Knots in Scythian bow slats

[Tom Dulaney]

Hello,

I am trying to understand the Scythian bows of Xinjiang. They have a very unique construction and this document is a great help in getting a basic understanding of how they are built:

http://www.atarn.org/chinese/Yanghai/Scythian_bow_ATARN.pdf

It is mentioned that the wooden slats used on the bow are split from saplings. In my personal experience it is very difficult to find saplings that don't have knots in them. Do yiu think it wohld be impossible to build a good Scythian bow, if the wooden slats had small pin knots on them?


Thanks for your time.

[stuckinthemud]

What a fascinating read.  Thanks for posting that Tom! 

It seems the slats are all quite short, the document states, "most lengths of timber were 15 cm long ..... as tamarisk does not seem to have been available in longer lengths".

Finding 6" lengths of good timber is quite straight-forward, even in really knotty saplings, so, while long lengths of timber seem to have been unavailable to the Scythian bowyers, good quality timber wouldn't have been too hard to come by in the lengths they needed. 

As I understand it, even pin-knots would be a really bad idea in a high-stress design, but I stand to be corrected.

[Urufu_Shinjiro]

There's a fellow on the ATARN Facebook group who's really into building these right now, I think he's working on his fourth in the last few months, lol. He goes on FB by the name Jason Beever, perhaps he could answer your question.

[Aaron H]

Jason also goes by jwb bows on you tube, he has a few short videos on his Scythian bows.

[mikekeswick]

The wood must be flawless.

[mikekeswick]

Saplings are used because the wood is very elastic before the tree grows bigger.
These bows are a crazy design! Fancy for fancies sake

[joachimM]

Saplings because juvenile wood is more elastic, at the expense of being less rigid.
Juvenile wood has a higher microfibril angle in its wood fibers (just like compression wood), allowing more bending before breaking (or set).
Since wood is a lot weaker in compression perpendicular to the grain, knots are generally not a good idea. However, in some softwoods (like larch, yew, oregon pine, ...), wood in branches is much denser (and therefore darker), which compensates to some extent for the loss of compression resistance along knots. 

[Tom Dulaney]

Thanks for the advice guys, glad you enjoyed the article. Can I just get a recap here?


 Why does it matter if the wood has tiny, smaller than 1mm knots in it?

 I just can't find any wood here that doesn't have knots in it, and it is driving me insane. Every time I think I got a perfect sapling, I peel the bark away (with torturous care) only to reveal yet another row of God's many disappointments. I'm getting chilld just thinking about it. I'm so angry I'm on the verge of burning all my wood and never thinking about bows and arrows ever again. I can't even find a six inch piece of wood on a sapling that doesn't have atleast two branch eminences in the wrong location, there's literally nothing to work with after cutting down enough saplings to feed a gorilla family of 5 for a week.

[mikekeswick]

Look harder!
It matters because knots mean there isn't a continuous unbroken set of straight fibers. Knots are weaknesses in these bows and the core will break there.

[stuckinthemud]

Yeh, I do sympathise, hunting for good quality bow-wood is one of the joys and frustrations of bow-building, and finding wood for horn bows is even more frustrating and rewarding!!

[willie]

In my personal experience it is very difficult to find saplings that don't have knots in them.

have you tried to find thick stands of saplings, possibly growing on previously disturbed soil, of the age where the pins are sufficiently grown over? Locations well shaded by overstory?or on the north side of hill? or in a gulch?

[mikekeswick]

What country are you in?
In general try looking at the bottom of steep valleys, ditches etc. anywhere where the light getting in is restricted.

[Limbit]

I don't think a pin knot 1mm is going to matter unless it is on an edge of your bow. If you are making a horn bow, the sinew and the horn will protect it to a large degree. The point the other guys are making is that the time spent finding good wood is time well spent. If for some reason you invest 6months to a year of your life arduously constructing a horn bow only to have it split on a pin knot...ouch. Not only that, a horn bow explosion can evidently be life-threatening. The wood mentioned in the article is incredibly hard to imagine pin-knot free when you see pictures of the plant, so maybe trusting ancient methods is fine in this circumstance. You could also try other wood. Notably, mulberry is mostly used in korean composite horn bows and a type of maple for Turkish horn bows. There is always yew if it is available as well as juniper. Mulberry and juniper have a huge range and you likely to have one of the two growing near you.

[mikekeswick]

I don't think a pin knot 1mm is going to matter unless it is on an edge of your bow. If you are making a horn bow, the sinew and the horn will protect it to a large degree. The point the other guys are making is that the time spent finding good wood is time well spent. If for some reason you invest 6months to a year of your life arduously constructing a horn bow only to have it split on a pin knot...ouch. Not only that, a horn bow explosion can evidently be life-threatening. The wood mentioned in the article is incredibly hard to imagine pin-knot free when you see pictures of the plant, so maybe trusting ancient methods is fine in this circumstance. You could also try other wood. Notably, mulberry is mostly used in korean composite horn bows and a type of maple for Turkish horn bows. There is always yew if it is available as well as juniper. Mulberry and juniper have a huge range and you likely to have one of the two growing near you.

Trust me - if a pin knot is in a hornbow core it will fail. The mulberry in use in the Korean bows is just for the tips. Yew and juniper are next to impossible to find flawless pieces from.

[Limbit]

Yeah, I think you are right. The video I was referring to about korean bow making has a heat treated bamboo core and mulberry siyahs. Pretty cool process regardless. https://www.youtube.com/watch?v=cicYRzWss74