Belly Patch ?

[Stick Bender]

This is a osage/sinew sapling bow I started a while back & sinewed it 2 months ago it was a problem from the beginning with 11 knots,wind checks & such & more  I pulled a splinter on one of the knots tillering before sinew & stopped leaving the bow thicker then I wanted and as a result I ended up with a belly tension crack as posted, so I want to make a belly patch in that area having never done one I was wondering about the processe , should I square up the joint like in A or just do a more rounded profile like in B or is there some other method ? I have a lot of time & problem solving in this bow & feel compelled to make it a bow one way or another ,the tension crack is about 10 1/2 in. From the tips on the outer 1/3 ?

[Stick Bender]

Reflex

[Stick Bender]

Belly crack

[DuBois]

So the crack is from sinew pulling into reflex and not from compression?

If it is needing more tillering you may be able to scrape down to get rid of the crack and not need a patch. does it still need more tiller work?

I've never tried a belly patch but if you can get rid of most of the crack maybe you could do a cyano saturation and then sinew wraps?

I know how it is to not give up on one to the point of madness!

[Stick Bender]

Yep it's a tension crack I plain and simple pulled in to much reflex wit it being to thick I should have learned my lesson did the same thing on a hickory bow before it measures 0.47 Thousands in that area 5 in from the static fades & 10 1/2 in from the tips this bow has close to 1200 grains of sinew on it needs a lot more tiller, some times these bows can be a sicknesse ether bow or burn pile?...lol  "

[Del the cat]

I've done belly patches on Yew where I've been pulling an old tired bow back straight and heat treating, I've gone long and shallows as possible to give maximum glue area and maximum flexibility in the patch so that it would bend as it strapped up and give a tight glue line.
Zero experience patching Osage, as it's harder and greasier I dunno if it would work.
Del

[Mo_coon-catcher]

Before gluing the piece in I would boil it to make it soft, then clamp it in so that it'll conform to each other. Then once cool, glue it in after an exetlne or alcohol wipe down.

Kyle

[Jim Davis]

That's an odd looking crack. First thing I'd do is smooth the belly to  get a good look at it.

 No patch is going to hold in tension against the sinew.

Belly patches are used to resist normal compression forces. For those, a 90-degree but joint is preferable. Bows have been made with bellies made of pieces of bone just butted together and glued to a core.

Here's some pix of a patch I did. This was several years ago and the bow is still a shooter..