looking bracelet I decided to go 'berserk' on this one by adding some decorative dots on the bracelet. Drill some shallow hole around the bracelet und plug the hole with small pieces of a bamboo skewer and some wood glue. Hammer them into place.
You might have some gaps between the layers. They are quite hard to avoid because we are no robots. The gaps can easily be filled up with some homemade filler made from the wood dust and glue. Get it to a peanut butter like thickness. I used a sieve made from a piece of mosquito mesh to get the smallest particles.
Put on plenty and spread with a wet finger to fill up all the irregular grooves. Of course a shop bought version will do just fine. Leave it overnight to dry.
Step 8: Final Finish
Summary of this step: smoothing out the remaining filler with sandpaper and giving it a layer of varnish or lacquer
The homemade filler made with woodglue needs to be smoothed out with sand paper. Wood glue, the one I am using is made of polyvinylacetate. This polymer is a thermoplastic polymer which means that heat causes it to melt. So when using a power tool for sanding you create heat by friction and therefor you should not be sanding on one spot for too long. Always work form rough to fine, starting with grit 100 and continue to work ending up with grit 400. A nice rub with a cotton cloth or even a piece of paper will polish it even more.
When applying the first layer of lacquer I often brush the first layer on the surface and then whipe it off with a tissue. When that layer is dry I continue the second layer. In the photos you see a simple tool to hold the bracelet while applying the lacquer.
I hope you appreciate the end result. For sure you will have a unique homemade bracelet that only take some time and little money to make. Please tell me what you think of this project and leave a comment when you think that this instructable was of any use to you. Thank you for checking out this instructable!