what is my problem

[robA72]

Okay guys,
I have made 1 3' kids bow that my 6-yr-old loves. and 5 larger bows (66"-72") that have all failed. These are red oak board bows that have cracked from the back. The last two were linen backed but still failed. The last one (pics here) was 72" and drawing at 40# at 28. I thought my tiller was good. I know the bottom limb was a little stiff but would that cause the top limb to develop a hinge and break?
Any advice is greatly appreciated. My older boy and wife are both waiting for bows! Not to mention I would like to be shooting one as well...   :mad:

[robA72]

Umm..also, having a problem posting pics. Anyone know what happened to the link to pic instructions? The oversized pic tutorial doesn't open anymore.

[CalebNH00]

some pics of the tillering on the bows would be helpful. Also, how wide were they?

[CalebNH00]

Well, just saw your new post. I was trying to find the link to the how to post pics post, maybe some one else will find it.

[The Gopher]

I'm not saying that good bows can't be made from red oak boards, there are many fine examples of them. However, i have made many that seemed to break for no obvious reason. One in particular i thought was tillered perfectly, it was the only bow i shot all summer long, several thousand shot through it, then one day i strung it, drew it back and SNAP!

On the other hand, i have yet to have a hickory bow break on me, board or stave.

[John Scifres]

When using a board, the most likely cause of failure is a grain problem.  If you could post pics of the breaks from the back, belly and sides, we could maybe diagnose.

You need to copy the URL (web address) of the pic and either paste (right click your mouse and "Paste")it directly into your post here and then it will be a link.   http://i1174.photobucket.com/albums/r607/jdscifres/IMG_20130421_112709.jpg

Or you can go the the "Full Reply" button below, click on "Image" and paste the URL in the dialogue box that opens. (This doesn't work in Windows 8 unless you are accessing the Web from your Desktop)

To copy the URL of the pic from Photobucket, open the pic, and there should be several options under the "Links to Share This Photo" on the right side of the page.  Click "Direct" and it will copy the URL.  Then paste it in your post or into the Image

[robA72]

Okay guys,
Thank you for the responses. i will be posting pics soon.

[robA72]

Here is the belly grain
 http://i1302.photobucket.com/albums/ag138/robA72/bellygrain_zpsfed1659c.jpg

And the back grain.
 http://i1302.photobucket.com/albums/ag138/robA72/backgrain_zps798a60f5.jpg

I hope you can see something from these pics. This is the most recent bow

[John Scifres]

What about the sides?

[Zradix]

what did the rings look like?

[LittleBen]

I would agree with everything already said here. Red oak is OK, but hickory is better.

White oak should be better than red oak as well. Stronger in tension (i.e. on the back).

The grain on that board looks good enough to me.

A couple questions, is it bendy handle or stiff handle? Where did it break? Did it break while tillering or while shooting? What is your draw length? How wide was the bow?

I would recommend several things:

Search for tillering gizmo and use it.
Round the corners on the back well before tillering to prevent splinters from lifting at the edges of the back.
Make both limbs equal length and equal stiffness (even tiller), a stiff bottom limb will make the top limb do more work, this can be drastic.
Post pictures as you tiller and some here will talk you through it (second set of eyes).
Start with 68-72" long and 2.5" wide or wider, and go with a basically pyramid bow, it's easier to tiller properly with a tillering gizmo.

[john fletch]

I have made a number of Hickory backed Red Oak that hold up well and perform reasonably.  I do not believe that Red oak has the tensile strength for the back of a bow - but it is reasonable for the compression wood of the belly.

It is easy to work with and less expensive than other hardwoods.  I still make most of my 'entry level' bows of Hickory or backed Hickory.  I believe that the cast is better and the string follow will be less if backed and if the grain is tight and vertical.

I have also used White Ash and Black Locust with good results.  I was given a 12' dia log of Chinese Elm - it has now fired 2 years so I will split a couple staves out and try that.  Will be interesting to see how they hold up and if they need backing.

[Roy from Pa]

You don't have to worry about the picture size anymore, tradgang took care of doing that within their software a couple months ago.

Have tradgang open in one window and open photobucket in another window. While on the photobucket page, open your library, move your mouse onto the picture you want to place here. When you place your mouse on a picture there in the library, in the upper right corner of that picture there will be a little gear like icon appear. Place your mouse on that gear icon, you don't need to click it, when you place your mouse on that icon, a drop down menu appears, go down and click GET LINKS. Another drop down menu appears, you want to left click the bottom one that says IMG code. As soon as you left click you will see copied appear there. Leave photobucket open with the last menu you were on and come back to tradgang and in the box where you type your message here, right click then click paste. Below where you type your message here is a window that says preview post, clicking that will show you what your picture and message will look like, if it's ok then close the preview window and hit submit like you always do.
   

   

[Roy from Pa]

If one limb is stiffer than the other limb, that will cause the weaker limb to bend more and it will bend more at it's weakest point, causing a hinge and possible breakage.

[George Tsoukalas]

There is a buildalong on my site. For your wife and youngsters rip the board 1-1.25 inches. Let it bend in the handle. Don't narrow the handle. Length of the bow should be as tall as the person. For you, go 1 3/8" wide. Grain is everything and it should be straight tip to tip. Jawge
 http://georgeandjoni.home.comcast.net/~georgeandjoni/index.html