Sansun-tsumari 弓;

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greybeard
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Sansun-tsumari 弓;

#1 Post by greybeard » Tue Jul 22, 2014 4:26 pm

Although there are numerous photos of this style of bow on the internet details such as the cross section dimensions of the various components are scarce.

There may be quite a lot of information on the net regarding Kyudo there is little detail regarding the construction of the bow.

Having a fair bit of experience with bamboo back and belly longbows I soon came to the realization that I would have to make up the build sequence as I went along.

Pole bamboo was chosen for the back and belly whilst vertically laminated bamboo edged with hardwood makes up the core. Cherry was used to build up the tips.
Materials.jpg
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Grinding Core Laminations.jpg
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Flattening Bamboo Pith.jpg
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Once the various components of the bow were complete it was time to make up the form but the big question being, how much reflex to build into the form.

Because of the amount of reflex that needed to be built into the bow an adjustable form was not a viable option. To obtain a minimum 12 inches of reflex I would need to build in 24 inches or so of reflex.
Glue Up And Laminations.jpg
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At times it is a little bit difficult to estimate the amount of reflex a bow can lose, even more so with this design.

The original design was to use three core laminations but because the pole bamboo had a relatively high crown the core was reduced to two laminations.

The form worked well as there appeared to be no limb twist.
Upper Limb Overlay.jpg
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Lower Limb Overlay.jpg
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I believe that these styles of bow are built with a slight dog leg to the left at the arrow pass to assist with arrow clearance; the arrow passes on the right hand side of the grip.

For my first attempt at building one of these bows I decided to do away with the dog leg.

Basic string nocks have been cut in so now I need to make up a temporary string and work out how to string the bow.

Final shaping and clean up should happen in the next few days [or after Gympie] and all going well some photos of the finished bow.

Daryl.
"And you must not stick for a groat or twelvepence more than another man would give, if it be a good bow.
For a good bow twice paid for, is better than an ill bow once broken.
[Ascham]

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Re: Sansun-tsumari 弓;

#2 Post by jcm » Tue Jul 22, 2014 4:38 pm

Look forward to see the photos of the finished bow.
Regards
John

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Re: Sansun-tsumari 弓;

#3 Post by Stickbow Hunter » Tue Jul 22, 2014 4:55 pm

Absolutely brilliant Daryl. I look forward to see how it all goes. :biggrin:

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Re: Sansun-tsumari 弓;

#4 Post by bigbob » Tue Jul 22, 2014 5:44 pm

that looks like it will be a very interesting project.
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Re: Sansun-tsumari 弓;

#5 Post by mikaluger » Tue Jul 22, 2014 9:18 pm

You are officially, a freak Daryl.......!!!!!!
Outstanding and it's not even finished yet.
Good photos of your equipment too!!!!!!! very interesting.

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Re: Sansun-tsumari 弓;

#6 Post by cmoore » Tue Jul 22, 2014 10:56 pm

24" of reflex :shock:
Set Happens

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Re: Sansun-tsumari 弓;

#7 Post by Dennis La Varenne » Wed Jul 23, 2014 2:00 am

Daryl,

The cross-sectional construction of your bow is exactly what I have found about the manufacture of Yumi bows, so we may have been looking at the same site perhaps. I do have it in print in my library somewhere as well. Not many people realise that the sidewalls of these bows were built using Cherry wood. I don't know if your Cherry is the same as that which the Japanese bowyers used, but they did use a Cherry for that same purpose. Those same sources did note that the centre laminations were vertical, but not of bamboo. I think from memory, they used a species of Mulberry.

That is an interesting point you make about the dog-legging of the area around the arrow pass. I have not found any reference to that, but my researches were by Western writers who may well not have noticed that feature. But, it makes sense of course - an eastern version of the Western arrow shelf/centre shot principle.

I did have a few shots from a Yumi at my old Club many years ago, but shooting an arrow on the 'wrong' side of the bow had me beat. It shot perfectly well from the 'proper' side and using a conventional Western draw, so I wondered why the Japanese and much of Eastern archery shot arrows from the off-side of their bows and for what advantage. It would be interesting to know that. I am sure they would have had a practical reason for it.

At any rate, once again, I commend your initiative in having a go at such a novel bow for us Western bowyers. I am also impressed by your form. I would never have thought of a horizontal style such as you thought up . . . and Crivens!!!! what a lot of clamps! You are a clever fellow indeed.
Dennis La Varénne

Have the courage to argue your beliefs with conviction, but the humility to accept that you may be wrong.

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Re: Sansun-tsumari 弓;

#8 Post by GrahameA » Wed Jul 23, 2014 7:50 am

Morning All.

So far it is impressive. And an excellent example of what can be achieved with a bit of thought and experience ... plus a lot of reading and viewing of things ... and having been willing to "have a go" at building things and learning from ones, and others, mistakes.
Dennis La Varenne wrote:... and Crivens!!!! what a lot of clamps! ...
There are more available if req'd.

p.s. Those photos were taken with a small Samsung camera with almost dead batteries. Which goes to show you don't need expensive camera gear to get good photos.
Grahame.
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Re: Sansun-tsumari 弓;

#9 Post by Bill » Wed Jul 23, 2014 5:05 pm

:smile: I found this, and you don't need to worry about clamps 8)

:sad: Sorry some of you may get an advertisement first but please be patient.

http://www.youtube.com/watch?feature=pl ... FEXjafZQRM

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Re: Sansun-tsumari 弓;

#10 Post by GrahameA » Wed Jul 23, 2014 5:30 pm

Afternoon.
Dennis La Varenne wrote:That is an interesting point you make about the dog-legging of the area around the arrow pass. I have not found any reference to that, ...
... At the center of the yumi, the tsuru is either centered or offset slightly to the right of center. ,,,
http://www.kyudo.org/html/articles/yumi_care.html
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Re: Sansun-tsumari 弓;

#11 Post by greybeard » Wed Jul 23, 2014 5:32 pm

Gentlemen, thank you for your interest in my latest adventure.

I managed to get some basic shaping of the nocks and tips done today so hopefully they will be finished tomorrow.

Details of the bow are; 214 cm n to n, the limb width being 27mm and limb thickness 13 mm tapering to 10mm.

In the plan view the limbs are parallel. Draw weight at present is a mystery however bear in mind that these bows are weighted at 31 inches.
Dennis La Varenne wrote:The cross-sectional construction of your bow is exactly what I have found about the manufacture of Yumi bows, so we may have been looking at the same site perhaps. I do have it in print in my library somewhere as well. Not many people realise that the sidewalls of these bows were built using Cherry wood. I don't know if your Cherry is the same as that which the Japanese bowyers used, but they did use a Cherry for that same purpose. Those same sources did note that the centre laminations were vertical, but not of bamboo. I think from memory, they used a species of Mulberry.
Dennis,

The time line chart [Wiki] illustrates how this particular style of bow evolved over the centuries.
Time Line Of Development.jpg
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Some of the preferred woods were;

Side woods for core: zelkova, bird's-eye/tiger maple, buckeye, wax tree/sumac, mulberry or catalpa.

Siyahs or nock woods: ebony, peach or cherry.
Dennis La Varenne wrote:That is an interesting point you make about the dog-legging of the area around the arrow pass. I have not found any reference to that, but my researches were by Western writers who may well not have noticed that feature. But, it makes sense of course - an eastern version of the Western arrow shelf/centre shot principle.
It may aid in the vertical rotation of the bow when the arrow is loosed.
Dennis La Varenne wrote:I did have a few shots from a Yumi at my old Club many years ago, but shooting an arrow on the 'wrong' side of the bow had me beat. It shot perfectly well from the 'proper' side and using a conventional Western draw, so I wondered why the Japanese and much of Eastern archery shot arrows from the off-side of their bows and for what advantage. It would be interesting to know that. I am sure they would have had a practical reason for it.
Perhaps it is because of the use of the thumb release and mounted archery such as the Huns, Mongols, and Samurai etc.

Italicised text is taken from; HEKI INSAI HA SCHOOL Technical Manual © Luigi Genzini, Rom.

“TORIKAKE
The thumb of the right hand must be perpendicular to the string. The arrow must be pressed against the bow by a slight counter clockwise rotation of the right forearm; this rotation must start lightly and gradually increase from Yugamae to Sanbun no ni; at the same time Teno uchi must tilt clockwise and increase according to the progressive Torikake movement.
The index and the middle finger must exert an equal pressure on the boushi (thumb of the glove). The pressure must be applied uniformly along the length of the finger rather than being concentrated at the finger tips. While drawing the bow you need to twist the right arm counter clockwise. Due to the backward movement of the right shoulder and arm from Sanbun no ni to Tsume ai the arrow comes close to the cheek.
Do not draw from the elbow, but imagine the point X moving on a line parallel to the arrow away from the target the angle Y then increases automatically. The point X should be about 10 cm from the elbow. If this is performed properly the arrow will not fall from the bow hand and a common reason for missing the target to the right will be avoided.”
Yumi Release.jpg
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http://www.youtube.com/watch?v=bfxpIDKOujw Release
Dennis La Varenne wrote: I am also impressed by your form. I would never have thought of a horizontal style such as you thought up . . . and Crivens!!!! what a lot of clamps! You are a clever fellow indeed.
I dare not trust myself with forty metres of cord, eighty to one hundred bamboo wedges and four glued up laminations.

In addition to the plastic clamps I have somewhere around one hundred ‘G’ and ‘F’ clamps covering 1”, 2”, 3”, 6”, 8”, 10” and 12”.
Dennis La Varenne wrote:At any rate, once again, I commend your initiative in having a go at such a novel bow for us Western bowyers.
Dennis, I firmly believe that to improve ones skill levels we must take on more daunting challenges.
cmoore wrote:24" of reflex :shock:
You will be surprised how much will pull out.

A note on tillering;

“Tillering a Yumi is done by bending in a form or heating of the limbs to conform to the right shape. Through experience, you will find the right amount of reflex and deflex to make perfect tiller. This is why it takes a 15 year apprenticeship to master the Yumi!”

Composite Turkish flight bows are tillered by placing the bow in a warming box and bent to the required shape before shooting.

Daryl.

For those interested in Kyudo the following link has a PDF for down loading.

http://www.google.com.au/url?sa=t&rct=j ... Q3iGQ5EGzA
"And you must not stick for a groat or twelvepence more than another man would give, if it be a good bow.
For a good bow twice paid for, is better than an ill bow once broken.
[Ascham]

“If a cluttered desk is a sign of a cluttered mind, of what, then, is an empty desk a sign?” [Einstein]

I am old enough to make my own decisions....Just not young enough to remember what I decided!....

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Re: Sansun-tsumari 弓;

#12 Post by bigbob » Wed Jul 23, 2014 5:42 pm

Man that IS some trial your are subjecting yourself to. Congratulations on your initiative and if any one can do it no doubt you will.
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Re: Sansun-tsumari 弓;

#13 Post by greybeard » Thu Jul 24, 2014 4:47 pm

Daughter and her husband were here for most of the day so little work was done.

The tips are close to their finished shape but I would like to shed a bit more weight from them and put a bit of shape in the back. Jute bindings are a temporary measure.
Tip Compilation - Copy.jpg
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Preliminary bending of the bow suggests that the lower limb is far too stiff but I feel it is wise to get the bow braced before doing any radical scraping of the bamboo.

As the bow nears brace height the upper limb is taking on a good profile so I will leave as is until the lower limb is adjusted.

Finishing the bow will have to wait until after Gympie.

Daryl.
"And you must not stick for a groat or twelvepence more than another man would give, if it be a good bow.
For a good bow twice paid for, is better than an ill bow once broken.
[Ascham]

“If a cluttered desk is a sign of a cluttered mind, of what, then, is an empty desk a sign?” [Einstein]

I am old enough to make my own decisions....Just not young enough to remember what I decided!....

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Re: Sansun-tsumari 弓;

#14 Post by Dennis La Varenne » Wed Aug 20, 2014 10:58 am

Preliminary bending of the bow suggests that the lower limb is far too stiff but I feel it is wise to get the bow braced before doing any radical scraping of the bamboo.
Daryl, could I suggest that once you get the bow braced, that if the lower limb is still too stiff that you use your heat gun and play it up and back along that limb for a few minutes.

I have done this often since I worked out my heat bending treatment and I use heat on bows where there is a modest amount of stiffness in one or the other of the limbs WHILE IT IS BRACED. The purpose is to have the stiffer limb weaken slightly through judicious application of the heat until both limbs balance each other out via the tension on the string.

I keep a ruler handy and keep measuring the difference in tiller until they equalise or come into about 2-3mm of positive tiller on a conventional bow. Once balanced I remove the string very quickly and leave the bow to cool completely. If the weakening process had caused the limbs to balance with more string follow that desired, I just put the bow back into the jig, pull BOTH limbs into the required degree of reflex plus an allowance for spring back, apply the heat and leave to cool again while mounted on the jig.

That has always worked for me so far. And . . . I don't have to remove any wood unless I need to sink the bow - which is rare.
Dennis La Varénne

Have the courage to argue your beliefs with conviction, but the humility to accept that you may be wrong.

QVIS CVSTODIET IPSOS CVSTODES (Who polices the police?) - DECIMVS IVNIVS IVVENALIS (Juvenal) - Satire VI, lines 347–8

What is the difference between free enterprise capitalism and organised crime?

HOMO LVPVS HOMINIS - Man is his own predator.

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Re: Sansun-tsumari 弓;

#15 Post by temudjin » Wed Aug 20, 2014 4:27 pm

Hey Greybeard,

this looks pretty special - can't wait to see the finished bow and how it shoots.
Are you going to shoot Kyudo style or a western style release??
Keep up the great work.. I have lots of asiatic style composite bows but no Yumi yet so you might get a flood of orders? :roll:

best regards,
Tom

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Re: Sansun-tsumari 弓;

#16 Post by greybeard » Thu Aug 21, 2014 8:30 pm

Dennis, thank you for your reply.

On bracing the bow the lower limb came around but unfortunately the bow did not exhibit the unique profile of a braced Yumi. Instead it looked like a lopsided longbow with the handle area being one third up from the lower nock.

I am still trying to resolve the issue with the focus being on the core profile adjacent to the handle area and the shape of the glue up form. There may also be merit utilising the string and bamboo wedge method.

More research will be required before I proceed with Mark II.

Tom, if I can make one Yumi that is faithful to the style I will lend the form to anyone who wants to have a go.

Daryl.
"And you must not stick for a groat or twelvepence more than another man would give, if it be a good bow.
For a good bow twice paid for, is better than an ill bow once broken.
[Ascham]

“If a cluttered desk is a sign of a cluttered mind, of what, then, is an empty desk a sign?” [Einstein]

I am old enough to make my own decisions....Just not young enough to remember what I decided!....

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Re: Sansun-tsumari 弓;

#17 Post by Dennis La Varenne » Thu Aug 21, 2014 10:59 pm

Daryl,

That almost suggests to me that there needs to be a much greater amount of reflex through the handle area in order to force the outer part of the lower limb to bend. I have no experience with this kind of bow of course but applying bending principles that I have learned, the secret may be in the position of the deepest part of the reflex and where it is positioned between the nocks.

I realise that the limbs have a 1/3 - 2/3 proportion, but that suggests to me that the reflex needs to be not only deeper perhaps, but the overall length of the reflex also needs to have the same 1/3 - 2/3 proportion which also means that it forms a sort of parabola with the lower limb having the greater amount of the curvature - if that makes sense.
Dennis La Varénne

Have the courage to argue your beliefs with conviction, but the humility to accept that you may be wrong.

QVIS CVSTODIET IPSOS CVSTODES (Who polices the police?) - DECIMVS IVNIVS IVVENALIS (Juvenal) - Satire VI, lines 347–8

What is the difference between free enterprise capitalism and organised crime?

HOMO LVPVS HOMINIS - Man is his own predator.

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Re: Sansun-tsumari 弓;

#18 Post by AndyF » Fri Aug 22, 2014 3:58 pm

Top work Greybeard. Wish I had the skill, time and workshop to attempt such things.

I'm heading to Japan in a couple of weeks, mainly driving around Hokkaido. However, I have a few days in Tokyo at the end and hope to go and see Kyudo somewhere. I believe there's a range at a sports complex near the Imperial Palace.

In fact, if anyone knows a good place to see Kyudo in Tokyo, please let me know.

A

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Re: Sansun-tsumari 弓;

#19 Post by Outbackdad » Fri Aug 22, 2014 5:29 pm

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Re: Sansun-tsumari 弓;

#20 Post by Dennis La Varenne » Fri Aug 22, 2014 10:43 pm

Daryl and Outbackdad,
Those pictures of a row of Yumi bows seem to have the kind of 1/3 - 2/3 centre reflex I was talking about above. The upper limb shape - a slow deflex which progresses to a shallow reflex also seems to be in the same 1/3 - 2/3 proportions as the lower limb which is the same shape as the upper limb above the reflexed mid-limb bow, but is about half the length of the upper outer limb and about half the depth from the bow's back surface at its most forward at the end of the lower centre reflex to the rearmost line of the bow's belly side at the nock.

There seems to my eye at least to be a very definite set of proportions of thirds involved in this style of bow.

AndyF,
I have a long time friend in Japan who reached the level of 12th Dan in Kyudo. He is a German who has lived there for over 30 years and teaches cultural anthropology at a private University somewhere near the old capital of Edo. He actually lives in a town called Nara-shi. I can contact him on your behalf and he is well able to steer you in the correct direction. He gave up Kyudo in favour of Western Archery because after so long, he found it boring. He has published a book entitled 'Kyudo' which has been translated into German as well as English. His name is Hans Joachim Stein, known to his uni students as Stein-sensei. He is a very great fan of Ned Kelly and teaches the social significance of the rôle of banditry in society.

Presently, he is 'holidaying' at a Buddhist temple somewhere north of Brisbane and must return to Japan when the summer break ends by the end of this month I think it is. I am out of contact with him until then.
Dennis La Varénne

Have the courage to argue your beliefs with conviction, but the humility to accept that you may be wrong.

QVIS CVSTODIET IPSOS CVSTODES (Who polices the police?) - DECIMVS IVNIVS IVVENALIS (Juvenal) - Satire VI, lines 347–8

What is the difference between free enterprise capitalism and organised crime?

HOMO LVPVS HOMINIS - Man is his own predator.

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Re: Sansun-tsumari 弓;

#21 Post by greybeard » Sat Aug 23, 2014 9:18 am

Dennis, deflex in the limbs is not all that apparent when you look at the unbraced bow in the photograph.

Perhaps a thickening in the core between points A and B may help to achieve the desired braced profile.

Building a glass laminated version would be a lot easier but it would not be historically correct.

Daryl.
Yumi Braced.jpg
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"And you must not stick for a groat or twelvepence more than another man would give, if it be a good bow.
For a good bow twice paid for, is better than an ill bow once broken.
[Ascham]

“If a cluttered desk is a sign of a cluttered mind, of what, then, is an empty desk a sign?” [Einstein]

I am old enough to make my own decisions....Just not young enough to remember what I decided!....

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Re: Sansun-tsumari 弓;

#22 Post by Dennis La Varenne » Sun Aug 24, 2014 12:37 am

Daryl,

I think you are onto something there. Your unbraced bow looks right certainly. If I could find my Kyudo book by Hans Joachim Stein, I could verify that.
Dennis La Varénne

Have the courage to argue your beliefs with conviction, but the humility to accept that you may be wrong.

QVIS CVSTODIET IPSOS CVSTODES (Who polices the police?) - DECIMVS IVNIVS IVVENALIS (Juvenal) - Satire VI, lines 347–8

What is the difference between free enterprise capitalism and organised crime?

HOMO LVPVS HOMINIS - Man is his own predator.

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Re: Sansun-tsumari 弓;

#23 Post by Dennis La Varenne » Sun Aug 24, 2014 10:33 pm

Daryl,

Have you thought of doing a heat reflexing job on the centre part of your Yumi? It is probably worth a go. You could put more bend there by setting it up on your forming jig with some wedges at the deepest part of the centre section to increase the curvature a good bit.

I have been having remarkable success with increasing the bends in my old bows by cooking them this way. I have stiffened up a couple of ELBs by putting a padded 2 inch block under the middle of the handle area and tying the limbs down at the midpoint of both limbs. After cooling, springback brought the centre curve back to only half and inch, but it certainly made the handle section stiffer (including the draw weight). I have given the bows (which are only 40lbs-ish anyway) a bit of a flogging and the additional stiffness is still there.

In your pic above, where you have marked the bow A and B would be where I would tie it down with the block between those two points. Leave the outer limbs alone. You could use a 3ft length of stiff board (I use a 100w x 50d mm length of pine) on which to tie the bow down and leave the outer limbs sticking out past the ends of the board.

Just a thought.
Dennis La Varénne

Have the courage to argue your beliefs with conviction, but the humility to accept that you may be wrong.

QVIS CVSTODIET IPSOS CVSTODES (Who polices the police?) - DECIMVS IVNIVS IVVENALIS (Juvenal) - Satire VI, lines 347–8

What is the difference between free enterprise capitalism and organised crime?

HOMO LVPVS HOMINIS - Man is his own predator.

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Re: Sansun-tsumari 弓;

#24 Post by AndyF » Wed Aug 27, 2014 9:20 am

Thanks for that info Dennis. It may be a bit late to get advice from your friend. I leave in a week, and the Tokyo leg is looking rather full anyway. We shall see. I'm sure I'll find something.

Thanks,

Andy

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