This style of bow has a lot of recurve and rigid tips to the bow limbs or siyahs. The tips act as levers, a bit
like the cams on a modern compound bow.

I was interested in the geometry and feel of Asiatic
recurve bows. I happened to have some old fibreglass laminations, and the first
maple
bow I made this year (which was too low a draw weight).
So why not combine the two?
I set about it, doing some of it the "wrong" way because I'm a tightwad. I based the geometry on a composite crossbow prod I'd made years ago,
information from various books and web sites, and a huge amount of guesswork.
By using assorted rasps, the old maple bow was worked down to become the core
of the Asiatic recurve bow. The levers were made from a piece of ash with a
natural curve that I cut from the limb of a fallen tree, and split.

The levers were spliced onto the tips. Then the fibreglass laminations were
glued on with epoxy one limb at a time, on a former made from some scrap plywood.

(Doing it one limb at a time is a bit mad, but I had
suitable timber).
The whole area was then bound with linen thread
coated in epoxy.

Ha! This is where the mistakes and guesswork became
apparent! It looked good, but there wasn't enough timber on the levers to cut
in the deep nocks needed on this type of bow.
I cut some water-buffalo horn to enlarge the nock area which solved that
problem and looked good too.

Then I put a long string* on it and winched it back. It took 60 pounds just to
get it to the braced position! (That's where it is when it's strung, but not
drawn). That was far too strong for the 75- lb target weight. (I wanted it to
be comparable with my longbow.)
So I grasped the nettle and stripped the glass off
the belly. I didn't mind doing this as I felt I hadn't done a very good job of
the gluing. (I got some good advice - "epoxy doesn't like sticking to epoxy" - and
a couple of other hints from Blink.)
I carefully worked the maple core down by about 20%.
This was a reasonable guess; stiffness being proportional to the cube of the
thickness (note my usual mathematic rigour).
Anyhow, here's the result. 55lb @ 28" and it will
draw back to 30" and beyond with no problem.
Here are the string
bridges. This picture shows the bow braced but not drawn up so that you can see
how the levers/bridges line up.


* Putting a long string on a bow can give slightly
unrealistic draw weights, I think the angle of the string changes the leverage,
but I probably need a mechanical engineer to write a discourse on this. As an
illustration of this, the first inch or two always feels very easy.
Note: Here
is a link to a
learned discourse on the topic which may interest our more
mathematically-inclined readers. The conclusions are, I think, slightly woolly
however.
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