Hollowing Out Bamboo

[vikingsnextfb]

What's the best way to hollow out bamboo?
I don't have access to any drills or anything, so what can I do?

I'm tryin to make a blowgun for a friend of mine and a "gift" because he's making a ninja suit, and what ninja is complete without a blowgun??

If I have to split it in half vertically and cut out the "walls" to the "chambers" in the bamboo, what could I use to glue it back together with an air-tight seal?

[Mark Meckes]

Hi vikingsnextfb,
The ease or difficulty of punching out the node diaphragms can vary with species of bamboo and diameter. Generally the smaller in diameter are harder. (less than an inch (2/3cm) diameter).
Usually one can use a metal pipe or rebar (used in concrete reinforcement and available cheaply in lengths at a 'HomeDepot' builders supply stores.
It's best to use a size that is a little smaller than the inner diameter or it might get stuck, or crack the bamboo during the process.
I always have several size diameters on hand.

The other method is to heat the tip of the metal rod/rebar over a gas flame or whatever, till it is red hot, and it will easily burn through the node stops.

Or after initially punching out the main portion of the diaphragm you can use the red hot tip to smooth the inside edges.

This is a smoky undertaking best done outdoors.

The other method is to use a long drill bit (often used for drilling lamp stands), with an extended shank, but these can be pricey.

Cutting/splitting the bamboo in half, removing these node diaphragms and regluing the 2 halves is a lot of work.
I would use this method as a last resort.

Cheers,
Mark

[vikingsnextfb]

Is there a certain type of metal that works best for the metal pipe?

[Mark Meckes]

Regular steel pipe or steel rods will do for punching out the node diaphragm. Rebar (reinforcement bar) works great.
The tip can also be heated red hot with a propane gas flame or wood charcoal bar-b-q flame to burn out the node stop. It will have to be reheated when it cools.
For heat burning holes in bamboo I've also used round files but they aren't long enough for long lengths of bamboo.
When heat burning it's the red hot heat not the punching that does the work.
For large diameter bamboo I've got lengths of steel pipe that is used for making chain link fences, commonly available at the hardware store for punching out the node stops.

[vikingsnextfb]

I used the technique you told me about to hollow out the bamboo with a red-hot piece of re-bar, but now I have another problem.

Rather than taking off the entire node and having a completely hallow piece of bamboo, I just put a hole in the node, rather than completely taking off the node.

I'm not to sure if you can see what I'm talking about, but instead of me having, let's say, a "bamboo pipe", I have a piece of bamboo with holes in the nodes.

Any advice?

[Mark Meckes]

Here are several options ...
- If the metal rod has a squared off of chiselled end, it's sometimes possible to chip off some of the protrusions by jabbing the edges with the metal rod.

- Repeat the hot tip process with a next sized larger metal rod.

- Rub the red hot heated tip of the metal bar up and down inside at the node, turning the bamboo gradually as you feel the diaphragm being seared off.
(You've probably found out that this is hot work - wear gloves and wrap a rag around the outside of the bamboo that you're holding so you don't get burned.

- Glue or tack some coarse sandpaper to the end of a wooden dowel or length of bamboo that can fit in the hole, and rubbing up and down, sand off any protruding edges.

- All of the above ;)

Let us know how it goes or if you found any other tricks to smoothing the edges.

Cheers,
Mark

[vikingsnextfb]

Will getting a pipe and sharpening the edges work?

[Mark Meckes]

This is definitely worth a try.
The smaller the diameter and longer the piece the more difficult it is to get in there and chip away the edges.
I once saw for sale a (very expensive) long half round chisel used in flute making to gouge out the inside edges.