Flat belly turned concave by sinew backing?

[burchett.donald]

Frodolf stated the sinew was pulling the sides of the limb up...That would give a concaved back and a convexd belly...
                                                                                                                                             Don

[PatM]

 He didn't describe this particular bow that way.

[burchett.donald]

Pat, I may be confused about his description...Frodolf can you post some pics?
                                                                                                                                           Don

[PatM]

"'The opposite of crowned".    Just think of one of simson's hollow limb designs.

[Frodolf]

Sorry for not responding earlier. Can't post pics, haven't got a camera for the moment. But Pat is correct. Think hollow limb design – or a (mild) half pipe!  My mentioning of "the opposite effect" to what happened to my bow was in reference to a description in TBB.

I put the bow by the wood stove today (warm and dry) and over the course of the day the amount of concave bend (concaveness?) went down with about a third. Good omen. It's getting there.

Thanks, LittleBen, for your comment. I'll keep it in mind!

[mikekeswick]

Yes it's just moisture.
However sinew shrinks in all directions when it dries - length,width,thickness. Length is good it gives up reflex! Thickness don't matter much just makes the backing thinner but width does matter as it pulls up the edges of the limb to make the belly slightly convex. A way to stop this being an issue is to make the belly slightly crowned. This will reverse the belly cross tension due to how the poisson effect works on the belly. It's not really an issue with wooden bows because they don't bend that far but interesting nonetheless. This is what happened with Erics bow, the weakness got pulled apart by the width of the sinew backing reducing.