Take down yew bow project.

[superdav95]

I’m posting this failure in particular to maybe help others out there that have thoughts of trying the same to possibly provide some insights perhaps and some words of caution.  I started this project last year and kind of just set it aside to recently start on it again. This was two separate pieces of yew billets that were of good quality. However  I now think it was a bad idea to use yew as a candidate for a take down socket and tenon using epoxy and or fg wrap.  A better use of these billets would have been a z splice.    You’ll see from the pics here that I’ve added horn and other hardwood inserts to stiffen up the tenon a bit as this build progressed.  I then added the 2 steel rods as a little more insurance.  This was all done as a fix for the sloppy loose fit of the tenon into the socket with just the yew wood alone.  It would shake loose and basically fall apart on me. Yew it too soft to hold a solid shape for a tenon.   I couldn’t even continue to tiller till I remedied this first.    I’ll post some pics here to explain why I think it’s a bad idea and to do an autopsy of sorts of the why it failed.  I did have hopes that it would work in the end and it was looking very good for bend.  I had it braced low with long string and was pulling to get it to 25” draw at 55lbs when it exploded.  My goal was 60lbs at 28-29”.  Bend was looking very good up to that point prior to exploding on me.   I had done some minor heat corrections on tip twist and a mild reflex in the bending limbs maybe an inch.  The main issue of failure was at the tenon where I cut into the sapwood in order to redo the tenon the second time for tighter fit.  The tenon fit nice and tight but left a week spot there at the cut layers of sapwood.  Is it possible that this could have worked if I did not have to redo the tenon and cut into the sapwood?  Yes but I do  think it’s worth the risk.  Will I attempt another one of these using yew?  No.  A better option for take down would be a brass and steel sleeve perhaps keeping sure to not violate the sapwood at crucial spots at the same spots.

Anyway I figured I post this failure firstly to warn any others thinking of doing anything similar to be aware of my struggles and the conclusions I came to and why.  The other reason is to show that failures happen sometimes. 

Thanks for looking guys.  Hope it helps out someone out there. 

Happy building!   

[PEARL DRUMS]

Dave, I had a similar failure using brass/steel sleeves. The portion that slides into the sleeves has to be fully intact. I approached mine the same as you did here. That squared off area of the male portion slid into the sleeve. That's where it peeled up and failed in dramatic fashion, very similar to yours. I essentially violated the back and we all know that cant happen. I'm not sure what I typed fully explains my scenario. It's difficult to put into words.

[Muskyman]

Well, way to scare a guy to death.. Here I am in the middle of trying to make my first yew bow and now that’s two I’ve seen on here that have exploded..
Sorry to hear about your bow Dave. Sucks for sure. I’m sure my time is coming. 

[Hamish]

Even if you can't see any bend, and the handle/fades are supposed to be stiff, there is still plenty of tension stress going on.
The use of a step down at the back part of the male tenon, automatically creates a weakness. Some people manage to get away with it, more by luck than by design, and it seems to be popular with fg bowyers. Fg bows tend to have longer stiff fades, and deeper handles.

Its a real shame because that bow was lookin real classy before it popped.

You are right about cause and remedy, as you mentioned in your assessment. Try another TD, just don't cut into the handle on the back, any more than minor adjustments to make it match the other billet, and feel good in the hand.

[superdav95]

Pearl drums. I hear ya.  Here’s a couple pics of my tenon and socket prior to redoing it as it got very loose on me I think because of the softer yew wood compared to other bow woods.  You can see from the pics that at that time k had maintained the sapwood for the most part knowing that this would likley be an issue.  Turns out it was in explosive fashion. 

[superdav95]

Even if you can't see any bend, and the handle/fades are supposed to be stiff, there is still plenty of tension stress going on.
The use of a step down at the back part of the male tenon, automatically creates a weakness. Some people manage to get away with it, more by luck than by design, and it seems to be popular with fg bowyers. Fg bows tend to have longer stiff fades, and deeper handles.

Its a real shame because that bow was lookin real classy before it popped.

You are right about cause and remedy, as you mentioned in your assessment. Try another TD, just don't cut into the handle on the back, any more than minor adjustments to make it match the other billet, and feel good in the hand.

Hamish. I may try another at some point.  Gonna work on finishing a few other projects first then come back to it.  I think your right that it’s possible to do despite the hurdles to make it work.  Would you do it the same as I’ve done minus the step it the male tenon at the sapwood???  My thinking was to try it again but just add more wraps or strips at the back to beef that area up a little.  This would allow not cutting into the sapwood at all if done right which I didn’t do obviously.  Your thoughts on this???

[Hamish]

Dave your fades look to be about 2" long? That's pretty normal on a good hunting bow. I would either make absolutely sure there is no apparent bend in the fades, and inner limbs or increase the fades to 3" to give you a little more wood to stiffen the transition area. Essentially the same thing, just a slight subtle difference, in design and or tillering.

I'd have no step down at the back. You could put a little extra wrap on the back area of the grip, when making the sleeve, but I don't think its absolutely necessary because the shell of the handle didn't fail.

I don't think you need to add any harder material along the side and belly like you did on the one that broke. You could still reinforce the end grain like you did. Your craftsmanship looks top notch!!!

I haven't made a resin/fg  wrap, shell handle with a softwood like yew before. I suspect you might have more likelihood of the joint getting a little loose over time, than if you use hickory or osage or some other genuine hardwood for the billets. A commercial metal sleeve carefully fitted would be more appropriate with yew, because the wood is protected from direct contact, and won't wear or compress.

[Del the cat]

Although you don't need to follow a ring on the back of a Yew bow... a sharp discontinuity like the step down into a sleeve is just asking for it to splinter. I've had it happen with a boo backed Yew, but then turned it into a Frankenbow takedown with the upper limb self Yew, taking care to let the sapwood run continuously right down into the socket.
https://bowyersdiary.blogspot.com/2017/03/the-frankenbow.html
Del

[superdav95]

Thanks hamish and Del for the info.  Very informative.  When making this bow I knew there would be challenges but was up for it.  Seeing your video del on you Frankenstein bow lit a fire under me with this one again and I have a smaller piece of yew that I may just have another crack at it sooner then later to get this back on track.  I may have to adjust my draw weight like you did depending on my replacement piece.  Thanks again guys!  Update shortly

[superdav95]

So I got to thinking about this project again after being inspired by dels Frankenstein bow.  Went out to the shop and found a sliver of yew wood I had planned on making a kids bow out of.  Decided to use it for this instead.  Sorry kids!  Sapwood is a little thick on this one and grain may not be quite as tight as my original but should work ok.  I’ll thin down the sapwood a tiny bit to somewhat match.  I think we may be back in business.  It’s either that or I’m just too stubborn to know when to quit! . 

[Selfbowman]

A suggestion Dave was take the glass down on the male end a 1-1-1/2 before the fade . I have a Osage two piece with a bow bolt in it. Yes wrapped the male and female with electric fence wire and covered it with leather.

[Selfbowman]

Pic

[Selfbowman]

Pic

[Selfbowman]

Here is a pic where you can barely see the wire.

[superdav95]

Huh interesting.  I’d have to redo my female socket side to make this bolt idea work. I like the look of that.  It would be less likley to loosen up too.  What size bolt did you use?   Any details on that hardware.