Bow autopsy and the lessons learned

[Nasr]

    Well as they say if you ain't breaking them you ain't making them. This was the bow from the post before where I had mentioned that a splinter had risen due to not rounding the corners well when finishing.

I am including the full draw pick in this post so that if anyone can spot an issue with tiller.



As you can see the bow is wrapped on the bottom limb where the splinter had risen. when fixing the limb it had seemed very superficial to me. I sanded and proceeded to wrap the limb where the splinter was. however it did not hold.



it seems that the splinter reopened and spread down limb which caused a week point and raised the other splinter above it ( bottom in picture ).



The first problem i can already tell from removing the wrap is the serving string did not soak up the glue as well as i thought it did. while it was hard to cut it took no effort at all to remove as it was dry. Also i did not remove finish so glue did not stick to wood as well.



And here you can see the first splinter ( top ) and the new one (bottom).

 This one really hurt as i have been shooting it almost everyday and have been putting some serious arrows through it.
 
lessons learned

1 don't neglect the basics a clean back with rounded corners should never be ignored.

2 if your gonna wrap a splinter make sure you do it right and take your time.

3 a splinter in a hunting situation can be fixed with a simple wrap and should last you a couple hundred shots even with such a bad wrap as mine.

4 i need to make more bows

[bjrogg]

I think your tillering looks good.

Guessing it is a board bow? Seems to me from what I can see the problem is the back. I’m thinking it has grain running off and out.

I think your wrap might have worked better if it had been wider. It really shouldn’t have to adhere to the wood, but it needs to be tight. Stay tight and cover the entire area in question and then some.

Bjrogg

PS I think you got the hard part good. The tillering. Keep it up. Your doing good

[bradsmith2010]

I agree a wider wrap may have worked, but sometimes a hidden flaw is the cause and will make the bow fail,,
a rawhide back can make the back a bit more durable,, as well,,
as I say this I know there are those that disagree and thats ok,,, but even Pope and Young said when they started rawhide backing bows the rate of failure was less,, I have found the same

[Nasr]

I think your tillering looks good.

Guessing it is a board bow? Seems to me from what I can see the problem is the back. I’m thinking it has grain running off and out.

I think your wrap might have worked better if it had been wider. It really shouldn’t have to adhere to the wood, but it needs to be tight. Stay tight and cover the entire area in question and then some.

Bjrogg

PS I think you got the hard part good. The tillering. Keep it up. Your doing good

Yes it’s a board bow almost all of my bows are board bows. Would like to harvest my own staves but not able to do so.

As for the grain run out the growth rings were parallel most of the way but it still could have been grain run out because growth rings don’t always tell the whole story. I do have another in the works if the same problem occurs despite all the fixes and proper tiller I will have to assume it’s from the piece of Ash I am cutting my backing from.

[Nasr]

I agree a wider wrap may have worked, but sometimes a hidden flaw is the cause and will make the bow fail,,
a rawhide back can make the back a bit more durable,, as well,,
as I say this I know there are those that disagree and thats ok,,, but even Pope and Young said when they started rawhide backing bows the rate of failure was less,, I have found the same

I definitely believe that rawhide backing would have helped but I don’t really have much of that lying around and prefer to have no backing apart from the ash of course. Only because it might slow the bow down. Now another issue I have found with this bow is it has come under weight slightly. If I had over built it a bit it might not have Had this issue.

[Kidder]

Your tillering looks solid. Just a couple thoughts - be equally careful about rounding the belly edge. A sharp edge on the belly will cause frets. Secondly see about getting some sinew and keeping it on hand for wraps. As others have mentioned the key to a good wrap is getting it tight enough. With sinew it shrinks as it dries so you really couldn’t end up with it lose.

[Nasr]

Your tillering looks solid. Just a couple thoughts - be equally careful about rounding the belly edge. A sharp edge on the belly will cause frets. Secondly see about getting some sinew and keeping it on hand for wraps. As others have mentioned the key to a good wrap is getting it tight enough. With sinew it shrinks as it dries so you really couldn’t end up with it lose.

I appreciate you and everyone’s comments on the tiller and for the sinew tip.  in the past I would have some sinew laying around but lately I have been on and off of bow making for a while. This was my first bow in almost a year. It was my only bow actually as I tend to give all my bows away. The rounding the belly corners is also something I usually do but being that this was my first bow back I overlooked many things. Hopefully I can rectify that with the next one.

[bownarra]

It was bending a bit much in the inner limbs.
This is the problem with quarter sawn wood if you don't know how to read the grain a quarter sawn board can look great with straight grain lines on the main face......BUT those fibers can be angling through the board just like yours was. Read the chapter in TBB4 ? on wood selection for board bows.
Rawhide wouldn't slow it down unless you put too much on.
You could also use linen material or silk is also good but more expensive. Lots of backing options for when you 'have' to use a dodgy grained board.

[Nasr]

It was bending a bit much in the inner limbs.
This is the problem with quarter sawn wood if you don't know how to read the grain a quarter sawn board can look great with straight grain lines on the main face......BUT those fibers can be angling through the board just like yours was. Read the chapter in TBB4 ? on wood selection for board bows.
Rawhide wouldn't slow it down unless you put too much on.
You could also use linen material or silk is also good but more expensive. Lots of backing options for when you 'have' to use a dodgy grained board.

Thank you Bownarra I do have the TBB4 i am gonna need to a refresher. As for the tiller as you have mentioned the bow does seem to bow more towards the inner limb. On the original post i also mention this but i thought it had to do with angle of the photo as the tiller on the tree seemed fine. I was wrong apparently. I hope next bow i make you can criticize it. It helps because i want to grow and i cant do that without pointers. I can be biased when looking at my own work 

[simk]

Thank you nasr for posting and sorry for you! this, was a nice bow for sure. I did a bunch of ash backed bows - never had this happen nor other failure. but well rounded corners for sure are a good idea! I always do because I always was afraid of exactly this type of failure! I still like these ash-backings as for they are much lighter than boo. for me they worked up to 60# bows

[Pat B]

When you look for a board with straight grain you not only have to consider the grain running down the back but also the grain running along the sides. To me it looks like it lifted splinters that are part of the grain along the sides. These splinters look like they are the tapered ends of that grain and when strained, they lifted. A soft backing, like rawhide, silk or linen can help hold these splinters down. A wrap will help in a specific area where as a full backing covers the entire back of the bow helping to hold down any possible splinters from lifting.
 It's very hard, almost impossible to find a sawn board that does not have grain violations. These runoffs on the belly are virtually irrelevant but on the back can lead to problems. 

[RyanY]

It was bending a bit much in the inner limbs.
This is the problem with quarter sawn wood if you don't know how to read the grain a quarter sawn board can look great with straight grain lines on the main face......BUT those fibers can be angling through the board just like yours was. Read the chapter in TBB4 ? on wood selection for board bows.
Rawhide wouldn't slow it down unless you put too much on.
You could also use linen material or silk is also good but more expensive. Lots of backing options for when you 'have' to use a dodgy grained board.

Was going to say the same thing about the quartersawn wood. Might have been unavoidable.

[Nasr]

It was bending a bit much in the inner limbs.
This is the problem with quarter sawn wood if you don't know how to read the grain a quarter sawn board can look great with straight grain lines on the main face......BUT those fibers can be angling through the board just like yours was. Read the chapter in TBB4 ? on wood selection for board bows.
Rawhide wouldn't slow it down unless you put too much on.
You could also use linen material or silk is also good but more expensive. Lots of backing options for when you 'have' to use a dodgy grained board.

It was the only backing I had on hand. It was a plain sawn board but I had used most of the other parts of it and was only left with the quarter sawn portion. I need to get my hands on some better backings. This is what I get for taking such a long break. Plus the tillering doesn’t seem so good now that bownarra mentions it. Outer limbs are stiff. Seems like mid limb are doing all the work.

Was going to say the same thing about the quartersawn wood. Might have been unavoidable.

[bownarra]

nothing wrong with quartersawn wood it is just that it can be misleading to untrained eyes....breaking a bunch of backing strips/bows concentrates the mind! It took me a while and many lam bows to get to a point when I know wether a backing will hold or not....no real short cut to it and lets face it getting perfect wood from a lumberyard ain't easy! That chapter will explain what I mean better than I can

[sleek]

It wasn't your tiller. Thats a very well tillered bow. Just bad materials.