Saplings with D Cross Section

[Dictionary]

This has been brought up before but I cannot find the thread! The wood i use mostly is HHB because it grows a lot here for starters.

I really like the Hadza bows. They are made from saplings and are all round in cross section and bend throughout.

I was curious how exactly you make a rounded belly as opposed to a flat belly and i searched and found this

https://www.primitivearcher.com/smf/index.php?topic=8028.0

the question i still had was, how do you rough out the bow using a hatchet/knife whilst at the same time retaining a circular cross section? I understand scraping/rasping the edges is used to tiller.

The main question i wanted to ask was, what is the benefit of using a circular cross section over a flatter one when using smaller saplings? Instead of being flat in the belly and crowned on the back like a "D" it is more like a "O" having both a crowned belly and back. Is this a good way to spread the forces over the belly and back evenly as both are crowned?


The common examples of hadza bows

[Dictionary]

no one has any input on this? 

[George Tsoukalas]

I never made an entire bow with a hatchet so I can't answer but my guess would be you just do it and keep the shape right from the beginning. The tiller shown will likely kick like a mule because there's a lot of bending at the handle. Better to limit the bending there  a bit more.
Jawge

[Carson (CMB)]

I subscribed to this thread hoping to learn more about that round cross-section...interesting stuff.  Looks like you have to just make one dictionary.  Why not just try an even taper out both limbs, so that you effectively have two elongated cones with their bases meeting at the handle?  Seems like you could skip the hatchet and start with a drawknife.  Use a wood that can handle ring violations on the back, i.e. not ring-porous. It is just a sapling, why not give it a go?  I have a yew shoot, I might try it on. 

You could limit handshock by shooting arrows like that hadza fellow has on the string, must be 40+ inches and likely close to 1000 grn. That would not leave much energy left in the limbs to kick.

[Dictionary]

George- i wasnt referring to tillering the bow with a hatchet, just roughing it out to bow dimensions whilst keeping the rounded cross section. Tillering is still done by scraping/rasping with a rasp,knife,cabinet scraper,etc.

I figure you're right CMB. I may just have to give it a go myself. HHB is what grows a lot here and it is a strong wood and grows fairly straight in small saplings so it is a good candidate.

Also i like a bow to bend in the handle visibly as well as feeling it bend but that bow does bend a bit much in the handle for my tastes. My arrows are 34 inches long.

Scott- ive seen that link before. Those bows remind me of the little bushman bows that shoot poisoned arrows from very weak bows with very low poundage.......

[RyanY]

My understanding is that a flat belly is better for a bow because it has more surface area to handle the compression than a rounded one. But I've also heard that a round belly makes up for its extra set by having less mass in the cross section. Rounded belly's are also easier to work with but I prefer a flat belly for most of my bows unless I find I want a rounded one for looks.

[Del the cat]

Try here...
http://bowyersdiary.blogspot.co.uk/2010_07_01_archive.html
Shows how I use an axe on the belly.
Del

[George Tsoukalas]

Oh, sorry. Sure you can do that. That's how I make bows. I don't use a bandsaw. I establish the cross section I want and then I keep it. I usually make a very slightly rounded belly. Jawge

[JackCrafty]

The main question i wanted to ask was, what is the benefit of using a circular cross section over a flatter one when using smaller saplings? Instead of being flat in the belly and crowned on the back like a "D" it is more like a "O" having both a crowned belly and back. Is this a good way to spread the forces over the belly and back evenly as both are crowned?

There is no benefit of using a circular cross section on smaller saplings in terms of efficiency or performance.  The wood on the back and belly are stressed much more on a circular cross section than a rectangular cross section, for example.

There are benefits, however, in the construction process.  Propeller twist is not an issue, there is little woodwork needed on the "skinny" side of the bow, and scraping is much easier on a rounded surface.  These three things drastically cut down the construction time, and effort, needed to make a bow.

This is a very ancient design and works well.  However, modern designs are more efficient and stress the wood less.

[crooketarrow]

  Jacks right but there are certen woods that a far more exsepable to this type of design.