Need help making a YUMI bow....

I would recommend making form and usage of C-clamps, instead of the tradiotional method.

Hardwood belly is sure to be easier, but then it would be quite questionable if that is yumi in the way you want to ... I think self-yumies did exist too...

Also tillering bamboo back/baboo belly bow is not an easy thing, since there is no tillering surface in normal mean of the word.

I would use 2 pieces of 10mm thick bamboo, boil and bend them on form, then tiller them separately and then glue together using epoxy on the same form and then correct tiller by side tillering.

Cannot say if this is good idea tough as i have not tried this.

One idea would be to use Woodbear bow calc, Supertiller or such program to calculate the tiller and then make the bow with 0.1mm and hope the calculated tiller correspond the real world.

Nodes should not be planed. Belly and back nodes should not be near each other,

jkekoni wrote:

I would use 2 pieces of 10mm thick bamboo, boil and bend them on form, then tiller them separately and then glue together using epoxy on the same form and then correct tiller by side tillering.

Cannot say if this is good idea tough as i have not tried this.

One idea would be to use Woodbear bow calc, Supertiller or such program to calculate the tiller and then make the bow with 0.1mm and hope the calculated tiller correspond the real world.

Nodes should not be planed. Belly and back nodes should not be near each other,

Thank you for the advise. As I understand there is also a multi-lam core of various woods between the two boo strips.
A form would be most easy, but not quite traditional method, as I've seen J. Koppedrayer use.

I've built a few boo backed longbows already and this style of Asian bow facinates me as well as the Turkish bows.
The programs you mention above???I've never heard of a computer program to tiller a bow. where can I find this???

Thanks again.

Easternarcher wrote:

Hi folks. I don't post alot here but I do learn alot from reading...
I hope to build a yumi this winter, and wuld like to do it the old way with cord and wedge method.
Information on this method sems to be very sketchy, and I'm wondering what to use for my wedges and how tight to wrap the cordage?
I've heard some use scrap raw bamboo for wedges because the curved inner surface holds better against the outer boo surfaces on back and belly...

Any help or at least recommended reading would be a great help.

Thanks.

Easternarcher go to the search page and under author, type (steve t.)
and go through the posts, you will find alot of info. if you really need help I could answer some questions, but can go straight to the source and contact Steve Thomson yourself he is more than willing to explain. Good luck

amaguk wrote:

Easternarcher wrote:

Hi folks. I don't post alot here but I do learn alot from reading...
I hope to build a yumi this winter, and wuld like to do it the old way with cord and wedge method.
Information on this method sems to be very sketchy, and I'm wondering what to use for my wedges and how tight to wrap the cordage?
I've heard some use scrap raw bamboo for wedges because the curved inner surface holds better against the outer boo surfaces on back and belly...

Any help or at least recommended reading would be a great help.

Thanks.

Easternarcher go to the search page and under author, type (steve t.)
and go through the posts, you will find alot of info. if you really need help I could answer some questions, but can go straight to the source and contact Steve Thomson yourself he is more than willing to explain. Good luck

Thank You for that info. I'll do that.

Jaap Koopedreyer (if you can find him) is the most accessible exponent of the traditional wedge method. I have watched him demonstrate it. The method has obvious advantages, because you can continuously mould the shape of the bow while the glue has not yet set, and then fix the shape by hammering in the wedges to tighten the binding. Aesthetically, it's much mopre impressive that G-clamps. Amaze your friends. 8)

That you can. However getting the bow to tiller does not happen automatically.

If there is a trick that does that I would like to hear about it, so far I have not and assume, that when you do enough of them you may start gettng it right... also the tiller is not that critical, since the bow is overbuilt.

Stephen Selby wrote:

Jaap Koopedreyer (if you can find him) is the most accessible exponent of the traditional wedge method. I have watched him demonstrate it. The method has obvious advantages, because you can continuously mould the shape of the bow while the glue has not yet set, and then fix the shape by hammering in the wedges to tighten the binding. Aesthetically, it's much mopre impressive that G-clamps. Amaze your friends. 8)

Thank You Mr. Selby! Didn't Jaap Koopedreyer have a video done of building the Yumi? If so, anybody know if and where it may be available?

The elegant simplicity or complexity of ancient engineering methods really facinates me, and I admit I have resisted this style of building for quite a while as it just looked too complicated. But as my own experience has grown in bowbuilding, I find I'm looking for that connection to the past.

I also have a gentleman who has asked me to build him a traditional turkish horn bow. Luckily I found Adam Karpowicz's book. Still studying that method tho.
Thanks.

Do a search on youtube for koppedreyer,he has some videos posted of him making a yumi.

PjSingh wrote:

Do a search on youtube for koppedreyer,he has some videos posted of him making a yumi.

So Sorry, but I'm still on dial-up so YouTube viewing is out for now.
Thanks anyways.

Eastern archer: I'm not sure where you are located in Canada,but I live in Southern Ontario, and would be happy to show you the rope and wedge method of gluing and setting curvatures. I'm just today building a yumi getting the core and bamboo plates ready to glue tomorrow. Node placement on the bamboo is very important to determine the position of the curves. So without proper node spacing it's pretty hard to get the right shape.Next is the core inside the yumi. I'm using 3 vertical bamboo strips and bubinga on the sides for mine. Jaap does have a series of short videos on you-tube, and I was there last year when it was made.Look up Koppedrayer on search and it will appear. We do use bamboo wedges as we have the scraps to make them and also they bend nicely under the rope to give a nice tight glueline.Just make them thin so they flex when tapped tight.A pressure plate is also needed to stop cracking between the rope and the bamboo faceplates when setting curves. Too much info. for this post so contact me if need something specific.
Steve Thomson