Yew billets belly drop build with sinew backing.

[superdav95]

Good day gang.  Here is a build I’ve wanting to do for some time.  I may also sinew back another yew selfbow too at the same time I do this one to compare.  This particular bow build will be built with very dense yew heartwood belly drops off another bow I recently built.  It’s heartwood only and I plan to apply a couple layers of sinew as backing.  Aiming for a 50-55 lbs bow.  I’ve got the z splice done already and then glued up a section for the handle to build up handle and fades area.  Glue I’m using is ea40 smooth on.  I use an old saw blade to rough up surfaces and acetone wipe them prior to glue up.  Clamp them tight for good fit.  Band saw used to cut my splice after tracing on my pattern on the two halves.  I’m not sure how this will go as there is no sapwood at all but my guess is that it will work ok.  I’ve heard of issues delaminating sapwood from the heartwood when sinew is used to back a yew selfbow.  I’ll compare and see.  Should be a good test to see if sinew alone can be adequate for backing heartwood only yew bow.  Let’s find out!  Anyways thanks for following along. 

[mmattockx]

Sweet, I always enjoy following your work Dave.


Mark

[Selfbowman]

I’m watching Dave. I’ve got a bunch of good Osage drops . Gave a bunch away too. I need to build some short bows for flight.

[Muskyman]

I been thinking about trying a splice myself so I’m all over these posts showing the process..
Looking good Dave

[Selfbowman]

Dave how thick is your drops at the z splice? I want to have minimum 3/4 to 1”.

[superdav95]

Dave how thick is your drops at the z splice? I want to have minimum 3/4 to 1”.

Mine here is about an inch.  The handle section glued on after is about 3/4”

[DV IN MN]

If you are gluing a handle piece on at splice how thin can the splice area be without fear of failure? The assumption that the handle piece glued on will stiffen and add strength to the splice area.?

[mmattockx]

If you are gluing a handle piece on at splice how thin can the splice area be without fear of failure? The assumption that the handle piece glued on will stiffen and add strength to the splice area.?

If you were to glue an overlay over top of the splice on the back and a handle riser on the belly the splice doesn't need to be very thick at all, no thicker than the limb thickness at the end of the fades.

It isn't just an assumption that the handle adds stiffness and strength, it is an structural fact.


Mark

[superdav95]

Ok guys.  I got my billet belly drops basically shaped up to the following dimensions,  approx 1/2” thick the entire length of each limb and ttt length at about 63-64”.  I’ll be cutting a little off so Likely closer to 62-63” ttt.  Limb width is 1 3/4” at widest and very slight taper to 1 1/2” at 10” from the tip where it narrows to 1/2” or so.  It will end little narrower in the end.  The handle is 4” with typical fades that dip into the limb wood.  I’ll be flipping the tips slightly and trying to get as much reflex as I can get from the sinew backing.  The other piece of yew shown here is a comparison build that will also receive same amount of sinew as the billet bow.  Goal is to build one yew billet heartwood sinew backed bow around 50lbs and then compare it with the selfbow then sinewed over the sapwood.  Both aiming to be 50lbs in the end at 28”.  Both similar dimensions and length ect.  I’ve always wanted to try a sinewed yew bow with and without sapwood so figured I’d try one of each method.  The stave I’m using is less then ideal for a selfbow anyway as there were some inclusions and sapsuckers that got to it. It also has a fair bit of crown too.  I think it’s a good candidate for this project.  Thanks for following along!   

[superdav95]

Few more…

[superdav95]

Spent an hour on the stave today and got it worked down some.  It’s at basic dimensions of the other for the most part.  It has some heat correction that needs attention and prop twist at the tips not not too bad.  Took sapwood down to about 1/8” approx.  it was quite thick before. 

[PEARL DRUMS]

My best yew bow was made from heartwood only billets and sinew backed. Old hippy gave them to me at the 2015 Classic.

[superdav95]

My best yew bow was made from heartwood only billets and sinew backed. Old hippy gave them to me at the 2015 Classic.

Well that sounds promising then!  Thanks PD.  Let’s see if I don’t screw it up then.  It will be interesting to compare the two as far as performance and other shoot ability factors like handshock or final mass as such.  I’ll dimension them similar in build dimensions but to get both of them to same weight in draw it may vary somewhat as the yew stave is quite crowned and the heartwood only is very flat.  I may try and round it a bit though a bit more.  My goal is to get two shootable bows in the end.  Not terribly scientific here but should be interesting anyway. 

[mmattockx]

The stave I’m using is less then ideal for a selfbow anyway as there were some inclusions and sapsuckers that got to it. It also has a fair bit of crown too.

Dave,

Since you're sinewing the stave have you considered flattening the crown to even up stresses in the wood? You may not have enough thickness to do that, though.


Just a thought,
Mark

[superdav95]

The stave I’m using is less then ideal for a selfbow anyway as there were some inclusions and sapsuckers that got to it. It also has a fair bit of crown too.

Dave,

Since you're sinewing the stave have you considered flattening the crown to even up stresses in the wood? You may not have enough thickness to do that, though.


Just a thought,
Mark

Mark,  yup I did a little decrowning.  I didn’t want to go right flat as to compromise the sapwood too much as this would negate the point of the comparison of the two builds.  It still has some crown but I did remove some so hoping it will work alright.  Right along the top peak of the crown the sapwood will be slightly thinner then on the rest of the bow.  The other alternative I’m considering is to hollow out a little the belly to compensate for this crown.  We shall see how things progress with each.   Today I’m working on the flipped tips on the billet bow.  I also glued on a flat piece on the handle of the stave bow to better match the billet bow.  I’ll post some pics of my progress tomorrow.  Thanks