Primitive Archer

Awesome bamboo selfbow, Dave! I love the splice and handle work!

Couple questions…What are the dimensions (length) on your handle and fades?  Any concern with the handle popping off or will the deflex in the handle help with that?  I’ll be watching to see how this one turns out for you.

I will second Marks advice about making a simple bend test.

Consider also that the Moe input in Virtualbow does nothing more than help you predict theoretical draw weight of your design at some arbitrary stress. Determining a pratical working stress for your materiel is more difficult and will take some trial and error.

Can your yew stash can provide some smaller samples that can be utilized to make some minibows that can be reverse modeled in virtualbow with the goal of fleshing out a suitable working stress?

And does anyone have any concrete information on how modulus of elasticity changes with specific gravity in yew? I've recently started using VirtualBow in the design phase (and a bit for informing tiller shape), and MoE is a key input.

Instead of trying to use some general rule of thumb on MoE you are better off measuring it directly with the wood you will actually be using. It isn't too hard to make a test rig that will get you much better data than information from someone else taken from a different piece of wood.


Mark

I am sure the man on here that might know this is Del.  He has a you tube channel that has a lot of info too with yew.  As for my anecdotal experiences with pacific yew.  Has been that it varies from stave to stave and tree to tree.  I’m sure this would be the same or similar with European yew.  Ring count for me is a bigger factor for yew.  The better bows I’ve made from yew have been those with higher ring count.  This is true for variety of bow builds.  I’m not saying that a decent cannot be made with yew with lower ring count but it’s my opinion that higher ring count is better.  Yew is magical stuff and quite different then really anything out there and hard to compare it with other woods.  It’s basically a natural composite.  The tension strong sap wood side and compression strong heartwood side.  Congratulations on your wood score.  You will have some good bows come from it and be surprised at how soft it is to work.  It’s softer but also springy wood.  Very cool stuff. 

That's looking awesome so far! Are there plans to add anything to the belly or is it just the moso bamboo? Nice work.

Thanks rob.  Ya it’s just the bamboo nothing on the belly.  It’s been heat treated like my other builds so it’s basically a tension monster.  I made one of these steam recurve selfbows earlier last year but it was only 30lbs.  Shot nice but very light.  I posted a short video last year on it.  Typically with my bamboo bows they were 5 piece builds so was testing out the recurves really.   I had been testing many methods to steam bend bamboo.  It’s sounds easy until you try it.   We think of bamboo as this magical grassy wood material that we imagine will bend however we want.  The fresh green or even recently green stuff bends like rubber but when it dries and hardens it’s a different story.  The bamboo moso pole that I use is the larger diameter stuff which enables me to get the wider limbs.