Crown problems?

[Rob W.]

I don't have any experience building bows out of smaller trees. I'm just wondering if I'm going to have problems with this smaller piece and what should kind of layout I should shoot for? I have plenty of length. Thanks guys!

[Pat B]

If that is osage you shouldn't have any problems with the crown. Do be sure you have a pristine back and a flat belly.  I've built a few osage "pole" bows, about 2" diameter, that pulled between 40# and 55# and all shot very well. I've even made them with sapwood on the back.

[DarkSoul]

Do be sure you have a pristine back and a flat belly. 

I would like to know why you advocate a flat belly here. My advice would actually be to round the belly a bit too, to make sure not all the forces are concentrated on the back. A round-ish belly will shift the neutral place more towards the back, thus taking away some of the forces from the back. That may be safer with this extreme crown. Don't round the belly as much as the back, but just a little bit.

[sapling bowyer]

Which wood?

[Pat B]

DS, I've only used a flat belly on this type of bow but will try a rounded belly next time.

[bradsmith2010]

I have done both round and flat,, both shot fine,, and have heard advocates in favor of both for one reason of the other,,, I still don't have any idea which one would be better or why,,

[Rob W.]

Yeah it's osage. I would like to build something around 64" but I can go longer if you guys think I should.

[joachimM]

If you dont like the high crown just decrown it, simple as that.
If you leave make sure the top of the crown has no irregularities, like minute pins.
Joachim

[scp]

A round-ish belly will shift the neutral place more towards the back, thus taking away some of the forces from the back.

I would think the neutral plane would shift toward the belly.

Anyhow as someone said, "Compression failure results in set, but bows with set still shoot. Tension failure makes for broken bows." It would be wiser to start with a rounded belly and flatten it if warranted, as we progress.

[George Tsoukalas]

I like to leave sapling bows a few inches longer for safety's sake because tension is concentrated right down the middle of the bow. Jawge

[bushboy]

Your draw length and weight desired?

[riverrat]

I would like to know why you advocate a flat belly here. My advice would actually be to round the belly a bit too, to make sure not all the forces are concentrated on the back. A round-ish belly will shift the neutral place more towards the back, thus taking away some of the forces from the back. That may be safer with this extreme crown. Don't round the belly as much as the back, but just a little bit.
probley because some folks cant tiller is what im thinking. i do it all the time. never had a problem yet.

[DarkSoul]

Riverrat, I'm sorry but I don't get it. What does tillering have to do with a round or flat belly design?

[joachimM]

A round-ish belly will shift the neutral place more towards the back, thus taking away some of the forces from the back.

I would think the neutral plane would shift toward the belly.

Anyhow as someone said, "Compression failure results in set, but bows with set still shoot. Tension failure makes for broken bows." It would be wiser to start with a rounded belly and flatten it if warranted, as we progress.

Indeed, the neutral plane of a crowned or trapped bow moves towards the widest surface. Crowned bows make for safer bellies but weaker backs. Since nearly all woods are stronger in tension than compression (at least above 6% MC), a crowned bow is less prone to set. The only wood I know of that isn't is Erica arborea, a mediterranean shrub.
Moisture control is key to keeping a crowned back in one piece.

Rather than having two crowned surfaces (back and belly), I'd decrown the back a bit and keep a flat belly.

[riverrat]

it shifts the neutral plain. as well as reduces weight in the lims. if you take it off, its off.