Sinew over yew heartwood

[stuckinthemud]

I am making a yew/sinew short bow. I have stripped off the sapwood and rasped a couple of knots smooth to the rest of the back. The limbs are just about moving and temporary knocks filed in.  How far can I bend this before I need to add the sinew. How much tillering can I realistically get done?

[Pat B]

Since you filed the knots down I wouldn't strain the bow without the sinew. I've never worked yew heartwood but even with other woods filing down the knots adds a weakness that isn't necessary and can cause problems even with a sinew backing.

[simson]

It depends a lot what design you are after. If the limbs are wide, a filed down knot isn't that dramatic.
Pics are helpful.
I've made some yew heartwood bows, some sinewed.
Here is one specimen, maybe helpful for you.

http://www.primitivearcher.com/smf/index.php?topic=40103.msg535277#msg535277

I've sawed out the side profile, then steamed, then sinewed. Tillered after sinew  curing. No bend before, the back was terrible 'violated' from the bandsaw.

[bownarra]

Not far, a mild floor tillering.
You have done it correctly. Leaving knots/bumps under sinew is a bad idea

[bradsmith2010]

why is leaving knots a bad idea, it works on a self bow,,

[stuckinthemud]

Because sinew sticks better to a smooth surface, especially once the bow starts flexing. Also, do you sinew over a knot or around it?

[bownarra]

why is leaving knots a bad idea, it works on a self bow,,

Because the concave sides around the knot will leave areas where the sinew is likely to pull. You also use a little more sinew (dead weight) nor is the sinew working properley over/around the knot.
knots can be left but it is not optimal. Anyway I wouldn't sinew a knotty piece of wood. Some pins on yew - yes but I always look for flawless wood if i'm going to put the time into sinewing.

[stuckinthemud]

Yeh, pretty sure you'd have burned this piece, even I'm questioning my sanity for working with it.