Order of operations

[Eric Garza]

Another on-going thread about sinew backing has inspired me to ask a question about order of operations for some of the different parts of the bow-making process.

Say I want to make a bow that is tillered (obviously), bent with heat on a caul, heat treated, and sinew backed.  What order would folks do these in?

[Del the cat]

Bend and heat treat can be done as one operation if you can clamp it to a form. Sinew is the last operation...
Del

[Eric Garza]

So am I right to assume that you bend, heat treat, and sinew back after tillering to final draw weight?

[gstoneberg]

I would not take the bow to final draw weight or complete the tillering before adding sinew.  You will need to do some subtle tillering after the sinew dries so you might as well wait until after that step to hit your goal weight and finish tillering.  Del is right in the order.  I normally sinew back when I have the bow tillered within about 2 or 3 inches from the target draw length.  But, I have sinew backed a finished bow hoping to add draw weight.  It didn't add enough weight to have been worth the hassle and work.

Good luck,
George

[JW_Halverson]

I have sinewed after final tillering, before final tillering, and several times just after the general shape of the limbs was finished.  Once I even sinewed a wet piece of hackberry the same day I cut it down. 

Just wait twice as long as you think you should wait for the sinew and glue to cure and for the wood to give up the moisture it picks up from the process.  Or else you will be chasing that tiller until you come in underweight. 

Good luck

[M-P]

Hi all,  I remember reading a book by J. Hamm that has a chapter on sinewing.  He said he used to finish the tillering on his bows before sinewing, but after awhile it came to him that he would break fewer bows by only tillering to ~ 1/2 draw, applying the sinew and then finishing the tillering after the sinew was dry.
One of the main benefits of sinewing is to protect the bow from tension failure.  Why test the bow to possible destruction by finishing the tillering, without having the sinew present?    I tend to at least floor tiller the stave before reflexing, or other heat treatment too.  The thinner wood responds much faster to heating.
So my process is 1) lay out the bow and at least partially tiller it.  2)Steam to remove and or induce curves.  3)Tiller further and then apply sinew.   4)Finish tillering after the sinew is dry.
I've successfully heat treated the belly of a sinewed bow, but it would be better to heat treat first and apply sinew second.    Ron