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Ken Wolfe

Forming Bamboo

22 posts in this topic

i have no experience in this whatsoever, but im very interested in this as well...i personally love the look of bamboo

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One way to form bamboo is to make it grow into the shape that you want. If you catch it at the culm stage and force it to grow into a pipe of the given shape that you want, the bamboo will grow to fill that space. And it won't take more than a few days but you have to do it in the Spring when the new shoots are starting to peak from the ground.

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Is that how the make the hook handle canes? I tried to take a 2 year old shoot and steam it and bend it, and all that happened was that it split and shattered. One thing I do know about bamboo is that as it grows older, the more the structure of the shoot is replaced by silicates. After 3-5 years for most varieties the silica chokes off the ability of the stem to transport water to the leaves and the shoot dies.

 

I have this image in my head of a grove of bamboo growing up through curved pipe, with the leaves sprouting out of the pipe end, like something out of a Dali painting.

 

The best way would be to find a stem that came close to the curve and take it as you find it. Or you could find a curved piece and make the blade to suit. Drying bamboo is another issue. Many types are so thin walled that split easily when they dry. I've found that standing the pieces upright for a year or so works best.

 

You might be able to tie a green shoot to a curved form, but you need to be careful. Green shoots are very soft and easily damaged. Once they are damaged, they often just die.

 

One odd thing about bamboo, the diameter the shoot breaks the ground with, is the diameter of that shoot. They don't gain girth after they break out. I had a stand of a timber bamboo at my last house. It takes 3-10 years for a stand to get established, but once it does, it goes pretty well. The first couple of years I got these shoots around an inch to an inch and half. In year four I had 20 shoots break ground all within a couple of days. The largest one was over 3 inches in diameter, and in the end about 60 feet tall. I gather that in better conditions (sub tropical) it can grow 6 to 10 inches in diameter and 100+ feet tall. Bamboo can grow a foot or more a day in the right conditions.

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Is that how the make the hook handle canes?

 

Those are actually made from the rhizome. A fresh green rhizome can be steamed and bent, but it's easer to find one that's naturally bent and just dry it on a from with the correct curvature.

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Those are actually made from the rhizome. A fresh green rhizome can be steamed and bent, but it's easer to find one that's naturally bent and just dry it on a from with the correct curvature.

Well I guess I'm not using what I have. I gathered a few poles the were down and dried off our California coast last year. Have a client that wants a curved one,but don't think he'll wait for it to grow. Not familiar with what a rhizome is.

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Rhizome is a fancy word for a type of root that isn't really a root. Iris "bulbs," ginger roots, and bamboo roots are all rhizomes. ;)

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I have steam bent bamboo. I used to make curved bamboo fukuro shinai for Kenjutsu training. I would take a turkey fryer burner, big pot with water at the bottom, a length of stove pipe and a lid. Steam for half hour then I had a form I put in my manual hydraulic press. I had to bend the bamboo way past where i wanted it because it would always spring back. I had some good luck with this and some bad luck ( I had one batch when I had half of the pieces break/split while bending). I would also figure out a way to stabilize the bamboo after bending because it seems to me that as bamboo ages it's more likely to split. I hope some of this helps.

 

 

Matt

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I have steam bent bamboo. I used to make curved bamboo fukuro shinai for Kenjutsu training. I would take a turkey fryer burner, big pot with water at the bottom, a length of stove pipe and a lid. Steam for half hour then I had a form I put in my manual hydraulic press. I had to bend the bamboo way past where i wanted it because it would always spring back. I had some good luck with this and some bad luck ( I had one batch when I had half of the pieces break/split while bending). I would also figure out a way to stabilize the bamboo after bending because it seems to me that as bamboo ages it's more likely to split. I hope some of this helps.

 

 

Matt

Thnks Matt, I give steaming a try. All it can do is break. <_< How did you clean out the inside and make the blade fit tightly. Would burning the blade in work?

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For a long blade, what I would do is find a section of very large bamboo, something in the 5" range will give you the thickest wall section depending on specie. I would then cut it into quarters being sure to keep the flattest sides oriented properly for my sheath.

 

Now, all you have to do is flatten the inside surface so you're left with just the "plank" of bamboo. This is very difficult to do, for me, but...

 

Steam, bend, hold to the jig and let dry. With two flat sections of bamboo curved properly, you can assemble a sheath just like you would with planks of oak. Keep the joints lined up and it will look like one solid piece if the joinery is well done.

 

 

 

Or, curve a whole piece and let it dry/cure to the form. Then simply drive the blade through the joints. The membrane at the joints isn't tough at all and usually breaks very closely to the size and shape of whatever's breaking through it. This will give you a very nice fit that you could augment with a cap at the top that really fits well to the ricasso, and looks better than the open end of a bamboo tube.

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Hey Ken

 

The bamboo is hollow except for the ribs. I would bend it and let it stay bent for a week until I cut it in half. Then I would probably line it with poplar or some other soft steel safe wood or else the blade is going to rattle around in the sheath.

 

Matt

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I've never fooled with bamboo but have bent a lot of canes from other woods like oak, hickory & ash. Almost any of the ring-porous hardwoods will bend. For them I would steam the cane (I started with a dowel 1 1/4" in diameter) for 20 minutes. You want the wood saturated with water and above 200 degrees Fareinheit. [Only steam the portion that you are bending and leave the remainder of the wood unsteamed so it will remain straight.] If you are using a cut or split piece, orient the grain so what was to the outside of the tree naturally is to the outside of the bend. Make the bend as quickly as possible after taking it out of the steam so not to let it cool any more than necessary.

 

Remember that when you bend wood, the outside of the bend is in tension and the inside is in compression. Most woods won't stretch more than 6-8% before splitting but they will compress close to 30%. That being said, you want to control the length of the outside of the bend. [Making a cane handle is asking about the maximum of the wood for bending.] I used a tension band of steel banding with a block attached to both ends matching the length of the piece of wood to keep it from stretching while being bent. Then hang it somewhere for a week or two and let it dry to shape (while in your bending jig). Remember to seal the wood once you have it finish sanded (steaming will raise the grain) so it won't draw moisture again which will relax the bend.

 

Good luck. Hope this helps.

 

Gary

Edited by Gary Mulkey

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Ken I live in an area that bamboo grows wild. It would not take much to find one growing wild with the arch you need. You would have to send me a cut out of the blade to match it up. Let me know Id be glad to help.

 

Kip

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Ken I live in an area that bamboo grows wild. It would not take much to find one growing wild with the arch you need. You would have to send me a cut out of the blade to match it up. Let me know Id be glad to help.

 

Kip

Kip,

Very kind offer.I may take you up on that. At first Client wanted a slight curve on the blade for a cane, but now says straight is OK. Matt, He would rather not have seam down the sides so cutting a large piece to slab won't work. Wants it to look like a stick and not a sword cane.

Trying to use the bamboo as is and getting the blade to fit tight inside is my challenge now. I can make the throat tight, but holding the tip secure??? Wonder if it would be possible to epoxy a wooden rod at the bottom that has a slot for the tip or something similar.

 

Ken

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Bamboo isn't very wear-resistant, so you'd definitely want some kind of tip. Fitting a wooden plug that acts as a traction/wear tip and has a slot to hold the tip of the blade wouldn't be an issue at all. Any epoxy would hold it in place, or you could pin it so it could be replaced as it wears.

 

The stuff splits fairly cleanly and I wonder if you could see the joint if you split the bamboo to access the inside and then glued it back together.

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For the sake of the bent bamboo sheath topic i wanted to share what i know and have learned from making archery bows. Bamboo is a wonderful material for the backing of a bow and has some impressive qualities. For bending bamboo is is best to use dry heat. A torch or hot gun will work much better then steam. The reason being is bamboo is literally a huge grass and has a lot of sugar in the fibers. As you heat with a torch the sugars become elastic allowing the fibers to shift, in turn allowing the cane to bend. A form can be used but i like to feel what is going on with my hands. I put it in a vice and heat with one hand and pull with the other. Its better to use a piece longer then what you need. The bend will come out smoother too. Simply add a little pressure and start heating in long strokes with the torch. You will FEEL the bamboo start to give. Go slow and be careful not to scorch the bamboo. Avoid using the hottest part of the torch. After you reach the bend you want go a little father and hold until the bamboo cools. You can even use the torch to change the color of the bamboo. Because of the sugar content bamboo will become a darker and more rich brown as you cook the sugars inside the cane. The problem with steam is bamboo is very sensitive to quick changes in moisture. If you steam bamboo you are adding moisture and allowing that moisture to escape rather quickly. This is what splits and cracks the bamboo.

 

I found a great demonstration of bending bamboo as far as a 90 degree angle on youtube,com: Click

 

I am in no way an expert and i am rather new to this forum so if I stated anything wrong please forgive and correct me. :) I should mention i have not started using bamboo to house sharp cutting tools just yet. But i have a few canes of bamboo drying in the garage for just that purpose. The idea of putting a plug of a hardwood in the bottom seems sound to me. Though it would be seem a good idea to add a ring or wrapping to keep the bamboo from ever splitting at the end. Just and idea...

Edited by Dave Wood

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Ken

 

did you end up making this ?? If you did and the Bamboo worked out well can you post a couple pic's of it?? I have a ton of Bamboo growing in my yard and would like to try to use some ..

 

Thanks Glendon

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Haven't seen this thread for awhile. Finally found a local place about 35 miles from me that grows and sells bamboo poles. Got a couple that are 1 1/2" in diameter. Should be able to fit a nice sized blade in there. Not going to bend the first one, but sounds like a heat gun would work the best to bend one. Thanks guys for all the input. Got to finish some knives before I start the sword cane.

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I've never tried with bamboo, but I've heated and bent hardwoods like oak and ash to make atlatls. This was the process I used:

  • Heat the wood until it is hot. Do not hold it too close to your heat source or it will char.
  • Bend the wood to the desired shape SLOWLY.
  • Hold/clamp it in place and then wipe it down with a wet rag.
  • Hold it there until it is cool, then repeat the process if necessary, until the curve is the shape and angle you like.

I've tried heating and bending wet wood, and learned that wet wood gives very little warning before it breaks. There's just sort of a soft, squishy, "pop!" followed by a loud, "Aww sh....!"

 

This is what I was able to do with this technique:

 

100_0491.jpg

 

The wood is pine. It's an atlatl for a 2-year old.

 

Incidentally, the heat, bend, and cool technique works well for PVC bows, too.

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You can permanently bend banboo with a few tools. The project was making out door lounging chairs.

Take a 6' pole as an example. knock out the interior stops by ramming a long pipe through. THen plug one hole with some cloth and solidly fill the interior with general sand till completely filled us another rag to close this end. Then heat the area to bend with a propane torch being careful not burn the surfrace.The sand inside add stability while the sand keeps structural support.

 

GT

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I have bamboo all kinds from very big around to skinny and black too.  My whole back yard is beautiful bamboo probably up to 30-40 feet high.  Guessing it high! Does anyone know of art projects you can do with the large seaths? Besides making papper.

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