siyah dimensions/materials

[looseplucker]

Gday Colleagues

One long term goal is to build a horsebow. I realise these can be tricky but there are some nice threads on the site with some good guidance.

I was wondering about dimensions and materials for siyahs. I have some osage offcuts which should serve - but am wondering if there are light woods that are unsuitable - ie would offcuts of vertical bamboo be wrong?

Look forward to hearing.

[pdccr]

I would love to make a horse bow but a bit too complicated for me yet. It would be great to see someone that has made one from aussie woods though. Good luck and im sure this will be a popular topic.

[looseplucker]

Greybeard (Daryl) posted a whiles back on this:

viewtopic.php?f=3&t=3714&p=30462#p30462

and it shows the use of his bamboo back and belly techniques.

First shot I will try with vertical boo flooring and see how we go.

[ichiban]

i think nowadays spruce is the recomended way to go.... and i have a supplier for you, at the kambah village there is a small model aircraft store and for the frames they use spruce. they would have to be glues togeather but that would probably be easyer/safer than heat bending

[looseplucker]

Thanks Ichi - I know that shop.

I have a pal who makes musical instruments - and he has a lot of spruce.

I have seen some designs on this site and others where the siyahs are not bent or angulated - but rather where the limb is recurved/reflexed at the tips and the siyah then sits in.

I'll email you off forum.

[ichiban]

yeah theres alot of diffrent ways to try a hose bow and i think for timber, possibly the best way to do it would be to have very thin limbs with massive reflex and recurves to achive the poundage rather than a shallower design with thicker material... if you know what i mean?

[looseplucker]

yup

[shikari]

I would definately recomend mulberry,the strength is 90%comparable to osage while it is 25% lighter in weight.I am currently trying some in red elm and bamboo,I intend to break each to see what kind of weight they can hold up to.What are you using for the core?Wish I had used mulberry for the first one I made would have improved the speed considerably.

[GrahameA]

G'day

I was wondering about dimensions and materials for siyahs. I have some osage offcuts which should serve - but am wondering if there are light woods that are unsuitable - ie would offcuts of vertical bamboo be wrong?

Opinion only.

Siyahs are located at the tips of the limbs and you will get better performance from the bow if you minimise the mass at the limb tips. Thus I would go for la ight timber that is strong enough to withstand the forces, etc.

Glue is relatively heavy. So you need to factor it in if you were to make laminated cross direction sections for use in the Siyahs. If you only have two or three layers if is of minimal consequence however if you are putting twenty layers in then it would be a serious issue.

The last Asiatic I made I sandwiched the Siyahs into the the two layers of glass. Not the easiest method to attach them but definitely strong and at the moment probably the way I will build the next one.

Regarding Siyah lengths - a read of Hickman's work from yonks ago and consideration of the Homlegaarde design is worthwhile and its performance characteristics . Against that you have to balance what the resultant bow would look like, what you want the bow to look like and what the dimesions of the working limb section would need to be. A perusal of a range Asiatics will show a wide range of Siyah length and proportion to the working limb section. With little or no reference data it really is an issue of take a best guess and something you like the look of.

WRT Vertical Bamboo - I would make up a few test pieces before I committed myself to using it. I don't know it well enough and would definitely play with a bit before commiting myself to its use.

[looseplucker]

Graham

a very informative post - thank you - - I have a thumbnail sketch of a bow of 60" from siyah fade to siyah fade -8-9" handle and siyahs minimum of 7" or so.

will do a buildalong and see how it goes

[pdccr]

Look forward to it

[looseplucker]

So do I - but methinks there will be breakage and swearage along the way, Toby

[pdccr]

There always is

[ichiban]

thats why i recomended spruce, from what i have read it is ment to be the strongest timber in the world (pound for pound) that being said i havent verafied that report