Sinew backed bamboo bow ideas
I have 10mm (6/16") thick bamboo "backings"*. They have pretty good numbers of fibres also on the belly side.
Estimation(without stacking) for 140cm ( 50") skin as belly pyramid flatbow with 4.5cm (1.8") wide at center and 20cm (8") non bending handle is 30#. Calculated based on 17cm(6") string height and 35cm(14") draw. Natural about 7cm (3") reflex.
My idea is to use 90cm long core. Attach 18cm-26cm ears and thin piece of bamboo flooring as semi bending handle. Flatten nodes at belly side. Taper the core from 4.5cm to 3.5 wide. Taper handle to 3-3.5cm wide.
Draw the bow to 30-40cm draw while tillering. Do tillering on back. Then glue a sinew backing and apply reverse draw. Leave to dry for few weeks. Possibly do so trick to keep the bow moist somehow at start of drying. Then start using drying closet with 50 celsius to finnish drying. Finnish the tiller when sinew is dry.
My target is 40#-50# at 70cm (28") draw.
Worries I have:
a) breaking/making unusable in the bow in "pretillering" before sinew
b) How to attach ears to core. Traditional V-splice requires separate belly piece. This has none. (See next post about ear attachment.)
c) Tiller in half draw is too different than at full draw and cannot be corrected with sinew attached by tapering limbs only. Longer draw makes mend to concentrate near handle, right?
c) sideway bending, since this is only one piece of bamboo...
d) should i leave the nodes thicker when tilering. They are initially flat.
e) I have idea of not heating this as it would all load on the back where there is less fibres as on the belly
*) not actually sold as backings but similar those, except the price.
Estimation(without stacking) for 140cm ( 50") skin as belly pyramid flatbow with 4.5cm (1.8") wide at center and 20cm (8") non bending handle is 30#. Calculated based on 17cm(6") string height and 35cm(14") draw. Natural about 7cm (3") reflex.
My idea is to use 90cm long core. Attach 18cm-26cm ears and thin piece of bamboo flooring as semi bending handle. Flatten nodes at belly side. Taper the core from 4.5cm to 3.5 wide. Taper handle to 3-3.5cm wide.
Draw the bow to 30-40cm draw while tillering. Do tillering on back. Then glue a sinew backing and apply reverse draw. Leave to dry for few weeks. Possibly do so trick to keep the bow moist somehow at start of drying. Then start using drying closet with 50 celsius to finnish drying. Finnish the tiller when sinew is dry.
My target is 40#-50# at 70cm (28") draw.
Worries I have:
a) breaking/making unusable in the bow in "pretillering" before sinew
b) How to attach ears to core. Traditional V-splice requires separate belly piece. This has none. (See next post about ear attachment.)
c) Tiller in half draw is too different than at full draw and cannot be corrected with sinew attached by tapering limbs only. Longer draw makes mend to concentrate near handle, right?
c) sideway bending, since this is only one piece of bamboo...
d) should i leave the nodes thicker when tilering. They are initially flat.
e) I have idea of not heating this as it would all load on the back where there is less fibres as on the belly
*) not actually sold as backings but similar those, except the price.
Ear attachment methods.
1 requires the belly of the skin side of bamboo to be flattened to be glued to ear.
2. Is simple lap joint. This worries that the start of glue line would be popping.
3. The trad V-splice. This has no belly piece, so I am worried if this would just hold.
NOTE: All will have sinew in back side and sinew or rawhide wrapping as reinforcement.
1 requires the belly of the skin side of bamboo to be flattened to be glued to ear.
2. Is simple lap joint. This worries that the start of glue line would be popping.
3. The trad V-splice. This has no belly piece, so I am worried if this would just hold.
NOTE: All will have sinew in back side and sinew or rawhide wrapping as reinforcement.
From your description, "Practice" means 'to practice making a sinew-backed bow', right? In China, they had a 'practice bow' for practicing shooting stance, which used no horn or sinew.
I remember sinew backed bamboo bows were called practice bows somewhere here. I cannot comment about where and when (if at all) this term was used.
(I changed subject not to contain "practice bow" word, if that is contraversal or wrong.)
I have made one sinew backed wood bow, but so in that sense not practice..
(I changed subject not to contain "practice bow" word, if that is contraversal or wrong.)
I have made one sinew backed wood bow, but so in that sense not practice..
All clear now. I think you want 'C'. The way I look at it, you need to give maximum strength to the joint and in C, you have good surface area contact for gluing attachment plus good surface area on the back of the bow where you can use sinew for extra reinforcement by putting a layer running from the back of the siyah to the back of the limb. Like a suspension bridge.
B can fail if the wood delaminates along the grain, like you said 'popping at the gluing line.'
I think 'sinew-backed bow' is a common term and 'practice bow' is not common.
S
B can fail if the wood delaminates along the grain, like you said 'popping at the gluing line.'
I think 'sinew-backed bow' is a common term and 'practice bow' is not common.
S
...a la turk... 50", 50lb/29", bamboo, pear, sinew backing, birch bark covering... Im still training, but horn is prepare already...
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Next work with bamboo and sinew and attempt cheat horn (which I havent now) with some synthetic fertilizer - only 40lb. Bad way... but shoot :roll:
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Peto; nice bows! The first one has the general shape of many Turkic bows of Siberia where the bow makers do not want to stress the materials so much as was done in temperate climates. I like the lower one too but am uncertain about your statement about fertilizer? Are you teaching Dusan?
If one uses bamboo flooring how can you be certain about the grain. Under the surface is weaker wood.
If one uses bamboo flooring how can you be certain about the grain. Under the surface is weaker wood.
Thanks Jack. Maybe synthetic material is better term(?) - (sorry my english lessons is long time ago)... and yes, Dusan is big source of knowledges about composites, good friend and big help for me ... bud this attempts without horn he hate... :D :D :D
How I can be certain about bamboo grain? I fear I dont understand... on bamboo surface is enough problem gluing anything ... (?)
How I can be certain about bamboo grain? I fear I dont understand... on bamboo surface is enough problem gluing anything ... (?)
Peto is very good craftsman. One day he would teach me... Evan now he was better in work vith wood and natural glues, and patienc. He was very skill and experience old violin master . Best ground for hornbow making :lol:
Peto - excellent bows! Very well done! Bamboo is a wonderful material in the right hands.